A linear flexible joint system using fractional order linear active disturbance rejection control is studied in this paper.With this control scheme,the performance against disturbances,uncertainties,and attenuation is...A linear flexible joint system using fractional order linear active disturbance rejection control is studied in this paper.With this control scheme,the performance against disturbances,uncertainties,and attenuation is enhanced.Linear active disturbance rejection control(LADRC)is mainly based on an extended state observer(ESO)technology.A fractional integral(FOI)action is combined with the LADRC technique which proposes a hybrid control scheme like FO-LADRC.Incorporating this FOI action improves the robustness of the standard LADRC.The set-point tracking of the proposed FO-LADRC scheme is designed by Bode’s ideal transfer function(BITF)based robust closed-loop concept,an appropriate pole placement method.The effectiveness of the proposed FO-LADRC scheme is illustrated through experimental results on the linear flexible joint system(LFJS).The results show the enhancement of the robustness with disturbance rejection.Furthermore,a comparative analysis is presented with the results obtained using the integer-order LADRC and FO-LADRC scheme.展开更多
Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or ...Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.展开更多
Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat...Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec,Canada(north shore of Saint-Lawrence River)to test conceptual models of joint formation in a natural setting.In the region,the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately.The joint-spacing-to-bed-thickness ratios(s/t)are much larger in these beds(s/t=4.3 for systematic joints,and 6.4 for cross-joints)than those in higher strained strata along the south shore of the Saint-Lawrence River(s/t=1),highlighting the effect of tectonic strain in decreasing fracture spacing and block size.The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached(as hypothesized in previous studies).We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures.The presence of ladder-shaped orthogonal joints suggests a state of effective stress withσ_(1)^(∗)≫0>σ_(2)^(∗)>σ_(3)^(∗)and whereσ_(2)^(∗)-σ_(3)^(∗)is within the range of fracture strength variability at the time of fracture.This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.展开更多
Precise and scarless DNA insertion and replacement represent two of the major challenges in plant genome editing.Numerous tools have been developed,including homology-directed repair-dependent tools and prime-editing-...Precise and scarless DNA insertion and replacement represent two of the major challenges in plant genome editing.Numerous tools have been developed,including homology-directed repair-dependent tools and prime-editing-mediated systems.However,none has fully resolved these challenges.In this study,we develop the“mortise-tenon joint system”(MT),a novel strategy that enables precise and efficient targeted DNA insertion and replacement.By leveraging the APOBEC-Cas9-uracil DNA glycosylase/(apurinic or apyrimidinic site)lyase within our previously reported APOBEC-Cas9 fusion-induced deletion system,which performs single-strand cleavage on the non-target strand and double-strand cleavage on the target strand,we generated a unique“mortise”structure,consisting of double-strand breaks with single or double non-complementary 5′overhangs.We further designed“tenons,”double-stranded DNA donors containing 5′sticky ends precisely matching the 5′overhangs of the mortises.The end-capture interaction between mortises and tenons facilitates precise targeted insertion and replacement,achieving frequencies of 16.30%-59.47%across seven tested targets using 21-85 bp donor inserts in rice.If long DNA donors with sticky ends complementary to the mortise structure can be generated,the MT system may enable highly precise targeted insertion and replacement of large DNA fragments.展开更多
BACKGROUND In the management of postoperative pain following total joint arthroplasty(TJA),the use of nonsteroidal anti-inflammatory drugs,including acetaminophen,plays a key role in alleviating pain.However,the compa...BACKGROUND In the management of postoperative pain following total joint arthroplasty(TJA),the use of nonsteroidal anti-inflammatory drugs,including acetaminophen,plays a key role in alleviating pain.However,the comparison between intravenous and oral acetaminophen administration in patients undergoing full joint replacement surgery remains controversial.AIM To assess the effectiveness of intravenous and oral acetaminophen in alleviating pain and supporting rehabilitation following TJA.METHODS PubMed,Embase and the Cochrane Library were comprehensively searched to identify cohort studies.The effects of intravenous and oral acetaminophen for managing pain and supporting rehabilitation following TJA were analysed using randomized controlled trials.PRISMA guidelines were followed.The effectiveness of the administration routes was compared based on visual analogue scale(VAS)scores at 24 and 48 h,total morphine usage within 24 h,and total duration of hospital stay.RESULTS The meta-analysis included seven studies comparing intravenous acetaminophen groups and oral acetaminophen groups.The results demonstrated that oral acetaminophen was comparable to intravenous acetaminophen with regard to VAS scores at 24 h and 48 h(P=0.76 and 0.08,respectively).The difference in total morphine use between the two groups was not significant(P=0.22).However,the total hospital stay duration of the intravenous acetaminophen groups was significantly reduced compared to the oral acetaminophen groups(P=0.0005),showing significant advantages in optimizing postoperative recovery and shortening hospitalisation time.CONCLUSION After TJA surgery,intravenous injection of acetaminophen can shorten hospitalisation time and is suitable for rapid analgesia,Oral administration has become the preferred choice for mild cases due to its convenience and economy,providing a basis for clinical drug selection.展开更多
