André Bégin-Drolet

Wind turbines are exposed to variable loads due to parameters such as wind speed, turbulence intensity, rotor angular velocity, nacelle yaw, and power generation. As variation in loads is the fundamental phenomenon leading to fatigue, understanding fatigue damage enables one to estimate the turbine remaining life and make informed decisions regarding its end of life (life extension, repowering, decommissioning, etc.). To optimize asset performance, it is important to manage aging wind turbines effectively. The aim of this paper is to estimate the remaining useful life (RUL) of a wind turbine tower using 10-min average Supervisory Control and Data Acquisition (SCADA) data. The approach used is to develop models that use SCADA data to estimate the bending moments in the tower. Then, the bending stress is computed, and a Rainflow counting algorithm is used to detect the stress cycles. The Goodman correction is applied to the stress cycles, and then Miner’s summation rule is applied against an S-N curve to calculate the damage in the tower. The study compared the RUL calculated using four bending-moment models with the RUL calculated from bending moments measured with strain gauges over a one-year period. The comparison showed that the RUL calculated with a bending-moment model can estimate the RUL with a 4% difference compared with the measured bending moments. A fatigue assessment of the 16-year-old tower using 11 years of data is also presented in this paper. The RUL assessment method presented in this paper is a simple method that could be used to do a pre-assessment on a wind farm to target the most critical asset before performing a more complete and costly method.

As de-icing and anti-icing blade heating systems for wind turbines continue to mature, operators have developed a clearer understanding of both their benefits and their limitations. This growing operational experience has increased the need for warranty frameworks that can verify whether such systems perform as intended under real icing conditions. This study builds upon existing approaches to blade heating system warranties and, based on case studies, proposes practical methods to improve them. The principal challenge lies in separating meteorological risk, namely the frequency and severity of icing events, from technological risk, namely the availability and effectiveness of the blade heating system. This paper provides an extensive review of existing approaches to blade heating system warranties and proposes a practical self-comparison methodology for evaluating turbine-level performance using measured operational data. The method defines the applicable warranty period from external icing measurements, excludes periods of active meteorological icing to reduce the influence of site-specific exposure, and evaluates the remaining production shortfall using the Warranted Icing Compensable Energy, WICE. The methodology is applied to five case studies from four wind farms, four turbine manufacturers, and four blade heating technologies. The proposed framework provides a transparent and operationally applicable bridge between existing warranty guidelines and the detailed implementation rules required for commercially meaningful performance assessment of wind turbine blade heating systems.

Current pediatric heart valve protheses lack growth potential, leading to repeated surgeries and long-term complications. Tissue-engineered heart valves (TEHVs), composed of living tissue, offer the ability to remodel and may accommodate somatic growth. This study introduces a sutureless fabrication strategy for TEHV designed to eliminate suture-related weak points and preserve valve geometry during in vitro maturation through a novel evolutive support system. This system was used to form and maintain the geometry of a fibrin-based valve scaffold embedded with human adipose-derived stromal cells during in vitro culture by mechanically constraining tissue contraction in all directions except thickness. Dimensional analysis confirmed geometry preservation throughout 28 days of perfusion bioreactor culture. At the end of the culture period, the matured valve was released from the evolution support system, after which the valve contracted to stable dimensions of approximately 16 mm in diameter, 23 mm in height, and 400 µm in thickness, corresponding to reductions of 26%, 43%, and 84% in diameter, height, and thickness, respectively, relative to the initial molded geometry. These ratios provide critical design guidance for pediatric target dimensions. Cell viability exceeded 90% upon molding, and cell density increased nearly 100-fold during culture. Histology revealed progressive collagen deposition, which correlated with improved mechanical properties. Stiffness increased nearly 9-fold and puncture strength 2.5-fold from fabrication to day 28. This reproducible sutureless strategy enables geometry retention of TEHV by guiding tissue contraction during in vitro culture, paving the way for pulsatile conditioning and further maturation to achieve mechanical properties approaching those of native valves and ensure long-term functionality.

