In this paper, the methods developed by?[1] are used to analyze flowback data, which involves modeling flow both before and after the breakthrough of formation fluids. Despite the versatility of these techniques, achi...In this paper, the methods developed by?[1] are used to analyze flowback data, which involves modeling flow both before and after the breakthrough of formation fluids. Despite the versatility of these techniques, achieving an optimal combination of parameters is often difficult with a single deterministic analysis. Because of the uncertainty in key model parameters, this problem is an ideal candidate for uncertainty quantification and advanced assisted history-matching techniques, including Monte Carlo (MC) simulation and genetic algorithms (GAs) amongst others. MC simulation, for example, can be used for both the purpose of assisted history-matching and uncertainty quantification of key fracture parameters. In this work, several techniques are tested including both single-objective (SO) and multi-objective (MO) algorithms for history-matching and uncertainty quantification, using a light tight oil (LTO) field case. The results of this analysis suggest that many different algorithms can be used to achieve similar optimization results, making these viable methods for developing an optimal set of key uncertain fracture parameters. An indication of uncertainty can also be achieved, which assists in understanding the range of parameters which can be used to successfully match the flowback data.展开更多
Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with ...Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.展开更多
The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film coo...The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film cooling holes.It has been demonstrated that conventional long-pulse lasers are incapable of meeting the elevated quality surface finish requirements for these holes,a consequence of the severe thermal defects.The employment of backside water-assisted laser drilling technology confers a number of distinct advantages in terms of mitigating laser thermal damage,thus representing a highly promising solution to this challenge.However,significant accumulation of bubbles and machining products during the backside water-assisted laser drilling process has been demonstrated to have a detrimental effect on laser transmission and machining stability,thereby reducing machining quality.In order to surmount these challenges,a novel method has been proposed,namely an ultrasonic shock water flow-assisted picosecond laser drilling technique.Numerical models for ultrasonic acoustic streaming and particle tracking for machining product transport have been established to investigate the mechanism.The simulation results demonstrated that the majority of the machining products could rapidly move away from the machining area because of the action of acoustic streaming,thereby avoiding the accumulation of bubbles and products.Subsequent analysis,comparing the process performance in micro-hole machining,confirmed that the ultrasonic field could effectively eliminate bubble and chip accumulation,thus significantly improving micro-hole quality.Furthermore,the impact of ultrasonic and laser parameters on micro-hole quality under varying machining methods was thoroughly investigated.The findings demonstrated that the novel methodology outlined in this study yielded superior-quality micro-holes at elevated ultrasonic and laser power levels,in conjunction with reduced laser frequency and scanning velocity.The taper of the micro-holes produced by the new method was reduced by more than 25%compared with the other conventional methods.展开更多
Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investi...Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investigates proppant transport behavior in hybrid systems combining self-suspended proppants with conventional 40/70 mesh quartz sand at various mixing ratios.A dedicated experimental apparatus was developed to replicate field-relevant complex fracture networks,consisting of a main fracture and two branching fractures with different deflection angles.Using this system,sand bank formation and proppant distribution were examined for both conventional quartz sand fracturing and fracturing augmented with self-suspended proppants.The effects of slurry discharge volume,proppant mixing ratio,sand ratio,and injection location of the self-suspended proppant on transport and placement behavior were systematically analyzed.According to the results,the incorporation of self-suspended proppants markedly enhances the proppant-carrying capacity of the slurry and substantially modifies sand bank morphology.Increasing the discharge volume raises the inlet slope angle and promotes greater proppant penetration into branch fractures.The proportion of self-suspended proppant governs slurry viscoelasticity and,consequently,proppant settling behavior.As the fraction of self-suspended proppant decreases,the equilibrium height of the sand bank increases,while the proppant mass fraction within branch fractures exhibits a non-monotonic response,initially decreasing and then increasing.Variations in sand ratio alter both overall proppant concentration and the self-suspended proppant-to-water ratio,thereby modulating slurry rheology and influencing proppant placement.In addition,changes in injection location affect near-wellbore vortex structures,leading to distinct sand bank morphologies.展开更多
Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1]....Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1].Depending on the scope of tumor invasion in bile duct,a combined resection of parts of the liver,hepatic ducts,common bile ducts,regional lymph nodes,and even parts of the duodenum and pancreas is necessary,along with biliary and gastrointestinal reconstructions[2].The surgical plan is complex,involving a large resection area and significant trauma.In recent years,laparoscopic or robot assisted radical resection of hilar cholangiocarcinoma has been applied clinically[3,4].With the advanced laparoscopic equipment,many patients undergo hepatopancreatoduodenectomy successfully[5].The limitations of traditional laparoscopic techniques restrict their wide application in clinical practice.However,the Da Vinci robot has been widely applied due to its clear field of vision and flexible manipulation.However,its utilization in hepato-pancreatoduodenectomy for hilar cholangiocarcinoma is still relatively rare.Here,we report a case with hilar cholangiocarcinoma at clinical stage IIIb who underwent robot-assisted hepato-pancreatoduodenectomy.展开更多
Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,...Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,and knee,caused by echinococ cosis.Artificial intelligence(AI)was used to develop a targeted surgical plan and to design a personalized prosthesis.Finite element analysis(FEA)was used to optimize the mechanical effectiveness of a customized integrated replacement prosthesis and to model stress distribution in the surrounding bone.Three-dimensional(3 D)printing was used to fabricate a customized prosthesis.With the assistance of AI,FEA,and 3 D printing technology,a personalized surgical plan and customized prosthesis were successfully constructed based on the patient’s disease.This approach achieved a successful therapeutic effect,demonstrating that AI-assisted personalized medicine holds great promise for the future.展开更多
1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-...1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.展开更多
Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncer...Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].展开更多
Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This charact...Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.展开更多
Microsphere assisted microscopy(MAM)has been rapidly developed to meet the measurement needs of microstructures.MAM can be integrated with optical interference microscopy(OIM)to achieve high lateral resolution surface...Microsphere assisted microscopy(MAM)has been rapidly developed to meet the measurement needs of microstructures.MAM can be integrated with optical interference microscopy(OIM)to achieve high lateral resolution surface profile measurement.However,the microspheres introduce intricate phase changes,resulting in optical path asymmetry which is very challenging to compensate for.This limitation constrains the application of MAM in OIM.In this paper,simulation analysis reveals that the phase transmission of the microsphere is influenced by parameters such as microsphere diameter and its relative position to the sample.It is concluded that a unique compensation process must be adopted for each individual microsphere.Addressing this issue,we proposed a phase compensation algorithm based on the three-dimensional position control of the microsphere and integrated it into our combined system of MAM and white light interferometry(WLI),reducing the phase errors introduced by the microspheres while enhancing the lateral resolution of optical system.This approach improved the profile measurement accuracy,offering a perspective for optically measuring the surface profile of intricate microstructures.展开更多
The unmanned aerial vehicle(UAV)-assisted mobile edge computing(MEC)has been deemed a promising solution for energy-constrained devices to run smart applications with computationintensive and latency-sensitive require...The unmanned aerial vehicle(UAV)-assisted mobile edge computing(MEC)has been deemed a promising solution for energy-constrained devices to run smart applications with computationintensive and latency-sensitive requirements,especially in some infrastructure-limited areas or some emergency scenarios.However,the multi-UAVassisted MEC network remains largely unexplored.In this paper,the dynamic trajectory optimization and computation offloading are studied in a multi-UAVassisted MEC system where multiple UAVs fly over a target area with different trajectories to serve ground users.By considering the dynamic channel condition and random task arrival and jointly optimizing UAVs'trajectories,user association,and subchannel assignment,the average long-term sum of the user energy consumption minimization problem is formulated.To address the problem involving both discrete and continuous variables,a hybrid decision deep reinforcement learning(DRL)-based intelligent energyefficient resource allocation and trajectory optimization algorithm is proposed,named HDRT algorithm,where deep Q network(DQN)and deep deterministic policy gradient(DDPG)are invoked to process discrete and continuous variables,respectively.Simulation results show that the proposed HDRT algorithm converges fast and outperforms other benchmarks in the aspect of user energy consumption and latency.展开更多
The interface microstructures and strain distribution of dissimilar friction stir welding(FSW)of AA7075/AZ31B joints with or without ultrasonic vibration were examined.The results reveal that the ultrasonic vibrations...The interface microstructures and strain distribution of dissimilar friction stir welding(FSW)of AA7075/AZ31B joints with or without ultrasonic vibration were examined.The results reveal that the ultrasonic vibrations and tool offset greatly influence the dynamic recovery towards the Mg side by reducing the non-indexing region at the interface.Moreover,the grain recrystallization near the interface differed from the other areas due to severe deformation.Continuous dynamic recrystallization(CDRX)occurs at the AA7075 side,whereas the Mg side exhibits discontinuous dynamic recrystallization(DDRX).The higher net strain component was observed for ultrasonic-assisted FSW(UVaFSW).The strain component was changed significantly towards the AA7075 side compared with the AZ31B side.It occurred because of different recrystallization mechanisms.The strain component was well spread towards the AA7075 side,whereas the dispersed strain component was observed towards the AZ31B.Along the plate thickness direction,the intermetallic compound layer(IMC)thickness first increases,then decreases,reaching a maximum value of 1.5–1.8 mm from the top.The ultrasonic vibration reduced the overall thickness of intermetallic in the joint interface,regardless of the tool offset conditions.展开更多
The rise in infertility rates has prompted research into the impact of vaginal microbiota on female fertility and the success of assisted reproductive technology(ART).Our study aimed to compare the vaginal microbiome ...The rise in infertility rates has prompted research into the impact of vaginal microbiota on female fertility and the success of assisted reproductive technology(ART).Our study aimed to compare the vaginal microbiome between fertile and infertile women and explore its influence on ART outcomes.Vaginal secretion samples were collected from 194 infertile women and 100 healthy controls at Shanghai Changzheng Hospital.The V3-V4 region of the 16S rRNA gene was amplified using polymerase chain reaction(PCR).A machine learning model was applied to predict infertility based on genus-level abundance,and the PICRUSt algorithm was employed to predict metabolic pathways related to infertility and ART outcomes.The results showed that infertile women exhibited a significantly different vaginal microbial composition compared to healthy controls,along with increased microbial diversity.Notably,the abundance of Burkholderia,Pseudomonas,and Prevotella was significantly elevated in the vaginal microbiota of the infertility group,while that of Bifidobacterium and Lactobacillus was reduced.Among infertile women,those with recurrent implantation failure(RIF)showed even higher vaginal microbial diversity,with specific genera such as Mobiluncus,Peptoniphilus,Prevotella,and Varibaculum being more abundant.Eleven metabolic pathways were identified to be associated with both RIF and infertility,with Prevotella showing stronger correlations with these pathways.This study elucidates differences in vaginal microbiome between healthy and infertile women,providing novel insights into how vaginal microbiota may impact infertility and ART outcomes.Our findings underscore the importance of specific microbial taxa in women with RIF,suggesting potential avenues for targeted interventions to improve embryo transplantation success rates.展开更多