With the development of marine resources,a dual-platform joint operation has been paid more attention.In this paper,the mooring layout space and relative motion limitation of the dual-platform berthing operation were ...With the development of marine resources,a dual-platform joint operation has been paid more attention.In this paper,the mooring layout space and relative motion limitation of the dual-platform berthing operation were fully considered.A new hybrid mooring system with“X+buoy”combination was designed based on the characteristics of catenary and tension mooring.The hydrodynamic characteristics of the new mooring system were analyzed by combining numerical simulation with model experiment.Under the regular and freak waves with different wave heights and periods,the time-domain full-coupling analysis method was used to study the hydrodynamic characteristics of the mooring system.It can be found that the arrangement of dual-platform under 0◦wave direction is optimal,and the“X+buoy”combined mooring system designed in this paper has a good follow-up between the two platforms under different regular and freak waves.The relative motion response between the two platforms can be effectively controlled,and finally the positioning of the dual-platform joint operation is realized.Research results of this paper provide a theoretical basis and technical support for the hydrodynamic performance analysis and safety assessment of deep-sea offshore platforms in China.展开更多
In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibil...In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibility of both the drum and inner ring,a novel rubbing force model applicable to drum-inner ring rubbing is proposed,and this model is partially validated with the measured vibration responses.Incorporating both drum-inner ring rubbing faults and bolt joint effects,a dynamic model of the shaft-diskdrum-inner ring-vane-casing system(SDDIRVCS)is established with beam-shell hybrid elements to investigate the nonlinear dynamic responses induced by rubbing at various rotational speeds.The established dynamic model of the SDDIRVCS is validated by the comparison of its modal characteristics with those obtained from the ANSYS simulations.The results indicate that the rotor spectrum is dominated by odd-multiple harmonics,while the stator spectrum exhibits prominent even-multiple harmonics.Moreover,the rubbing location between the drum and the inner ring varies with the dynamic behavior of the rotor system.展开更多
Dear Editor,This letter presents a joint probabilistic scheduling and resource allocation method(PSRA) for 5G-based wireless networked control systems(WNCSs). As a control-aware optimization method, PSRA minimizes the...Dear Editor,This letter presents a joint probabilistic scheduling and resource allocation method(PSRA) for 5G-based wireless networked control systems(WNCSs). As a control-aware optimization method, PSRA minimizes the linear quadratic Gaussian(LQG) control cost of WNCSs by optimizing the activation probability of subsystems, the number of uplink repetitions, and the durations of uplink and downlink phases. Simulation results show that PSRA achieves smaller LQG control costs than existing works.展开更多
With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative...With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative rehabilitation nursing,as a crucial aspect of enhancing surgical outcomes,reducing complications,and facilitating patients’return to normal life,has its scientific and effective protocols directly influencing patient prognosis.This article systematically reviews the core research findings on rehabilitation nursing after joint replacement surgery based on the concept of evidence-based medicine,aiming to provide references for the formulation of standardized and personalized rehabilitation nursing plans in clinical settings.展开更多
