Computational Investigation of Wind Loads on Tilted Roof-Mounted Solar Array

A detailed computational investigation of the wind field around tilted solar modules mounted on a large building roof has been undertaken, utilizing the Reynolds-Averaged Navier-Stokesv (RANS) approach supplied with the SST k − ω turbulence model. The study investigated the flow field for various tilt angle of modules at normal wind directions relative to the wall. Then the shape factors and moment coefficients of modules were explored. The results show that the recirculation vortex generated by the building edge is disintegrated to smaller local vortices. With the increasing of the tilt angle, an increasing number of local vortices emerged at the leading rows, leading to a relatively large wind pressure and shape factor at the corner of the array. In most tilt angles at 0° and 180° wind direction the shape factors are negative. However, for the 40° and 55° tilt angles at 180° wind direction, the shape factors on the lower surfaces are positive, due to the dominating of approaching flow rather than the local vortices. The array is divided into six zones based on the distribution of shape factors. As the shape factors on upper and lower are similar, the shape factors in most zones for tilt angles from 5° to 55° are quite small. However, shape factors in the leading row for 30°, 40° and 55° are relatively large. This indicates that the shading effect of front rows can significantly reduce the shape factors of the rear rows. Compared to the values calculated by Chinese, American and Japanese standards, the shape factors by simulation are quite small. The moment induced by nonuniform wind pressure, which is often ignored in the literature and standards, is quite large at the leading zones, with a maximum of 0.28 for 55° tilt angle. Ignoring the wind induced moment on the leading zones may make the wind resistance design of the solar module support structure unsafe

Computational Investigation of Wind Loads on Tilted Roof-Mounted Solar Array

A detailed computational investigation of the wind field around tilted solar modules mounted on a large building roof has been undertaken, utilizing the Reynolds-Averaged Navier-Stokesv (RANS) approach supplied with the SST k − ω turbulence model. The study investigated the flow field for various tilt angle of modules at normal wind directions relative to the wall. Then the shape factors and moment coefficients of modules were explored. The results show that the recirculation vortex generated by the building edge is disintegrated to smaller local vortices. With the increasing of the tilt angle, an increasing number of local vortices emerged at the leading rows, leading to a relatively large wind pressure and shape factor at the corner of the array. In most tilt angles at 0° and 180° wind direction the shape factors are negative. However, for the 40° and 55° tilt angles at 180° wind direction, the shape factors on the lower surfaces are positive, due to the dominating of approaching flow rather than the local vortices. The array is divided into six zones based on the distribution of shape factors. As the shape factors on upper and lower are similar, the shape factors in most zones for tilt angles from 5° to 55° are quite small. However, shape factors in the leading row for 30°, 40° and 55° are relatively large. This indicates that the shading effect of front rows can significantly reduce the shape factors of the rear rows. Compared to the values calculated by Chinese, American and Japanese standards, the shape factors by simulation are quite small. The moment induced by nonuniform wind pressure, which is often ignored in the literature and standards, is quite large at the leading zones, with a maximum of 0.28 for 55° tilt angle. Ignoring the wind induced moment on the leading zones may make the wind resistance design of the solar module support structure unsafe

Proppant Transport Characteristics in Tortuous Fractures Induced by Supercritical CO2 Fracturing

Supercritical CO2 fracturing is an important development trend to reach the goal of ''dual carbon'' and avoid the problem that hydraulic fracturing is influenced by water resource. In order to clarify the transport characteristics of proppant in the fractures induced by supercritical CO2 fracturing, this paper reconstructs the fracture surface of rock samples after supercritical CO2 fracturing using the laser morphological scanning technology, and establishes a model of proppant carrying and transport of supercritical CO2 in tortuous fractures on the basis of CFD-DEM method. In addition, the transport and placement characteristics of proppant in tortuous fractures are analyzed by comparing with flat fractures, and the effects of proppant density, injection rate of proppant carrying liquid, proppant concentration and other key parameters on proppant transport and distribution in fractures are investigated. And the following research results are obtained. First, compared with those in flat fractures, the flow paths of the proppant carrying supercritical CO2 liquid in tortuous fractures are tortuous and diverse, and the proppant presents stronger fluctuations and jumps laterally and vertically during its transport. Second, the proppant placement in tortuous fractures morphologically presents a wavy or even clustered non-uniform distribution. Third, low-density proppant has a better pass-ability in tortuous fractures, and the high injection rate can reduce the influence of tortuous fracture structure on proppant blocking. Fourth, if the concentration of injected proppant in the tortuous fracture is too low, good fracturing support effect cannot be achieved, and the optimal value under the simulation conditions in this paper is around 3%. In conclusion, the simulation results are of important theoretical and engineering significance to understanding the mechanism of proppant blocking in the pumping process of proppant carrying liquid for supercritical CO2 fracturing and optimizing the field fracturing design

Finite Element Analysis for Biodegradable Dissolving Microneedle Materials on Skin Puncture and Mechanical Performance Evaluation

In this study, a micro-molding technology was used to prepare the microneedles (MNs), while a texture analyzer was used to measure its Young’s modulus, Poisson’s ratio and compression breaking force, to evaluate whether the MNs can penetrate the skin. The effects of different materials were characterized by their ability to withstand stresses using the Structural Mechanics Module of COMSOL Multiphysics. Carboxymethylcellulose (CMC) was chosen as the needle formulation material with varying quantities of polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and hyaluronic acid (HA) to adjust the viscosity, brittleness, hardness and solubility of the material. The results of both the experimental tests and the predictions indicated that the hardest tip material had a solids content of 15% (w/w ) with a 1:2 (w/w) CMC: HA ratio. Furthermore, it was shown that a solid content of 10% (w/w) with a 1:5 (w/w) CMC: PVA ratio is suitable for making patches. The correlation between the mechanical properties and the different materials was found using the simulation analysis as well as the force required for different dissolving microneedles (DMNs) to penetrate the skin, which significantly promoted the research progress of microneedle transdermal drug delivery

Ginkgolide B Inhibits Human Bladder Cancer Cell Migration and Invasion Through MicroRNA-223-3p

Background/Aims: Ginkgolide B (GB) is currently used as an anticancer drug for treatment of some malignant cancers. However, whether it may have therapeutic effects on bladder cancer remains unknown. Here, we studied the effects of GB on bladder cancer cells. Methods: Bladder cells were treated with different doses of GB, and the effects on ZEB1 and microRNA-223-3p (miR-223-3p) were analyzed by RT-qPCR and/or Western blot. Prediction of a regulatory relationship between miR-93 and 3'-UTR of Beclin-1 mRNA was performed by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. Results: We found that GB dose-dependently decreased ZEB1 protein, but not mRNA, in bladder cancer cells, resulting in suppression of cell invasion. Moreover, in bladder cancer cells, GB dose-dependently decreased the levels of miR-223-3p, which suppressed the protein translation of ZEB1 through binding to 3'-UTR of ZEB1 mRNA. Overexpression of miR-223-3p decreased ZEB1 protein, while depletion of miR-223-3p increased ZEB1 protein in bladder cancer cells. Conclusion: GB inhibits bladder cancer cell invasiveness through suppressing ZEB1 protein translation via upregulating miR-223-3p

Innovations in Shiplift Navigation Concepts

Shiplifts are one of the main types of navigation structures in canals and high dams in natural rivers.SCOPUS: cp.kinfo:eu-repo/semantics/publishe