With the continuous escalation of modern war,soldiers need to transport more combat materials to the combat area.The limited load-bearing capacity of soldiers seriously restricts their carrying capacity and mobility.I...With the continuous escalation of modern war,soldiers need to transport more combat materials to the combat area.The limited load-bearing capacity of soldiers seriously restricts their carrying capacity and mobility.It is urgent to develop a power-assisted exoskeleton robot suitable for individual combat.In the past,most power-assisted exoskeleton robots were driven by motors.This driving method has an excellent power-assisted effect,but the endurance is often insufficient.In view of this shortcoming,this study designed an ankle exoskeleton robot based on an active-passive combined drive through simulation analysis of human motion.It used OpenSim software to simulate and verify that the addition of spring could achieve a good effect.At the same time,according to the gait characteristics of the human body,the gait planning of an exoskeleton robot was carried out.Afterwards,theoretical analysis explained that the cooperation among spring,motor and wearer could be realized in this gait.Finally,the assisting ability and driving coordination of the active-passive combination driven ankle exoskeleton robot were verified through experiments.展开更多
Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and...Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and superior electromagnetic shielding properties.However,their poor corrosion resistance and high susceptibility to environmentally assisted cracking(EAC)significantly limit broader application.In recent years,growing attention has been directed toward understanding the corrosion and EAC behavior of Mg-Li alloys,as localized corrosion areas and hydrogen generated during the corrosion process can serve as crack initiation points and promote crack propagation.A comprehensive understanding of these mechanisms is essential for enhancing the reliability and performance of Mg-Li alloys in practical environments.This paper presents a detailed review of corrosion and EAC in Mg-Li alloys,focusing on corrosion behavior,crack initiation and propagation mechanisms,and the key factors influencing these processes.It summarizes recent advances in alloying,heat treatment,mechanical processing,microstructural control,environmental influences,mechanical loading,and surface treatments.In addition,the paper explores future research directions,highlights emerging trends,and proposes strategies to improve the durability and service performance of Mg-Li alloys.展开更多
Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of preci...Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of precipitates during fabrication,which is strongly correlated with defect concentration.For Fe-Ga alloys,giant magnetostriction can be induced by the precipitation of the nanoscale tetragonal L60 phase.By introducing quenched-in vacancies,we significantly enhance the magnetostriction of the aged Fe81Ga19 polycrystalline alloys to~305 ppm,which is close to the level of single crystals.Although vacancies were found to facilitate the generation of the L60 phase,their impact on the precipitation mechanism and kinetics has yet to be revealed.This study combined transmission electron microscopy(TEM)and time-resolved small-angle neutron scattering(SANS)to investigate the precipitation of the L60 phase during the isothermal aging at 350 and 400℃,respectively.The evolution of L60 nanophase in morphology and number density in as-cast(AC)and liquid nitrogen quenched(LN)Fe81Ga19 alloys with aging time were quantitatively compared.Interestingly,the nucleation of the L60 phase proceeds progressively in AC while suddenly in LN specimens,indicating the homogenous to heterogeneous mechanism switching in-duced by concentrated vacancies.Moreover,excess vacancies can change the shape of nanoprecipitates and significantly accelerate the growth and coarsening kinetics.The magnetostrictive coefficient is opti-mized when the size(long-axis)of L60 precipitates lies between 100 and 110Åwith a number density between 3.2-4.3×10-7Å-3.Insight from this study validates the feasibility of achieving high magnetoe-lastic properties through precise manipulation of the nanostructure.展开更多
BACKGROUND The gold standard for colorectal polyp screening is currently colonoscopy,but the miss rate is still high and the adenoma detection rate and polyp detection rate are still low.The risk factors include the p...BACKGROUND The gold standard for colorectal polyp screening is currently colonoscopy,but the miss rate is still high and the adenoma detection rate and polyp detection rate are still low.The risk factors include the patient,operators,and the tools used.The use of artificial intelligence(AI)in colonoscopy has gained popularity by assisting endoscopists in the detection and characterization of polyps.AIM To evaluate the diagnostic performance of AI-assisted colonoscopy[computer assisted diagnosis(CAD)eye function]for colorectal polyp characterization.METHODS This study used a cross-sectional design conducted at the Gastrointestinal Endoscopy Center of Dr.Cipto Mangunkusumo Hospital in January-May 2024 on adult patients with suspected colorectal polyps.RESULTS A total of 60 patients with 100 polyps were involved in this study.Based on the results of the examination,it was found that the AI CAD eye function examination had a sensitivity of 79.17%,specificity of 75.00%,positive predictive value(PPV)of 89.06%,negative predictive value(NPV)of 58.33%,and accuracy of 78.00%.In polyps with diminutive size,sensitivity was 86.27%,specificity was 60.00%,PPV was 95.65%,NPV was 30.00%,and accuracy was 83.93%.Meanwhile,in polyps with non-diminutive size,sensitivity was 61.90%,specificity was 78.26%,PPV was 72.22%,NPV was 69.23%,and accuracy was 70.45%.In polyps on the left side of the colon,sensitivity was 78.85%,specificity was 81.25%,PPV was 93.18%,NPV was 54.17%,and accuracy was 79.41%.Meanwhile,in rightsided polyps the sensitivity was 80.00%,specificity was 66.67%,PPV was 80.00%,NPV was 66.67%,and accuracy was 75.00%.In sessile polyps the sensitivity was 81.54%,specificity was 50.00%,PPV was 91.38%,NPV was 29.41%,and accuracy was 77.33%.Meanwhile,in non-sessile polyps,the sensitivity was 57.14%,specificity was 88.89%,PPV was 66.67%,NPV was 84.21%,and accuracy was 80.00%.CONCLUSION AI CAD eye function examination had a high sensitivity value in diminutive,sessile polyps and right-sided polyps and a high specificity in non-diminutive,non-sessile polyps and left-sided polyps.展开更多