To address the issues of poor adaptability in resource allocation and low multi-agent cooperation efficiency in Joint Radar and Communication(JRC)systems under dynamic environments,an intelligent optimization framewor...To address the issues of poor adaptability in resource allocation and low multi-agent cooperation efficiency in Joint Radar and Communication(JRC)systems under dynamic environments,an intelligent optimization framework integrating Deep Reinforcement Learning(DRL)and Graph Neural Network(GNN)is proposed.This framework models resource allocation as a Partially Observable Markov Game(POMG),designs a weighted reward function to balance radar and communication efficiencies,adopts the Multi-Agent Proximal Policy Optimization(MAPPO)framework,and integrates Graph Convolutional Networks(GCN)and Graph Sample and Aggregate(Graph-SAGE)to optimize information interaction.Simulations show that,compared with traditional methods and pure DRL methods,the proposed framework achieves improvements in performance metrics such as communication success rate,Average Age of Information(AoI),and policy convergence speed,effectively enabling resource management in complex environments.Moreover,the proposed GNN-DRL-based intelligent optimization framework obtains significantly better performance for resource management in multi-agent JRC systems than traditional methods and pure DRL methods.展开更多
Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogen...Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogeneity remains challenging.To address this,this study first captures the morphology of large-scale(1000 mm × 1000 mm) slate and granite joints via 3D laser scanning.Analysis of these surfaces and corresponding push/pull tests on carved specimens revealed a potential correlation between the heterogeneity of roughness and shear strength.A comparative evaluation of five statistical metrics identified information entropy(Hs) as the most robust indicator for quantifying rock joint heterogeneity.Further analysis using Hsreveals that the heterogeneity is anisotropic and,critically,that shear strength heterogeneity is governed not only by roughness heterogeneity but is also significantly influenced by the mean roughness value,normal stress,and intact rock tensile strength.Consequently,a simple comparison of roughness Hsvalues is insufficient for reliably comparing shear strength heterogeneity.To overcome this limitation,a theoretical framework is developed to explicitly map fundamental roughness statistics(mean and heterogeneity) to shear strength heterogeneity.This framework culminates in a practical workflow that allows for the rapid,field-based assessment of shear strength heterogeneity using readily obtainable rock joint roughness data.展开更多
To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework ba...To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework based on face-pedestrian joint feature modeling.By constructing a joint tracking model centered on“intra-class independent tracking+cross-category dynamic binding”,designing a multi-modal matching metric with spatio-temporal and appearance constraints,and innovatively introducing a cross-category feature mutual verification mechanism and a dual matching strategy,this work effectively resolves performance degradation in traditional single-category tracking methods caused by short-term occlusion,cross-camera tracking,and crowded environments.Experiments on the Chokepoint_Face_Pedestrian_Track test set demonstrate that in complex scenes,the proposed method improves Face-Pedestrian Matching F1 area under the curve(F1 AUC)by approximately 4 to 43 percentage points compared to several traditional methods.The joint tracking model achieves overall performance metrics of IDF1:85.1825%and MOTA:86.5956%,representing improvements of 0.91 and 0.06 percentage points,respectively,over the baseline model.Ablation studies confirm the effectiveness of key modules such as the Intersection over Area(IoA)/Intersection over Union(IoU)joint metric and dynamic threshold adjustment,validating the significant role of the cross-category identity matching mechanism in enhancing tracking stability.Our_model shows a 16.7%frame per second(FPS)drop vs.fairness of detection and re-identification in multiple object tracking(FairMOT),with its cross-category binding module adding aboute 10%overhead,yet maintains near-real-time performance for essential face-pedestrian tracking at small resolutions.展开更多
The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural ...The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.展开更多
As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,t...As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,the heterogeneity of aircraft,partial observability,and dynamic uncertainty in operational airspace pose significant challenges to autonomous collision avoidance using traditional methods.To address these issues,this paper proposes an adaptive collision avoidance approach for UAVs based on deep reinforcement learning.First,a unified uncertainty model incorporating dynamic wind fields is constructed to capture the complexity of joint operational environments.Then,to effectively handle the heterogeneity between manned and unmanned aircraft and the limitations of dynamic observations,a sector-based partial observation mechanism is designed.A Dynamic Threat Prioritization Assessment algorithm is also proposed to evaluate potential collision threats from multiple dimensions,including time to closest approach,minimum separation distance,and aircraft type.Furthermore,a Hierarchical Prioritized Experience Replay(HPER)mechanism is introduced,which classifies experience samples into high,medium,and low priority levels to preferentially sample critical experiences,thereby improving learning efficiency and accelerating policy convergence.Simulation results show that the proposed HPER-D3QN algorithm outperforms existing methods in terms of learning speed,environmental adaptability,and robustness,significantly enhancing collision avoidance performance and convergence rate.Finally,transfer experiments on a high-fidelity battlefield airspace simulation platform validate the proposed method's deployment potential and practical applicability in complex,real-world joint operational scenarios.展开更多
