Search Results (9)

Wearable technologies have become powerful tools for health and fitness and are indispensable everyday tools for many individuals; however, significant limitations exist related to the validity of the metrics these monitors purport to measure. Thus, the purpose of the present study was to validate the step count of three wearable monitors (i.e., Yamax 3D Power-Walker, Garmin Vivofit 3 and Medisana Vifit), as well as two Android apps (i.e., Accupedo Pedometer and Pedometer 2.0), in a sample of healthy adults. These monitors and apps were evaluated in a lab-based semi-structured study and a 3-day field study under habitual free-living conditions. A convenience sample of 24 healthy adults (14 males and 10 females; 32.6 ± 2.5 years) participated in both studies. Direct step observation and Actigraph served as the criterion methods and validity was evaluated by comparing each monitor and app with the criterion measure using mean absolute percentage errors (MAPE), Bland–Altman plots, and Intraclass Correlation Coefficients. The results revealed high validity for the three wearable monitors during the semi-structured study, with MAPE values approximately 5% for Yamax and Vifit and well below 5% for Vivofit, while the two apps showed high MAPE values over 20%. In the free-living study all monitors and apps had high MAPE, over 10%. The lowest error was observed for Yamax, Vifit and Pedometer app, while Accupedo app had the highest error, overestimating steps by 32%. The present findings cannot support the value of wearable monitors and apps as acceptable measures of PA and step count in free-living contexts. Wearable monitors and apps that might be valid in one context, might not be valid in different contexts and vice versa, and researchers should be aware of this limitation. Full article

The biaxial fatigue crack growth behavior of commercial pure titanium TA2 of cruciform specimens with different crack inclination angles (β = 90°, 60°, 45°) under various biaxial load ratios (λ = 0, 0.5, 1) and different stress ratios (R = 0, 0.1, 0.3) is studied by an IPBF-5000 biaxial testing machine. The test results prove that the maximum tangential stress criterion is suitable for predicting the initiation angle of uniaxial and biaxial mixed-mode I–II fatigue cracks. The fatigue crack growth rate of a cruciform specimen with mode I and mixed-mode I–II cracks decreases with the increase of biaxial load ratio and increases with the stress ratio. The Walker model and Kujawski model have better compression effects on fatigue crack growth data than the Paris model. Full article

It is difficult to accurately identify the dynamic deformation of bridges from Global Navigation Satellite System (GNSS) due to the influence of the multipath effect and random errors, etc. To solve this problem, an improved empirical wavelet transform (EWT)-based procedure was proposed to denoise GNSS data and identify the modal parameters of bridge structures. Firstly, the Yule–Walker algorithm-based auto-power spectrum and Fourier spectrum were jointly adopted to segment the frequency bands of structural dynamic response data. Secondly, the improved EWT algorithm was used to decompose and reconstruct the dynamic response data according to a correlation coefficient-based criterion. Finally, Natural Excitation Technique (NExT) and Hilbert Transform (HT) were applied to identify the modal parameters of structures from the decomposed efficient components. Two groups of simulation data were used to validate the feasibility and reliability of the proposed method, which consisted of the vibration responses of a four-storey steel frame model, and the acceleration response data of a suspension bridge. Moreover, field experiments were carried out on the Wilford suspension bridge in Nottingham, UK, with GNSS and an accelerometer. The fundamental frequency (1.6707 Hz), the damping ratio (0.82%), as well as the maximum dynamic displacements (10.10 mm) of the Wilford suspension bridge were detected by using this proposed method from the GNSS measurements, which were consistent with the accelerometer results. In conclusion, the analysis revealed that the improved EWT-based method was capable of accurately identifying the low-order, closely spaced modal parameters of bridge structures under operational conditions. Full article

There is an urgent need to enhance agricultural production as well as productivity to meet the food demand of the growing population, estimated to be 10 billion by 2050, using a holistic and sustainable approach. The daily food sources for almost three-fourth of the global population, cereals and millets, are prone to several biotic factors and abiotic pressures. In particular, cereals and millet cultivation are limited by the polyphagous pink stem borer, Sesamia inferens Walker (Lepidoptera:Noctuidae) gaining national importance, since its larvae and pupae are concealed within the stem, none of the management measures have been found effective in controlling the menace. However, host plant resistance (HPR) is a reasonable and ecologically safe method wherein resistance mechanisms of crops could lower the stem borer infestation. The foremost challenge in understanding the mechanism would be to detecting the genes of interest in the crop using novel biotechnological approaches. The fundamental criterion for developing insect-resistant lines relies on recognizing the mechanism of plant resistance. The entire life cycle of this group of borers is completed or hidden within the stem, posing a hurdle in their management. Thus, molecular markers and Quantitative Trait Locus (QTL) mapping offer a more efficient approach to entomologists and plant breeders wherein they can work with traits like QTLs for stem borer resistance. In this review, an attempt has been made to provide an extensive summary of the host range and crop losses due to this borer, besides its taxonomic position, geographic distribution, bionomics, genetics of resistance, and molecular perspectives. Full article

