Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

Coordinated Control of Cascaded Current-Source Converter Based Offshore Wind Farm

Abstract: Offshore wind farms with cascaded PWM current-source converters (CSCs) at both generator- and grid-side can eliminate the need for bulky central offshore converter platform, which is usually used in a voltage-source converter (VSC) based counterpart. This novel system structure can simplify the system configuration and operation. However, the wind speed inconsistency at each turbine causes different dc-link current requirements for each CSC. This causes a considerable challenge for systems in which each CSC shares equal dc-link current. In order to overcome the problem, a coordinated control scheme for the dc-link current regulation, which considers wind speed difference of each turbine, is proposed. This control scheme enables the system to operate at minimum dc-link current, contributing to a lower operation losses. In the meantime, the independent control capability of each generator is guaranteed (e.g., maximum power tracking to make full utilization of available wind energy). Furthermore, the whole wind farm control strategy, which consists of wind farm supervisory control (WFSC), local wind turbine control and centralized grid control, is investigated and studied, where maximum power tracking and power limitation modes can be easily achieved. Both simulation and experimental verification of the proposed system with use of two permanent-magnet synchronous generators (PMSGs) are provided.

Quantitative ultrasound evaluation of tumor cell death response in locally advanced breast cancer patients receiving chemotherapy.

Abstract: Purpose: Quantitative ultrasound techniques have been recently shown to be capable of detecting cell death through studies conducted on in vitro and in vivo models. This study investigates for the first time the potential of early detection of tumor cell death in response to clinical cancer therapy administration in patients using quantitative ultrasound spectroscopic methods. Experimental Design: Patients ( n = 24) with locally advanced breast cancer received neoadjuvant chemotherapy treatments. Ultrasound data were collected before treatment onset and at 4 times during treatment (weeks 1, 4, and 8, and preoperatively). Quantitative ultrasound parameters were evaluated for clinically responsive and nonresponding patients. Results: Results indicated that quantitative ultrasound parameters showed significant changes for patients who responded to treatment, and no similar alteration was observed in treatment-refractory patients. Such differences between clinically and pathologically determined responding and nonresponding patients were statistically significant ( P Conclusion: This study reports for the first time that quantitative ultrasound spectroscopic methods can be applied clinically to evaluate cancer treatment responses noninvasively. The results form a basis for monitoring chemotherapy effects and facilitating the personalization of cancer treatment. Clin Cancer Res; 19(8); 2163–74. ©2013 AACR .

Effect of heat treatment on mechanical properties of Ti–6Al–4V ELI alloy

Abstract: Ti–6Al–4V alloy of extra low interstitial (ELI) grade has been used in the biomedical applications because of its high strength-to-weight ratio and excellent biocompatibility. However, its relatively poor wear resistance leading to excessive wear and implant loosening requires proper surface hardening. The body implants are also subjected to a variety of loads at varying strain rates. The objective of this study was to evaluate the hardening behavior, strain rate sensitivity and fracture mechanisms with or without hardened surface layer. It was observed that the hardened surface layer had only a small effect on the strength but reduced the ductility. The yield strength (YS) and ultimate tensile strength (UTS) were higher in the water quenching and aging condition while the ductility was lower, when compared to the as-received condition and air cooling and aging condition. As the strain rate increased both YS and UTS increased and ductility decreased. The strain hardening exponent decreased with increasing strain rate. The strain rate sensitivity evaluated via both the common approach and Lindholm approach decreased as the true strain increased. Fractal dimension of fracture surfaces was observed to be associated with the heat treatment condition, ductility, fracture surface characteristics and roughness. The fractal dimension increased with increasing roughness of fracture surfaces.