A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brit...A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brittleness.A joint with good formability and tensile properties was obtained.The microstructure and element distribution of the joint were observed by metallographic microscopy,scanning electron microscopy and electron probe microanalysis.The shear resistance exhibited an initial increase,followed by a subsequent decrease,with an increase in heat input.It reached a maximum value of 2470 N at a welding energy of 267 kJ/m.The Fe-Ti brittle IMCs in TC4/DP780 joints are replaced by Fe-Cu phase and Cu-Ti phase,which reduces the brittleness at TC4/DP780 interface.The results show that the TC4/DP780 joint forms numerousα-Cu andγ-Fe solid solutions through the mutual diffusion and solid solution between H62 and TC4 layers of metals,which effectively inhibits the diffusion of Ti atoms and reduces the formation of brittle Ti-Fe IMCs.At the H62/TC4 interface,a composite layer composed of Cu-Ti IMCs and Cu-based solid solutions is formed.The composite layer grows dendritically from the TC4 alloy to the H62 interlayer.The microstructure at the TC4/DP780 interface changes from fine dendrites to coarse dendrites with the increase in Ti content and heat input.When the heat input is lower,the interfacial elements do not react sufficiently.When the heat input is excessive,microcracks appear at the TC4/DP780 interface,which limits the improvement of mechanical properties of TC4/DP780 joint.展开更多
As part of my master’s programme in resource use and environmental science at China Agricultural University,I had the privilege of joining a study trip to the Shiyang River Basin and its surrounding areas from 17 to ...As part of my master’s programme in resource use and environmental science at China Agricultural University,I had the privilege of joining a study trip to the Shiyang River Basin and its surrounding areas from 17 to 21 July 2025.This trip to Gansu Province was organised under the China-Africa Joint Centre for Agricultural Demonstration and Training in Arid Regions programme,an initiative aligned with President Xi Jinping’s call for deeper China-Africa cooperation.展开更多
BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affectin...BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.展开更多
To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on ...To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load beating capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame （CSF）, and relative slippages between the CSF and embedded limbic steel frame （ELSF） were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable.展开更多
In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, ...In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.展开更多
A new hybrid method of frequency domain and time domain is developed in this paper to predict the motion responses of a flexibly joint multi-body floating system to irregular waves. The main idea of the method is that...A new hybrid method of frequency domain and time domain is developed in this paper to predict the motion responses of a flexibly joint multi-body floating system to irregular waves. The main idea of the method is that the three-dimensional frequency method is used to obtain the hydrodynamic coefficients and the response equations are solved in time domain step by step. All the forces can be obtained at the same time. The motions and nonlinear mooring forces of a box type six-body floating system are predicted. A comparison of the theoretical method-based Solutions with experimental results has shown good agreement.展开更多
基金This research work was funded by Institutional Fund Projects under Grant No.(IFPRC-027-135-2020).
文摘A linear flexible joint system using fractional order linear active disturbance rejection control is studied in this paper.With this control scheme,the performance against disturbances,uncertainties,and attenuation is enhanced.Linear active disturbance rejection control(LADRC)is mainly based on an extended state observer(ESO)technology.A fractional integral(FOI)action is combined with the LADRC technique which proposes a hybrid control scheme like FO-LADRC.Incorporating this FOI action improves the robustness of the standard LADRC.The set-point tracking of the proposed FO-LADRC scheme is designed by Bode’s ideal transfer function(BITF)based robust closed-loop concept,an appropriate pole placement method.The effectiveness of the proposed FO-LADRC scheme is illustrated through experimental results on the linear flexible joint system(LFJS).The results show the enhancement of the robustness with disturbance rejection.Furthermore,a comparative analysis is presented with the results obtained using the integer-order LADRC and FO-LADRC scheme.
基金supported by the National Natural Science Foundation of China(11032009 and 11272236)
文摘Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.
基金The authors express their gratitude to the Natural Sciences and Engineering Research Council of Canada for financial support through a Discovery Grant(Grant No.06408).
