FILM COOLING EFFECTIVENESS MEASUREMENT OF FAN-SHAPED HOLES MANUFACTURED USING EDM TECHNIQUE

In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (a), and lateral expansion angle (α) on film cooling effectiveness of holes made using EDM is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant to mainstream blowing ratio (M). The considered flat plate model incorporates engine sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the Pressure Sensitive Paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on α is prescribed. An accurate qualification of hole morphology is also recommended.

Optimization of Rib Shape and Inclination in a Square Duct with Response Surface Methodology

The paper conducts numerical investigation coupled with Reynolds-averaged Navier Stokes method on detailed flow field and heat transfer characteristics of ribbed channel with symmetric ribs mounted on two walls. The physical domain is modeled by reference to a practical turbine blade internal cooling channel. The effects of three selected geometric factors of ribs, i.e. rib inclination angle, dimensionless rib height and dimensionless rib pitch, on the flow and heat transfer are investigated by variable-controlled simulations with the Reynolds number ranges from 5,000 to 90,000. The parameter ranges are 30°≤a≤90°, 0.5≤e/w≤1.5 and 5≤P/w≤15 with the rib width w fixed at 1mm. It is newly found that the friction factor does not follow a monotonical trend with respect to the Reynolds number under certain rib configurations. In addition, three-level numerical calculations about three geometric factors as well as the Reynolds number are conducted with the response surface method (RSM). Quadratic regression model for the targeted response, TPF, is obtained. The optimal rib shape for the goal of maximizing the channel overall thermal performance turns out to be e/w=0.5, P/w=15, a=30° as Re is fixed at 30,000.

Geometry of anchoring miniscrew in the lateral palate that support a tissue bone borne maxillary expander affects neighboring root damage

Anchoring miniscrews used for a tissue bone borne maxillary expander (C-expander) can fail if they contact tooth roots or perforate the maxillary sinus. Cone beam computed tomography images were reviewed retrospectively to evaluate the geometric factors of miniscrew placement in the palate that contribute to root proximity (RP) and sinus perforation (SP), and to investigate the differences of miniscrew placement depth (PD) and placement angle (PA) among the groups in each variable from 340 anchoring miniscrews on 70 patients whose C-expanders showed sufficient stability after palatal expansion for orthodontic treatment. Two types of miniscrews were used: a self-tapping miniscrew with 1.8 mm-in-diameter, and a self-drilling miniscrew with 1.6 mm-in-diameter. While the self-tapping larger diameter miniscrew influenced root proximity significantly, the screw location and PD affected the rate of sinus perforation. PA was significantly different between the right and left sides of the palate. The results of this study confirmed that root proximity and sinus perforation of anchoring miniscrews in a tissue bone borne palatal expander occurred due to certain risk factors, even when the palates were expanded successfully. Knowledge of these factors can help the clinician place miniscrews with less risk of root proximity or sinus perforation.

Insights into the Pollutant Removal Performance of Stormwater Green Infrastructures: A Case Study of Detention Basins and Retention Ponds

The quality of water has deteriorated due to urbanization and the occurrence of urban stormwater runoff. To solve this problem, this study investigated the pollutant reduction effects from the geometric and hydrological factors of green infrastructures (GIs) to more accurately design GI models, and evaluated the factors that are required for such a design. Among several GIs, detention basins and retention ponds were evaluated. This study chose the inflow, outflow, total suspended solids (TSS), total phosphorus (TP), watershed area, GI area (bottom area in detention basins and permanent pool surface area in retention ponds), and GI volume (in both detention basins and retention ponds) for analysis and applied both ordinary least squares (OLS) regression and multiple linear regression (MLR). The geometric factors do not vary within each GI, but there may be a bias due to the number of stormwater events. To solve this problem, three methods that involved randomly extracting data with a certain range and excluding outliers were applied to the models. The accuracies of these OLS and MLR models were analyzed through the percentage bias (PBIAS), Nash-Sutcliffe efficiency (NSE), and RMSE-observations standard deviation ratio (RSR). The results of this study suggest that models which consider the influent concentration combined with the hydrological and GI geometric parameters have better correlations than models that consider only a single parameter.

