Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,an...Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.展开更多
P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned fractures.However,there are few existing models that incorporate the multiple wave attenuation me...P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned fractures.However,there are few existing models that incorporate the multiple wave attenuation mechanisms from the microscopic scale to the macroscopic scale.Hence,in this work,we developed a unified model to incorporate the wave attenuation mechanisms at different scales,which includes the microscopic squirt flow between the microcracks and pores,the mesoscopic wave-induced fluid flow between fractures and background(FB-WIFF),and the macroscopic Biot's global flow and elastic scattering(ES)from the fractures.Using Tang's modified Biot's theory and the mixed-boundary conditions,we derived the exact frequency-dependent solutions of the scattering problem for a single penny-shaped fracture with oblique incident P-and SV-waves.We then developed theoretical models for a set of aligned fractures and randomly oriented fractures using the Foldy approximation.The results indicated that microcrack squirt flow considerably influences the dispersion and attenuation of P-and SV-wave velocities.The coupling effects of microcrack squirt flow with the FB-WIFF and ES of fractures cause much higher velocity dispersion and attenuation for P waves than for SV waves.Randomly oriented fractures substantially reduce the attenuation caused by the FB-WIFF and ES,particularly for the ES attenuation of SV waves.Through a comparison with existing models in the limiting cases and previous experimental measurements,we validated our model.展开更多
Mechanically aligned total knee arthroplasty (TKA) for valgus knee is considered a “challenging surgery.” Recently, the kinematic alignment (KA) method has gained attention. This study aimed to present objective cli...Mechanically aligned total knee arthroplasty (TKA) for valgus knee is considered a “challenging surgery.” Recently, the kinematic alignment (KA) method has gained attention. This study aimed to present objective clinical data, such as intraoperative balance assessment and radiographic evaluation of postoperative lower extremity alignment after TKA using the KA method for valgus deformity. Twenty-one TKA knees (mean age, 74 years;2 males, 19 females) with KA for severe valgus deformity (hip-knee-ankle-angle ≥ 10°) performed at our department in the past 3 years were included in this study. Intraoperative gap and balance measurements and postoperative radiographic evaluation were performed. A total arc of range of motion was achieved up to 98% of preoperative values at 3 weeks postoperatively. Intraoperative gap and balance were stable throughout the entire range of motion. In addition, there were no statistically significant differences in either balance or gap values at each flexion angle. KA TKA is a “simple surgery” rather than a “challenging surgery” because additional soft tissue procedures are not required, operative time is short, intraoperative and postoperative balance is very stable, and a good alignment is achieved. This procedure may relieve surgeons of the stress of TKA for valgus deformities.展开更多
In wireless communication networks,mobile users in overlapping areas may experience severe interference,therefore,designing effective Interference Management(IM)methods is crucial to improving network performance.Howe...In wireless communication networks,mobile users in overlapping areas may experience severe interference,therefore,designing effective Interference Management(IM)methods is crucial to improving network performance.However,when managing multiple disturbances from the same source,it may not be feasible to use existing IM methods such as Interference Alignment(IA)and Interference Steering(IS)exclusively.It is because with IA,the aligned interference becomes indistinguishable at its desired Receiver(Rx)under the cost constraint of Degrees-of-Freedom(DoF),while with IS,more transmit power will be consumed in the direct and repeated application of IS to each interference.To remedy these deficiencies,Interference Alignment Steering(IAS)is proposed by incorporating IA and IS and exploiting their advantages in IM.With IAS,the interfering Transmitter(Tx)first aligns one interference incurred by the transmission of one data stream to a one-dimensional subspace orthogonal to the desired transmission at the interfered Rx,and then the remaining interferences are treated as a whole and steered to the same subspace as the aligned interference.Moreover,two improved versions of IAS,i.e.,IAS with Full Adjustment at the Interfering Tx(IAS-FAIT)and Interference Steering and Alignment(ISA),are presented.The former considers the influence of IA on the interfering user-pair's performance.The orthogonality between the desired signals at the interfered Rx can be maintained by adjusting the spatial characteristics of all interferences and the aligned interference components,thus ensuring the Spectral Efficiency(SE)of the interfering communication pairs.Under ISA,the power cost for IS at the interfered Tx is minimized,hence improving SE performance of the interfered communication-pairs.Since the proposed methods are realized at the interfering and interfered Txs cooperatively,the expenses of IM are shared by both communication-pairs.Our in-depth simulation results show that joint use of IA and IS can effectively manage multiple disturbances from the same source and improve the system's SE.展开更多
In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Lar...In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist.展开更多
Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-b...Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.展开更多