文摘Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec,Canada(north shore of Saint-Lawrence River)to test conceptual models of joint formation in a natural setting.In the region,the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately.The joint-spacing-to-bed-thickness ratios(s/t)are much larger in these beds(s/t=4.3 for systematic joints,and 6.4 for cross-joints)than those in higher strained strata along the south shore of the Saint-Lawrence River(s/t=1),highlighting the effect of tectonic strain in decreasing fracture spacing and block size.The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached(as hypothesized in previous studies).We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures.The presence of ladder-shaped orthogonal joints suggests a state of effective stress withσ_(1)^(∗)≫0>σ_(2)^(∗)>σ_(3)^(∗)and whereσ_(2)^(∗)-σ_(3)^(∗)is within the range of fracture strength variability at the time of fracture.This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.
基金supported by Project TSQN202103160 from the Taishan Scholar Foundation of Shandong Province(to H.Z.)Project ZR2021JQ08 from the Shandong Provincial Natural Science Foundation(to H.Z.)+1 种基金the National Natural Science Foundation of China(32430003 to X.M.)the National Key Research and Development Program of China(2022YFF1001800).
文摘Precise and scarless DNA insertion and replacement represent two of the major challenges in plant genome editing.Numerous tools have been developed,including homology-directed repair-dependent tools and prime-editing-mediated systems.However,none has fully resolved these challenges.In this study,we develop the“mortise-tenon joint system”(MT),a novel strategy that enables precise and efficient targeted DNA insertion and replacement.By leveraging the APOBEC-Cas9-uracil DNA glycosylase/(apurinic or apyrimidinic site)lyase within our previously reported APOBEC-Cas9 fusion-induced deletion system,which performs single-strand cleavage on the non-target strand and double-strand cleavage on the target strand,we generated a unique“mortise”structure,consisting of double-strand breaks with single or double non-complementary 5′overhangs.We further designed“tenons,”double-stranded DNA donors containing 5′sticky ends precisely matching the 5′overhangs of the mortises.The end-capture interaction between mortises and tenons facilitates precise targeted insertion and replacement,achieving frequencies of 16.30%-59.47%across seven tested targets using 21-85 bp donor inserts in rice.If long DNA donors with sticky ends complementary to the mortise structure can be generated,the MT system may enable highly precise targeted insertion and replacement of large DNA fragments.
基金Supported by National Natural Science Foundation of China,No.11772226 and No.81572154.
文摘BACKGROUND In the management of postoperative pain following total joint arthroplasty(TJA),the use of nonsteroidal anti-inflammatory drugs,including acetaminophen,plays a key role in alleviating pain.However,the comparison between intravenous and oral acetaminophen administration in patients undergoing full joint replacement surgery remains controversial.AIM To assess the effectiveness of intravenous and oral acetaminophen in alleviating pain and supporting rehabilitation following TJA.METHODS PubMed,Embase and the Cochrane Library were comprehensively searched to identify cohort studies.The effects of intravenous and oral acetaminophen for managing pain and supporting rehabilitation following TJA were analysed using randomized controlled trials.PRISMA guidelines were followed.The effectiveness of the administration routes was compared based on visual analogue scale(VAS)scores at 24 and 48 h,total morphine usage within 24 h,and total duration of hospital stay.RESULTS The meta-analysis included seven studies comparing intravenous acetaminophen groups and oral acetaminophen groups.The results demonstrated that oral acetaminophen was comparable to intravenous acetaminophen with regard to VAS scores at 24 h and 48 h(P=0.76 and 0.08,respectively).The difference in total morphine use between the two groups was not significant(P=0.22).However,the total hospital stay duration of the intravenous acetaminophen groups was significantly reduced compared to the oral acetaminophen groups(P=0.0005),showing significant advantages in optimizing postoperative recovery and shortening hospitalisation time.CONCLUSION After TJA surgery,intravenous injection of acetaminophen can shorten hospitalisation time and is suitable for rapid analgesia,Oral administration has become the preferred choice for mild cases due to its convenience and economy,providing a basis for clinical drug selection.
