This study applies dynamic mode decomposition to motion-capture-based kinematics of straight flight in the great roundleaf bat (Hipposideros armiger) to identify dominant frequency components and evaluate their aerodynamic effects using prescribed-kinematics computational fluid dynamics. Three dominant mode pairs capture the primary deformation content: a zero-frequency static mode representing mean posture, a fundamental flapping mode at 9.2 Hz, and a superharmonic twisting mode at 18.6 Hz. Spatial localization shows the flapping mode represents the global stroke motion, with amplitude increasing toward the wingtip, whereas twisting is concentrated on the outboard wing, strongest near the distal trailing edge. Two temporal descriptions are compared: eigenvalue-based predictive dynamics with nearly constant-amplitude sinusoidal evolution, and data-projected dynamics exhibiting stroke-phase-dependent amplitude modulation. Aerodynamic results show that reconstructions retaining the static and flapping modes reproduce the dominant downstroke lift trend but underpredict thrust, particularly near stroke transitions. Incorporating the twisting mode substantially improves thrust recovery and increases lift recovery by preserving distal wing reorientation and associated pressure-difference signatures. Predictive dynamics provide actuator-ready commands but can introduce phase offsets relative to the measured, phase-modulated kinematics. Overall, bat straight flight kinematics support a compact frequency basis, but realistic force production requires stroke-phase-dependent modulation rather than purely harmonic evolution.

Metallic probe carriers are commonly used in magnetic flux leakage (MFL) inspection to support sensing elements and maintain lift-off, but a conductive carrier located near the sensor can act as an active electromagnetic boundary. This study investigates the carrier-induced waveform reconstruction caused by such a conductive near-field boundary. A theoretical model is developed to describe the induced current, secondary magnetic field, and relaxation-related downstream memory generated when the carrier moves through a non-uniform leakage field. Transient finite-element simulations are used to examine the effects of carrier material, scanning speed, and concave carrier geometry. Compared with the air reference, aluminum and copper carriers produce stage-dependent waveform reconstruction, including valley modification, peak modulation, feature-position shift, and trailing-side extension. The quantitative waveform-deviation indicators increase with increasing speed and are further regulated by carrier geometry. Experimental results based on repeated magnetic response events confirm amplitude suppression, non-zero residual after amplitude matching, response broadening, and enhanced trailing asymmetry. These results demonstrate that the metallic probe carrier is not an electromagnetically transparent holder but an active near-field conductive boundary that should be considered in probe-carrier design and MFL signal interpretation.

Proper handling of data below the lower limit of quantification (BLQ) is crucial for accurate pharmacokinetic parameter estimation. The M3 method proposed by Beal uses a likelihood-based approach that is precise but has been reported to suffer from numerical issues in converging. Common alternatives include ignoring the BLQs (M1), imputing half of the lower limit of quantification and ignoring trailing BLQs (M6) or imputing zero (M7). The imputation methods fail to account for the additional uncertainty affecting imputed observations. We used NONMEM with FOCE-I/Laplace to compare the stability, bias, and precision of methods M1, M3, M6, M7, and modified versions M6+ and M7+ that inflate the additive residual error for BLQs. Real and simulated datasets with a two-compartment model were used to assess stability through parallel retries with perturbed initial estimates. The resulting differences in objective function values (OFV) were compared. Bias and precision were evaluated on simulated data using stochastic simulations and estimations. M3 yielded different OFV across retries (±14.7), though the parameter estimates were similar. All other methods, except M7 (±130), were stable. M3 demonstrated the best bias and precision (average rRMSE 18.7%), but M6+ and M7+ performed comparably (26.0% and 23.3%, respectively). The unstable OFV produced by M3 represents a challenge when used to guide model development. Imputation methods showed superior stability, and including inflated additive error improved bias and precision to levels comparable with M3. For these reasons, M7+ (of simpler implementation than M6+) is an attractive alternative to M3, especially during model development.

