The twin vertical-axis wind turbine (VAWT) system is a high-performance design in which two turbines are placed side by side with a variable gap distance. In this paper, the large eddy simulation and ...the sliding mesh technique are employed to numerically study the aerodynamic performance of the dual-rotor configuration. First, the reliability of this CFD model is validated, including computational stability analysis, time-step dependency study, and grid convergence verification. The turbine power coefficients under different tip speed ratios are calculated and results exhibit a satisfactory agreement with the available experimental data. Then, the wind energy utilization of side-by-side placed twin VAWTs under different gap ratios and various azimuth angle shifts are investigated, respectively. The results reveal that compared with two isolated turbines, the power coefficient of a twin-turbine system has a significant enhancement. Moreover, the paper analyzes the mechanism for obtaining gains. In regard to the study of azimuth angle shifts between two adjacent turbines, this paper demonstrates that the blade azimuth angles of twin VAWTs do not need to be synchronized. The azimuth angle shift has little effect on the aerodynamic performance of the twin-turbine system.
•The power coefficient can be increased by 18% by applying the twin-turbine system.•A smaller gap distance between two VAWTs can induce a larger power output.•The phase angle of two turbines has little effect on the aerodynamic performance.
Three-dimensional (3D) printing utilizing controlled polymerization systems is emerging as a powerful approach to fabricate “living” objects, which can be further modified with various ...functionalities. Here, we report photoinduced free radical-promoted cationic reversible addition–fragmentation chain transfer (RAFT) polymerization under broad wavelengths from ultraviolet (UV) to near-infrared (NIR) light. A commercially available iron catalyst, cyclopentadienyl iron dicarbonyl dimer (Fe2(Cp)2(CO)4), was used as the photocatalyst, and several diphenyliodonium salts were examined as oxidants. Various poly(vinyl ether)s with controlled molecular weights and a narrow dispersity (1.06–1.32) were prepared through this method. Relatively high chain-end fidelity can be observed and has been demonstrated by successful chain-extension experiments. In addition, benefiting from the penetrating ability of NIR light, 3D objects with different thicknesses were achieved by employing stereolithography-based 3D printing techniques. Furthermore, the postfunctionalization of these 3D printed objects with fluorescent monomers provides a facile method to build 3D objects with complex functionality and potential applications in anticounterfeiting materials.
Traditional injection and extraction devices often appear painful and cumbersome for patients. In recent years, polymer microneedles (MNs) have become a novel tool in the field of clinical medicine ...and health. However, the cost of building MNs into any shapes still remains a challenge. In this paper, we proposed hydrogel microneedles fabricated by high-precision digital light processing (H-P DLP) 3D printing system. Benefits from the sharp protuberance and micro-porous of the hydrogel microneedle, the microneedle performed multifunctional tasks such as drug delivery and detection with minimally invasion. Critical parameters for the fabrication process were analyzed, and the mechanical properties of MNs were measured to find a balance between precision and stiffness. Results shows that the stiffness and precision were significantly influenced by exposure time of each layer, and optimized printing parameters provided a balance between precision and stiffness. Bio-compatible MNs based on our H-P DLP system was able to execute drug injection and drug detection in our experiments. This work provided a low-cost and fast method to build MNs with 3D building, qualified the mechanical performance, drug injection, drug detection ability of MNs, and may be helpful for the potential clinical application.
Road collapse has always been an important safety hazard for urban traffic, causing a serious threat to the safety of passing vehicles and citizens. However, the complex urban surface environment ...with obstacles such as huge buildings, hardened roads, and river network limits the application of ERT in cities. Here we present an innovative cross-street electrical resistivity imaging method. This method abandons the mandatory electrode grid layout that conventional 3D ERT required. Only two survey lines are required to be laid along sides of the street parallelly, gathering the apparent resistivity data set by the combination of current supply and potential electrodes across the street and obtaining the 3D resistivity imaging under street. It is well suitable for detecting and monitoring of hardened road and enhances the feasibility and the adaptability of ERT in urban. A series of numerical models and comparisons among this method and conventional ERT had been done. The modeling results show that this cross-street method reaches the resolution of the conventional 5-lines ERT, and its resolution to objects cross road are better than the conventional ERT. This method can both satisfy the exploration needs with difficult surface conditions such as roads, and greatly reduce the exploration workload. It shows well application prospects, such as hidden geological problem monitoring while combining with time-lapse ERT instruments.
•An innovative cross-street electrical resistivity imaging survey design.•3D imaging can be achieved using only two survey lines.•This method can adapt to the complex surface environment.
Long noncoding RNAs (lncRNAs) play critical roles in the development of myocardial hypertrophy and may stimulate endogenous myocardial regeneration to prevent heart failure after myocardial ...infarction (MI). However, whether lncRNAs are involved in regulating myocardial regeneration after MI remains unclear. The present study aimed to identify human-derived lncRNAs that are involved in endogenous cardiomyocyte (CM) regeneration. By analyzing publicly available RNA-seq data of human fetal and normal adult cardiac tissues, we identified a novel human-derived adult upregulated lncRNA designated cardiomyocyte regeneration-related lncRNA (CRRL). Bioinformatics analysis indicated that CRRL is involved in the negative regulation of CM proliferation. First, we observed that the loss of CRRL attenuates post-MI remodeling and preserves cardiac function in adult rats. Through loss-of-function approaches, we found that CRRL knockdown promotes neonatal rat CM proliferation both in vivo and in vitro. Furthermore, we demonstrated that CRRL acts as a competing endogenous RNA (ceRNA) by directly binding to miR-199a-3p and thereby increasing the expression of Hopx, a target gene of miR-199a-3p and a critical negative regulatory factor of CM proliferation. Thus, CRRL suppresses cardiomyocyte regeneration by directly binding to miR-199a-3p, indicating that loss of CRRL facilitates myocardial regeneration and may be a new potential therapeutic strategy for heart failure.