基金the National Natural Science Foundation of China(No.52071161)。
文摘With the development of marine resources,a dual-platform joint operation has been paid more attention.In this paper,the mooring layout space and relative motion limitation of the dual-platform berthing operation were fully considered.A new hybrid mooring system with“X+buoy”combination was designed based on the characteristics of catenary and tension mooring.The hydrodynamic characteristics of the new mooring system were analyzed by combining numerical simulation with model experiment.Under the regular and freak waves with different wave heights and periods,the time-domain full-coupling analysis method was used to study the hydrodynamic characteristics of the mooring system.It can be found that the arrangement of dual-platform under 0◦wave direction is optimal,and the“X+buoy”combined mooring system designed in this paper has a good follow-up between the two platforms under different regular and freak waves.The relative motion response between the two platforms can be effectively controlled,and finally the positioning of the dual-platform joint operation is realized.Research results of this paper provide a theoretical basis and technical support for the hydrodynamic performance analysis and safety assessment of deep-sea offshore platforms in China.
基金supported by the Fundamental Research Funds for the Central Universities(No.N25BSS052)the National Science and Technology Major Project(No.J2022-IV-0005-0022)+2 种基金the Aero Science Foundation of China(No.20230015050001)the Shenyang Science and Technology Plan Project of China(No.24-202-6-01)the Independent Research Project of the National Key Laboratory of Strength and Structural Integrity(No.BYST-QZSYS-24-072-8)。
文摘In addition to blade-to-casing rubbing,drum-to-labyrinth rubbing is another common interaction in aero-engines.In this study,the labyrinth seal is simplified and modeled as an inner ring.First,considering the flexibility of both the drum and inner ring,a novel rubbing force model applicable to drum-inner ring rubbing is proposed,and this model is partially validated with the measured vibration responses.Incorporating both drum-inner ring rubbing faults and bolt joint effects,a dynamic model of the shaft-diskdrum-inner ring-vane-casing system(SDDIRVCS)is established with beam-shell hybrid elements to investigate the nonlinear dynamic responses induced by rubbing at various rotational speeds.The established dynamic model of the SDDIRVCS is validated by the comparison of its modal characteristics with those obtained from the ANSYS simulations.The results indicate that the rotor spectrum is dominated by odd-multiple harmonics,while the stator spectrum exhibits prominent even-multiple harmonics.Moreover,the rubbing location between the drum and the inner ring varies with the dynamic behavior of the rotor system.
基金supported by the Liaoning Revitalization Talents Program(XLYC2203148)
文摘Dear Editor,This letter presents a joint probabilistic scheduling and resource allocation method(PSRA) for 5G-based wireless networked control systems(WNCSs). As a control-aware optimization method, PSRA minimizes the linear quadratic Gaussian(LQG) control cost of WNCSs by optimizing the activation probability of subsystems, the number of uplink repetitions, and the durations of uplink and downlink phases. Simulation results show that PSRA achieves smaller LQG control costs than existing works.
文摘With the intensification of population aging,knee and hip joint replacement surgeries have become core methods for treating end-stage joint diseases,with over a million cases performed globally each year.Postoperative rehabilitation nursing,as a crucial aspect of enhancing surgical outcomes,reducing complications,and facilitating patients’return to normal life,has its scientific and effective protocols directly influencing patient prognosis.This article systematically reviews the core research findings on rehabilitation nursing after joint replacement surgery based on the concept of evidence-based medicine,aiming to provide references for the formulation of standardized and personalized rehabilitation nursing plans in clinical settings.
基金funded by Shandong Provincial Natural Science Foundation,grant number ZR2023MF111.
文摘To address the issues of poor adaptability in resource allocation and low multi-agent cooperation efficiency in Joint Radar and Communication(JRC)systems under dynamic environments,an intelligent optimization framework integrating Deep Reinforcement Learning(DRL)and Graph Neural Network(GNN)is proposed.This framework models resource allocation as a Partially Observable Markov Game(POMG),designs a weighted reward function to balance radar and communication efficiencies,adopts the Multi-Agent Proximal Policy Optimization(MAPPO)framework,and integrates Graph Convolutional Networks(GCN)and Graph Sample and Aggregate(Graph-SAGE)to optimize information interaction.Simulations show that,compared with traditional methods and pure DRL methods,the proposed framework achieves improvements in performance metrics such as communication success rate,Average Age of Information(AoI),and policy convergence speed,effectively enabling resource management in complex environments.Moreover,the proposed GNN-DRL-based intelligent optimization framework obtains significantly better performance for resource management in multi-agent JRC systems than traditional methods and pure DRL methods.
