Search Results (98)

This study aimed to evaluate cow longevity and identify the main culling reasons in dairy herds in Southern Brazil. Two data sets from 26 predominantly confined Holstein herds were analyzed over a 10-year period (2007–2016). The first included 11,150 cows that were culled, died, or sold, and the second comprised 636,739 cows for demographic analysis. The average annual culling rate was 24.2%, mainly due to reproductive disorders (34.0%), mastitis/high somatic cell count (20.4%), and feet and leg problems (17.9%). Involuntary causes represented 89.5% of all culling. The death rate averaged 3.8%, with the most frequent causes being unknown (27.3%), other reasons (25.6%), tick fever (10.2%), and accidents/injuries (10.0%). Larger herds had higher culling rates than smaller ones (26.2% vs. 22.8%; p = 0.04), as did higher-producing herds compared to lower-producing ones (25.7% vs. 22.0%; p = 0.02). Cows with ≥5 calvings were culled more often (p < 0.01) than those in earlier lactations. Culling was lowest (p < 0.02) in spring and highest (p < 0.01) during early (0–60 d) and late (>420 d) lactation. Herds with a higher proportion of older cows had slightly lower milk yields (p < 0.01), indicating longevity does not always enhance productivity. Full article

The presented study demonstrates that UAVs can be flown with a morphing wing to develop essential aerodynamic efficiency without a tail structure, which decides the operational cost and flight safety. The mechanical control for morphing is discussed, where the system design, simulation, and experimental realization of ±15° SDOF sweep motion for a 7 kg eVTOL wing are detailed. The methodology, developed through a mathematical modeling of the mechanism’s kinematics and dynamics, is explained using Denavit–Hartenberg (D-H) convention, Lagrangian mechanics, and Euler–Lagrangian equations. The simulation and MBD analyses were performed in MATLAB R2021 and by Altair Motion Solve, respectively. The experiment was conducted on a dedicated test rig with two wing variants fitted with IMUs and an autopilot. The results from various methods were analyzed and experimentally compared to provide an accurate insight into the system’s design, modeling, and performance of the sweep morphing wing. The theoretical calculations by the mathematical model were compared with the test results. The sweep requirement is essential for eVTOL to have long endurance and multi-mission capabilities. Therefore, the developed sweep morphing mechanism is very useful, meeting such a demand. However, the results for three-dimensional morphing, operating sweep, pitch, and roll together are also presented, for the sake of completeness. Full article

One of the most popular alloys for biomedical applications is TiAl6V4. Even though TiAl6V4 is widely used, it faces several challenges. Firstly, TiAl6V4 is prone to stress shielding caused by the difference in Young’s moduli of the alloy (110 GPa) and human bones (20–30 GPa). Secondly, there is the presence of cytotoxic elements, aluminum and vanadium. Researchers have proposed Ti-35Nb-7Zr-5Ta (TNZT) alloy to overcome these disadvantages, an excellent substitute for natural human bones. This alloy offers a lower elastic modulus (up to 81 GPa), much closer to human bones than TiAl6V4 alloy. Also, TNZT alloy contains no cytotoxic elements and has excellent biocompatibility and high corrosion resistance. Given the positive outcomes on powder-mixed micro electro-discharge machining (PM-μ-EDM) of Ti alloy using hydroxyapatite (HA) powder, we studied the machinability of TNZT alloy using HA powder mixed-μ-EDM by changing the HA powder concentration (0, 5, and 10 g/L), gap voltage (90, 100, and 110 V), and capacitance (10, 100, and 400 nF) according to the Taguchi L9 method. Machining performance metrics such as material removal rate (MRR), overcut, and circularity were examined using a tungsten carbide tool of 237 µm diameter. The results showed an overcut of 10.33 µm, circularity of 8.47 µm, and MRR of 6030.89 µm³/s for the lowest energy setup. Full article