Accurate forecasting of time series is crucial across various domains.Many prediction tasks rely on effectively segmenting,matching,and time series data alignment.For instance,regardless of time series with the same g...Accurate forecasting of time series is crucial across various domains.Many prediction tasks rely on effectively segmenting,matching,and time series data alignment.For instance,regardless of time series with the same granularity,segmenting them into different granularity events can effectively mitigate the impact of varying time scales on prediction accuracy.However,these events of varying granularity frequently intersect with each other,which may possess unequal durations.Even minor differences can result in significant errors when matching time series with future trends.Besides,directly using matched events but unaligned events as state vectors in machine learning-based prediction models can lead to insufficient prediction accuracy.Therefore,this paper proposes a short-term forecasting method for time series based on a multi-granularity event,MGE-SP(multi-granularity event-based short-termprediction).First,amethodological framework for MGE-SP established guides the implementation steps.The framework consists of three key steps,including multi-granularity event matching based on the LTF(latest time first)strategy,multi-granularity event alignment using a piecewise aggregate approximation based on the compression ratio,and a short-term prediction model based on XGBoost.The data from a nationwide online car-hailing service in China ensures the method’s reliability.The average RMSE(root mean square error)and MAE(mean absolute error)of the proposed method are 3.204 and 2.360,lower than the respective values of 4.056 and 3.101 obtained using theARIMA(autoregressive integratedmoving average)method,as well as the values of 4.278 and 2.994 obtained using k-means-SVR(support vector regression)method.The other experiment is conducted on stock data froma public data set.The proposed method achieved an average RMSE and MAE of 0.836 and 0.696,lower than the respective values of 1.019 and 0.844 obtained using the ARIMA method,as well as the values of 1.350 and 1.172 obtained using the k-means-SVR method.展开更多
Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients’facial aesthetics and mental health.The...Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients’facial aesthetics and mental health.The traditional orthodontic treatment strategy often involves extracting 4 first premolars and conventional fixed techniques,combined with mini-implant screws,to retract the anterior teeth and improve facial protrusion.In recent years,an invisible orthodontic technique,without brackets,has become increasingly popular.However,while an invisible aligner has been used in some cases with reasonable results,there remain significant challenges in achieving a perfect outcome.This case report presents an adolescent patient with bimaxillary protrusion and mandibular retrognathia.Based on the characteristics of the invisible aligners and the growth characteristics of the adolescent’s teeth and jawbone,we designed precise three-dimensional tooth movement and corresponding resistance/over-correction for each tooth,while utilizing the patient’s jawbone growth potential to promote rapid development of the mandible,accurately and efficiently correcting bimaxillary protrusion and skeletal mandibular retrognathia.The patient’s facial aesthetics,especially the lateral morphology,have been greatly improved,and various aesthetic indicators have also shown significant changes,and to the patient’s great benefit,invasive mini-implant screws were not used during the treatment.This case highlights the advantages of using invisible aligners in adolescent maxillary protrusion combined with mandibular retraction patients.Furthermore,comprehensive and accurate design combined with good application of growth potential can also enable invisible orthodontic technology to achieve perfect treatment effects in tooth extractions,providing clinical guidance for orthodontists.展开更多
In this paper, we investigate a 1D pressureless Euler-alignment system with a non-local alignment term, describing a kind of self-organizing problem for flocking. As a result, by the transport equation theory and Lagr...In this paper, we investigate a 1D pressureless Euler-alignment system with a non-local alignment term, describing a kind of self-organizing problem for flocking. As a result, by the transport equation theory and Lagrange coordinate transformation, the local well-posedness of the solutions for the 1D pressureless Euler-alignment in Besov spaces with 1≤p∞ is established. Next, the ill-posedness of the solutions for this model in Besov spaces with 1≤p and is also deduced. Finally, the precise blow-up criteria of the solutions for this system is presented in Besov spaces with 1≤p .展开更多
With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel(CA) with highly enhanced thermal conductivity(TC) in vertical...With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel(CA) with highly enhanced thermal conductivity(TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires(SiC NWs)/boron nitride(BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m^(-1) K^(-1) at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy(EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 10^(11) Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of-21.5 dB and a wide effective absorption bandwidth(<-10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.展开更多
Aligned SnS nanowires arrays were grown via a simple chemical vapor deposition method.As-synthesized SnS nanowires are single crystals grown along the[111]direction.The single SnS nanowire based device showed excellen...Aligned SnS nanowires arrays were grown via a simple chemical vapor deposition method.As-synthesized SnS nanowires are single crystals grown along the[111]direction.The single SnS nanowire based device showed excellent response to near infrared lights with good responsivity of 267.9 A/W,high external quantum efficiency of 3.12×10^4%and fast response time.Photodetectors were built on the aligned SnS nanowire arrays,exhibiting a light on/off ratio of 3.6,and the response and decay time of 4.5 and 0.7 s,respectively,to 1064 nm light illumination.展开更多
