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To achieve simple and reliable conversion from constant current (CC) charging mode to constant voltage (CV) charging mode in wireless power transfer systems, this paper proposes a hybrid topology equipped with a reconfigurable rectifier. An AC switch is adapted to simultaneously realize the change from half-bridge rectification to full-bridge rectification and achieve the shift from a topology with capacitors in the series compensated primary and secondary sides to a topology with capacitors in the series compensated primary side and the inductor-capacitor-inductor (LCL) compensated secondary side. Notably, communication between the transmitter and receiver sides is not necessary in the proposed method. Furthermore, the zero phase angle characteristic is successfully maintained in both charging modes. The experimental results obtained using the 48 V/0.7 A experimental prototype, which was built to validate the relevant theoretical analysis, show that output current/voltage can be achieved in CC/CV charging mode independent of load resistance. Notably, the maximum power transfer efficiency of the system during the charging process reached 95.33%.

Abstract Although various ferroptosis inducers including magnetic nanoparticles (Fe3O4) and iron‐organic frameworks have been applied in cancer treatment, the mild immunogenicity, low targeting efficiency to the tumor, and poor tissue penetration have limited the therapeutic efficacy. Herein, a supramolecularly engineered conjugate between living bacteria (facultative anaerobic Salmonella typhimurium VNP20009, VNP) and cancer cell membranes‐coated Fe3O4 nanoparticles is developed for improving targeted delivery of Fe3O4 nanoparticles into the tumor tissue and for synergistic ferroptosis and immunotherapy of tumor. The enhanced ferroptosis induced by both Fe3O4 nanoparticles and the loaded ferroptosis inducing agent (sulfasalazine (SAS)) effectively inhibits tumor growth and generates immune response via immunogenic cell death (ICD). The colonization of VNP in tumors also induces adaptive immune responses and further promotes ferroptosis. Fundamentally, the supramolecular conjugate of VNP and cell membranes‐coated Fe3O4 can potentiate the therapeutic capability of each other through mutually magnifying the ferroptosis and immunotherapy, resulting in significantly enhanced antitumor effects.

Genetic circuits that control transgene expression in response to pre-defined transcriptional cues would enable the development of smart therapeutics. Here the authors engineer programmable RNA sensors, DART VADARs, in which ADARs autocatalytically convert target hybridization into a translational output, thus amplifying editing by endogenous ADAR via positive feedback and conferring high dynamic range and a small genetic footprint.

Abstract Background Severe respiratory and neurological diseases caused by human enterovirus D68 (EV-D68) pose a serious threat to public health, and there are currently no effective drugs and vaccines. Adenosine deaminase acting on RNA1 (ADAR1) has diverse biological functions in various viral infections, but its role in EV-D68 infections remains undetermined. Methods Rhabdomyosarcoma (RD) and human embryonic kidney 293 T (293 T) cells, and HeLa cells were used to evaluate the expression level of ADAR1 upon EV-D68 (Fermon strain) and human parainfluenza virus type 3 (HPIV3; NIH47885) infection, respectively. Knockdown through silencing RNA (siRNA) and overexpression of either ADAR1p110 or ADAR1p150 in cells were used to determine the function of the two proteins after viral infection. ADAR1p110 double-stranded RNA binding domains (dsRBDs) deletion mutation was generated using a seamless clone kit. The expression of ADAR1, EV-D68 VP1, and HPIV3 hemagglutinin–neuraminidase (HN) proteins was identified using western blotting. The median tissue culture infectious dose (TCID50) was applied to detect viral titers. The transcription level of EV-D68 mRNA was analyzed using reverse transcription-quantitative PCR (RT-qPCR) and the viral 5′-untranslated region (5′-UTR)-mediated translation was analyzed using a dual luciferase reporter system. Conclusion We found that the transcription and expression of ADAR1 was inhibited upon EV-D68 infection. RNA interference of endogenous ADAR1 decreased VP1 protein expression and viral titers, while overexpression of ADAR1p110, but not ADAR1p150, facilitated viral replication. Immunofluorescence assays showed that ADAR1p110 migrated from the nucleus to the cytoplasm after EV-D68 infection. Further, ADAR1p110 lost its pro-viral ability after mutations of the active sites in the deaminase domain, and 5′-UTR sequencing of the viral genome revealed that ADAR1p110 likely plays a role in EV-D68 RNA editing. In addition, after ADAR1 knockdown, the levels of both phosphorylated double-stranded RNA dependent protein kinase (p-PKR) and phosphorylated eukaryotic initiation factor 2α (p-eIF2α) increased. Attenuated translation activity of the viral genome 5′-UTR was also observed in the dual-luciferase reporter assay. Lastly, the deletion of ADAR1p110 dsRBDs increased the level of p-PKR, which correlated with a decreased VP1 expression, indicating that the promotion of EV-D68 replication by ADAR1p110 is also related to the inhibition of PKR activation by its dsRBDs. Our study illustrates that ADAR1p110 is a novel pro-viral factor of EV-D68 replication and provides a theoretical basis for EV-D68 antiviral research.