As de-icing and anti-icing blade heating systems for wind turbines continue to mature, operators have developed a clearer understanding of both their benefits and their limitations. This growing operational experience has increased the need for warranty frameworks that can verify whether such systems perform as intended under real icing conditions. This paper reviews existing approaches to blade heating system warranties and, based on case studies, proposes practical methods to improve them. The principal challenge lies in separating meteorological risk, namely the frequency and severity of icing events, from technological risk, namely the availability and effectiveness of the blade heating system. This paper reviews existing approaches to blade heating system warranties and proposes a practical self-comparison methodology for evaluating turbine-level performance using measured operational data. The method defines the applicable warranty period from external icing measurements, excludes periods of active meteorological icing to reduce the influence of site-specific exposure, and evaluates the remaining production shortfall using the Warranted Icing Compensable Energy, WICE. The methodology is applied to five case studies from four wind farms, four turbine manufacturers, and four blade heating technologies. The proposed framework provides a transparent and operationally applicable bridge between existing warranty guidelines and the detailed implementation rules required for commercially meaningful performance assessment of wind turbine blade heating systems.

The fabrication of anatomically accurate, cellularized heart valve substitutes remains a significant challenge in tissue engineering, particularly for pediatric and patient-specific applications. While three-dimensional (3D) bioprinting enables the creation of complex geometries, it often compromises cell viability and lacks the precision required for small-scale constructs. In this study, we present a high-fidelity, reproducible molding technique using 3D-printed sugar glass molds to engineer custom, alginate-based hydrogel cellularized heart valves. Human adipose-derived stromal cells (ASCs) were used as the cell source due to their accessibility and regenerative potential. This approach overcomes the limitations of conventional molding and bioprinting by enabling the reproduction of intricate anatomical features, including the sinuses of Valsalva, which are critical for physiological hemodynamics. The molding method maintains high cell viability (>90%) at the time of fabrication and the process supports both scalability and automation. Sugar glass molds for valve sizes from 16 to 26 mm inner diameter were printed with 90% of the mold surface within a ±0.3 mm deviation of the reference computer-aided design model. Cellularized valves cultured in a custom perfusion bioreactor retained structural integrity and cell viability over a 14 d period. This biofabrication strategy offers a promising platform for engineering patient-specific heart valves and also lays the groundwork for in vitro disease modeling, including valve mineralization, using living cells such as ASCs.

A critical function of tertiary packaging is to ensure cargo stability and security during transportation, preventing load shifts that may cause accidents or damage. This paper addresses the complexities of securing loads, particularly focusing on the coefficient of friction between the load and the transport vehicle's surface, which plays a crucial role in load stability and packaging system design. Anti‐slip mats, widely used in securing cargo, rely on a well‐defined friction coefficient. However, this coefficient varies with transport conditions and is rarely characterized under dynamic loading scenarios. The primary objective of this study is to introduce an innovative experimental method to study the friction coefficient of anti‐slip mats under conditions that replicate real transportation dynamics. To establish a foundation, we first analysed typical accelerations encountered in road transportation. Using a custom GPS‐accelerometer sensor embedded, we captured in situ acceleration data. These measurements offer insights into the frequency spectrum and amplitude of transport‐induced accelerations, vital for replicating such conditions in laboratory settings. Subsequently, we present the design of a testing machine that simulates the variation of normal load under a cargo caused by the transport vehicle dynamics and vibration. This compact system uses two symmetrical motors that oscillate masses at desired positions to produce a varying normal force. By measuring both normal load and traction force required to move the machine, it enables the calculation of friction coefficient variations as the applied load changes dynamically. The results contribute to establishing a more accurate characterization of anti‐slip materials behaviour under realistic dynamic transport conditions.

Road agency initiatives to reduce traffic-related greenhouse gas emissions are limited by the inability of current experimental methods to assess pavement impacts on vehicle energy consumption. This study addresses this by examining the rolling resistance of a semi-trailer suspension under highway conditions using a precise measurement system with embedded transducers. Data were collected over 174 km of highway, covering various pavement types under mild summer conditions. The analysis revealed notable differences in rolling resistance due to pavement characteristics, with more pronounced variations observed within pavement types than between them. For instance, geographically consecutive jointed rigid pavements showed a 34% variation in rolling resistance, likely correlated with harmonic excitations generated by slab presence, while flexible pavements exhibited up to a 21% variation under similar tire operating conditions. Composite pavements generally performed the worst, possibly due to interactions between bituminous materials and older cement-based foundations. The study also highlighted the critical role of tire operating conditions, showing a decrease of 0.09 kg/tonne in rolling resistance for every 1 °C increase in temperature. This research shows that precisely measuring the rolling resistance (±0.1 kg/tonne) in situ for heavy vehicles is feasible and underscores the need for additional data in diverse weather scenarios to better align laboratory results with on-road realities.