This paper presents a three-dimensional fluid-structure-coupled simulation of a flexible caudal fin with different trailing-edge shapes. The influences of caudal-fin shape on hydrodynamic performance are investigated by comparing the results of a simplified model of a square caudal fin with forked and deeply forked caudal fins under a wider range of non-dimensional flapping frequency, 0.6 < f* < 1.5, where f* is the ratio of flapping frequency to the natural frequency of each caudal fin, i.e., f* = f/fn. The leading edge of each caudal fin is forced to oscillate vertically in a water tank with zero free-stream conditions. The numerical results show that the amount of forking in the geometry of the caudal fin has significant effects on its hydrodynamic performance. A comparison of thrust coefficients shows that the square caudal fin has a greater thrust coefficient in the non-dimensional frequency range of 0.6 < f* < 1.2, while the deeply forked caudal fin generates higher thrust when 1.2 < f* < 1.5. In terms of propulsive efficiency, the square caudal fin is more efficient when 0.6 < f* < 0.9, while the propulsive efficiency of a deeply forked caudal fin is significantly enhanced when 0.9 < f* < 1.5. Based on our results, the deeply forked caudal fin has greater thrust coefficients and a higher propulsive efficiency in a higher frequency range than the natural frequency of each caudal fin. The thrust characteristics and flow fields around each caudal fin are investigated in detail.

This article assesses how the economic context of higher education expansion since the mid-20th century has shaped families' financial lives-in terms of income and wealth/debt-as well as how these trends have differed for Black and White women and men. We use data from the NLSY-79 (comprising trailing-edge Baby Boomers) and NLSY-97 (comprising early Millennials) to show how academically similar students in these two cohorts fared in terms of educational attainment, household income, household wealth, and total student debt accrued by age 35. While we discuss findings across race-gender groups, our results call attention to the education-related economic disadvantages faced by Black women that have accelerated across cohorts. Over time, Black women's educational attainment has increased substantially, and high-achieving Black women, in particular, have become uniquely likely to progress beyond the BA. But while high-achieving Black women have made many advances in higher education, they also have become more likely than similarly high-achieving White men, White women, and Black men to have zero or negative wealth at the household level, and to accrue student debt for themselves and for their children. Our findings demonstrate that the costs of expanded access to credit for higher education have not been borne equally across race, gender, and achievement, and that these patterns have multigenerational financial consequences for college attendees and their families.

Trailing edge serrations have shown remarkable ability to reduce noise, but their effectiveness can be significantly impacted by flow misalignment, particularly under aerodynamic loading conditions. This paper presents a comprehensive study on the effect of incorporating streamwise vane treatments at the root of the trailing edge serrations on its noise reduction performance. Experiments were performed on a 100 mm chord NACA 0012 wing model with sawtooth type trailing edge serration. The aeroacoustic performance was investigated for serrations with non-zero flap angle at various angles of attack between -5° and 8.5°. The findings reveal that streamwise vanes can reduce the high-frequency noise by over 5 dB when placed at the root. Furthermore, particle image velocimetry measurements in the wall-normal plane demonstrate a significant decrease in cross-flow and turbulence generation when the treatment was placed near the root of serrations. In addition, the load measurements indicate no noticeable variation in the lift coefficient and up to 6% increase in the drag coefficients in the pre-stall region.

Large Eddy Simulation (LES) and Ffowcs Williams-Hawkings acoustic analogy are performed to study the effect of trailing-edge blowing on airfoil self-noise. Simulations were conducted using a National Advisory Committee for Aeronautics 0012 airfoil at zero angle of attack and a chord-based Reynolds number of 4 × 10 5. The aerodynamic and aeroacoustic characteristics of the baseline airfoil were thoroughly verified by comparison with previous numerical and experimental data. The noise reduction effects of continuous and local blowing with different blowing ratios and blowing momentum coefficients were compared. A maximum noise reduction of 20 dB was achieved via trailing-edge blowing and the noise reduction mechanisms of the two blowing methods were discussed. The LES results show a pair of recirculation bubbles in the airfoil wake which are suppressed by trailing-edge blowing. As the blowing vortices convect into the wake, they stretch and stabilize the shear flows from airfoil surfaces. Instantaneous vorticity and root mean square velocity fluctuations are also weakened. There is a decrease in the spanwise coherence and an increase in the phase difference, which contribute to noise reduction. It is concluded that the suppression of turbulence fluctuations in the near wake is the main mechanism of noise reduction for airfoil trailing-edge blowing.