The injury-triggered reocclusion (restenosis) of arteries treated with angioplasty to relieve atherosclerotic obstruction remains a challenge due to limitations of existing therapies. A combination of magnetic guidance and affinity-mediated arterial binding can pave the way to a new approach for treating restenosis by enabling efficient site-specific localization of therapeutic agents formulated in magnetizable nanoparticles (MNPs) and by maintaining their presence at the site of arterial injury throughout the vulnerability period of the disease. In these studies, we investigated a dual-targeted antirestenotic strategy using drug-loaded biodegradable MNPs, surface-modified with a fibrin-avid peptide to provide affinity for the injured arterial wall. The MNPs were characterized with regard to their magnetic properties, efficiency of surface functionalization, disassembly kinetics, and interaction with fibrin-coated substrates. The antiproliferative effects of MNPs formulated with paclitaxel were studied in vitro using a fetal cell line (A10) exhibiting the defining characteristics of neointimal smooth muscle cells. Animal studies examined the efficiency of combined (physical/affinity) MNP targeting to stented arteries in Sprague Dawley rats using fluorimetric analysis and fluorescent in vivo imaging. The antirestenotic effect of the dual-targeted therapy was determined in a rat model of in-stent restenosis 28 days post-treatment. The results showed that MNPs can be efficiently functionalized to exhibit a strong binding affinity using a simple two-step chemical process, without adversely affecting their size distribution, magnetic properties, or antiproliferative potency. Dual-targeted delivery strongly enhanced the localization and retention of MNPs in stented carotid arteries up to 7 days post-treatment, while minimizing redistribution of the carrier particles to peripheral tissues. Of the two targeting elements, the effect of magnetic guidance was shown to dominate arterial localization (p = 0.004 vs. 0.084 for magnetic targeting and peptide modification, respectively), consistent with the magnetically driven MNP accumulation step defining the extent of the ultimate affinity-mediated arterial binding and subsequent retention of the carrier particles. The enhanced arterial uptake and sustained presence of paclitaxel-loaded MNPs at the site of stent deployment were associated with a strong inhibition of restenosis in the rat carotid stenting model, with both the neointima-to-media ratio (N/M) and % stenosis markedly reduced in the dual-targeted treatment group (1.62 ± 0.2 and 21 ± 3 vs. 2.17 ± 0.40 and 29 ± 6 in the control animals; p < 0.05). We conclude that the dual-targeted delivery of antirestenotic agents formulated in fibrin-avid MNPs can provide a new platform for the safe and effective treatment of in-stent restenosis.

