The current study is to observe the effect of the locking system strengthened by biomimetic mineralized collagen putty for the treatment of senile proximal humeral osteoporotic fractures.From January 2012 to December ...The current study is to observe the effect of the locking system strengthened by biomimetic mineralized collagen putty for the treatment of senile proximal humeral osteoporotic fractures.From January 2012 to December 2015,80 cases of senile patients with osteoporotic proximal humeral fractures were randomly divided into an observation group and a control group,each group with a total of 40 cases.The control group was simply treated with locking plate.The observation group was treated with locking plate in combination with biomimetic mineralized collagen putty.The therapeutic effect thereby was observed.The excellent and satisfactory rate was 90%in observation group and was 72.5%in control group.The difference between the two groups was statistically significant(χ^(2)=5.3312,P<0.05).The fracture healing time was 11.8263.62 weeks in observation group and 19.7865.46 weeks in control group.The shoulder joint function score was 89.6368.12 in observation group and 76.9268.18 in control group.There was significant difference between the two groups(t=7.1272;12.7834,P<0.05).The complication rate was 10%in the observation group and 32.5%in the control group(χ^(2)=7.3786,P<0.05).Locking system strengthened by biomimetic mineralized collagen putty has advantages such as accelerating healing of senile proximal humeral fracture,improving the therapeutic effect,reducing the complications.As one of the optimal internal fixation method,it provides a new option for better treatment of senile osteoporotic fracture.展开更多
We present a novel homodyne frequency-shifting interference pattern locking system to enhance the exposure contrast of interference lithography and scanning beam interference lithography(SBIL). The novel interferenc...We present a novel homodyne frequency-shifting interference pattern locking system to enhance the exposure contrast of interference lithography and scanning beam interference lithography(SBIL). The novel interference pattern locking system employs a special homodyne redundant phase measurement interferometer(HRPMI) as the sensor and an acousto-opto modulator(AOM) as the actuator. The HRPMI offers the highly accurate value as well as the direction recognition of the interference pattern drift from four quadrature interference signals. The AOM provides a very fine resolution with a high speed for phase modulation. A compact and concise system with a short optical path can be achieved with this new scheme and a small power laser head in tens of microwatts is sufficient for exposure and phase locking, which results in a relatively low-cost system compared with the heterodyne system. More importantly, the accuracy of the system is at a high level as well as having robustness to environmental fluctuation. The experiment results show that the short-time(4 s) accuracy of the system is 0.0481 rad e3σT at present. Moreover, the phase of the interference pattern can also be set arbitrarily to any value with a high accuracy in a relatively large range, which indicates that the system can also be extended to the SBIL application.展开更多
Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electri...Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electrical and/or optical injection and phase locking.However,these techniques normally involve complex experimental facilities.Therefore,an easy implementation of the stability evaluation of a laser is still challenging,especially for lasers emitting in the terahertz(THz)frequency range because the broadband photodetectors and mature locking techniques are limited.In this work,we propose a simple method,i.e.,relative phase locking,to quickly evaluate the stability of THz lasers without a need of a THz local oscillator.The THz laser system consists of a THz quantum cascade laser(QCL)frequency comb and a single-mode QCL.Using the single-mode laser as a fast detector,heterodyne signals resulting from the beating between the singlemode laser and the comb laser are obtained.One of the heterodyne beating signals is selected and sent to a phase-locked loop(PLL)for implementing the relative phase locking.Two kinds of locks are performed by feeding the output error signal of the PLL,either to the comb laser or to the single-mode laser.By analyzing the current change and the corresponding frequency change of the PLL-controlled QCL in each phase-locking condition,we,in principle,are able to experimentally compare the stability of the emission frequency of the single-mode QCL(f s)and the carrier envelope offset frequency(f CEO)of the QCL comb.The experimental results reveal that the QCL comb with the repetition frequency injection locked demonstrates much higher stability than the single-mode laser.The work provides a simple heterodyne scheme for understanding the stability of THz lasers,which paves the way for the further locking of the lasers and their high-precision applications in the THz frequency range.展开更多
We have developed two 474 THz(633 nm)new iodine stabilized He-Ne lasers with compatible system of third and fifth harmonic locking.The frequency stability is 1.0×10-11/ 1s and 3.5×10-12 / 10s with third harm...We have developed two 474 THz(633 nm)new iodine stabilized He-Ne lasers with compatible system of third and fifth harmonic locking.The frequency stability is 1.0×10-11/ 1s and 3.5×10-12 / 10s with third harmonic locking,and corresponding values are 1.3×10-11/1s and 4.0×10-12/ 10s with fifth harmonic locking.We found that the frequency difference between the same component with third and fifth harmonic locking are from 5 kHz to SO kHz.Our experiment and analysis indicate that the center of fifth harmonic signals is closer to the Lorentzian center in iodine absorption component than one of the third harmonic signals,and the reproducibility with fifth harmonic locking is also better than one with third harmonic locking.展开更多