The potential deformation and failure of a slope with typical 3D shapes involve 3D characteristics, such that these factors cannot be simulated using 2D methods. If 3D characteristics are not considered in expressway slope monitoring, an excessive number of monitoring points may be arranged in the stable/safe part, whereas insufficient monitoring points may be arranged in the unstable/dangerous part. In this study, the 3D deformation and failure characteristics of the Lijiazhai slope of the Shicheng-Ji'an Expressway in Jiangxi Province, China were analyzed by 3D numerical simulations using the strength reduction method. The potential 3D slope surface displacement trends, initial position of failure, and maximum depth of potential slip surface were simulated and discussed. The deformation of Slope A was generally small. The slope ranging from the third platform to the slope top was located in Region I, where the deformation was approximately equal to zero. The deformation of Slope B was located in Region V, where the displacement generally was larger than 2 cm in the range from the first-third platforms to the slope top, and the deformation of the trailing edge exceeded 5 cm. The surface displacement monitoring points should be arranged in Region V. Monitoring was then optimized considering the 3D characteristics of the deformation and failure of a slope. Accordingly, surface and deep displacement monitoring networks were effectively arranged in the unstable/dangerous part of the slope. Results may be used as references for similar projects.

The European swallowtail butterfly (Papilio machaon) is so named, because of the long and narrow prominences extending from the trailing edge of their hindwings and, although not a true tail, they are referred to as such. Despite being a defining feature, an unequivocal function for the tails is yet to be determined, with predator avoidance (diverting an attack from the rest of the body), and enhancement of aerodynamic performance suggested. The swallowtail, however, is sexually size dimorphic with females larger than males, but whether the tail is also sexually dimorphic is unknown. Here, museum specimens were used to determine whether sexual selection has played a role in the evolution of the swallowtail butterfly tails in a similar way to that seen in the tail streamers of the barn swallow (Hirundo rustica), where the males have longer streamers than those of the females. Previously identified sexual dimorphism in swallowtail butterfly size was replicated, but no evidence for dimorphism in tail length was found. If evolved to mimic antennae and a head to divert a predatory attack, and if an absolute tail size was the most effective for this, then the tail would probably be invariant with butterfly hindwing size. The slope of the relationship between tail length and size, however, although close to zero, was nonetheless statistically significantly above (tail length ∝ hindwing area 0.107 ± 0.011). The slope also did not equate to that expected for geometric similarity (tail length ∝ hindwing area1/2) suggesting that tail morphology is not solely driven by aerodynamics. It seems likely then, that tail morphology is primarily determined by, and perhaps a compromise of several, factors associated with predator avoidance (e.g. false head mimicry and a startling function). Of course, experimental data are required to confirm this.