Abstract Background and Aims Few studies have meta‐analyzed different prognostic models developed for older adults, especially nursing home residents. We aimed to systematically review and meta‐analyze the performance of all published models that predicted all‐cause mortality among older nursing home residents. Methods We systematically searched PubMed and EMBASE from the databases' inception to January 1, 2020 to capture studies developing and/or validating a prognostic/prediction model for all‐cause mortality among nursing home residents. We then carried out both qualitative and quantitative analyses evaluating these models' risks of bias and applicability. Results The systematic search yielded 23,975 articles. We identified 28 indices that predicted the risk of all‐cause mortality from 14 days to 39 months among older adults in nursing homes. The most used predictors were age, sex, body weight, swallowing problem, congestive heart failure, shortness of breath, body mass index, and activities of daily living. Of the 28 indices, 8 (29%) and 3 (11%) were internally and externally validated, respectively. None of the indices was validated in more than one cohort. Of the 28 indices, 22 (79%) reported the C‐statistic, while only 6 (6%) reported the 95% confidence interval for the C statistic in the development cohorts. In the validation cohorts, 11 (39%) reported the C‐statistic and 8 (29%) reported the 95% confidence interval. The meta‐analyzed C statistic for all indices is 0.733 (95% prediction interval: 0.669−0.797). All studies/indices had high risks of bias and high concern for applicability according to PROBAST. Conclusion We identified 28 indices for predicting all‐cause mortality among older nursing home residents. The overall quality of evidence was low due to a high degree of bias and poor reporting of model performance statistics. Before any prediction model could be recommended in routine care, future research is needed to rigorously validate existing prediction models and evaluate their applicability and develop new prediction models.

Pet owners rely on information and advice from their veterinary practice to effectively manage their pet’s weight. This study investigated weight management information and services displayed on practice websites in Ontario, Canada. Information collected from the websites of 50 randomly selected small and mixed-animal practices included practice and staff demographics and the type of weight management services, products, and information advertised or displayed. The most frequently advertised weight management service and product were nutritional counselling (34%) and therapeutic diets (25%), respectively. Current bodyweight measurement was advertised on just over half of the websites (54%), while physical therapy counselling was the least-advertised service (16%). Further statistical analyses were performed in an exploratory fashion to determine areas for future research. Binary logistic regression analyses were used to investigate the association between practice demographics and the type of weight management information advertised online. A maximum of two predictor variables were included in each regression model. Exploratory analyses indicated that when controlling for the number of veterinarians in each practice, having a higher number of veterinary technicians was associated with increased odds of a practice website advertising current bodyweight measurement by 80.1% (odds ratio (OR) = 1.80, p = 0.05). Additionally, when controlling the number of veterinary technicians, having a higher number of veterinarians was associated with increased odds of a practice website advertising sales of therapeutic diets by 119.0% (OR = 2.19, p = 0.04). When using corporate practices as reference, independently owned practices had decreased odds of advertising sales of treats and weight management accessories on their practice websites by 78.7% (OR = 0.21, p = 0.03). These preliminary results suggest that advertising weight management information is not prioritized on veterinary practice websites in Ontario, especially those with lower staff numbers. The findings of this study raise awareness on the current state of weight management promotion for pets on veterinary practice websites and highlight ways to improve upon a practice’s online presence.

In order to solve the problem of power transmission efficiency reduction resulting from misalignment in the Wireless Power Transfer (WPT) system for Autonomous Underwater Vehicle (AUVs), a novel coupling structure with strong tolerance to misalignment is proposed. A solenoid coil is selected as the transmitting coil, and the receiving coil is composed of dual combined planar coils. The WPT system can still maintain stable output under uncertain axial misalignments for AUVs. The magnetic field distribution of the proposed magnetic coupling structure is analyzed theoretically, and the distance between the coils in the dual combined planar receiving coil is optimized. The theoretical analysis shows that the proposed solenoid-dual combined planar coils coupling structure can effectively maintain a stable mutual inductance between the transmitting coil and receiving coil under different axial misalignments compared with solenoid-unipolar planar coil coupling structure. An S-S resonant compensated WPT experimental prototype is built to verify the output characteristics of the proposed magnetic coupling structure. Compared to the magnetic coupler with the unipolar planar coil, it is validated by experiment that the proposed magnetic coupler substantially enhances the stability of power transmission efficiency and output power when axial misalignment occurs. The power transmission efficiency decreases by 6.74% when axial misalignment increases from 0 to 40 mm in saltwater. Meanwhile, the variation of output power is less than 4.15%.