We develop a general approach to the fabrication of films with unidirectional grooves, such as silicon nitride, silicon dioxide and aluminium oxide, in which the surface is not required to be treated. Super-aligned ca...We develop a general approach to the fabrication of films with unidirectional grooves, such as silicon nitride, silicon dioxide and aluminium oxide, in which the surface is not required to be treated. Super-aligned carbon nanotube (SACNT) film may be used as a template and as sacrificial layer, which is subsequently removed by heating in an atmosphere of air. The unidirectional morphology of the SACNT film turns into a desired film, which is found to possess the ability to align liquid crystal molecules. This approach also features high efficiency, low cost and easy scaling-up for mass production.展开更多
Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic ...Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic techniques vastly en-hancing the feasibility of applying polarization channels,the data fidelity in reconstructed bits has been constrained by severe crosstalks occurring between varied polarization angles during data recording and reading process,which gravely hindered the utilization of this technique in practice.In this paper,we demonstrate an ultra-low crosstalk polarization-en-coding multilayer ODS technique for high-fidelity data recording and retrieving by utilizing a nanofibre-based nanocom-posite film involving highly aligned gold nanorods(GNRs).With parallelizing the gold nanorods in the recording medium,the information carrier configuration minimizes miswriting and misreading possibilities for information input and output,respectively,compared with its randomly self-assembled counterparts.The enhanced data accuracy has significantly im-proved the bit recall fidelity that is quantified by a correlation coefficient higher than 0.99.It is anticipated that the demon-strated technique can facilitate the development of multiplexing ODS for a greener future.展开更多
Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic ...Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.展开更多
To investigate the contribution of fibre arrangement to guiding the aligned growth of corneal stroma cells,aligned and randomly oriented fibrous scaffolds of gelatin and poly-L-lactic acid(PLLA) were fabricated by e...To investigate the contribution of fibre arrangement to guiding the aligned growth of corneal stroma cells,aligned and randomly oriented fibrous scaffolds of gelatin and poly-L-lactic acid(PLLA) were fabricated by electrospinning.A comparative study of two different systems with corneal stroma cells on randomly organized and aligned fibres were conducted.The efficiency of the scaffolds for inducing the aligned growth of cells was assessed by morphological observation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide(MTT) assay.Results show that the cells cultured on both randomly oriented and aligned scaffolds maintained normal morphology and well spreading as well as long term proliferation.Importantly,corneal stroma cells grew high orderly on the aligned scaffold,while the cells grew disordered on the randomly oriented scaffold.Moreover,the cells exhibited higher viability in aligned scaffold than that in randomly oriented scaffold.These results indcate that electrospinng to prepare aligned fibrous scaffolds has provided an effective approach to the aligned growth of corneal stroma cells in vitro.Our findings that fiber arrangement plays a crucial role in guiding the aligned growth of cells may be helpful to the development of better biomaterials for tissue engineered cornea.展开更多
The field emission (FE) properties of vertically aligned graphene sheets (VAGSs) grown on different SiC substrates are reported. The VAGSs grown on nonpolar SiC (10-10) substrate show an ordered alignment with t...The field emission (FE) properties of vertically aligned graphene sheets (VAGSs) grown on different SiC substrates are reported. The VAGSs grown on nonpolar SiC (10-10) substrate show an ordered alignment with the graphene basal plane-parallel to each other, and show better FE features, with a lower turn-on field and a larger field enhancement factor. The VAGSs grown on polar SiC (000-1 ) substrate reveal a random petaloid-shaped arrangement and stable current emission over 8 hours with a maximum emission current fluctuation of only 4%. The reasons behind the differing FE characteristics of the VAGSs on different SiC substrates are analyzed and discussed.展开更多
Nerve conduits enhance nerve regeneration in the repair of long-distance peripheral nerve defects. To help optimize the effectiveness of nerve conduits for nerve repair, we developed a multi-step electrospinning proce...Nerve conduits enhance nerve regeneration in the repair of long-distance peripheral nerve defects. To help optimize the effectiveness of nerve conduits for nerve repair, we developed a multi-step electrospinning process for constructing nerve guide conduits with aligned nanofibers. The alignment of the nerve guide conduits was characterized by scanning electron microscopy and fast Fourier transform. The mechanical performance of the nerve guide conduits was assessed by testing for tensile strength and compression resistance. The biological performance of the aligned fibers was examined using Schwann cells, PC12 cells and dorsal root ganglia in vitro. Immunohistochemistry was performed for the Schwann cell marker S100 and for the neurofilament protein NF200 in PC12 cells and dorsal root ganglia. In the in vivo experiment, a 1.5-cm defect model of the right sciatic nerve in adult female Sprague-Dawley rats was produced and bridged with an aligned nerve guide conduit. Hematoxylin-eosin staining and immunohistochemistry were used to observe the expression of ATF3 and