基金supported by the National Natural Science Foundation of China (Nos.42422705,42207175,42177117 and 42577170)the Ningbo Youth Leading Talent Project (No.2024QL051)+1 种基金the Chinese Academy of Engineering Science and Technology Strategy Consulting Project (No.2025-XZ-57)the Central Government Funding Program for Guiding Local Science and Technology Development (No.2025ZY01028)。
文摘Rock mass stability is significantly influenced by the heterogeneity of rock joint roughness and shear strength.While modern technology facilitates assessing roughness heterogeneity,evaluating shear strength heterogeneity remains challenging.To address this,this study first captures the morphology of large-scale(1000 mm × 1000 mm) slate and granite joints via 3D laser scanning.Analysis of these surfaces and corresponding push/pull tests on carved specimens revealed a potential correlation between the heterogeneity of roughness and shear strength.A comparative evaluation of five statistical metrics identified information entropy(Hs) as the most robust indicator for quantifying rock joint heterogeneity.Further analysis using Hsreveals that the heterogeneity is anisotropic and,critically,that shear strength heterogeneity is governed not only by roughness heterogeneity but is also significantly influenced by the mean roughness value,normal stress,and intact rock tensile strength.Consequently,a simple comparison of roughness Hsvalues is insufficient for reliably comparing shear strength heterogeneity.To overcome this limitation,a theoretical framework is developed to explicitly map fundamental roughness statistics(mean and heterogeneity) to shear strength heterogeneity.This framework culminates in a practical workflow that allows for the rapid,field-based assessment of shear strength heterogeneity using readily obtainable rock joint roughness data.
基金supported by the confidential research grant No.a8317。
文摘To address the issues of frequent identity switches(IDs)and degraded identification accuracy in multi object tracking(MOT)under complex occlusion scenarios,this study proposes an occlusion-robust tracking framework based on face-pedestrian joint feature modeling.By constructing a joint tracking model centered on“intra-class independent tracking+cross-category dynamic binding”,designing a multi-modal matching metric with spatio-temporal and appearance constraints,and innovatively introducing a cross-category feature mutual verification mechanism and a dual matching strategy,this work effectively resolves performance degradation in traditional single-category tracking methods caused by short-term occlusion,cross-camera tracking,and crowded environments.Experiments on the Chokepoint_Face_Pedestrian_Track test set demonstrate that in complex scenes,the proposed method improves Face-Pedestrian Matching F1 area under the curve(F1 AUC)by approximately 4 to 43 percentage points compared to several traditional methods.The joint tracking model achieves overall performance metrics of IDF1:85.1825%and MOTA:86.5956%,representing improvements of 0.91 and 0.06 percentage points,respectively,over the baseline model.Ablation studies confirm the effectiveness of key modules such as the Intersection over Area(IoA)/Intersection over Union(IoU)joint metric and dynamic threshold adjustment,validating the significant role of the cross-category identity matching mechanism in enhancing tracking stability.Our_model shows a 16.7%frame per second(FPS)drop vs.fairness of detection and re-identification in multiple object tracking(FairMOT),with its cross-category binding module adding aboute 10%overhead,yet maintains near-real-time performance for essential face-pedestrian tracking at small resolutions.
基金supported by the National Natural Science Foundation of China (Nos. 52075449, 51975480)。
文摘The dissimilar 2B06 and 7B04 Al alloy joints were prepared by refill friction stir spot welding(RFSSW),and the microstructural evolution and corrosion behavior of the joints were investigated.Based on microstructural analysis,the welded joints exhibit distinct microstructural zones,including the stir zone(SZ),thermomechanically affected zone(TMAZ),and heat-affected zone(HAZ).The grain size of each zone is in the order of HAZ>TMAZ>SZ.Notably,the TMAZ and HAZ contain significantly larger secondary-phase particles compared to the SZ,with particle size in the HAZ increasing at higher rotational speeds.Electrochemical tests indicate that corrosion susceptibility follows the sequence of HAZ>TMAZ>SZ>BM,with greater sensitivity observed at increased rotational speeds.Post-corrosion mechanical performance degradation primarily arises from crevice corrosion at joint overlaps,but not from the changes in the microstructure.
基金supported by the National Key Research and Development Program of China(No.2022YFB4300902).