In this paper, a wireless power transfer (WPT) system with a compact planar magnetic coupler for an autonomous underwater vehicle (AUV) is proposed. A passive induction (PI) coil is integrated into the circular transmitter (Tx) coil to build a uniform magnetic field (UMF), which can guarantee the stable output of the WPT system under uncertain radial and axial misalignments for AUV. Based on normalized magnetic induction intensity distribution analysis, a UMF constructing method with a PI coil is given, aiming to eliminate the fluctuation of magnetic field intensity, and the PI coil design principles and flow chart are obtained. The theoretical analysis shows the proposed integrated coil can effectively enhance the radial misalignment tolerance compared with a conventional circular spiral coil. The zero-phase angle (ZPA) input condition can be achieved by adjusting the series capacitor connected with the Tx coil in S-S compensation topology. Experimental results show that the proposed magnetic coupler containing an integrated coil significantly improves the stability of output power and power transfer efficiency within the possible radial and axial misalignments compared with a conventional coupler. It was demonstrated that the output power changes less than 5.5% and the power transfer efficiency maintains at approximately 84.5% in arbitrary radial positions within the possible working region with an axial transfer distance of 50 mm in saltwater.

Architectural heritage in historic districts, as a complex type of heritage, encompasses both the uniqueness of the building itself and also shows cultural and regional characteristics as a group, especially for the heritage site that contains multi-culture features. The digitalization research of this type of heritage often focuses on the digital archiving and modeling of heritages but rarely considers the combination of culture analysis and digitalization. This paper develops a digital form generation method for the heritages in historical districts by means of typological plan analysis, the Shape Grammar method, and Grasshopper software. Based on the case study of the modern Western-style house on Kulangsu, a world heritage site and historical district, this paper include three results: (1) dividing the layout plans of Kulangsu modern Western-style houses into three types, that is, native prototypes, foreign prototypes, and mixed prototypes, with 39 sub-types in total; (2) establishing shape grammar for the layout plans of Kulangsu modern Western-style houses with shape grammar sets and “S, L, R, I” expression rules; (3) creating a digital form generation method based on shape grammar result by Grasshopper software, including function cluster creation, function cluster connection and final model generation. This paper presents an example of quantitative analysis of heritage culture and a rapid modeling method of heritage, providing a reference for the construction of a heritage culture database and digital heritage management in historic districts.

A better fundamental understanding of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) has the potential to advance applications ranging from drug discovery to cardiac repair. Automated quantitative analysis of beating hiPSC-CMs is an important and fast developing component of the hiPSC-CM research pipeline. Here we introduce "Sarc-Graph," a computational framework to segment, track, and analyze sarcomeres in fluorescently tagged hiPSC-CMs. Our framework includes functions to segment z-discs and sarcomeres, track z-discs and sarcomeres in beating cells, and perform automated spatiotemporal analysis and data visualization. In addition to reporting good performance for sarcomere segmentation and tracking with little to no parameter tuning and a short runtime, we introduce two novel analysis approaches. First, we construct spatial graphs where z-discs correspond to nodes and sarcomeres correspond to edges. This makes measuring the network distance between each sarcomere (i.e., the number of connecting sarcomeres separating each sarcomere pair) straightforward. Second, we treat tracked and segmented components as fiducial markers and use them to compute the approximate deformation gradient of the entire tracked population. This represents a new quantitative descriptor of hiPSC-CM function. We showcase and validate our approach with both synthetic and experimental movies of beating hiPSC-CMs. By publishing Sarc-Graph, we aim to make automated quantitative analysis of hiPSC-CM behavior more accessible to the broader research community.