Irrigation is crucial for agricultural production in dry regions. However, water salinity is a risk for the soil–plant combination and the longevity of the materials that make up the irrigation system. Drip irrigation using direct and intermittent photovoltaic pumping can be key for optimizing irrigation with saline water. This article compares two pump models to understand which has the greatest capacity to reduce the risks of salinity in irrigated agriculture, aiming to make the system more sustainable through more efficient irrigation, without the need for highly expensive corrective cleaning measures. The ideal pump was evaluated using the motor pump’s electrical and hydraulic parameters and the water’s quality parameters applied by irrigation. The results indicate that the diaphragm pump is more sensitive to disturbances in irrigation management when compared to the centrifugal pump; however, it stands out in the following areas: it is more efficient, that is, it operates for more hours of the day with a direct connection with the photovoltaic panels; delivers better distribution uniformity in both continuous and pulsed application; and it makes the drip irrigation system with saline water more resistant to clogging. Full article

Aluminium thin wall castings are gaining wide acceptance in the automotive industry because of their incomparable design flexibility and higher mechanical properties. For these thin wall castings, fluidity plays a vital role in determining the quality of the final product. The aim of this work is to provide a detailed insight into the development of a multi-channel testing methodology to evaluate the fluidity of aluminium foundry alloys for thin wall applications. AlSi10MnMg foundry alloy has been used to conduct a series of experiments with the aim of designing operative protocols that achieve higher repeatability of the results. The fluidity of the investigated alloy was observed in channels of various cross-sections at three different pouring temperatures, i.e., 680, 710, and 740 °C. The obtained results show that experiments conducted following closely the designed operative protocols, result in achieving higher repeatability. It was also observed that by increasing the pouring temperature, the fluidity and repeatability of the alloy increased greatly. The 3D transient simulations were conducted by means of Altair^® Inspire™ Cast 2021.2 software to study the molten metal behaviour, i.e., solidification temperature and time at the end of each strip for the studied pouring temperatures. The results further reveal that the design methodology, if executed with intrinsic accuracy and precision, will provide a reliable pathway to determine the fluidity of aluminium alloys for various industrial applications. Full article

Scrub mangrove forests, dominated by Rhizophora mangle L., are characterized by high porewater salinity, which might compromise individual sap flow rates (SF) due to seasonal and diurnal microenvironmental variations. We tested the functional, anatomical, and SF responses of 12 individuals to microenvironmental variables such as solar radiation, photosynthetic photon flux, wind speed, evaporative demand, and porewater salinity, measured using an in situ weather station. Measurements were made in the dry and rainy seasons in the Yucatan Peninsula, using Granier heat dissipation sensors, installed on tree branches. During the rainy season, SF was twice as high as that during the dry season (0.22 ± 0.00 L h⁻¹ and 0.11 ± 0.00 L h⁻¹, respectively), despite lower evaporative demand. In both seasons, negative relationships between SF with vapor pressure deficit (VPD; dry τ = −0.54; rainy τ = −0.56) and with photosynthetic photon flux (PPF; dry τ = −0.97; rainy τ = −0.98) were found, indicating a strong hydraulic coupling to atmospheric conditions. Sap flow and transpiration rates of this R. mangle scrub mangrove forest exceeded those of some tropical dry deciduous forests, suggesting adaptations that support water transport in saline environments. The clustered xylem vessels of R. mangle ensure safe sap flow year-round. As an evergreen species, it contributes water to the atmosphere all year-round, underscoring its critical role in the tropical ecohydrological environment. Full article

Snakebites caused by Bothrops snakes are the most prevalent in the Amazon region, causing local and systemic complications. Local complications are mostly represented by necrosis, secondary bacterial infection and compartment syndrome. There are reports of long-term disabilities, but their burden is poorly investigated. This study aims to describe and estimate the frequency of physical and sensory long-term disabilities from Bothrops snakebites in the Manaus Region, in the western Brazilian Amazon region. Participants were >18-years individuals that accepted to return to the hospital 3–12 months (average follow-up time of 195 days) after the discharge for neuromusculoskeletal, chronic pain and sensory assessments. Assessment of disability was also performed using the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0). Factors associated with summary disability using WHODAS 2.0 were identified. Fifty participants were enrolled. A frequency of 20% of the participants reported difficulty in moving the affected limb (20%), and 23.7% reported difficulty in walking. Limitations of daily activities were reported by 26% of the patients. Decreased strength of the affected limb was observed in 22% of the patients. Decreased range of joint motion was seen in 20% of the patients. Chronic pain was reported in 48% of the patients. Tactile sensibility was decreased in 30%, thermal sensibility in 14%, painful sensibility (hypoalgesia) in 12%, kinetic-postural sensibility (hypokinesthesia) in 4% and vibratory sensibility was decreased or abolished in 16% of the participants. Cognition and mobility domains were those with the highest frequencies of participants with any degree of disability, each with 57%. The summary WHODAS 2.0 disability rate was 59%. Age > 59 years (p = 0.02)] was associated with protection against disability. Difficulty in moving the limb (p = 0.05), pain at the affected limb (p < 0.01), limitations of daily activities (p < 0.01) and decreased thermal sensibility (p = 0.05) were significantly associated with disability. The present study consists of the first follow-up investigation involving Bothrops snakebite patients related to long-term disabilities. These findings represent important data on Bothrops snakebites causing clinically significant long-term neuromusculoskeletal and sensory disabilities, resulting in reduced quality of life of the patients. Full article