cleaved caspase-3 in the regenerating matrix. The recovery of motor function was evaluated using the static sciatic nerve index. The number of myelinated fibers, axon diameter, fiber diameter, and myelin thickness in the distal nerve were observed by electron microscopy. Gastrocnemius muscle mass ratio was also determined. The analyses revealed that aligned nanofiber nerve guide conduits have good mechanical properties and can induce Schwann cells, PC12 cells and dorsal root ganglia to aggregate along the length of the nanofibers, and promote the growth of longer axons in the latter two(neuronal) cell types. The aligned fiber nerve conduits increased the expression of ATF3 and cleaved caspase-3 at the middle of the regenerative matrix and at the distal nerve segment, improved sciatic nerve function, increased muscle mass of the gastrocnemius muscle, and enhanced recovery of distal nerve ultrastructure. Collectively, the results show that highly aligned nanofibers improve the performance of the nerve conduit bridge, and enhance its effectiveness in repairing peripheral nerve defects.展开更多
Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluc...Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluctuating strong force field with short correlation length.展开更多
Directionally distributed steel fiber cement-based composites(SFCCs)were prepared by magnetic field(MF)induction technology.The orientation factor of steel fibers in the as-obtained SFCCs was determined.Besides,the el...Directionally distributed steel fiber cement-based composites(SFCCs)were prepared by magnetic field(MF)induction technology.The orientation factor of steel fibers in the as-obtained SFCCs was determined.Besides,the electrical resistivity and piezoresistive responses in two directions of aligned steel fiber cement-based composites,i e,parallel and perpendicular to MF,were measured.The effects of several variables,eg,steel fiber content,curing age,humidity,and temperature,on anisotropic electrical property were studied.The cyclic and failure piezoresistive responses in different directions were tested.It is found that the aligned steel fibers in the as-obtained SFCCs have a high orientation factor more than 0.88.Besides,SFCCs with aligned steel fibers exhibit an obvious anisotropic conductivity and piezoelectric sensitivity.The electrical conductivity of SFCCs with aligned steel fibers is less affected by temperature and humidity.At the steel fiber content of 2.5wt%,the piezoelectric sensitivity coefficient of SFCCs in the direction parallel to MF has the highest value of 324.14.In addition,the piezoresistive properties of SFCCs with aligned steel fibers in the direction parallel to MF indicate excellent sensitivity and stability under cyclic loading and monotonic loading.展开更多
基金The financial support by the National Natural Science Foundation of China(No.52002020)is acknowledged.
文摘Stemming from the unique in-plane honeycomb lattice structure and the sp^(2)hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds,graphene exhibits remarkable anisotropic electrical,mechanical,and thermal properties.To maximize the utilization of graphene’s in-plane properties,pre-constructed and aligned structures,such as oriented aerogels,films,and fibers,have been designed.The unique combination of aligned structure,high surface area,excellent electrical conductivity,mechanical stability,thermal conductivity,and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions,enabling advancements in diverse fields.This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites.It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively.The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties,showing enhanced electrical,mechanical,and thermal properties along the alignment at the sacrifice of the perpendicular direction.This review showcases remarkable properties and applications of aligned graphene aerogels and their composites,such as their suitability for electronics,environmental applications,thermal management,and energy storage.Challenges and potential opportunities are proposed to offer new insights into prospects of this material.
基金This work was supported by the Laoshan National Laboratory Science and Technology Innovation Project(No.LSKJ202203407)the National Natural Science Foundation of China(Grant Nos.42174145,41821002,42274146)+1 种基金Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology(2022B1212010002)Shenzhen Stable Support Plan Program for Higher Education Institutions(20220815110144003).
文摘P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned fractures.However,there are few existing models that incorporate the multiple wave attenuation mechanisms from the microscopic scale to the macroscopic scale.Hence,in this work,we developed a unified model to incorporate the wave attenuation mechanisms at different scales,which includes the microscopic squirt flow between the microcracks and pores,the mesoscopic wave-induced fluid flow between fractures and background(FB-WIFF),and the macroscopic Biot's global flow and elastic scattering(ES)from the fractures.Using Tang's modified Biot's theory and the mixed-boundary conditions,we derived the exact frequency-dependent solutions of the scattering problem for a single penny-shaped fracture with oblique incident P-and SV-waves.We then developed theoretical models for a set of aligned fractures and randomly oriented fractures using the Foldy approximation.The results indicated that microcrack squirt flow considerably influences the dispersion and attenuation of P-and SV-wave velocities.The coupling effects of microcrack squirt flow with the FB-WIFF and ES of fractures cause much higher velocity dispersion and attenuation for P waves than for SV waves.Randomly oriented fractures substantially reduce the attenuation caused by the FB-WIFF and ES,particularly for the ES attenuation of SV waves.Through a comparison with existing models in the limiting cases and previous experimental measurements,we validated our model.