In tissue engineering(TE),tissue-inducing scaffolds are a promising solution for organ and tissue repair owing to their ability to attract stem cells in vivo,thereby inducing endogenous tissue regeneration through top...In tissue engineering(TE),tissue-inducing scaffolds are a promising solution for organ and tissue repair owing to their ability to attract stem cells in vivo,thereby inducing endogenous tissue regeneration through topological cues.An ideal TE scaffold should possess biomimetic cross-scale structures,similar to that of natural extracellular matrices,at the nano-to macro-scale level.Although freeform fabrication of TE scaffolds can be achieved through 3D printing,this method is limited in simultaneously building multiscale structures.To address this challenge,low-temperature fields were adopted in the traditional fabrication processes,such as casting and 3D printing.Ice crystals grow during scaffold fabrication and act as a template to control the nano-and micro-structures.These microstructures can be optimized by adjusting various parameters,such as the direction and magnitude of the low-temperature field.By preserving the macro-features fabricated using traditional methods,additional micro-structures with smaller scales can be incorporated simultaneously,realizing cross-scale structures that provide a better mimic of natural organs and tissues.In this paper,we present a state-of-the-art review of three low-temperature-field-assisted fabrication methods—freeze casting,cryogenic3D printing,and freeze spinning.Fundamental working principles,fabrication setups,processes,and examples of biomedical applications are introduced.The challenges and outlook for low-temperature-assisted fabrication are also discussed.展开更多
In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to ...In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.展开更多
文摘In this paper, the methods developed by?[1] are used to analyze flowback data, which involves modeling flow both before and after the breakthrough of formation fluids. Despite the versatility of these techniques, achieving an optimal combination of parameters is often difficult with a single deterministic analysis. Because of the uncertainty in key model parameters, this problem is an ideal candidate for uncertainty quantification and advanced assisted history-matching techniques, including Monte Carlo (MC) simulation and genetic algorithms (GAs) amongst others. MC simulation, for example, can be used for both the purpose of assisted history-matching and uncertainty quantification of key fracture parameters. In this work, several techniques are tested including both single-objective (SO) and multi-objective (MO) algorithms for history-matching and uncertainty quantification, using a light tight oil (LTO) field case. The results of this analysis suggest that many different algorithms can be used to achieve similar optimization results, making these viable methods for developing an optimal set of key uncertain fracture parameters. An indication of uncertainty can also be achieved, which assists in understanding the range of parameters which can be used to successfully match the flowback data.
基金supported by the National Science Foundation for Distinguished Young Scholars of China(No.52325506)the Fundamental Research Funds for the Central Universities(No.DUT22LAB501)。
文摘Ultrasonic-Assisted Grinding(UAG)is a novel manufacturing technology that shows promising promise for use in processing Ceramic Matrix Composites(CMCs).Nevertheless,analyzing the material removal process of CMCs with multidirectional structure during UAG is challenging,impeding the progress and improvement of the UAG process.This work examined the impact of ultrasonic vibration on the dynamic mechanical characteristics during processing.Additionally,we experimentally elucidated the material removal mechanism of CMCs during the scratching process under the influence of vertical vibration.The results indicate that the introduction of ultrasonic vibration causes a strain rate effect,resulting in a modification of the material removal mechanism,subsequently impacting the processing quality.Ultrasonic vibration increases the dynamic strength and brittleness of the fibers in CMCs,leading to more cracks at fracture,which changes from the original bending fracture to shear fracture.In addition,ultrasonic vibration can effectively inhibit the impact of scratching depth and anisotropy on the removal mechanism of CMCs,resulting in a more uniform surface of CMCs after processing.
基金supported by the National Natural Science Foundation of China(No.52205468,No.52275431,No.52375186)China Postdoctoral Science Foundation(No.2025M771349)Zhejiang Province Natural Science Foundation(No.LD22E050001)。
文摘The latest generation of aero engines has set higher standards for thrust-to-weight ratio and energy conversion efficiency,making it imperative to address the challenge of efficiently and accurately machining film cooling holes.It has been demonstrated that conventional long-pulse lasers are incapable of meeting the elevated quality surface finish requirements for these holes,a consequence of the severe thermal defects.The employment of backside water-assisted laser drilling technology confers a number of distinct advantages in terms of mitigating laser thermal damage,thus representing a highly promising solution to this challenge.However,significant accumulation of bubbles and machining products during the backside water-assisted laser drilling process has been demonstrated to have a detrimental effect on laser transmission and machining stability,thereby reducing machining quality.In order to surmount these challenges,a novel method has been proposed,namely an ultrasonic shock water flow-assisted picosecond laser drilling technique.Numerical models for ultrasonic acoustic streaming and particle tracking for machining product transport have been established to investigate the mechanism.The simulation results demonstrated that the majority of the machining products could rapidly move away from the machining area because of the action of acoustic streaming,thereby avoiding the accumulation of bubbles and products.Subsequent analysis,comparing the process performance in micro-hole machining,confirmed that the ultrasonic field could effectively eliminate bubble and chip accumulation,thus significantly improving micro-hole quality.Furthermore,the impact of ultrasonic and laser parameters on micro-hole quality under varying machining methods was thoroughly investigated.The findings demonstrated that the novel methodology outlined in this study yielded superior-quality micro-holes at elevated ultrasonic and laser power levels,in conjunction with reduced laser frequency and scanning velocity.The taper of the micro-holes produced by the new method was reduced by more than 25%compared with the other conventional methods.