Inductive power transfer (IPT) technology is widely used in autonomous underwater vehicles (AUVs) to achieve safety and flexibility. However, the eddy current loss (ECL) will be generated in the seawater due to the high-frequency alternating current in the transmitter and receiver. An underwater IPT system with a series-none (SN) compensation topology is proposed in this paper to achieve a compact receiver for AUVs and reduce the ECL. The analytical model of the IPT system is built to analyze its transfer performance. The phase difference between the transmitter and receiver current of the SN compensation topology is larger than 90° compared to that of the conventional series-series (SS) topology, which can significantly decrease the magnitude of the electric field caused by coil currents; thus, the eddy current loss is reduced. Moreover, the optimal load resistance of the seawater IPT system is lower than that in the air, and the SN compensation topology has a more compact receiver with no compensation capacitor in the receiving side, which can save the internal space in the AUVs. An experimental prototype based on the SN topology is built, and the experimental results have verified the analysis.

Background and Objectives: Prior studies suggested that residential proximity to major roadways was associated with increased risks of cardiovascular diseases in developed countries, for which one explanation is that road proximity could heighten the risks of hypertension. However, the association of residential distance to major roadways with hypertension is still unclear in low- and middle-income countries (LMICs) with levels of air pollution and socioeconomic development distinctively different from developed countries.Methods: We derived data from the eighth wave of the Chinese Longitudinal Healthy Longevity Survey, a nationwide prospective cohort. The present study included 12,881 individuals older than 65 years (mean age, 85.2 ± 11.7 years) with 55.8% of them being female. We ascertained the residential proximity to major roadways based on self-reports and hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg. We then used logistic regression to examine the association between residential distance to major roadways and hypertension.Results: The odds ratios (ORs) of hypertension for participants living 50 to 100, 101 to 200, and ≥200 meters from major roads were 1.17 [95% confidence interval (95% CI) = 1.02–1.33], 1.21 (95% CI = 1.05–1.41), and 1.22 (95% CI = 1.10–1.34), respectively, compared to those living within 50 m (Pfor trend < 0.001). Significant effects of modifications from socioeconomic status and accessibility to health care resources were observed (Ps for interaction < 0.05). Compared to living within 50 m from a major roadway, the ORs of hypertension for living ≥50 m were higher in manual/agricultural workers, low-education groups, participants without household ventilation, and participants lacking in health education and health care resources. We observed considerable variations across geographic regions with the association in question attenuating in Eastern China but remaining significant in other regions.Conclusion: Residential proximity to major roadways was associated with lower odds of hypertension among older adults in China. The utility of residential proximity to major roadways as a marker of increased risks of hypertension and cardiovascular diseases may need to be revisited in LMICs.

When the wireless power transfer (WPT) system is installed on the autonomous underwater vehicle (AUV), there is a non-negligible eddy current loss around the coupler. The existence of the ferrite core causes the nonlinear distortion of the magnetic field, which makes the design of the WPT coupler more complicated and difficult. In this paper, the key parameters that affect the performance of the coupler were obtained through calculation and finite element analysis (FEA). Then, the coupler was parametrically modeled in Maxwell, and the Non-dominated Sorting Genetic Algorithm (NSGA-II) was used to optimize its design, considering two objective functions: mutual inductance and equivalent coupler loss impedance (ECLI). Finally, twenty groups of Pareto optimal points were evaluated using the Technique for Ordering Preferences by Similarity to Ideal Solution (TOPSIS) method. Five groups of design points with different weights were screened out. The effectiveness of the optimization process was verified by comparing the optimization results with the initial results.

Power Transfer Efficiency (PTE) and Transferred Power (TP) are two crucial indicators of the wireless power transfer (WPT) system. However, in most compensatory topologies, the ideal coils design parameters of PTE and TP are inconsistent, implying that optimizing for one indicator would make another indicator less effective. As a result, in this article, the Thompson sampling efficient multi-objective optimization (TSEMO) algorithm is used to simultaneously optimize PTE and TP in the S-S compensation topology. Through the co-calculation of MATLAB and COMSOL, the coils can be optimized in the environment of magnetic material (ferrite) and conductive material (aluminum). Coils larger than the underwater vehicle’s size are deleted during the data interaction between MATLAB and COMSOL to guarantee that the optimal PTE and TP can be attained within the constrained area. Due to the open standard external software packages between MATLAB and COMSOL, the entire optimization process may be automated. The results show that for WPT systems with restricted input voltage, such as the battery, this design strategy can achieve better TP at the expense of lower PTE, which is highly beneficial in improving the system’s overall performance.