文摘Mechanically aligned total knee arthroplasty (TKA) for valgus knee is considered a “challenging surgery.” Recently, the kinematic alignment (KA) method has gained attention. This study aimed to present objective clinical data, such as intraoperative balance assessment and radiographic evaluation of postoperative lower extremity alignment after TKA using the KA method for valgus deformity. Twenty-one TKA knees (mean age, 74 years;2 males, 19 females) with KA for severe valgus deformity (hip-knee-ankle-angle ≥ 10°) performed at our department in the past 3 years were included in this study. Intraoperative gap and balance measurements and postoperative radiographic evaluation were performed. A total arc of range of motion was achieved up to 98% of preoperative values at 3 weeks postoperatively. Intraoperative gap and balance were stable throughout the entire range of motion. In addition, there were no statistically significant differences in either balance or gap values at each flexion angle. KA TKA is a “simple surgery” rather than a “challenging surgery” because additional soft tissue procedures are not required, operative time is short, intraoperative and postoperative balance is very stable, and a good alignment is achieved. This procedure may relieve surgeons of the stress of TKA for valgus deformities.
基金supported in part by NSF of Shaanxi Province under Grant 2021JM-143the Fundamental Research Funds for the Central Universities under Grant JB211502+5 种基金the Project of Key Laboratory of Science&Technology on Communication Network under Grant 6142104200412the National Natural Science Foundation of China under Grant 62072351the Academy of Finland under Grant 308087,Grant 335262 and Grant 345072the Shaanxi Innovation Team Project under Grant 2018TD-007the 111 Project under Grant B16037,JSPS KAKENHI Grant Number JP20K14742the Project of Cyber Security Establishment with Inter University Cooperation.
文摘In wireless communication networks,mobile users in overlapping areas may experience severe interference,therefore,designing effective Interference Management(IM)methods is crucial to improving network performance.However,when managing multiple disturbances from the same source,it may not be feasible to use existing IM methods such as Interference Alignment(IA)and Interference Steering(IS)exclusively.It is because with IA,the aligned interference becomes indistinguishable at its desired Receiver(Rx)under the cost constraint of Degrees-of-Freedom(DoF),while with IS,more transmit power will be consumed in the direct and repeated application of IS to each interference.To remedy these deficiencies,Interference Alignment Steering(IAS)is proposed by incorporating IA and IS and exploiting their advantages in IM.With IAS,the interfering Transmitter(Tx)first aligns one interference incurred by the transmission of one data stream to a one-dimensional subspace orthogonal to the desired transmission at the interfered Rx,and then the remaining interferences are treated as a whole and steered to the same subspace as the aligned interference.Moreover,two improved versions of IAS,i.e.,IAS with Full Adjustment at the Interfering Tx(IAS-FAIT)and Interference Steering and Alignment(ISA),are presented.The former considers the influence of IA on the interfering user-pair's performance.The orthogonality between the desired signals at the interfered Rx can be maintained by adjusting the spatial characteristics of all interferences and the aligned interference components,thus ensuring the Spectral Efficiency(SE)of the interfering communication pairs.Under ISA,the power cost for IS at the interfered Tx is minimized,hence improving SE performance of the interfered communication-pairs.Since the proposed methods are realized at the interfering and interfered Txs cooperatively,the expenses of IM are shared by both communication-pairs.Our in-depth simulation results show that joint use of IA and IS can effectively manage multiple disturbances from the same source and improve the system's SE.
基金supported by Beijing Insititute of Technology Research Fund Program for Young Scholars(2020X04104)。
文摘In this paper,an improved spatio-temporal alignment measurement method is presented to address the inertial matching measurement of hull deformation under the coexistence of time delay and large misalignment angle.Large misalignment angle and time delay often occur simultaneously and bring great challenges to the accurate measurement of hull deformation in space and time.The proposed method utilizes coarse alignment with large misalignment angle and time delay estimation of inertial measurement unit modeling to establish a brand-new spatiotemporal aligned hull deformation measurement model.In addition,two-step loop control is designed to ensure the accurate description of dynamic deformation angle and static deformation angle by the time-space alignment method of hull deformation.The experiments illustrate that the proposed method can effectively measure the hull deformation angle when time delay and large misalignment angle coexist.
基金supported by the National Natural Science Foundation of China(No.11975227)。
文摘Beams typically do not travel through the magnet centers because of errors in storage rings.The beam deviating from the quadrupole centers is affected by additional dipole fields due to magnetic field feed-down.Beam-based alignment(BBA)is often performed to determine a golden orbit where the beam circulates around the quadrupole center axes.For storage rings with many quadrupoles,the conventional BBA procedure is time-consuming,particularly in the commissioning phase,because of the necessary iterative process.In addition,the conventional BBA method can be affected by strong coupling and the nonlinearity of the storage ring optics.In this study,a novel method based on a neural network was proposed to determine the golden orbit in a much shorter time with reasonable accuracy.This golden orbit can be used directly for operation or adopted as a starting point for conventional BBA.The method was demonstrated in the HLS-II storage ring for the first time through simulations and online experiments.The results of the experiments showed that the golden orbit obtained using this new method was consistent with that obtained using the conventional BBA.The development of this new method and the corresponding experiments are reported in this paper.