Several emerging strategies to engineer artificial organs employ 3D printing to create vascular templates to provide nutrients and oxygen to immobilized cells. Significant challenges emerge when considering clinical implementation such as immune rejection of allogeneic cell sources, as well as achieving adequate perfusion and integration with endogenous vasculature. We propose a method by which cell-laden hydrogels are molded around ready-made polymeric vascular templates created via 3D printing to create human-scale artificial organs with internal vasculature. We applied this technique to create bioartificial pancreas systems with up to 9 internal flow channels via sacrificial carbohydrate glass 3D printing, porogen-loaded polycarbonate polyurethane dip-coating, followed by casting cell-laden hydrogels around the vascular templates. We optimized porogen size and concentration to maximise the porosity of our scaffolds without compromising mechanical properties, resulting in suture retention strength and compliance respectively matching commercial vascular grafts and native vessels. Bioreactor perfusion studies showed survival and maturation of stem cell derived pancreatic islets without significant differences to traditional suspension culture protocols. Insulin response dynamics were rapid in response to a glucose challenge at the perfusion inlet. Transplantation of the devices as iliac arteriovenous shunts in nondiabetic pigs confirmed safety and patency. These results show promise for the development of an implantable vascularized pancreas for the treatment of type 1 diabetes and demonstrate how bioartificial organs with engineered vascular geometries can be designed for translational applications.

Background: Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a prevalent condition affecting a substantial portion of the global population, with its prevalence increasing over the past 2 decades. OSAHS is characterized by recurrent upper airway (UA) closure during sleep, leading to significant impacts on quality of life and heightened cardiovascular and metabolic morbidity. Despite continuous positive airway pressure (CPAP) being the gold standard treatment, patient adherence remains suboptimal due to various factors, such as discomfort, side effects, and treatment unacceptability. Objective: Considering the challenges associated with CPAP adherence, an alternative approach targeting the UA muscles through myofunctional therapy was explored. This noninvasive intervention involves exercises of the lips, tongue, or both to improve oropharyngeal functions and mitigate the severity of OSAHS. With the goal of developing a portable device for home-based myofunctional therapy with continuous monitoring of exercise performance and adherence, the primary outcome of this study was the degree of completion and adherence to a 4-week training session. Methods: This proof-of-concept study focused on a portable device that was designed to facilitate tongue and lip myofunctional therapy and enable precise monitoring of exercise performance and adherence. A clinical study was conducted to assess the effectiveness of this program in improving sleep-disordered breathing. Participants were instructed to perform tongue protrusion, lip pressure, and controlled breathing as part of various tasks 6 times a week for 4 weeks, with each session lasting approximately 35 minutes. Results: Ten participants were enrolled in the study (n=8 male; mean age 48, SD 22 years; mean BMI 29.3, SD 3.5 kg/m2; mean apnea-hypopnea index [AHI] 20.7, SD 17.8/hour). Among the 8 participants who completed the 4-week program, the overall compliance rate was 91% (175/192 sessions). For the tongue exercise, the success rate increased from 66% (211/320 exercises; SD 18%) on the first day to 85% (272/320 exercises; SD 17%) on the last day (P=.05). AHI did not change significantly after completion of training but a noteworthy correlation between successful lip exercise improvement and AHI reduction in the supine position was observed (Rs=–0.76; P=.03). These findings demonstrate the potential of the device for accurately monitoring participants’ performance in lip and tongue pressure exercises during myofunctional therapy. The diversity of the training program (it mixed exercises mixed training games), its ability to provide direct feedback for each exercise to the participants, and the easy measurement of treatment adherence are major strengths of our training program. Conclusions: The study’s portable device for home-based myofunctional therapy shows promise as a noninvasive alternative for reducing the severity of OSAHS, with a notable correlation between successful lip exercise improvement and AHI reduction, warranting further development and investigation.