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Abstract Objective There is currently a lack of in-depth comparative evaluation regarding the biomechanical properties of novel intramedullary nail devices in the treatment of basal femoral neck fractures (BFNF). This study aims to utilize finite element analysis to compare the performance differences of two novel devices with traditional PFNA and InterTan nails in the fixation of BFNF. Methods Based on a validated finite element model, this study constructed an accurate BFNF model and implanted four different intramedullary nail devices: PFNA, InterTan nail, PFBN (proximal femoral biomimetic nail), and NIS (novel intramedullary system). Under a vertical load of 2100N, the displacement and Von Mises stress (VMS) distribution of each group of models were evaluated through simulation testing. Results Under a load of 2100N, the PFBN device exhibited the best performance in terms of displacement and peak stress, while PFNA performed poorly. The peak displacement of the NIS device was lower than that of PFNA and InterTan nails, while the peak stress of the InterTan nail was lower than that of PFNA and NIS. Conclusion The PFBN device demonstrates stronger load-bearing and shear-resistant properties in the treatment of BFNF, and the NIS device also shows significant improvement in stability. Therefore, both the PFBN and NIS devices are reliable internal fixation techniques for the treatment of CFIFs, with potential clinical application prospects.

Abstract Objective Given the recent application of two new types of intramedullary nail devices in the treatment of comminuted femoral intertrochanteric fractures (CFIFs), there is still a lack of deep understanding and comparative evaluation of their biomechanical properties. Therefore, this study aims to systematically compare the advantages and disadvantages of these two new devices with traditional proximal femoral nail antirotation (PFNA) and InterTan nails in the fixation of CFIFs through finite element analysis. Methods Based on the validated finite element model, this study constructed an accurate CFIFs model. In this model, PFNA, InterTan nails, proximal femoral bionic nails (PFBN), and new intramedullary systems (NIS) were implanted, totaling four groups of finite element models. Each group of models was subjected to simulation tests under a vertical load of 2100 N to evaluate the displacement and Von Mises stress (VMS) distribution of the femur and intramedullary nail devices. Results Under a vertical load of 2100 N, a comparative analysis of the four finite element models showed that the NIS device exhibited the most superior performance in terms of peak displacement, while the PFNA device performed relatively poorly. Although the NIS device had the highest peak stress in the femur, it had the smallest peak displacement of both the femur and intramedullary nail devices, and the peak stress was mainly concentrated on the lateral side of the femur, with significantly lower stress in the proximal femur compared to the other three intramedullary nail devices. In contrast, the PFBN device had the lowest peak stress in the femur, and its peak displacement of both the femur and intramedullary nail devices was also less than that of PFNA and InterTan nails. Conclusion This study demonstrates that in the treatment of CFIFs, PFBN and NIS devices exhibit superior biomechanical performance compared to traditional PFNA and InterTan nail devices. Especially the NIS device, which can achieve good biomechanical results when fixing femoral intertrochanteric fractures with missing medial wall. Therefore, both PFBN and NIS devices can be considered reliable closed reduction and internal fixation techniques for the treatment of CFIFs, with potential clinical application value.

As the wind power generation becomes increasingly popular, the conventional inverter control methods may lead to power grid instability due to the reduction of inertia and susceptibility to parameter variations. In order to address this problem, a virtual synchronous generation (VSG) technology is combined with the quasi Z-source inverter (qZSI), which has the built-in boost function. To begin with, a finite switch sequence control strategy and an unconstrained optimization model predictive control (MPC) strategy are introduced to achieve multi-objective optimal control of the qZSI-VSG system. The average switching frequency of the inverter is reduced, the ability of the system to mitigate fluctuations in wind turbine output is enhanced, and the current harmonics are minimized. In addition, the computational complexity of the algorithm is simplified by eliminating the need for weight coefficients to be directly added to the cost function. Finally, the correctness and effectiveness of the proposed control strategy are verified by theoretical analysis and experimental results. Overall, this approach offers a promising solution to the challenges posed by the increasing integration of wind power into the power grid.

Abstract Objective We analyzed the influence of the location of the upper and lower cement on the sandwich vertebrae (SV) by computer finite element analysis. Materials and Methods A finite element model of the spinal segment of T11‐L1 was constructed and 6 mL of cement was built into T11 and L1 simultaneously. According to the various distributions of bone cement at T11 and L1, the following four groups were formed: (i) Group B‐B: bilateral bone cement reinforcement in both T11 and L1 vertebral bodies; (ii) Group L‐B: left unilateral reinforcement in T11 and bilateral reinforcement in L1; (iii) Group L‐R: unilateral cement reinforcement in both T11 and L1 (cross); (iv) Group L‐L: unilateral cement reinforcement in both T11 and L1 (ipsilateral side). The maximum von Mises stress (VMS) and maximum displacement of the SV and intervertebral discs were compared and analyzed. Results The maximum VMS of T12 was in the order of size: group B‐B