基金funded by the Fujian Province Science and Technology Plan,China(Grant Number 2019H0017).
文摘Accurate forecasting of time series is crucial across various domains.Many prediction tasks rely on effectively segmenting,matching,and time series data alignment.For instance,regardless of time series with the same granularity,segmenting them into different granularity events can effectively mitigate the impact of varying time scales on prediction accuracy.However,these events of varying granularity frequently intersect with each other,which may possess unequal durations.Even minor differences can result in significant errors when matching time series with future trends.Besides,directly using matched events but unaligned events as state vectors in machine learning-based prediction models can lead to insufficient prediction accuracy.Therefore,this paper proposes a short-term forecasting method for time series based on a multi-granularity event,MGE-SP(multi-granularity event-based short-termprediction).First,amethodological framework for MGE-SP established guides the implementation steps.The framework consists of three key steps,including multi-granularity event matching based on the LTF(latest time first)strategy,multi-granularity event alignment using a piecewise aggregate approximation based on the compression ratio,and a short-term prediction model based on XGBoost.The data from a nationwide online car-hailing service in China ensures the method’s reliability.The average RMSE(root mean square error)and MAE(mean absolute error)of the proposed method are 3.204 and 2.360,lower than the respective values of 4.056 and 3.101 obtained using theARIMA(autoregressive integratedmoving average)method,as well as the values of 4.278 and 2.994 obtained using k-means-SVR(support vector regression)method.The other experiment is conducted on stock data froma public data set.The proposed method achieved an average RMSE and MAE of 0.836 and 0.696,lower than the respective values of 1.019 and 0.844 obtained using the ARIMA method,as well as the values of 1.350 and 1.172 obtained using the k-means-SVR method.
基金supported by grants from the Interdisciplinary Program of Wuhan National High Magnetic Field Center(No.WHMFC202207)China Oral Health Foundation(No.A2023-009).
文摘Maxillary protrusion combined with mandibular retraction is a highly prevalent but extremely complex maxillofacial deformity that can have a serious negative impact on patients’facial aesthetics and mental health.The traditional orthodontic treatment strategy often involves extracting 4 first premolars and conventional fixed techniques,combined with mini-implant screws,to retract the anterior teeth and improve facial protrusion.In recent years,an invisible orthodontic technique,without brackets,has become increasingly popular.However,while an invisible aligner has been used in some cases with reasonable results,there remain significant challenges in achieving a perfect outcome.This case report presents an adolescent patient with bimaxillary protrusion and mandibular retrognathia.Based on the characteristics of the invisible aligners and the growth characteristics of the adolescent’s teeth and jawbone,we designed precise three-dimensional tooth movement and corresponding resistance/over-correction for each tooth,while utilizing the patient’s jawbone growth potential to promote rapid development of the mandible,accurately and efficiently correcting bimaxillary protrusion and skeletal mandibular retrognathia.The patient’s facial aesthetics,especially the lateral morphology,have been greatly improved,and various aesthetic indicators have also shown significant changes,and to the patient’s great benefit,invasive mini-implant screws were not used during the treatment.This case highlights the advantages of using invisible aligners in adolescent maxillary protrusion combined with mandibular retraction patients.Furthermore,comprehensive and accurate design combined with good application of growth potential can also enable invisible orthodontic technology to achieve perfect treatment effects in tooth extractions,providing clinical guidance for orthodontists.
文摘In this paper, we investigate a 1D pressureless Euler-alignment system with a non-local alignment term, describing a kind of self-organizing problem for flocking. As a result, by the transport equation theory and Lagrange coordinate transformation, the local well-posedness of the solutions for the 1D pressureless Euler-alignment in Besov spaces with 1≤p∞ is established. Next, the ill-posedness of the solutions for this model in Besov spaces with 1≤p and is also deduced. Finally, the precise blow-up criteria of the solutions for this system is presented in Besov spaces with 1≤p .
基金financial support from National Natural Science Foundation of China(21704096,51703217)the China Postdoctoral Science Foundation(Grant No.2019M662526)financial support from Taif University Researchers Supporting Project Number(TURSP-2020/135),Taif University,Taif,Saudi Arabia。
文摘With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel(CA) with highly enhanced thermal conductivity(TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires(SiC NWs)/boron nitride(BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m^(-1) K^(-1) at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy(EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 10^(11) Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of-21.5 dB and a wide effective absorption bandwidth(<-10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.
