Microwave Through Wall Imaging via An Induced Current Learning Method

In this paper,an induced current learning method(ICLM)for microwave through wall imaging(TWI),named as TWI-ICLM,is proposed.In the inversion of induced current,the unknown object along with the enclosed walls are treated as a combination of scatterers.Firstly,a non-iterative method called distorted-Born backpropagation(DB-BP)is utilized to generate the initial result.In the training stage,several convolutional neural networks(CNNs)are cascaded to improve the estimated induced current.In addition,a hybrid loss function consisting of the induced current error and the permittivity error is used to optimize the network parameters.Finally,the relative permittivity images are conducted analytically using the predicted current based on ICLM.Both the numerical and experimental TWI tests prove that,the proposed method can achieve better imaging accuracy compared to traditional distorted-Born iterative method(DBIM).

刚柔并济的仿生凝胶聚合物电解质助力稳定的锂电池

凝胶聚合物电解质(GPE)因其优良的热稳定性和卓越的电化学性能而具备增强锂离子电池性能的潜力,从而受到越来越多的认可.尽管其具有上述优点,但传统GPE的实际应用通常因其溶胀性和有限的机械强度而受到阻碍.为了解决这些问题,本项研究工作提出了一种通过简单方法构建的刚柔并济的仿生GPE,由聚环氧乙烷(PEO)和聚偏二氟乙烯-六氟丙烯(PVDF-HFP)组成并通过Kevlar纤维织物进行增强.所得的PEO/PVDF-HFP/Kevlar(PPK)GPE表现出2.815 mS cm^(−1)的优异离子电导率和0.571的锂离子迁移数,以及32.59 MPa的超高机械强度.这些特性有助于防止锂枝晶生长并增强LiFePO4电池的电化学性能,从而实现稳定的循环性能.PPK GPE可以为高性能锂离子电池的各种实际应用提供理论基础.

Recent progress on electro-sorption technology for lithium recovery from aqueous sources

Lithium is known as the“white petroleum”of the electrification era,and the global demand for lithium grows rapidly with the quick development of new energy industry.The aqueous solutions,such as salt lake brine,underground brine,and seawater,have large lithium reserves,thus this kind of lithium resource has become a research hotspot recently.Compared with other lithium extraction technologies,electro-sorption method shows good prospects for practical applications with advantages in the aspects of efficiency,recovery ratio,cost,and environment.Herein,this review covers recent progress on electro-sorption technology for lithium recovery from aqueous solutions,including the concept illustration,research progress of the applied working electrodes and counter electrodes,and the evaluation indicators of electro-sorption system.Meanwhile,some prospects for the development of this technology are also proposed.We hope this review is beneficial for the construction of high-efficient electrochemical lithium recovery system to achieve an adequate lithium supply in the future.

PVDF-HFP-SN-based gel polymer electrolyte for high-performance lithium-ion batteries

Gel polymer electrolytes(GPEs)have attracted extensive attention in lithium-ion batteries due to their high security and excellent electrochemical performance.However,their inferior Li-ion transference number,low room-temperature ionic conductivity,and poor long cycle stability raise challenges in practical applications.Herein,a flexible poly(vinylidene fluoride-cohexafluoropropylene)-butanedinitrile(PVDF-HFP-SN)-based GPE(PSGPE)is synthesized successfully by a general immersion precipitation method.The resultant PSGPEs have numerous connecting pores to ensure sufficient space for liquid electrolytes.Moreover,the reduced crystallinity of PVDF-HFP and the high polarity of SN can reduce the energy barrier of Li-ions shuttling between pores.The synergistic effect possesses a high ionic conductivity of 1.35 mS·cm^(-1)at room temperature with a high Li-ion transference number of 0.69.The PVDF-HFP-SN-based GPE is applied in a LiFePO_(4)/graphite battery,which can realize stable cycling performance for 350 cycles and good rate performance at room temperature.These results demonstrate that the novel PSGPE possesses advantage in simplified production process,which can improve the practicability of gel polymer lithium-ion batteries.