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•CRRL was identified as a novel adult up-regulated lncRNA.•Loss of CRRL promotes CM proliferation both in vivo and in vitro.•Loss of CRRL improves cardiac repairs in neonatal and adult rats post-MI.•CRRL regulates CM regeneration via CRRL/miR-199a-3p/Hopx regulatory loop.
Accurate estimation of the state of charge (SOC) is an important criterion to prevent the batteries from being over-charged or over-discharged, and this assures an electric vehicle’s safety and ...reliability. To investigate the effect of different operating conditions on the SOC estimation results, a dual-polarization model (DPM) and a fractional-order model (FOM) are established in this study, taking into account the prediction accuracy and structural complexity of a battery model. Based on these two battery equivalent circuit models (ECMs), a hybrid Kalman filter (HKF) algorithm is adopted to estimate the SOC of the battery; the algorithm comprehensively utilizes the ampere-hour (Ah) integration method, the Kalman filter (KF) algorithm, and the extended Kalman filter (EKF) algorithm. The SOC estimation results of the DPM and FOM, under the dynamic stress test (DST), federal urban driving schedule (FUDS), and hybrid pulse power characteristic (HPPC) cycle conditions, are compared and analyzed through six sets of experiments. Simulation results show that the SOC estimation accuracy of both the models is high and that the errors are within the range of ±0.06. Under any operating conditions, the SOC estimation error, based on the FOM, is always lower than the SOC estimation error of the DPM, but the adaptability of the FOM is not as high as that of the DPM.
The hydrodynamic performance of the floating foundation for offshore wind turbines is essential to its stability and energy harvesting. A semi-submersible platform with an integral heave plate is ...proposed in order to reduce the vertical motion responses. In this study, we compare the heave, pitch, and roll free decay motions of the new platform with a WindFloat-type platform based on Reynolds-Averaged Navier-Stokes simulations. The differences of the linear and quadratic damping properties between these platforms are revealed. Then, a FAST (Fatigue, Aerodynamics, Structures, and Turbulence) model with the consideration of fluid viscosity effects is set up to investigate the performance of the new platform under storm and operational conditions. The time-domain responses, motion spectra, and the mooring-tension statistics of these two platforms are evaluated. It is found that the integral heave plate can increase the viscous hydrodynamic damping, significantly decrease the heave and pitch motion responses, and increase the safety of the mooring cables, especially for the storm condition.
A near-infrared (NIR) light induced controlled cationic polymerization is presented here. The halide abstraction reaction between the cyclopentadienyl iron dicarbonyl dimer (Fe2(Cp)2(CO)4) and an ...organic halide is utilized to generate initial radicals or cations under mild conditions, which can be further combined with both radical and cationic reversible addition–fragmentation chain transfer (RAFT) polymerization. Well-defined poly(vinyl ether)s and polyacrylates are prepared successfully under NIR light by this method. The excellent penetration ability of NIR light through thick barriers has been verified by polymerization in the presence of an A4 paper. In addition, iron-based radical polymerization has been used for three-dimensional (3D) printing to fabricate materials with different thicknesses.
A procedure for 3D printing of silicone elastomers with a direct ink writing (DIW) process has demonstrated great potential in areas as diverse as flexible electronics, medical devices, and soft ...robotics. In this report, we propose a comprehensive guide for printing highly stretchable silicones in response to material, equipment and process dilemmas. Specifically, we first tested the material properties of Dow Corning 737, then modeled and simulated two commonly used needles to select a suitable needle, followed by parameter optimization experiments using the built DIW printer to find out the appropriate printing speed and layer height with a defined air pressure and needle diameter. Finally, the optimal combination of parameters was obtained. For further demonstration, artificial muscles and structurally complex soft grippers were also printed directly to verify the feasibility of high-precision 3D printing of soft actuators with soft materials. We believe that this work could provide a guide for further work using the DIW process to print soft matter in a wide range of application scenarios.
The lift force of a T-foil, which varies with ship motion, can counteract the wave exciting force during wave encounters. The phase difference between the periodic lift force and the wave exciting ...force significantly impacts the T-foil’s effectiveness. This study investigates the phase difference between lift force and motion to optimize the control equation for the T-foil’s angle, thereby reducing negative feedback. The T-foil’s hydrodynamic performance is first calculated using computational fluid dynamics. Time-domain calculations of the phase lag between lift force and motion under open-loop control in still water are then used to determine the dimensionless phase lag of the T-foil’s angle at various frequencies, facilitating further optimization of the control method. Finally, calculations of trimaran heave and pitch in regular waves are conducted. The results demonstrate that, under phase lag control, the T-foil’s lift force phase precedes ship motion by approximately 0.2 s, reducing hysteresis in the anti-vertical motion effect. Comparisons of vertical hull motions between different control methods reveal a 20% reduction in vertical motion with phase lag control compared to pitch control. This study concludes that phase lag is a crucial factor in T-foil control optimization.
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