Wireless charging in the marine environment has problems such as high loss and low efficiency. In order to solve these problems, based on the wireless power transmission technology in the seawater environment, this paper studies the multi-physical field coupling relationship of the underwater IPT system. Through researching on the law of mutual influence and interaction between the fields, the relationship between the physical fields is established. The software is used to establish a system simulation model, the dataset is solved and analyzed to get the distribution of electric field, magnetic field, thermal field, and flow field, which provides a theoretical basis for the model and optimization of the IPT system in the seawater.

A continuous control set model predictive power control strategy for an indirect matrix converter is proposed in this paper. The load reactive power, the load active power, and the input reactive power are controlled simultaneously. This control strategy can obtain output waveforms with fixed switching frequency. Additionally, an optimal switching sequence is proposed to simplify the commutations of the indirect matrix converter. To suppress the input filter resonance, an active damping method is proposed. Experimental results prove that the proposed method features controllable input reactive power, controllable load active and reactive power, fixed switching frequency output waveforms, zero-current switching operations, and effectively suppresses input filter resonance.

This paper proposes a novel model predictive current control scheme for two-stage matrix converter. The switching frequency is kept constant by fixing the switching instant. The control strategy achieves to control source reactive power in the input side and output currents in the output side. In addition, the advantage of the proposed strategy compared with conventional model predictive control is firstly proved using the principle of vector synthesis and the law of sines in the vector distribution area. Moreover, a zero-current switching sequence is proposed and implemented to insure zero-current switching operations and reduce the switching losses. Furthermore, in order to suppress the input filter resonance, which is easier to be inspired by the model predictive control, compared with traditional control strategies, an innovative active damping technique is proposed and implemented. Finally, both simulation and experiment are implemented to verify the performance of the proposed strategy. The results demonstrate that the control system features both good steady and transient performance.

AMP-activated protein kinase (AMPK) is a metabolic enzyme that can be activated by nutrient stress or genetic mutations. Missense mutations in the regulatory subunit, PRKAG2, activate AMPK and cause left ventricular hypertrophy, glycogen accumulation, and ventricular pre-excitation. Using human iPS cell models combined with three-dimensional cardiac microtissues, we show that activating PRKAG2 mutations increase microtissue twitch force by enhancing myocyte survival. Integrating RNA sequencing with metabolomics, PRKAG2 mutations that activate AMPK remodeled global metabolism by regulating RNA transcripts to favor glycogen storage and oxidative metabolism instead of glycolysis. As in patients with PRKAG2 cardiomyopathy, iPS cell and mouse models are protected from cardiac fibrosis, and we define a crosstalk between AMPK and post-transcriptional regulation of TGFβ isoform signaling that has implications in fibrotic forms of cardiomyopathy. Our results establish critical connections among metabolic sensing, myocyte survival, and TGFβ signaling.

In the marine environment, the inductive power transfer (IPT) technology offers many benefits such as increased flexibility and complete rejection of the winding problem. However, for underwater vehicles, the impact of seawater flow vibration will affect the stability of the power transmission. In this paper, a symmetrical double coil structure named 1×1×1 system is proposed to reduce the eddy current loss (ECL) and enhance the power transmission stability of the system under the impact of seawater flow vibration. Firstly, based on the discretization of the electric fields excited by each turn of two transmitting coils, the novel calculation method proposed is that the synthetic electric field at each discrete point is the sum of the electric field vector. Then the synthetic electric field and induced voltage of the 1×1×1 system are simulated by the finite element simulation software COMSOL to verify the calculated results. Finally, experiments are conducted to illustrate that the 1×1×1 system has good ability to resist Z-axial interference and reduce the impact of the seawater flow vibration.

