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The combination of magnetoresistive (MR) element and magnetic flux concentrators (MFCs) offers highly sensitive magnetic field sensors. To maximize the effect of MFC, the geometrical design between the MR element and MFCs is critical. In this paper, we present simulation and experimental studies on the effect of the geometrical relationship between current-in-plane giant magnetoresistive (GMR) element and MFCs made of a NiFeCuMo film. Finite element method (FEM) simulations showed that although an overlap between the MFCs and GMR element enhances their magneto-static coupling, it can lead to a loss of magnetoresistance ratio due to a magnetic shielding effect by the MFCs. Therefore, we propose a comb-shaped GMR element with alternate notches and fins. The FEM simulations showed that the fins of the comb-shaped GMR element provide a strong magneto-static coupling with the MFCs, whereas the electric current is confined within the main body of the comb-shaped GMR element, resulting in improved sensitivity. We experimentally demonstrated a higher sensitivity of the comb-shaped GMR sensor (36.5 %/mT) than that of a conventional rectangular GMR sensor (28 %/mT).

Frequency response analysis (FRA) is being employed worldwide as one of the main methods for the internal condition assessment of transformers due to its capability of detecting mechanical changes. Nonetheless, the objective interpretation of FRA measurements is still a challenge for the industry. This is mainly attributable to the lack of complete data from the same or similar units. A large database of FRA measurements can contribute to improving classification algorithms and lead to a more objective interpretation. Due to their destructive nature, mechanical deformations cannot be performed on real transformers to collect data from different scenarios. The use of simulation and laboratory transformer models is necessary. This research contribution is based on a new method using Finite Element Method simulation and a lumped element circuit to obtain FRA traces from a laboratory model at healthy and faulty states, along with an optimization method to improve capacitive parameters from estimated values. The results show that measured and simulated FRA traces are in good agreement. Furthermore, the faulty FRA traces were analyzed to obtain the characterization of faults based on the variation of the lumped element’s parameters. This supports the use of the proposed method in the generation of faulty frequency response traces and its further use in classifying and localizing faults in the transformer windings. The proposed approach is therefore tailored for generating a larger and unique database of FRA traces with industrial importance and academic significance.

Focusing on the engineering challenge of complex and unpredictable interfacial impact load transfer during the penetration process of a certain type of bomb, this study integrates hammer impact testing and finite element simulation methods to quantitatively analyse the dynamic response characteristics at the nose section/projectile and projectile/base section interfaces. The input and output responses of the interfaces under impact loads were obtained through hammer tests, revealing the variation patterns of peak load and stress during interfacial transfer. Based on Matlab model identification tools, an equivalent transfer model for interfacial loads was established, enabling effective prediction of peak load and pulse width changes during load propagation. The prediction error of the numerical model is less than 15%, meeting engineering accuracy requirements. The research findings provide direct data support and a modeling basis for enhancing the performance of weapon systems.

Squeeze Film Dampers play a crucial role in rotating machinery by effectively dampening vibration amplitudes. As a result, various designs of SFDs have been developed for widespread industrial applications...

We propose a dual-core, highly sensitive PCF SPR biosensor with C-shaped grooves based on a fusion of graphene and gold film. The performance of our sensor is enhanced by our circular fibre lattice with perforated air holes. We evaluate the biosensor's sensitivity to variations in refractive index (RI) in cancer cells numerically using the Finite Element Method (FEM) in COMSOL Multiphysics. After enhancing fiber parameters and using numerical results from amplitude method and spectral interrogation methods, we found that the biosensor demonstrates the highest sensitivity for MCF7 cells, 2142.86 nm/RIU under spectral interrogation. With HeLa cells, the biosensor shows a sensitivity of – 1058.039 1/RIU under the amplitude interrogation approach. Moreover, for MCF7, the biosensor reaches a resolution of 04.60 × 1E–5 RIU.

The purpose of this parametric study was to develop a numerical simulation model calibrated with experimental data to predict the flexural behavior of prestressed concrete (PSC) girders subjected to long-term prestress losses. The model is capable of accurately simulating the flexural behavior of PSC girders using commercial finite-element (FE) software in the ABAQUS/Explicit program. The accuracy of the model was validated by comparing its results with flexural response test data from three post-tensioned girders, with the tendons ultimately having tensile strength capacities of 1860 MPa, 2160 MPa, and 2400 MPa. The comparison demonstrated generally excellent agreement between numerical and experimental results in terms of the load–deflection response and crack propagation behavior, from the onset of first cracking through the maximum load and into the ductile response range. Subsequently, a parametric study was conducted to evaluate the effects of tendon ultimate strength, amount of long-term prestress loss, grouting defects, degradation-induced reductions in concrete strength, and reductions in tendon cross-sectional area on girder flexural behavior. Through this parametric investigation, the study identified key factors with respect to long-term prestress loss that may influence the flexural behavior of aging PSC structures.