While contamination of indoor environment with organochlorine compounds (OCs) is well documented worldwide, only a few studies highlighted the problem of indoor pollution in Indian sub-continent, including Nepal. This study insight the contamination level, distribution pattern, and sources of OCs in indoor dust from a rural area of Nepal. Additionally, daily exposure risk through different intake pathways was estimated in order to mark the potential risk of OCs to local residents. Results indicated the predominance of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in dust. Ʃ26OCPs (median 87 ng/g) in dust was about 7-8 times greater than Ʃ30PCBs (median 10.5 ng/g). DDT was the most abundant chemical among Ʃ26OCPs, followed by HCHs and endosulfan, and accounted for 73%, 7%, and 4% of Ʃ26OCPs, respectively. A relatively high level of ƩDDT than other OCPs suggests the existence of DDT source in the Nepalese environment. Among PCB, tetra-CBs were most prevalent, trailed by penta-CBs, hexa-CBs, and hepta-CBs, and comprised 28%, 21%, 17% and 17% of Ʃ30PCBs, respectively. Dioxin like-PCBs (median 3.48 ng/g) was about two times higher than the total indicator-PCB (median 1.63 ng/g). High p,p-DDT/p,p-DDE ratio (median 2.89) suggested fresh application and minimal degradation of DDT in the local environment of Kopawa. While lower α-/γ-HCH ratio (median 0.75) indicated lindane contamination as the primary sources of HCH. Moreover, the low α-/β-endosulfan ratio (median 0.86) specified the fresh use of commercial endosulfan. Among OCPs, only DDT positively related to total organic carbon (TOC) (Rho = 0.55, p < 0.05) but not black carbon (BC), proposing minimal or zero impact of TOC and BC. For PCBs, PCB-126 was moderately and negatively correlated with TOC (Rho = -0.49, p < 0.05), but not BC. The daily risk exposure (DRE) assessment showed that children are more vulnerable to OCs than the adult. The DRE of OCs in this study were 2-4 order of magnitude lower than their corresponding reference dose (RfD), proposing insignificant risk.

In this study, we explore the use of synthetic jet (SJ) in manipulating the vortices around a rigid heaving airfoil, so as to enhance its aerodynamic performance. The airfoil heaves at two fixed pitching angles, with the Strouhal number, reduced frequency and Reynolds number chosen as St = 0.3, k = 0.25 and Re = 100, respectively, all falling in the ranges for natural flyers. As such, the vortex force plays a dominant role in determining the airfoil's aerodynamic performance. A pair of in-phase SJs is implemented on the airfoil's upper and lower surfaces, operating with the same strength but in opposite directions. Such a fluid-structure interaction problem is numerically solved using a lattice Boltzmann method based numerical framework. It is found that, as the airfoil heaves with zero pitching angle, its lift and drag can be improved concurrently when the SJ phase angle [Formula: see text] relative to the heave motion varies between [Formula: see text] and [Formula: see text]. But this concurrent improvement does not occur as the airfoil heaves with [Formula: see text] pitching angle. Detailed inspection of the vortex evolution and fluid stress over the airfoil surface reveals that, if at good timing, the suction and blowing strokes of the SJ pair can effectively delay or promote the shedding of leading edge vortices, and mitigate or even eliminate the generation of trailing edge vortices, so as to enhance the airfoil's aerodynamic performance. Based on these understandings, an intermittent operation of the SJ pair is then proposed to realize concurrent lift and drag improvement for the heaving airfoil with [Formula: see text] pitching angle.

Wing tip slots are a distinct morphological trait broadly expressed across the avian clade, but are generally perceived to be unique to soaring raptors. These slots are the result of emarginations on the distal leading and trailing edges of primary feathers, and allow the feathers to behave as individual airfoils. Research suggests these emarginate feathers are an adaptation to increase glide efficiency by mitigating induced drag in a manner similar to aircraft winglets. If so, we might expect birds known for gliding and soaring to exhibit emarginate feather morphology; however, that is not always the case. Here, we explore emargination across the avian clade, and examine associations between emargination and ecological and morphological variables. Pelagic birds exhibit pointed, high-aspect ratio wings without slots, whereas soaring terrestrial birds exhibit prominent wing-tip slots. Thus, we formed four hypotheses: (1) Emargination is segregated according to habitat (terrestrial, coastal/freshwater, pelagic). (2) Emargination is positively correlated with mass. (3) Emargination varies inversely with aspect ratio and directly with wing loading and disc loading. (4) Emargination varies according to flight style, foraging style, and diet. We found that emargination falls along a continuum that varies with habitat: Pelagic species tend to have zero emargination, coastal/freshwater birds have some emargination, and terrestrial species have a high degree of emargination. Among terrestrial and coastal/freshwater species, the degree of emargination is positively correlated with mass. We infer this may be the result of selection to mitigate induced power requirements during slow flight that otherwise scale adversely with increasing body size. Since induced power output is greatest during slow flight, we hypothesize that emargination may be an adaptation to assist vertical take-off and landing rather than glide efficiency as previously hypothesized.