基金the China National Petroleum Corporation’s Forward-Looking Fundamental Technology Breakthrough Project(2021DJ2305).
文摘Self-suspended proppants,which enable clear-water fracturing,represent a promising new class of materials for reservoir stimulation.Given the economic limitations associated with their exclusive use,this study investigates proppant transport behavior in hybrid systems combining self-suspended proppants with conventional 40/70 mesh quartz sand at various mixing ratios.A dedicated experimental apparatus was developed to replicate field-relevant complex fracture networks,consisting of a main fracture and two branching fractures with different deflection angles.Using this system,sand bank formation and proppant distribution were examined for both conventional quartz sand fracturing and fracturing augmented with self-suspended proppants.The effects of slurry discharge volume,proppant mixing ratio,sand ratio,and injection location of the self-suspended proppant on transport and placement behavior were systematically analyzed.According to the results,the incorporation of self-suspended proppants markedly enhances the proppant-carrying capacity of the slurry and substantially modifies sand bank morphology.Increasing the discharge volume raises the inlet slope angle and promotes greater proppant penetration into branch fractures.The proportion of self-suspended proppant governs slurry viscoelasticity and,consequently,proppant settling behavior.As the fraction of self-suspended proppant decreases,the equilibrium height of the sand bank increases,while the proppant mass fraction within branch fractures exhibits a non-monotonic response,initially decreasing and then increasing.Variations in sand ratio alter both overall proppant concentration and the self-suspended proppant-to-water ratio,thereby modulating slurry rheology and influencing proppant placement.In addition,changes in injection location affect near-wellbore vortex structures,leading to distinct sand bank morphologies.
文摘Based on the Bismuth-Corlette classification of hilar cholangiocarcinoma,the patients with types I,II,and III can undergo radical resection in the absence of extensive intrahepatic metastasis and vascular invasion[1].Depending on the scope of tumor invasion in bile duct,a combined resection of parts of the liver,hepatic ducts,common bile ducts,regional lymph nodes,and even parts of the duodenum and pancreas is necessary,along with biliary and gastrointestinal reconstructions[2].The surgical plan is complex,involving a large resection area and significant trauma.In recent years,laparoscopic or robot assisted radical resection of hilar cholangiocarcinoma has been applied clinically[3,4].With the advanced laparoscopic equipment,many patients undergo hepatopancreatoduodenectomy successfully[5].The limitations of traditional laparoscopic techniques restrict their wide application in clinical practice.However,the Da Vinci robot has been widely applied due to its clear field of vision and flexible manipulation.However,its utilization in hepato-pancreatoduodenectomy for hilar cholangiocarcinoma is still relatively rare.Here,we report a case with hilar cholangiocarcinoma at clinical stage IIIb who underwent robot-assisted hepato-pancreatoduodenectomy.
基金partially supported by the National Natural Science Foundation of China(Nos.32471474 and 82102574)the Precision Medicine Project of People’s Hospital of Xinjiang Uygur Autonomous Region(No.20220305)+4 种基金Chengdu Advanced Metal Materials Industry Technology Research Institute Co.,Ltd.Support Project(No.24H0802)Sichuan Science and Technology Program(Nos.2025YFHZ0086,2023YFS0053,2024YFHZ0125,and 2025ZNSFSC0381)Project of Tianfu Jincheng Laboratory(No.2025ZH009)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515220102)Xinjiang Autonomous Region Science and Technology Support Project Plan(Directive)Project(No.2024E02049)。
文摘Cases of widespread bone hydatid infection are relatively rare in clinical practice.In this study,we reported for the first time a validated integrated repair therapy for multiple bone tissues,including the hip,femur,and knee,caused by echinococ cosis.Artificial intelligence(AI)was used to develop a targeted surgical plan and to design a personalized prosthesis.Finite element analysis(FEA)was used to optimize the mechanical effectiveness of a customized integrated replacement prosthesis and to model stress distribution in the surrounding bone.Three-dimensional(3 D)printing was used to fabricate a customized prosthesis.With the assistance of AI,FEA,and 3 D printing technology,a personalized surgical plan and customized prosthesis were successfully constructed based on the patient’s disease.This approach achieved a successful therapeutic effect,demonstrating that AI-assisted personalized medicine holds great promise for the future.
基金supported by the National Natural Science Foundation of China(No.52061135101 and 52001078)the German Research Foundation(DFG,No.448318292)+3 种基金the Technology Innovation Guidance Special Foundation of Shaanxi Province(No.2023GXLH-085)the Fundamental Research Funds for the Central Universities(No.D5000240161)the Project of Key areas of innovation team in Shaanxi Province(No.2024RS-CXTD-20)The author Yingchun Xie thanks the support from the National Key R&D Program(No.2023YFE0108000).
文摘1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.