Inductive power transfer (IPT) realizes no physical connection and make it possible to be a substitute for conductive charging in autonomous underwater vehicle (AUV) power feeding applications. However, in marine environment, the seawater stream vibration could bring disturbance and change the primary and secondary parameters, which reduces the stability of the power transmission system. This paper proposes a concentric circular ring structure applied in AUV’s IPT system for resisting the disturbance of ocean current. The study focuses on its misalignment tolerance. It is found that the 3rd coupler (19:24 turns) has better tolerance on axial misalignment among the three couplers with different secondary winding turns. It improves the coupling coefficient reduction from 34.7% to 23.6% when the axial misalignment varies from 0 to 50 mm and the radial displacement almost has no influence on coupling coefficient if radial misalignment is much smaller than the diameter of coils. Experiment results show that the system efficiency drops from 93.2% to 82.4%, when the axial misalignment changes from 0 to 50 mm.

Underwater wireless power transfer (WPT) has gained a lot of popularity in recent years. In the seawater environment, the electrical conductivity is non-negligible compared with that in the air. Therefore, the eddy current loss is generated by the high-frequency alternating currents in the coils. The eddy current loss of the aligned coils has been analyzed while the eddy current loss of the misaligned coils has not been explored yet, which is crucial because misaligned coils are more common in practical applications. In this paper, an analytical model for the eddy current loss of a coreless WPT system in the seawater with misalignments is established with Maxwell’s equations. The theoretical expressions of the electric field intensity and the eddy current loss are derived. Then the eddy current loss is analyzed under different misalignments and frequencies. It is found that the efficiency in the seawater remains stable at a frequency range of 215.5 kHz to 248.4 kHz. Moreover, the efficiency is relatively unchanged under a small lateral misalignment and decreases sharply when the lateral misalignment keeps growing. An underwater WPT prototype is built and the experiments verify the theoretical analysis.

The wireless power transfer shows great potential in the future for its safety and convenience. Autonomous underwater vehicle is one of the important tools to explore and develop oceans. In this study, we develop and analyze a wireless power transfer system based on magnetic resonance coupling to charge the autonomous underwater vehicle underwater. We have adopted a way that energy transmission underneath the vehicle and the coils in the wireless power transfer system were proposed to obtain a higher mutual inductance based on the shape of the vehicle in this study. In addition, we analyze the equivalent circuit model and propose a kind of impedance matching network to maintain system security. The coils we used in the proposed system are 20 turns and their radii are 70 mm. The system works well with 100 W output and 72% efficiency.

This paper introduces the working principle of the inductive power transfer (IPT) system from the perspective of the electromagnetic field. Using Maxwell’s equations, the analytical solution for the electromagnetic field, synthesized by the primary and secondary circular coils in an IPT system, is deduced in detail to obtain the electric field in the IPT system, and the derivation process is easy to understand for researchers engaged in IPT. The final solutions are obtained by combining analytical derivation and the numerical integration method to find the induced voltage in the secondary coil. Finally, by comparison, the simulation results from the finite element software are in a good agreement with those from the analytical analysis. Moreover, an IPT system is set up to validate the analytical and simulation results, and the maximal relative error is under 6% in different working conditions, which shows that it is feasible to understand the working principle of IPT systems from the viewpoint of the electromagnetic field.

Wireless Power Transfer (WPT) for autonomous underwater vehicles (AUVs) has been a research focus in recent years. This paper studies the inductor-capacitor-capacitor and parallel (LCC-P) compensation topology to achieve a compact receiver for AUVs. Unlike the series-series (SS) compensation topology, the LCC-P topology retains the advantages of the double-sided LCC topology and has a more compact receiver than the double-sided LCC topology with fewer elements used on the receiver side. The analytical model of such a WPT system is established to analyze the output power and transfer efficiency. The LCC-P topology has a higher efficiency compared to the SS topology due to the smaller conduction loss of the inverter. Moreover, a method of eliminating the DC filter inductor L0 is proposed to further decrease the size and weight of the receiver. The amplitude of the withstanding voltage on the receiver compensation capacitor without L0 is approximately decreased by 40% compared to that with L0. Both cases of with and without L0 have a constant current output and the peak efficiency without L0 is about 94%, which is 1% lower than that with L0. A prototype was built and the experimental results verified the theoretical analysis.