COMPUTATIONAL MODEL OF INTERSECTIONS REPRESENTATION AS APPARATUS OF CONTENTS MULTI-SCALAR, RETROSPECTIVE AND RESILIENT FOR THE RESEARCH OF CONNOTATIONS, SIMULATIONS AND SUSTAINABILITY IN THE LANDSCAPE ASSETS

The research project’s objective, based on defining a “Computational Model of Intersections Simulation/Representation” as complex digital cultural infrastructure and computational knowledge, acquires the identity characteristics of the Computational Representation (phenomenological, geometry, visual, resilience, scalability analytical-interpretative knowledge) to promote for landscape and Cultural Heritage (CH): a) of systematize environmental information and protective by intersections of resilience’s categories in the “thematic systems of families and types” of the landscape; b) a model of Smart CH for Industry 4.0 – 2021. The same time favors: a) thematic and retrospective intersections between formal and interpretative layers for the return of information from a spatial and functional; b) innovation by introduction of professional figures of the contemporary digital. The methodology is articulated on following intersection models: Connotations, Composition, Development (combination of complex formal, structural and geometric factors); Morphogenesis (innovative concepts of transformations form), Sustainability. From the point of view the results and conclusion the study allowed to highlight: a) “network of multi-scalar discrete relationships” with sequences of digital models for the relative tessellation of the surfaces; b) “resilience measure” by “building a digital model of morphogenesis”; c) systematize environmental information and protective by intersections of resilience’s categories in the “thematic systems of families and types” of the landscape; d) “operative and phenomenological reading” of the changing complexity of environmental reality with connections between the behavioural and physical structures of the place.

Aortic Geometric Alteration Associated With Acute Type B Aortic Dissection: Angulation, Tortuosity, and Arch Type

Background: Acute type B aortic dissection is a highly serious aortic pathology. Aortic geometric parameters may be useful variables related to the occurrence of acute type B aortic dissection (aTBAD). The aim of the study is to delineate the alteration in aortic geometric parameters and analyze the specific geometric factors associated with aTBAD.Methods: The propensity score matching method was applied to control confounding factors. The aortic diameter, length, angulation, tortuosity, and type of aortic arch of the aTBAD and control group were retrospectively analyzed via three-dimensional computed tomography imaging created by the 3mensio software (version 10.0, Maastricht, The Netherlands). The geometric variables of true lumen and false lumen in the descending aorta were measured to estimate the severity of aortic dissection. Multivariable logistic regression models were used to investigate the significant and specific factors associated with aTBAD occurrence. The area under the receiver operating characteristic curve (AUC) was used to estimate the performance of the model.Results: After propensity score matching, 168 matched pairs of patients were selected. The ascending aorta and aortic arch diameters were dilated, and the ascending aorta and total aorta lengths were elongated in aTBAD group significantly (P < 0.001). The ascending aorta and aortic arch angulations in the aTBAD group were sharper than those of the controls (P = 0.01, P < 0.001, respectively). The aortic arch and total aorta tortuosities were significantly higher in the aTBAD group (P = 0.001, P < 0.001, respectively). There were more type III arch patients in the aTBAD group than the controls (67.9 vs. 22.6%). The true lumen angulation was sharper than that in the false lumen (P < 0.01). The true lumen tortuosity was significantly lower than that in the false lumen (P < 0.001). The multivariable models identified that aortic arch angulation, tortuosity, and type III arch were independent and specific geometric factors associated with aTBAD occurrence. The AUC of the multivariable models 1, 2, 3 were 0.945, 0.953, and 0.96, respectively.Conclusions: The sharper angulation and higher tortuosity of aortic arch and type III arch were the geometric factors associated with aTBAD in addition to the ascending aorta elongation and aortic arch dilation. The angulation and tortuosity of the true and false lumens may carry significant clinical implications for the treatment and prognosis of aTBAD.

Damped Oscillations – A smartphone approach

The study of the influence of geometric factors on an oscillating pendulum under various damping conditions is reported. Different cross-section areas perpendicular to the motion of the pendulum mass were studied. A smartphone was used as a pendulum and at the same time as a data recorder. Results show that the smartphone is an effective and reliable tool to be used when performing educational activities, and at the same time it presents students with a variety of ways for learning new content and physical concepts. It offers the opportunity to carry out experiments in the classroom, in the laboratory, or at home. In this way, the increment in the cross-section area slightly increases the damping coefficient, and rapidly decreases the oscillation amplitude as time passes. Additionally, the time necessary to decrease the amplitude by half is inversely proportional to the cross-section area of the pendulum. As expected, no significant variation in the period nor the angular frequency were found, due to the air-pendulum drag properties and to the slow pendulum speed.

Damped Oscillations – A smartphone approach

The study of the influence of geometric factors on an oscillating pendulum under various damping conditions is reported. Different cross-section areas perpendicular to the motion of the pendulum mass were studied. A smartphone was used as a pendulum and at the same time as a data recorder. Results show that the smartphone is an effective and reliable tool to be used when performing educational activities, and at the same time it presents students with a variety of ways for learning new content and physical concepts. It offers the opportunity to carry out experiments in the classroom, in the laboratory, or at home. In this way, the increment in the cross-section area slightly increases the damping coefficient, and rapidly decreases the oscillation amplitude as time passes. Additionally, the time necessary to decrease the amplitude by half is inversely proportional to the cross-section area of the pendulum. As expected, no significant variation in the period nor the angular frequency were found, due to the air-pendulum drag properties and to the slow pendulum speed.