ObjectiveThe objective of the present study is to conduct a comparative analysis of the biomechanical advantages and disadvantages associated with a biplanar double support screw (BDSF) internal fixation device.MethodsTwo distinct femoral neck fracture models, one with a 30° angle and the other with a 70° angle, were created using a verified and effective finite element model. Accordingly, a total of eight groups of finite element models were utilized, each implanted with different configurations of fixation devices, including distal screw 150° BDSF, distal screw 165° BDSF, 3 CLS arranged in an inverted triangle configuration, and 4 CLS arranged in a “α” configuration. Subsequently, the displacement and distribution of Von Mises stress (VMS) in the femur and internal fixation device were assessed in each fracture group under an axial load of 2100 N.ResultsAt Pauwels 30° Angle, the femur with a 150°-BDSF orientation exhibited a maximum displacement of 3.17 mm, while the femur with a 165°-BDSF orientation displayed a maximum displacement of 3.13 mm. When compared with the femoral neck fracture model characterized by a Pauwels Angle of 70°, the shear force observed in the 70° model was significantly higher than that in the 30° model. Conversely, the stability of the 30° model was significantly superior to that of the 70° model. Furthermore, in the 70° model, the BDSF group exhibited a maximum femur displacement that was lower than both the 3CCS (3.46 mm) and 4CCS (3.43 mm) thresholds.ConclusionThe biomechanical properties of the BDSF internal fixation device are superior to the other two hollow screw internal fixation devices. Correspondingly, superior biomechanical outcomes can be achieved through the implementation of distal screw insertion at an angle of 165°. Thus, the BDSF internal fixation technique can be considered as a viable closed reduction internal fixation technique for managing femoral neck fractures at varying Pauwels angles.

Purpose: This study aimed to compare the biomechanical effects of different bone cement distribution methods on osteoporotic vertebral compression fractures (OVCF). Patients and methods: Raw CT data from a healthy male volunteer was used to create a finite element model of the T12-L2 vertebra using finite element software. A compression fracture was simulated in the L1 vertebra, and two forms of bone cement dispersion (integration group, IG, and separation group, SG) were also simulated. Six types of loading (flexion, extension, left/right bending, and left/right rotation) were applied to the models, and the stress distribution in the vertebra and intervertebral discs was observed. Additionally, the maximum displacement of the L1 vertebra was evaluated. Results: Bone cement injection significantly reduced stress following L1 vertebral fractures. In the L1 vertebral body, the maximum stress of SG was lower than that of IG during flexion, left/right bending, and left/right rotation. In the T12 vertebral body, compared with IG, the maximum stress of SG decreased during flexion and right rotation. In the L2 vertebral body, the maximum stress of SG was the lowest under all loading conditions. In the T12-L1 intervertebral disc, compared with IG, the maximum stress of SG decreased during flexion, extension, and left/right bending and was basically the same during left/right rotation. However, in the L1-L2 intervertebral discs, the maximum stress of SG increased during left/right rotation compared with that of IG. Furthermore, the maximum displacement of SG was smaller than that of IG in the L1 vertebral bodies under all loading conditions. Conclusions: SG can reduce the maximum stress in the vertebra and intervertebral discs, offering better biomechanical performance and improved stability than IG.

Objective Bone cement leakage is a major complication of percutaneous vertebroplasty (PVP) while treating Kümmell's disease and it is a focus of close attention during the surgical procedure. The study aimed to investigate whether pre‐injecting a composite of bone cement and gelatine sponge (the “bone cement‐gelatine sponge composite”) before injecting bone cement during PVP aids in lowering the leakage rate in stage I and II Kümmell's disease. Methods This prospective analysis evaluated 74 patients with stage I and II Kümmell's disease who underwent PVP treatment at our hospital from December 2019 to December 2021. The participants were divided randomly into groups based on whether the bone cement‐gelatine sponge composite was used during the surgery. The two groups were the bone cement‐gelatine sponge composite group (GS group, comprising 37 patients) and the no bone cement‐gelatine sponge composite group (N‐GS group, comprising 37 patients). The independent samples t‐test and chi‐square test were employed to compare general information, operative time, cement injection volume, intraoperative bleeding, and bone cement leakage between the two groups. Additionally, the visual analogue scale (VAS) score, Oswestry disability index (ODI), anterior vertebral height ratio (AVHR), and the kyphotic Cobb angle were compared between the two groups at the preoperative, 2 days postoperative, and 6 months postoperative stages using repeated measures analysis of variance. Results All patients were followed up for more than 6 months, with an average of (11.19 ± 2.21) months. No significant differences were observed in terms of the operative time, cement injection volume, and intraoperative bleeding between the two groups (P > 0.05). The incidence of bone cement leakage in the N‐GS group (32.43%) was significantly higher than that in the GS group (5.41%), and the difference was statistically significant (P 0.05). Conclusion The bone cement‐gelatine sponge composite intravertebral prefilling technique can lower bone cement leakage in stage I and II Kümmell's disease and can also relieve pain and improve vertebral body height.