基金National Natural Science Foundation of China(61625404,61888102).
文摘Aligned SnS nanowires arrays were grown via a simple chemical vapor deposition method.As-synthesized SnS nanowires are single crystals grown along the[111]direction.The single SnS nanowire based device showed excellent response to near infrared lights with good responsivity of 267.9 A/W,high external quantum efficiency of 3.12×10^4%and fast response time.Photodetectors were built on the aligned SnS nanowire arrays,exhibiting a light on/off ratio of 3.6,and the response and decay time of 4.5 and 0.7 s,respectively,to 1064 nm light illumination.
基金Project supported by the National Basic Research Program of China(Grant Nos.2005CB623606 and 2007CB935301)the National Natural Science Foundation of China(Gang Nos.10704044,50825201,and 10721404)
文摘We develop a general approach to the fabrication of films with unidirectional grooves, such as silicon nitride, silicon dioxide and aluminium oxide, in which the surface is not required to be treated. Super-aligned carbon nanotube (SACNT) film may be used as a template and as sacrificial layer, which is subsequently removed by heating in an atmosphere of air. The unidirectional morphology of the SACNT film turns into a desired film, which is found to possess the ability to align liquid crystal molecules. This approach also features high efficiency, low cost and easy scaling-up for mass production.
基金financial supports from the National Natural Science Foundation of China(Grant Nos.62174073,61875073,11674130,91750110 and 61522504)the National Key R&D Program of China(Grant No.2018YFB1107200)+3 种基金the Guangdong Provincial Innovation and Entrepren-eurship Project(Grant No.2016ZT06D081)the Natural Science Founda-tion of Guangdong Province,China(Grant Nos.2016A030306016 and 2016TQ03X981)the Pearl River Nova Program of Guangzhou(Grant No.201806010040)the Technology Innovation and Development Plan of Yantai(Grant No.2020XDRH095).
文摘Encoding information in light polarization is of great importance in facilitating optical data storage(ODS)for information security and data storage capacity escalation.However,despite recent advances in nanophotonic techniques vastly en-hancing the feasibility of applying polarization channels,the data fidelity in reconstructed bits has been constrained by severe crosstalks occurring between varied polarization angles during data recording and reading process,which gravely hindered the utilization of this technique in practice.In this paper,we demonstrate an ultra-low crosstalk polarization-en-coding multilayer ODS technique for high-fidelity data recording and retrieving by utilizing a nanofibre-based nanocom-posite film involving highly aligned gold nanorods(GNRs).With parallelizing the gold nanorods in the recording medium,the information carrier configuration minimizes miswriting and misreading possibilities for information input and output,respectively,compared with its randomly self-assembled counterparts.The enhanced data accuracy has significantly im-proved the bit recall fidelity that is quantified by a correlation coefficient higher than 0.99.It is anticipated that the demon-strated technique can facilitate the development of multiplexing ODS for a greener future.
基金support of National Key R&D Program of China (2021YFB3502500)Provincial Key Research and Development Program of Shandong (2019JZZY010312, 2021ZLGX01)+4 种基金Natural Science Foundation of Shandong Province (2022HYYQ-014)New 20 Funded Programs for Universities of Jinan (2021GXRC036)Qilu Young Scholar Program of Shandong University (31370082163127)the assistance of Shandong University Testing and Manufacturing Center for Advanced Materialssupport from the National Science Foundation Engineering Research Center for Power Optimization of Electro Thermal Systems (POETS) under Grant No. EEC 1449548.
文摘Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.
基金Supported by the National Natural Science Foundation of China(No.50673032)the Graduate Student Innovation Foundation of Jilin University,China(No.20111035)
文摘To investigate the contribution of fibre arrangement to guiding the aligned growth of corneal stroma cells,aligned and randomly oriented fibrous scaffolds of gelatin and poly-L-lactic acid(PLLA) were fabricated by electrospinning.A comparative study of two different systems with corneal stroma cells on randomly organized and aligned fibres were conducted.The efficiency of the scaffolds for inducing the aligned growth of cells was assessed by morphological observation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide(MTT) assay.Results show that the cells cultured on both randomly oriented and aligned scaffolds maintained normal morphology and well spreading as well as long term proliferation.Importantly,corneal stroma cells grew high orderly on the aligned scaffold,while the cells grew disordered on the randomly oriented scaffold.Moreover,the cells exhibited higher viability in aligned scaffold than that in randomly oriented scaffold.These results indcate that electrospinng to prepare aligned fibrous scaffolds has provided an effective approach to the aligned growth of corneal stroma cells in vitro.Our findings that fiber arrangement plays a crucial role in guiding the aligned growth of cells may be helpful to the development of better biomaterials for tissue engineered cornea.