This work proposes a model-based control scheme using a sliding mode controller (SMC) and an immersion and invariant (I&I) observer. The objective of the proposed control scheme is to be applied to a three-phase grid-tied inverter, which could operate as a shunt active power filter when the photovoltaic array is not generating power (night-time operation). The grid-tied inverter always remains operational, ensuring continuous support of the power quality improvement, as well as current harmonic compensation due to nonlinear loads and power factor correction. An external control loop is included to keep the voltage of the DC-link capacitor regulated. As can be explained in detail along with the work, a battery stack is avoided in this proposed research. Thus, a decision stage is added to the control scheme to select the night or day operation. Simulation results are carried out using Altair-PSIM© to demonstrate the effectiveness of the proposed control scheme in several scenarios. Full article

Turn-to-turn short circuit faults in the primary winding of generator terminal voltage transformers can lead to erroneous operation of stator grounding protection systems. This paper analyzes the fault characteristics associated with such failures and derives formulas for the fault phase current and zero-sequence voltage during a turn-to-turn short circuit in the primary winding. A 3D finite element model of the generator terminal voltage transformer is established by using Altair Flux 3D, and the accuracy of the model is verified. Based on this model, simulation tests were conducted to investigate turn-to-turn short circuits in the primary winding. The results reveal that as the number of shorted turns increases, the voltage of the fault phase decreases continuously while the voltages of the other two phases increase. The current in the short-circuited phase rises significantly, accompanied by an increase in zero-sequence voltage. Visualizations of magnetic field parameters indicate that as the number of shorted turns increases, the magnetic induction magnitude of the fault phase rises steadily and approaches saturation, resulting in heightened magnetic field intensity near the shorted turns. This analysis of fault characteristics through simulation contributes to the advancement of fault diagnosis systems for generator terminal voltage transformers. Full article

An exact non-perturbative model of a gravitational wave with pure radiation is constructed. It is shown that the presence of dust matter in this model contradicts Einstein’s field equations. The exact solution to Einstein’s equations for gravitational wave and pure radiation is obtained. The trajectories of propagation and the characteristics of radiation are found. For the considered exact model of a gravitational wave, a retarded time equation for radiation is obtained. The obtained results are used to construct an exact model of gravitational wave and pure radiation for the Bianchi type IV universe. Full article

This review article examines global initiatives in the adoption of building information modeling (BIM) for road infrastructure. It begins with an overview of the distinctions between BIM applications for buildings and infrastructure projects. This study evaluates noteworthy BIM publications (NBPs) from various countries and organizations to understand BIM’s transformative impact on roadway infrastructure projects. It analyzes the evolution of these publications, compares academic output with NBP, identifies the stages of BIM maturity, and evaluates adherence to ISO 19650 standards. Through this analysis, the article presents current global and regional scenarios, providing a comprehensive overview of the current state and future prospects of BIM implementation in the road infrastructure sector. Full article