ObjectiveThe aim of this study was to investigate the biomechanical stress of sandwich vertebrae (SVs) and common adjacent vertebrae in different degrees of spinal mobility in daily life.Materials and methodsA finite element model of the spinal segment of T10-L2 was developed and validated. Simultaneously, T11 and L1 fractures were simulated, and a 6-ml bone cement was constructed in their center. Under the condition of applying a 500-N axial load to the upper surface of T10 and immobilizing the lower surface of L2, moments were applied to the upper surface of T10, T11, T12, L1, and L2 and divided into five groups: M-T10, M-T11, M-T12, M-L1, and M-L2. The maximum von Mises stress of T10, T12, and L2 in different groups was calculated and analyzed.ResultsThe maximum von Mises stress of T10 in the M-T10 group was 30.68 MPa, 36.13 MPa, 34.27 MPa, 33.43 MPa, 26.86 MPa, and 27.70 MPa greater than the maximum stress value of T10 in the other groups in six directions of load flexion, extension, left and right lateral bending, and left and right rotation, respectively. The T12 stress value in the M-T12 group was 29.62 MPa, 32.63 MPa, 30.03 MPa, 31.25 MPa, 26.38 MPa, and 26.25 MPa greater than the T12 stress value in the other groups in six directions. The maximum stress of L2 in M-T12 in the M-L2 group was 25.48 MPa, 36.38 MPa, 31.99 MPa, 31.07 MPa, 30.36 MPa, and 32.07 MPa, which was greater than the stress value of L2 in the other groups. When the load is on which vertebral body, it is subjected to the greatest stress.ConclusionWe found that SVs did not always experience the highest stress. The most stressed vertebrae vary with the degree of curvature of the spine. Patients should be encouraged to avoid the same spinal curvature posture for a long time in life and work or to wear a spinal brace for protection after surgery, which can avoid long-term overload on a specific spine and disrupt its blood supply, resulting in more severe loss of spinal quality and increasing the possibility of fractures.

An Improved Speed Loop (ISL) and Extended State Observer (ESO) strategy based on Model Predictive Control (MPC) of the Permanent Magnet Synchronous Motor (PMSM) is proposed in this paper. Firstly, considering the impact of load torque sudden changes on speed tracking performance, a reduced-order Luenberger observer is utilized to observe the load torque and combine with model prediction to form ISL. Secondly, the ESO is utilized to estimate the lumped disturbance and feedforward compensated to the improved speed loop, which improves the system's anti-interference performance. Then, a cost function that introduces the current tracking error at the switching point is constructed, reducing the current ripple. Finally, the experiments show that compared with the traditional PI speed control, the proposed strategy reduces the speed overshoot over a wide range of speeds, improves the speed tracking performance, and has superior dynamic performance and anti-disturbance performance under different operating conditions. [ABSTRACT FROM AUTHOR]

Multi-vector model predictive control (MPC) of permanent magnet synchronous motors (PMSM) has two issues: selecting the optimal voltage vector (VV) combination is very complicated, and multiple prediction calculations to minimize the cost function result in a heavy computational burden; applying a VV with a short duration may generate narrow pulses, while the effect of reducing torque ripples and stator current harmonics is not obvious. The hybrid-vector model prediction flux control (HV-MPFC) strategy considering narrow pulse suppression is proposed in this paper. First, the optimal VV combination is quickly identified by the sector where the stator flux error vector is located, which lowers the control complexity and computational burden. Secondly, by the relationship between the action time of three VVs and the set time threshold, the hybrid-vector strategy to switch among three VVs, two VVs, and a single VV is employed to prevent the generation of narrow pulses. Finally, experimental results show that, compared with the existing three-vector MPC strategy, the HV-MPFC strategy effectively suppresses the generation of narrow pulses and achieves smaller torque ripples and stator current harmonics at the same switching frequency. [ABSTRACT FROM AUTHOR]

Model predictive current control (MPCC) suffers from high computational effort, and control performance is affected by parameter mismatch. In this paper, a robust MPCC strategy with low complexity for permanent magnet synchronous motor (PMSM) is proposed, which reduces the computational complexity and improves robustness. First, a low-pass filter is used to obtain the current actual voltage, and the next-cycle voltage vector is obtained by angle compensation. Alternative voltage vectors (AVVs) are selected according to the location of the next-cycle voltage vector to reduce the control system computation. This part does not use motor parameters to avoid the influence of parameter changes. Then, the relationship between the current error and the input voltage and current sampling value is analysed. A low-complexity current prediction error compensation algorithm is designed to compensate the error caused by the mismatch of motor inductance and flux linkage, which enhances the robustness of the system. Finally, the experimental results demonstrate the correctness and effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]