文摘As joint operations have become a key trend in modern military development,unmanned aerial vehicles(UAVs)play an increasingly important role in enhancing the intelligence and responsiveness of combat systems.However,the heterogeneity of aircraft,partial observability,and dynamic uncertainty in operational airspace pose significant challenges to autonomous collision avoidance using traditional methods.To address these issues,this paper proposes an adaptive collision avoidance approach for UAVs based on deep reinforcement learning.First,a unified uncertainty model incorporating dynamic wind fields is constructed to capture the complexity of joint operational environments.Then,to effectively handle the heterogeneity between manned and unmanned aircraft and the limitations of dynamic observations,a sector-based partial observation mechanism is designed.A Dynamic Threat Prioritization Assessment algorithm is also proposed to evaluate potential collision threats from multiple dimensions,including time to closest approach,minimum separation distance,and aircraft type.Furthermore,a Hierarchical Prioritized Experience Replay(HPER)mechanism is introduced,which classifies experience samples into high,medium,and low priority levels to preferentially sample critical experiences,thereby improving learning efficiency and accelerating policy convergence.Simulation results show that the proposed HPER-D3QN algorithm outperforms existing methods in terms of learning speed,environmental adaptability,and robustness,significantly enhancing collision avoidance performance and convergence rate.Finally,transfer experiments on a high-fidelity battlefield airspace simulation platform validate the proposed method's deployment potential and practical applicability in complex,real-world joint operational scenarios.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001141 and 52475360).
文摘A thorny problem in the miscible Ti/Fe system is the unavoidable formation of numerous brittle intermetallic compounds(IMCs).Adding H62 interlayer is an essential method to reduce the brittle IMCs or decrease the brittleness.A joint with good formability and tensile properties was obtained.The microstructure and element distribution of the joint were observed by metallographic microscopy,scanning electron microscopy and electron probe microanalysis.The shear resistance exhibited an initial increase,followed by a subsequent decrease,with an increase in heat input.It reached a maximum value of 2470 N at a welding energy of 267 kJ/m.The Fe-Ti brittle IMCs in TC4/DP780 joints are replaced by Fe-Cu phase and Cu-Ti phase,which reduces the brittleness at TC4/DP780 interface.The results show that the TC4/DP780 joint forms numerousα-Cu andγ-Fe solid solutions through the mutual diffusion and solid solution between H62 and TC4 layers of metals,which effectively inhibits the diffusion of Ti atoms and reduces the formation of brittle Ti-Fe IMCs.At the H62/TC4 interface,a composite layer composed of Cu-Ti IMCs and Cu-based solid solutions is formed.The composite layer grows dendritically from the TC4 alloy to the H62 interlayer.The microstructure at the TC4/DP780 interface changes from fine dendrites to coarse dendrites with the increase in Ti content and heat input.When the heat input is lower,the interfacial elements do not react sufficiently.When the heat input is excessive,microcracks appear at the TC4/DP780 interface,which limits the improvement of mechanical properties of TC4/DP780 joint.
文摘As part of my master’s programme in resource use and environmental science at China Agricultural University,I had the privilege of joining a study trip to the Shiyang River Basin and its surrounding areas from 17 to 21 July 2025.This trip to Gansu Province was organised under the China-Africa Joint Centre for Agricultural Demonstration and Training in Arid Regions programme,an initiative aligned with President Xi Jinping’s call for deeper China-Africa cooperation.
基金approved by Institutional Review Board of Faculty of Medicine in Assiut University,No.04-2024-300470.
文摘BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.
文摘To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load beating capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame （CSF）, and relative slippages between the CSF and embedded limbic steel frame （ELSF） were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable.
基金supported by NSFC (No. 61571055)fund of SKL of MMW (No. K201815) Important National Science & Technology Specific Projects (2017ZX03001028)
文摘In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.
基金This project was supported by the National Natural Science Foundation of China (Grant No. 50039010)
文摘A new hybrid method of frequency domain and time domain is developed in this paper to predict the motion responses of a flexibly joint multi-body floating system to irregular waves. The main idea of the method is that the three-dimensional frequency method is used to obtain the hydrodynamic coefficients and the response equations are solved in time domain step by step. All the forces can be obtained at the same time. The motions and nonlinear mooring forces of a box type six-body floating system are predicted. A comparison of the theoretical method-based Solutions with experimental results has shown good agreement.