文摘Assisted hatching(AH)is commonly performed before trophectoderm(TE)biopsy for preimplantation genetic testing for aneuploidy(PGT-A),yet whether AH timing influences the detection of chromosomal mosaicism remains uncertain.Beyond timing,procedural choices in PGT-A must balance diagnostic yield against potential harm from additional handling(e.g.,repeat TE biopsy or cryopreservation steps),as underscored by a recent systematic review and meta-analysis[1].
基金supported by the National Natural Science Foundation of China(Grant No.52206165)。
文摘Flammable ionic liquids exhibit high conductivity and a broad electrochemical window,enabling the generation of combustible gases for combustion via electrochemical decomposition and thermal decomposition.This characteristic holds significant implications in the realm of novel satellite propulsion.Introducing a fraction of the electrical energy into energetic ionic liquid fuels,the thermal decomposition process is facilitated by reducing the apparent activation energy required,and electrical energy can trigger the electrochemical decomposition of ionic liquids,presenting a promising approach to enhance combustion efficiency and energy release.This study applied an external voltage during the thermal decomposition of 1-ethyl-3-methylimidazole nitrate([EMIm]NO_(3)),revealing the effective alteration of the activation energy of[EMIm]NO_(3).The pyrolysis,electrochemical decomposition,and electron assisted enhancement products were identified through Thermogravimetry-Differential scanning calorimetry-Fourier transform infrared-Mass spectrometry(TG-DSC-FTIR-MS)and gas chromatography(GC)analyses,elucidating the degradation mechanism of[EMIm]NO_(3).Furthermore,an external voltage was introduced during the combustion of[EMIm]NO_(3),demonstrating the impact of voltage on the combustion process.
基金supported by National Natural Science Foundation of China(No.52275540).
文摘Microsphere assisted microscopy(MAM)has been rapidly developed to meet the measurement needs of microstructures.MAM can be integrated with optical interference microscopy(OIM)to achieve high lateral resolution surface profile measurement.However,the microspheres introduce intricate phase changes,resulting in optical path asymmetry which is very challenging to compensate for.This limitation constrains the application of MAM in OIM.In this paper,simulation analysis reveals that the phase transmission of the microsphere is influenced by parameters such as microsphere diameter and its relative position to the sample.It is concluded that a unique compensation process must be adopted for each individual microsphere.Addressing this issue,we proposed a phase compensation algorithm based on the three-dimensional position control of the microsphere and integrated it into our combined system of MAM and white light interferometry(WLI),reducing the phase errors introduced by the microspheres while enhancing the lateral resolution of optical system.This approach improved the profile measurement accuracy,offering a perspective for optically measuring the surface profile of intricate microstructures.
基金supported by National Natural Science Foundation of China(No.62471254)National Natural Science Foundation of China(No.92367302)。
文摘The unmanned aerial vehicle(UAV)-assisted mobile edge computing(MEC)has been deemed a promising solution for energy-constrained devices to run smart applications with computationintensive and latency-sensitive requirements,especially in some infrastructure-limited areas or some emergency scenarios.However,the multi-UAVassisted MEC network remains largely unexplored.In this paper,the dynamic trajectory optimization and computation offloading are studied in a multi-UAVassisted MEC system where multiple UAVs fly over a target area with different trajectories to serve ground users.By considering the dynamic channel condition and random task arrival and jointly optimizing UAVs'trajectories,user association,and subchannel assignment,the average long-term sum of the user energy consumption minimization problem is formulated.To address the problem involving both discrete and continuous variables,a hybrid decision deep reinforcement learning(DRL)-based intelligent energyefficient resource allocation and trajectory optimization algorithm is proposed,named HDRT algorithm,where deep Q network(DQN)and deep deterministic policy gradient(DDPG)are invoked to process discrete and continuous variables,respectively.Simulation results show that the proposed HDRT algorithm converges fast and outperforms other benchmarks in the aspect of user energy consumption and latency.
基金supported by postdoctoral program of Shandong University,Jinan,Chinathe financial support from the National Natural Science Foundation of China(Grant Nos.52035005)the Key R&D Program of Shandong Province in China(Grant No.2021ZLGX01)。
文摘The interface microstructures and strain distribution of dissimilar friction stir welding(FSW)of AA7075/AZ31B joints with or without ultrasonic vibration were examined.The results reveal that the ultrasonic vibrations and tool offset greatly influence the dynamic recovery towards the Mg side by reducing the non-indexing region at the interface.Moreover,the grain recrystallization near the interface differed from the other areas due to severe deformation.Continuous dynamic recrystallization(CDRX)occurs at the AA7075 side,whereas the Mg side exhibits discontinuous dynamic recrystallization(DDRX).The higher net strain component was observed for ultrasonic-assisted FSW(UVaFSW).The strain component was changed significantly towards the AA7075 side compared with the AZ31B side.It occurred because of different recrystallization mechanisms.The strain component was well spread towards the AA7075 side,whereas the dispersed strain component was observed towards the AZ31B.Along the plate thickness direction,the intermetallic compound layer(IMC)thickness first increases,then decreases,reaching a maximum value of 1.5–1.8 mm from the top.The ultrasonic vibration reduced the overall thickness of intermetallic in the joint interface,regardless of the tool offset conditions.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1303900)the National Natural Science Foundation of China(Grant No.82271662)the Shanghai Municipal Health Commission Discipline Leader Training Program(Grant No.2022XD003).
