Vibration Analysis of a Composite Wing Box with Arbitrarily Shaped Spars and Ribs

In this research, the free vibration analysis of composite wing boxes with curvilinear spars and ribs is performed. Modern manufacturing technologies, such as Electron Beam Freeform Fabrication and Friction Stir Welding, have allowed the manufacturing of arbitrarily shaped stiffeners. Curvilinear stiffeners provide flexibility in design as they can assume an infinite number of paths. Curvilinear spars and ribs can in some instances provide a better vibration and static response than their straight counterparts while reducing the overall mass of the structure. An equivalent continuum plate model of a wing box using energy formulations is proposed at the preliminary design stage to reduce the high and costly CPU time incurred from the optimization of finite element models. In the present plate model, the bottom and top skins of the wing box are treated as plates, and the internal structures are treated as beams. The deformations and strains of the model are developed according to the FSDT. The Chebyshev polynomials are the bases of the displacement and rotation functions in the Ritz method. To assess the accuracy and feasibility of the proposed model, several numerical cases of the free vibration and aeroelastic flutter of stiffened panels have been analyzed. The model of a wing box with straight spars and ribs and models with curvilinear spars and ribs made of graphite/epoxy were compared with ANSYS® models. Reasonable agreement has been achieved

Design, Analysis and Experimental Evaluation of 3D Printed Variable Stiffness Structures

The rapid progress of additive manufacturing (AM) introduces new opportunities but also new challenges for design and optimization to ensure manufacturability, testability and accurate representation/prediction of the models. The present dissertation builds a bridge between design, optimization, AM, testing and simulation of advanced optimized variable-stiffness structures. The first part offers an insight on the mechanical, viscoelastic and failure characteristics of AM continuous fiber composites. This understanding was used in the second part to investigate the feasibility of different topology and fiber-orientation optimization methods and the manufacturability of the resulting models. The study also assesses the effects of the manufacturing constraints on the stiffness. In the third part, a framework was used to optimize the topology and orientation of lattice structures subjected to stress constraints. This framework uses homogenized stiffness and strength to expedite the optimization, and Hill’s criterion to express the stress constraint. Those properties are implemented in the macrostructure topology optimization to improve the lattice structure stiffness. The optimized design is projected and post-treated to ensure manufacturability. The framework tested for two case studies producing designs with enhanced yield strength. The last part of this research challenges the capabilities of AM to fabricate, for the first time, an optimized flexible wing model with internal structures. The wing was tested in a low-speed wind tunnel to validate a robust computational model which enables the future study of the aeroelastic performance of different optimized wing models. This dissertation demonstrates that the conjoint use of topology and orientation optimization and AM results in advanced lighter structures with enhanced stiffness and/or strength

Emerging Strategies in Classroom Management: Impact on the 21st Century Skills Competency of Grade 10 Students

The study was an attempt to determine if there is a significant relationship between teachers’ use of different classroom management strategies and the 21st-century skills competency of Grade 10 students. This research used a random sampling technique to determine the specific number of student respondents to the study. A self-made survey questionnaire was developed in this study. The researcher sought the assistance of different research professionals, master teachers in English, and experts in the field to validate the research instrument. The following are the findings of the study: The extent of utilization of teachers on preventive, supportive, and corrective classroom management strategies are all interpreted as utilized. The levels of students’ learning and innovation skills, life and career skills, and information, media, and technology skills are interpreted as very good. There is a significant relationship between classroom management strategies and the skills competency of the students. And classroom management strategies are significant predictors of students’ 21st skills competency

Searching for Hyperspectral Optical Proxies to Aid Chesapeake Bay Resource Managers in the Detection of Poor Water Quality

Shellfish aquaculture is a growing industry in the Chesapeake Bay. As population grows near the coast, extreme weather events cause a greater volume of pollutant runoff from impervious surfaces and agricultural lands. Resource managers who monitor shellfish beds need reliable information on a variety of water quality indicators at higher frequency than is possible through field monitoring programs and at a higher level of detail than current satellite products can provide. Although many factors causing degraded water quality that can impact human health are not currently discernable by traditional multispectral techniques, hyperspectral imagery offers a new opportunity to detect phytoplankton communities associated with harmful algal blooms and biotoxin production. Together with resource managers in their routine monitoring of sites around the bay from small boats, we have been exploring remotely sensed optical proxies for the detection of harmful algal blooms and sewage. Early warning by remote sensing could guide sampling and improve the efficiency of shellfish bed closures, ultimately improving health outcomes for humans and animals. An extensive network of routine sampling by Chesapeake Bay Program managers makes this is an ideal location to develop and test future satellite data products to support management decisions. Next generation hyperspectral measurements from the future Plankton Aerosol Cloud ocean Ecosystem (PACE) mission at nearly daily frequency, combined with the potential of higher spatial resolution from the Surface Biology and Geology (SBG) observing system recommended in the recent Decadal Survey, along with high frequency observations from the newly selected Geostationary Littoral Imaging and Monitoring Radiometer (GLIMR) Earth Venture Instrument make this a critical time for defining the needs of the aquaculture and resource management community to save lives, time, and money

Exponential stability of the solutions of the Boltzmann equation for the Benard problem