The squeeze flow of a bi-viscosity fluid between two rigid spheres with wall slip

In this paper,the squeeze flow between two rigid spheres with a bi-viscosity fluid is examined.Based on lubrication theory,the squeeze force is calculated by deriving the pressure and velocity expressions.The results of the normal squeeze force are discussed,and fitting functions of the squeeze and correction coefficients are given.The squeeze force between the rigid spheres increases linearly or logarithmically with the velocity when most or part of the boundary fluid reaches the yield state,respectively.Furthermore,the slip correction coefficient decreases with the increase in the velocity.The investigation may contribute to the further study of bi-viscosity fluids between rigid spheres with wall slip.

Targeting slug-mediated non-canonical activation of c-Met to overcome chemo-resistance in metastatic ovarian cancer cells

Metastasis-associated drug resistance accounts for high mortality in ovarian cancer and remains to be a major barrier for effective treatment. In this study, SKOV3/T4, a metastatic subpopulation of ovarian cancer SKOV3 cells, was enriched to explore potential interventions against metastaticassociated drug resistance. Quantitative genomic and functional analyses were performed and found that slug was significantly increased in the SKOV3/T4 subpopulation and contributed to the high resistance of SKOV3/T4. Further studies showed that slug activated c-Met in a ligand-independent manner due to elevated levels of fibronectin and provoked integrin α V function, which was confirmed by the significant correlation of slug and p-Met levels in 121 ovarian cancer patient samples. Intriguingly,c-Met inhibitor(s) exhibited greatly enhanced anti-cancer effects in slug-positive ovarian cancer models both in vitro and in vivo. Additionally, IHC analyses revealed that slug levels were highly correlated with reduced survival of ovarian cancer patients. Taken together, this study not only uncovers the critical roles of slug in drug resistance in ovarian cancer but also highlights a promising therapeutic strategy by targeting the noncanonical activation of c-Met in slug-positive ovarian cancer patients with poor prognosis.

Error modeling and compensating of a novel 6-DOF aeroengine rotor docking equipment

In the docking process of aeroengine rotor parts,docking accuracy that indicates the gaps between the end faces is strictly required.A key issue is improving docking accuracy using automated docking equipment.In this paper,a systematic study is carried out on the error modeling and compensation of a novel six-degrees-of-freedom(6-DOF)docking equipment for aeroengine rotors.First,a new model for indicating the main indexes of docking accuracy is proposed.Then,the error model of a specially designed 6-DOF docking equipment is established based on a modified Denavit Hartenberg method with five parameters.Subsequently,two error compensation methods are proposed.Based on the above models,a docking accuracy simulation algorithm is proposed using the Monte Carlo method.Finally,verification experiments are conducted.The results show that,for the maximum values and standard deviations of the gaps between the rotor end-faces in the actual and target positions and attitudes,i.e.,main indexes that represent docking accuracy,the deviation rates between the simulation and experimental results are less than20%.The modeling methods have referential significance.The decline rates of these values are 50–65%when using the two proposed compensation methods.The compensation methods significantly improve the docking accuracy.

Interwoven nickel(II)-dimethylglyoxime nanowires in 3D nickel foam for dendrite-free lithium deposition

Metal skeletons,such as Nickel Foam(NF) has attracted worldwide interests as stable host for lithium metal anode because of its high stability,large specific surface area and high conductivity.However,most metal skeletons have lithophobic surface and uneven current distribution that result in sporadic lithium nucleation and uncontrolled dendrites growth.Herein,we describe a sequential immersing strategy to generate interwoven Nickel(Ⅱ)-dimethylglyoxime(Ni-DMG) nanowires at NF to obtain composite skeleton(NDNF),which can be used as an stable host for Li metal storage.The Ni-DMG has proved effective to realize uniform lithium nucleation and dendrite-free lithium deposition.Combing with the three dimensional(3 D) hierarchical porous structure,the composite host shows a significantly improved coulombic efficiency(CE) than pristine commercial nickel foam.Moreover,the corresponding Li‖Li symmetrical cells can run more than 700 h with low voltage hysteresis 22 mV at 1.0 mA/cm^(2),and Li@NDNF‖LiFePO;full-cell exhibits a high capacity retention of 82.03% at 1.0 C during 630 cycles.These results proved the effectiveness of metal-organic complexes in governing Li metal growth and can be employed as a new strategy for dendrite-free Li metal anode and safe Li metal batteries(LMBs).