文摘The rise in infertility rates has prompted research into the impact of vaginal microbiota on female fertility and the success of assisted reproductive technology(ART).Our study aimed to compare the vaginal microbiome between fertile and infertile women and explore its influence on ART outcomes.Vaginal secretion samples were collected from 194 infertile women and 100 healthy controls at Shanghai Changzheng Hospital.The V3-V4 region of the 16S rRNA gene was amplified using polymerase chain reaction(PCR).A machine learning model was applied to predict infertility based on genus-level abundance,and the PICRUSt algorithm was employed to predict metabolic pathways related to infertility and ART outcomes.The results showed that infertile women exhibited a significantly different vaginal microbial composition compared to healthy controls,along with increased microbial diversity.Notably,the abundance of Burkholderia,Pseudomonas,and Prevotella was significantly elevated in the vaginal microbiota of the infertility group,while that of Bifidobacterium and Lactobacillus was reduced.Among infertile women,those with recurrent implantation failure(RIF)showed even higher vaginal microbial diversity,with specific genera such as Mobiluncus,Peptoniphilus,Prevotella,and Varibaculum being more abundant.Eleven metabolic pathways were identified to be associated with both RIF and infertility,with Prevotella showing stronger correlations with these pathways.This study elucidates differences in vaginal microbiome between healthy and infertile women,providing novel insights into how vaginal microbiota may impact infertility and ART outcomes.Our findings underscore the importance of specific microbial taxa in women with RIF,suggesting potential avenues for targeted interventions to improve embryo transplantation success rates.
基金the National Natural Science Foundation of China(No.52075264)。
文摘With the continuous escalation of modern war,soldiers need to transport more combat materials to the combat area.The limited load-bearing capacity of soldiers seriously restricts their carrying capacity and mobility.It is urgent to develop a power-assisted exoskeleton robot suitable for individual combat.In the past,most power-assisted exoskeleton robots were driven by motors.This driving method has an excellent power-assisted effect,but the endurance is often insufficient.In view of this shortcoming,this study designed an ankle exoskeleton robot based on an active-passive combined drive through simulation analysis of human motion.It used OpenSim software to simulate and verify that the addition of spring could achieve a good effect.At the same time,according to the gait characteristics of the human body,the gait planning of an exoskeleton robot was carried out.Afterwards,theoretical analysis explained that the cooperation among spring,motor and wearer could be realized in this gait.Finally,the assisting ability and driving coordination of the active-passive combination driven ankle exoskeleton robot were verified through experiments.
基金supported by the National Natural Science Foundation of China Projects under Grant(nos.52301112,52331004,U21A2049,and 51871211)Guangdong Basic and Applied Basic Research Foundation(Grant no.2024A1515030065)+4 种基金Basic and Applied Basic Research Project of Guangzhou(Grant no.2024A04J6299)LiaoNing Revitalization Talents Program(XLYC1907062,and XLYC2403026)Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program(RC231178)the Fundamental Research Funds for the Central Universities(N25GFY002)the Innovation Fund of Institute of Metal Research(IMR),Chinese Academy of Sciences(CAS).
文摘Mg-Li alloys hold significant potential for applications in aerospace,automotive manufacturing,military weaponry,and biomedical implants,due to their excellent recyclability,high specific strength,biocompatibility,and superior electromagnetic shielding properties.However,their poor corrosion resistance and high susceptibility to environmentally assisted cracking(EAC)significantly limit broader application.In recent years,growing attention has been directed toward understanding the corrosion and EAC behavior of Mg-Li alloys,as localized corrosion areas and hydrogen generated during the corrosion process can serve as crack initiation points and promote crack propagation.A comprehensive understanding of these mechanisms is essential for enhancing the reliability and performance of Mg-Li alloys in practical environments.This paper presents a detailed review of corrosion and EAC in Mg-Li alloys,focusing on corrosion behavior,crack initiation and propagation mechanisms,and the key factors influencing these processes.It summarizes recent advances in alloying,heat treatment,mechanical processing,microstructural control,environmental influences,mechanical loading,and surface treatments.In addition,the paper explores future research directions,highlights emerging trends,and proposes strategies to improve the durability and service performance of Mg-Li alloys.
基金supported by the National Natural Science Foundation of China(Grant No.12275154)the Guangdong Basic and Applied Basic Research Foundation,China(Project No.2021B1515140028)+1 种基金the Youth Innovation Promotion Association,CAS(No.2020010)the National Key Research and Development Program of China,grant number(Nos.2021YFA1600701 and 2021YFB3501201).
文摘Solid-state precipitation is an effective strategy for tuning the mechanical and functional properties of ad-vanced alloys.Structure design and modification necessitate good knowledge of the kinetic evolution of precipitates during fabrication,which is strongly correlated with defect concentration.For Fe-Ga alloys,giant magnetostriction can be induced by the precipitation of the nanoscale tetragonal L60 phase.By introducing quenched-in vacancies,we significantly enhance the magnetostriction of the aged Fe81Ga19 polycrystalline alloys to~305 ppm,which is close to the level of single crystals.Although vacancies were found to facilitate the generation of the L60 phase,their impact on the precipitation mechanism and kinetics has yet to be revealed.This study combined transmission electron microscopy(TEM)and time-resolved small-angle neutron scattering(SANS)to investigate the precipitation of the L60 phase during the isothermal aging at 350 and 400℃,respectively.The evolution of L60 nanophase in morphology and number density in as-cast(AC)and liquid nitrogen quenched(LN)Fe81Ga19 alloys with aging time were quantitatively compared.Interestingly,the nucleation of the L60 phase proceeds progressively in AC while suddenly in LN specimens,indicating the homogenous to heterogeneous mechanism switching in-duced by concentrated vacancies.Moreover,excess vacancies can change the shape of nanoprecipitates and significantly accelerate the growth and coarsening kinetics.The magnetostrictive coefficient is opti-mized when the size(long-axis)of L60 precipitates lies between 100 and 110Åwith a number density between 3.2-4.3×10-7Å-3.Insight from this study validates the feasibility of achieving high magnetoe-lastic properties through precise manipulation of the nanostructure.