基金Project supported by the National Key Basic Research Program of China (Grant No.2011CB932700)the National Natural Science Foundation of China (Grant Nos.51272279,51072223,and 50972162)
文摘The field emission (FE) properties of vertically aligned graphene sheets (VAGSs) grown on different SiC substrates are reported. The VAGSs grown on nonpolar SiC (10-10) substrate show an ordered alignment with the graphene basal plane-parallel to each other, and show better FE features, with a lower turn-on field and a larger field enhancement factor. The VAGSs grown on polar SiC (000-1 ) substrate reveal a random petaloid-shaped arrangement and stable current emission over 8 hours with a maximum emission current fluctuation of only 4%. The reasons behind the differing FE characteristics of the VAGSs on different SiC substrates are analyzed and discussed.
基金supported by the National Natural Science Foundation of China,No.31771052(to YW)the National Basic Research Program of China(973 Program),No.2014CB542201(to JP)+4 种基金the National Key Research and Development Program of China,No.2016YFC1101601(to QZ),2017YFA0104702(to YW)the PLA General Hospital Translational Medicine Project of China,No.2016TM-030(to QZ)the Beijing Municipal Natural Science Foundation of China,No.7172202(to YW)the PLA Youth Training Project for Medical Science,China,No.16QNP144(to YW)the Beijing Municipal Science and Technology Project,China,No.Z161100005016059(to YW)
文摘Nerve conduits enhance nerve regeneration in the repair of long-distance peripheral nerve defects. To help optimize the effectiveness of nerve conduits for nerve repair, we developed a multi-step electrospinning process for constructing nerve guide conduits with aligned nanofibers. The alignment of the nerve guide conduits was characterized by scanning electron microscopy and fast Fourier transform. The mechanical performance of the nerve guide conduits was assessed by testing for tensile strength and compression resistance. The biological performance of the aligned fibers was examined using Schwann cells, PC12 cells and dorsal root ganglia in vitro. Immunohistochemistry was performed for the Schwann cell marker S100 and for the neurofilament protein NF200 in PC12 cells and dorsal root ganglia. In the in vivo experiment, a 1.5-cm defect model of the right sciatic nerve in adult female Sprague-Dawley rats was produced and bridged with an aligned nerve guide conduit. Hematoxylin-eosin staining and immunohistochemistry were used to observe the expression of ATF3 and cleaved caspase-3 in the regenerating matrix. The recovery of motor function was evaluated using the static sciatic nerve index. The number of myelinated fibers, axon diameter, fiber diameter, and myelin thickness in the distal nerve were observed by electron microscopy. Gastrocnemius muscle mass ratio was also determined. The analyses revealed that aligned nanofiber nerve guide conduits have good mechanical properties and can induce Schwann cells, PC12 cells and dorsal root ganglia to aggregate along the length of the nanofibers, and promote the growth of longer axons in the latter two(neuronal) cell types. The aligned fiber nerve conduits increased the expression of ATF3 and cleaved caspase-3 at the middle of the regenerative matrix and at the distal nerve segment, improved sciatic nerve function, increased muscle mass of the gastrocnemius muscle, and enhanced recovery of distal nerve ultrastructure. Collectively, the results show that highly aligned nanofibers improve the performance of the nerve conduit bridge, and enhance its effectiveness in repairing peripheral nerve defects.
文摘Observation of unexpectedly large global spin alignment of φ vector mesons in non-central heavy-ion collisions by STAR experiment may reveal the non-perturbative nature of quark interaction in hot matter through fluctuating strong force field with short correlation length.
基金Funded by the National Natural Science Foundation of China(Nos.51478164 and 52079048)the Key Research&Development Plan of Jiangsu Province,China(No.BE2021704)。
文摘Directionally distributed steel fiber cement-based composites(SFCCs)were prepared by magnetic field(MF)induction technology.The orientation factor of steel fibers in the as-obtained SFCCs was determined.Besides,the electrical resistivity and piezoresistive responses in two directions of aligned steel fiber cement-based composites,i e,parallel and perpendicular to MF,were measured.The effects of several variables,eg,steel fiber content,curing age,humidity,and temperature,on anisotropic electrical property were studied.The cyclic and failure piezoresistive responses in different directions were tested.It is found that the aligned steel fibers in the as-obtained SFCCs have a high orientation factor more than 0.88.Besides,SFCCs with aligned steel fibers exhibit an obvious anisotropic conductivity and piezoelectric sensitivity.The electrical conductivity of SFCCs with aligned steel fibers is less affected by temperature and humidity.At the steel fiber content of 2.5wt%,the piezoelectric sensitivity coefficient of SFCCs in the direction parallel to MF has the highest value of 324.14.In addition,the piezoresistive properties of SFCCs with aligned steel fibers in the direction parallel to MF indicate excellent sensitivity and stability under cyclic loading and monotonic loading.