The adoption of additive manufacturing (AM) to complement conventional manufacturing to produce industrial components has been widely accepted. This is critical to the fabrication of designs with high complexity, which traditional manufacturing cannot match. In this regard, a commercial Pelton turbine with a traditional design was improved using both reverse engineering and hydro-dynamic finite element method simulations to produce a new design. Then, the performance of our new design is experimentally evaluated in terms of its rotational speed. In our new design, using the Design for AM (DfAM), several drawbacks of the traditional Pelton turbine design (e.g., improper welding and alignment and blunt splitters that lead to a heeling effect) were overcome by the following steps: (i) employing computational fluid dynamics analysis, (ii) consequently, extracting key geometrical characteristics from the original design, such as the number of buckets, runner wheel diameter, and bucket width, and length (iii) finally, referencing other design parameters using generally known empirical data . DfAM techniques were applied to reduce the post-processing requirements of additively manufactured turbine buckets, considering minimum feature size and avoidance of support structures on water-contacted surfaces, as well as simple and manual support removal. The new design in this study exhibits high rotational speeds ranging from 8.2 to 32.73% at an inlet pressure of 5 MPa and different nozzle angles.

Miniaturized pressure sensors fabricated via micro-electro-mechanical systems (MEMSs) technology are ubiquitous in modern applications. However, the massively produced MEMS pressure sensors, prior to being practically used, need to be calibrated one by one to eliminate or minimize nonlinearity and zero drift. This paper presents a systematic design for the testing and calibration process of MEMS-based absolute pressure sensors. Firstly, a numerical analysis is carried out using finite element method (FEM) simulation, which verifies the accuracy of the temperature control of the physical calibration system. The simulation results reveal a slight non-uniformity of temperature distribution, which is then taken into consideration in the calibration algorithm. Secondly, deploying a home-made calibration system, the MEMS pressure sensors are tested automatically and rapidly. The experimental results show that each batch, which consists of nine sensors, can be calibrated in 80 min. The linearity and temperature coefficient (TC) of the pressure sensors are reduced from 46.5% full-scale (FS) and −1.35 × 10−4 V·K−1 to 1.5% FS and −8.8 × 10−7 V·K−1.

The monitoring of some parameters, such as pressure loads, temperature, and glucose level in sweat on the plantar surface, is one of the most promising approaches for evaluating the health state of the diabetic foot and for preventing the onset of inflammatory events later degenerating in ulcerative lesions. This work presents the results of sensors microfabrication, experimental characterization and FEA-based thermal analysis of a 3D foot-insole model, aimed to advance in the development of a fully custom smart multisensory hardware–software monitoring platform for the diabetic foot. In this system, the simultaneous detection of temperature-, pressure- and sweat-based glucose level by means of full custom microfabricated sensors distributed on eight reading points of a smart insole will be possible, and the unit for data acquisition and wireless transmission will be fully integrated into the platform. Finite element analysis simulations, based on an accurate bioheat transfer model of the metabolic response of the foot tissue, demonstrated that subcutaneous inflamed lesions located up to the muscle layer, and ischemic damage located not below the reticular/fat layer, can be successfully detected. The microfabrication processes and preliminary results of functional characterization of flexible piezoelectric pressure sensors and glucose sensors are presented. Full custom pressure sensors generate an electric charge in the range 0–20 pC, proportional to the applied load in the range 0–4 N, with a figure of merit of 4.7 ± 1 GPa. The disposable glucose sensors exhibit a 0–6 mM (0–108 mg/dL) glucose concentration optimized linear response (for sweat-sensing), with a LOD of 3.27 µM (0.058 mg/dL) and a sensitivity of 21 µA/mM cm2 in the PBS solution. The technical prerequisites and experimental sensing performances were assessed, as preliminary step before future integration into a second prototype, based on a full custom smart insole with enhanced sensing functionalities.

In order to predict the bolt’s stress distribution under the pre-tightening state and the loosening process under the transverse load, a 3D model considering the bolt thread structure was established by finite element method (FEM). In this study, the looseness effect of transverse load amplitude, the friction coefficient of the bolt head load bearing surface and the thread contact surface are mainly studied. The result indicated that the stress under bolt pre-tightening is mainly concentrated on the contact part of the bolt’s head and bar. At the contact area of the load threads at one end and the transition part between the bolt bar and the thread, the stress and axial direction of the thread part are offset. Under the transverse displacement load, the sliding of the bolt can be divided into three stages: full contact, viscous contact, and full slip. The numerical model of bolt relaxation obtained in this paper can provide reference for the application, checking and prediction of threaded fasteners.