文摘BACKGROUND The gold standard for colorectal polyp screening is currently colonoscopy,but the miss rate is still high and the adenoma detection rate and polyp detection rate are still low.The risk factors include the patient,operators,and the tools used.The use of artificial intelligence(AI)in colonoscopy has gained popularity by assisting endoscopists in the detection and characterization of polyps.AIM To evaluate the diagnostic performance of AI-assisted colonoscopy[computer assisted diagnosis(CAD)eye function]for colorectal polyp characterization.METHODS This study used a cross-sectional design conducted at the Gastrointestinal Endoscopy Center of Dr.Cipto Mangunkusumo Hospital in January-May 2024 on adult patients with suspected colorectal polyps.RESULTS A total of 60 patients with 100 polyps were involved in this study.Based on the results of the examination,it was found that the AI CAD eye function examination had a sensitivity of 79.17%,specificity of 75.00%,positive predictive value(PPV)of 89.06%,negative predictive value(NPV)of 58.33%,and accuracy of 78.00%.In polyps with diminutive size,sensitivity was 86.27%,specificity was 60.00%,PPV was 95.65%,NPV was 30.00%,and accuracy was 83.93%.Meanwhile,in polyps with non-diminutive size,sensitivity was 61.90%,specificity was 78.26%,PPV was 72.22%,NPV was 69.23%,and accuracy was 70.45%.In polyps on the left side of the colon,sensitivity was 78.85%,specificity was 81.25%,PPV was 93.18%,NPV was 54.17%,and accuracy was 79.41%.Meanwhile,in rightsided polyps the sensitivity was 80.00%,specificity was 66.67%,PPV was 80.00%,NPV was 66.67%,and accuracy was 75.00%.In sessile polyps the sensitivity was 81.54%,specificity was 50.00%,PPV was 91.38%,NPV was 29.41%,and accuracy was 77.33%.Meanwhile,in non-sessile polyps,the sensitivity was 57.14%,specificity was 88.89%,PPV was 66.67%,NPV was 84.21%,and accuracy was 80.00%.CONCLUSION AI CAD eye function examination had a high sensitivity value in diminutive,sessile polyps and right-sided polyps and a high specificity in non-diminutive,non-sessile polyps and left-sided polyps.
基金National Natural Science Foundation Council of China(Grant No.52305359)Hubei Provincial Natural Science Foundation of China(Grant No.2023AFB141)National Medical Products Administration Key Laboratory for Dental Materials(PKUSS20240401)。
文摘In tissue engineering(TE),tissue-inducing scaffolds are a promising solution for organ and tissue repair owing to their ability to attract stem cells in vivo,thereby inducing endogenous tissue regeneration through topological cues.An ideal TE scaffold should possess biomimetic cross-scale structures,similar to that of natural extracellular matrices,at the nano-to macro-scale level.Although freeform fabrication of TE scaffolds can be achieved through 3D printing,this method is limited in simultaneously building multiscale structures.To address this challenge,low-temperature fields were adopted in the traditional fabrication processes,such as casting and 3D printing.Ice crystals grow during scaffold fabrication and act as a template to control the nano-and micro-structures.These microstructures can be optimized by adjusting various parameters,such as the direction and magnitude of the low-temperature field.By preserving the macro-features fabricated using traditional methods,additional micro-structures with smaller scales can be incorporated simultaneously,realizing cross-scale structures that provide a better mimic of natural organs and tissues.In this paper,we present a state-of-the-art review of three low-temperature-field-assisted fabrication methods—freeze casting,cryogenic3D printing,and freeze spinning.Fundamental working principles,fabrication setups,processes,and examples of biomedical applications are introduced.The challenges and outlook for low-temperature-assisted fabrication are also discussed.
基金supported in part by the National Natural Science Foundation of China under Grants 62325107,62341107,62261160650,and U23A20272in part by the Beijing Natural Science Foundation under Grant L222002.
文摘In this paper,we propose a sub-6GHz channel assisted hybrid beamforming(HBF)for mmWave system under both line-of-sight(LOS)and non-line-of-sight(NLOS)scenarios without mmWave channel estimation.Meanwhile,we resort to the selfsupervised approach to eliminate the need for labels,thus avoiding the accompanied high cost of data collection and annotation.We first construct the dense connection network(DCnet)with three modules:the feature extraction module for extracting channel characteristic from a large amount of channel data,the feature fusion module for combining multidimensional features,and the prediction module for generating the HBF matrices.Next,we establish a lightweight network architecture,named as LDnet,to reduce the number of model parameters and computational complexity.The proposed sub-6GHz assisted approach eliminates mmWave pilot resources compared to the method using mmWave channel information directly.The simulation results indicate that the proposed DCnet and LDnet can achieve the spectral efficiency that is superior to the traditional orthogonal matching pursuit(OMP)algorithm by 13.66% and 10.44% under LOS scenarios and by 32.35% and 27.75% under NLOS scenarios,respectively.Moreover,the LDnet achieves 98.52% reduction in the number of model parameters and 22.93% reduction in computational complexity compared to DCnet.