Fatigue is the most common mechanical failure type in dental implants. ISO 14801 standardizes fatigue testing of dental implants, providing the load-life curve which is most useful for comparing the fatigue behavior of different dental implant designs. Based on it, many works were published in the dental implant literature, comparing different materials, component geometries, connection types, surface treatments, etc. These works are useful for clinicians in order to identify the best options available in the market. The present work is intended not for clinicians but for dental implant manufacturers, developing a design tool that combines Finite Element Analysis, fatigue formulation and ISO 14801 experimental tests. For that purpose, 46 experimental tests were performed on BTI INTERNA^® IIPSCA4513 implants joined with INPPTU44 abutments by means of INTTUH prosthetic screws under three different tightening torque magnitudes. Then, the load case was reproduced in a FE model from where the nominal stress state in the fatigue critical section was worked out. Finally, Walker criterion was used to represent accurately the effects of mean stress and predict fatigue life of the studied dental implant assembly, which can be extended to most of the products of BTI manufacturer. By means of this tool, dental implant manufacturers will be able to identify the critical design and assembly parameters in terms of fatigue behavior, evaluate their influence in preliminary design stages and consequently design dental implants with significantly better fatigue response which in turn will reduce future clinical incidences. Full article

Flesh flies (Sarcophagidae) are necrophagous insects initially colonizing on a corpse. The species-specific developmental data of the flies collected from a death scene can be used to estimate the minimum postmortem interval (PMI_min). Thus, the first crucial step is to correctly identify the fly species. Because of the high similarity among species of flesh flies, DNA-based identification is considered more favorable than morphology-based identification. In this study, we demonstrated the effectiveness of combined sequences (2216 to 2218 bp) of cytochrome c oxidase subunit I and II genes (COI and COII) for identification of the following 14 forensically important flesh fly species in Thailand: Boettcherisca nathani Lopes, Fengia ostindicae (Senior-White), Harpagophalla kempi (Senior-White), Liopygia ruficornis (Fabricius), Lioproctia pattoni (Senior-White), Lioproctia saprianovae (Pape & Bänziger), Parasarcophaga albiceps (Meigen), Parasarcophaga brevicornis (Ho), Parasarcophaga dux (Thomson), Parasarcophaga misera (Walker), Sarcorohdendorfia antilope (Böttcher), Sarcorohdendorfia inextricata (Walker), Sarcorohdendorfia seniorwhitei (Ho) and Seniorwhitea princeps (Wiedemann). Nucleotide variations of Thai flesh flies were evenly distributed throughout the COI-COII genes. Mean intra- and interspecific variations ranged from 0.00 to 0.96% and 5.22% to 12.31%, respectively. Using Best Match (BM) and Best Close Match (BCM) criteria, identification success for the combined genes was 100%, while the All Species Barcodes (ASB) criterion showed 76.74% success. Maximum Likelihood (ML) and Bayesian Inference (BI) phylogenetic analyses yielded similar tree topologies of monophyletic clades between species with very strong support values. The achieved sequences covering 14 forensically important flesh fly species including newly submitted sequences for B. nathani, F. ostindicae and S. seniorwhitei, can serve as a reliable reference database for further forensic entomological research in Thailand and in other areas where those species occur. Full article

For the risk assessment of a satellite to determine whether the satellite tank explodes under the hypervelocity impact, the Walker–Wasley criterion is selected to predict the shock initiation of the satellite tank. Then, the minimum power density of liquid hydrazine is determined based on the tests, the expressions of shock wave pressure and pressure duration are constructed based on the one-dimensional wave theory, and the initiation criterion for the liquid hydrazine tank is established. Finally, numerical simulation and the initiation criterion are adopted to calculate the power density in the satellite tank under the debris impact at the velocity of 10 km/s. The calculated power density agrees well with the simulated power density, they are both larger than the minimum power density, demonstrating that the shock wave generated by the hypervelocity impact is sufficient to trigger an explosion in the satellite tank. Full article

The $F(R,G)$ theory of gravity, where R is the Ricci scalar and G is the Gauss-Bonnet invariant, is studied in the context of existence the Noether symmetries. The Noether symmetries of the point-like Lagrangian of $F(R,G)$ gravity for the spatially flat Friedmann-Lemaitre-Robertson-Walker cosmological model is investigated. With the help of several explicit forms of the $F(R,G)$ function it is shown how the construction of a cosmological solution is carried out via the classical Noether symmetry approach that includes a functional boundary term. After choosing the form of the $F(R,G)$ function such as the case $(i):F(R,G)=f_0{R}^n+g_0{G}^m$ and the case $(ii):F(R,G)=f_0{R}^n{G}^m$ , where n and m are real numbers, we explicitly compute the Noether symmetries in the vacuum and the non-vacuum cases if symmetries exist. The first integrals for the obtained Noether symmetries allow to find out exact solutions for the cosmological scale factor in the cases (i) and (ii). We find several new specific cosmological scale factors in the presence of the first integrals. It is shown that the existence of the Noether symmetries with a functional boundary term is a criterion to select some suitable forms of $F(R,G)$ . In the non-vacuum case, we also obtain some extra Noether symmetries admitting the equation of state parameters $w\equiv p/\rho$ such as $w=-1,-2/3,0,1$ etc. Full article

Delamination in Wind Turbine Blades (WTB) is a common structural problem that can generate large costs. Delamination is the separation of layers of a composite material, which produces points of stress concentration. These points suffer greater traction and compression forces in working conditions, and they can trigger cracks, and partial or total breakage of the blade. Early detection of delamination is crucial for the prevention of breakages and downtime. The main novelty presented in this paper has been to apply an approach for detecting and diagnosing the delamination WTB. The approach is based on signal processing of guided waves, and multiclass pattern recognition using machine learning. Delamination was induced in the WTB to check the accuracy of the approach. The signal is denoised by wavelet transform. The autoregressive Yule–Walker model is employed for feature extraction, and Akaike’s information criterion method for feature selection. The classifiers are quadratic discriminant analysis, k-nearest neighbors, decision trees, and neural network multilayer perceptron. The confusion matrix is employed to evaluate the classification, especially the receiver operating characteristic analysis by: recall, specificity, precision, and F-score. Full article