Short-circuit impedance is an important economic and technical index to test the cost, efficiency and operation safety of transformers. Increasing the short-circuit impedance of the transformer can reduce the influence of the transformer fault current on the system. The short-circuit impedance of a general power transformer is 4~7%. When the short-circuit impedance is too small, the short-circuit current is too large, which will cause harm to electrical equipment. This paper proposes a method to adjust the short-circuit impedance by adding magnetic shunts of different thicknesses between the high and low voltage windings of the transformer. Compared with other methods, this method does not change the structure of the transformer core and winding, and is simple and efficient. In this paper, a three-dimensional simulation model of a single-phase multi-winding transformer is established by Altair Flux to study the influence of the thickness of magnetic shunts on the short-circuit impedance of a transformer. The feasibility of the proposed method is verified by comparing the simulation with the measured values. The magnetic shunt is also introduced into the three-phase transformer. The result shows that adding magnetic shunts of different thicknesses between the high and low voltage windings of the transformer will change the distribution and size of the leakage of the magnetic field. The short-circuit impedance increases significantly with the increase in the thickness of the magnetic shunt, but a certain number of magnetic shunts have minimal effects on the efficiency of the transformer. Full article

Continuous efforts are being made to improve fertilizer efficiency by improving fertilizer technology, quality, and application rates. Granular organic fertilizers are more difficult to achieve uniform application because their physical–mechanical properties differ significantly from mineral fertilizers. The properties of granular organic fertilizers can best be determined experimentally. However, these studies are often quite complex. Modern engineering modeling software makes it possible to model the properties of granular fertilizers and their dispersion. This study deals with the theoretical and experimental verification of the physical–mechanical properties of organic bone meal granular fertilizer. For the verification of selected properties of bone meal granules, the following studies were carried out on the granules: determination of poured bulk density, static and dynamic angles of repose, static and dynamic friction coefficients of granule surface, etc. The results showed that for modeling fertilizer properties, it is sufficient to carry out a static compression test to determine the modulus of elasticity and a friction test between granules and the contacting surface to determine the static and dynamic friction coefficients. The remaining properties of the granules can be modeled and calibrated with the DEM software Altair EDEM 2023. Full article

Recently, the role of trace elements in the pathophysiology of obesity, insulin resistance (IR), and metabolic diseases has been explored. In this cross-sectional study, we aimed to assess the association of overweight, obesity, and cardiometabolic traits with serum copper (Cu) levels in 346 Mexican adults. Serum Cu level was measured by inductively coupled plasma mass spectrometry (ICP-MS). Anthropometrical data were collected, and biochemical parameters were measured. The triglyceride-glucose (TyG) index was used as a surrogate marker to evaluate IR. Overweight and obesity status was positively associated with the serum Cu level (β = 19.434 ± 7.309, p = 0.008). Serum Cu level was observed to have a positive association with serum triglycerides level (β = 0.160 ± 0.045, p < 0.001) and TyG (β = 0.001 ± 0.001, p < 0.001). Additionally, high serum Cu level was positively associated with overweight and obesity status (odds ratio [OR] = 1.9, 95% confidence interval [95% CI] 1.1–3.4, p = 0.014), hypertriglyceridemia (OR = 3.0, 95% CI 1.7–5.3, p < 0.001), and IR (OR = 2.6, 95% CI 1.4–4.6, p = 0.001). In conclusion, our results suggest that overweight, obesity, hypertriglyceridemia, and IR are positively associated with serum Cu levels in Mexican adults. Full article

The mechanical integrity of two commercially available lithium-ion battery separators was investigated under uniaxial and biaxial loading conditions. Two dry-processed microporous films with polypropylene (PP)/polyethylene (PE)/polypropylene (PP) compositions were studied: Celgard H2010 Trilayer and Celgard Q20S1HX Ceramic-Coated Trilayer. The uniaxial tests were carried out along the machine direction (MD), transverse direction (TD), and diagonal direction (DD). In order to generate a state of in-plane biaxial tension, a pneumatic bulge test setup was prioritized over the commonly performed punch test in an attempt to eliminate the effects of contact friction. The biaxial flow stress–strain behavior of the membranes was deduced via the Panknin–Kruglov method coupled with a 3D Digital Image Correlation (DIC) technique. The findings demonstrate a high degree of in-plane anisotropy in both membranes. The ceramic coating was found to negatively affect the mechanical performance of the trilayer microporous separator, compromising its strength and stretchability, while preserving its failure mode. Derived from experimentally calibrated constitutive models, a finite element model was developed using the explicit solver OpenRadioss. The numerical model was capable of predicting the biaxial deformation of the semicrystalline membranes up until failure, showing a fairly good correlation with the experimental observations. Full article