International audienceWe complete the result in the former paper 'Stability for Rayleigh-benard convective solutions of the Boltzmann equation' by showing the exponential decay of the perturbation of the laminar solution below the critical Rayleigh number and of the convective solutions above the critical Rayleigh number, in the kinetic framework

Investigating Macroexpressions and Microexpressions in Computer Graphics Animated Faces

Due to varied personal, social, or even cultural situations, people sometimes conceal or mask their true emotions. These suppressed emotions can be expressed in a very subtle way by brief movements called microexpressions. We investigate human subjects’ perception of hidden emotions in virtual faces, inspired by recent psychological experiments. We created animations with virtual faces showing some facial expressions and inserted brief secondary expressions in some sequences, in order to try to convey a subtle second emotion in the character. Our evaluation methodology consists of two sets of experiments, with three different sets of questions. The first experiment verifies that the accuracy and concordance of the participant’s responses with synthetic faces matches the empirical results done with photos of real people in the paper by X.-b. Shen, Q. Wu, and X.-l. Fu, 2012, “Effects of the duration of expressions on the recognition of microexpressions,” Journal of Zhejiang University Science B, 13(3), 221–230. The second experiment verifies whether participants could perceive and identify primary and secondary emotions in virtual faces. The third experiment tries to evaluate the participant’s perception of realism, deceit, and valence of the emotions. Our results show that most of the participants recognized the foreground (macro) emotion and most of the time they perceived the presence of the second (micro) emotion in the animations, although they did not identify it correctly in some samples. This experiment exposes the benefits of conveying microexpressions in computer graphics characters, as they may visually enhance a character’s emotional depth through subliminal microexpression cues, and consequently increase the perceived social complexity and believabilit

Physical Growth, Biological Age, And Nutritional Transitions Of Adolescents Living At Moderate Altitudes In Peru

Background: Peru is experiencing a stage of nutritional transition where the principal characteristics are typical of countries undergoing development. Objectives: The objectives of this study were the following: (a) compare physical growth patterns with an international standard; (b) determine biological age; and (c) analyze the double nutritional burden of adolescents living at a moderate altitude in Peru. Design: Weight, standing height, and sitting height were measured in 551 adolescents of both sexes (12.0 to 17.9 years old) from an urban area of Arequipa, Peru (2328 m). Physical growth was compared with the international standard of the CDC-2000. Biological age was determined by using a non-invasive transversal technique based on years from age at peak height velocity (APHV). Nutritional state was determined by means of weight for age and height for age. Z scores were calculated using international standards from the CDC-2000. Results: Body weight for both sexes was similar to the CDC-2000 international standards. At all ages, the girls' height (p < 0.05) was below the standards. However, the boys' height (p < 0.05) was less at ages, 15, 16, and 17. Biological age showed up in girls at age 12.7 years and for boys at 15.2 years. Stunted growth (8.7% boys and 18.0% girls) and over weight (11.3% boys and 8.8% girls) occurred in both groups. A relationship existed in both sexes between the categories of weight for the age and stunted growth by sex. Conclusions: Adolescents living at a moderate altitude exhibited stunted linear growth and biological maturation. Furthermore, adolescents of both sexes showed the presence of the double nutritional burden (stunted growth and excessive weight).1210120821209

Mitochondrial F0F1-ATP synthase is a molecular target of 3-iodothyronamine, an endogenous metabolite of thyroid hormone

Background & Purpose:\u2002 T1AM is a thyronamine derivative of thyroid hormone acting as a signalling molecule via non-genomic effectors and can reach intracellular targets. In light of the importance of F(0) F(1) -ATPsynthase as a target in drug development, T1AM interaction with the enzyme is demonstrated by its effects on the activity and a model of binding locations is depicted. Experimental Approach:\u2002 Kinetic analyses were performed on F(0) F(1) -ATPsynthase in sub-mitochondrial particles and soluble F(1) -ATPase. Activity assays and immunodetection of the inhibitor protein IF(1) were used and combined with molecular docking analyses. In situ respirometric analysis of T1AM effect was investigated on H9c2 cardiomyocytes. Key Results:\u2002 T1AM is a non-competitive inhibitor of F(0) F(1) -ATPsynthase whose binding is mutually exclusive with that of the inhibitors IF(1) and aurovertin B. Distinct T1AM binding sites are consistent with results from both kinetic and docking analyses: at low nanomolar concentrations, T1AM binds to a high affinity-region likely located within the IF(1) binding site, causing IF(1) release; at higher concentrations, T1AM binds to a low affinity-region likely located within the aurovertin binding cavity and inhibits enzyme activity. Low nanomolar concentrations of T1AM elicit in cardiomyocytes an increase in ADP-stimulated mitochondrial respiration indicative for an activation of F(0) F(1) -ATPsynthase consistent with displacement of endogenous IF(1, ) thereby reinforcing the in vitro results. Conclusions & Implications:\u2002 The T1AM effects upon F(0) F(1) -ATPsynthase are twofold: IF(1) displacement and enzyme inhibition. By targeting F(0) F(1) -ATPsynthase within mitochondria T1AM might affect cell bioenergetics with a positive effect on mitochondrial energy production at low endogenous concentration. T1AM putative binding locations overlapping with IF(1) and aurovertin binding sites are depicted