Graphic processing units (GPUs) have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due ...Graphic processing units (GPUs) have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due to the lack in framework for real-time analysis. In order to guarantee real-time requirements while maintaining system utilization ~in modern heterogeneous systems, such as multicore multi-GPU systems, a novel suspension-based k-exclusion real-time locking protocol and the associated suspension-aware schedulability analysis are proposed. The proposed protocol provides a synchronization framework that enables multiple GPUs to be efficiently integrated in multicore real-time systems. Comparative evaluations show that the proposed methods improve upon the existing work in terms of schedulability.展开更多
It is demonstrated how superconducting iced particles of the protoplanetary cloud of Saturn are coming to magnetic equator plane and create the stable enough rings disk. There are two steps. First, after appearance of...It is demonstrated how superconducting iced particles of the protoplanetary cloud of Saturn are coming to magnetic equator plane and create the stable enough rings disk. There are two steps. First, after appearance of the Saturn magnetic field due to Meissner phenomenon, all particles orbits are moving to the magnetic equator plane. Finally they become distributed as rings and gaps like iron particles around magnet on laboratory table. And they are separated from each other by the magnetic field expelled from them. It takes up to few tens of thousands years with ten meters rings disk thickness. Second, because of quantum locking all particles become to be locked within magnetic well at the magnetic equator plane due to Abrikosov vortex for superconductor. Finally each particle is locked within three-dimensional magnetic well. It works even when particles have small fraction of superconductor. During the rings evolution some contribution to the disk also could come from the collision-generated debris of the current moon, coming meteorites and from the geysers like it happened due to magnetic coupling of Saturn and Enceladus. The rings are relict of the early days of the magnetic field of Saturn system.展开更多
Mode locking can be effectively achieved by using the thermo-optic effects in the whispering gallery mode(WGM)optical microcavity,without the help of external equipment.Therefore,it has the advantages of small size,lo...Mode locking can be effectively achieved by using the thermo-optic effects in the whispering gallery mode(WGM)optical microcavity,without the help of external equipment.Therefore,it has the advantages of small size,low integration costs,and self-locking,which shows great potential for application.However,the conventional single-channel microcavity thermal-locking method that relies solely on internal thermal balance will inevitably be disturbed by the external environment.This limitation affects the locking time and stability.Therefore,in this paper,we propose a new method for closed-loop thermal locking of a dual-channel microcavity.The thermal locking of the signal laser and the thermal regulation of the control laser are carried out respectively by synchronously drawing a dual-path tapered fiber.The theoretical model of the thermal dynamics of the dual-channel microcavity system is established,and the influence of the control-laser power on the thermal locking of the signal laser is confirmed.The deviation between the locking voltage of the signal laser and the set point value is used as a closed-loop feedback parameter to achieve long-term and highly stable mode locking of the signal laser.The results show that in the 2.63 h thermal-locking test,the locking stability is an order of magnitude higher than that of the single tapered fiber.This solution addresses the issue of thermal locking being disrupted by the external environment,and offers new possibilities for important applications such as spectroscopy and micro-optical sensor devices.展开更多
According to the United Nations,a moderately aging society refers to a country where those aged 65 and above exceed 14%of the total population.Data released by the Ministry of Civil Affairs showed that there were 296....According to the United Nations,a moderately aging society refers to a country where those aged 65 and above exceed 14%of the total population.Data released by the Ministry of Civil Affairs showed that there were 296.97 million people aged 60 and above in China by the end of 2023,accounting for 21.1%of the total population.Among them,216.76 million were aged 65 and above,making up 15.4%of the total population.This indicates that China has officially crossed the threshold into a moderately aging society.展开更多
Background: Fractures of humeral shaft in adults are common injuries. Humeral shafts non-union either from late presentation after initial treatment by traditional bone setters or failed non-operative orthodox care is...Background: Fractures of humeral shaft in adults are common injuries. Humeral shafts non-union either from late presentation after initial treatment by traditional bone setters or failed non-operative orthodox care is a major problem in this part of the world. This non-union is a major treatment challenge with increased cost of care and morbidity in this part of the world. Humeral shaft non-union can be treated with locked intra-medullary nailing (LIMN) or dynamic compression plating (DCP). Study on comparison of these methods of fixation in this part of the world is scarce in literature search, hence the reason for this study. Objective: The objectives of this study are: (1) to compare early clinical outcome following fixation of humeral shaft fracture nonunion with DCP versus LIMN;(2) to compare the time of radiologic fracture union of DCP with LIMN;(3) to compare complications following fixation of humeral shaft fracture nonunion with DCP versus LIMN. Patients and Methods: This was a randomized control study done for 2 years in which fifty adult patients with humeral shaft non-union were recruited. The patients were grouped into 2 (P = DCP & N = LIMN). Forty five of the patients completed the follow up periods of the study and then analyzed. The P group had ORIF with DCP while the N group had ORIF with LIMN. Both groups had grafting with cancellous bones. Each patient was followed up for a period of 6 months at the time which radiographic union is expected. Any patient without clinical and/or radiographic evidence of union after six months of surgery was diagnosed as having recurrent non-union. The data generated was analyzed using SPSS Version 23. The results were presented in charts and tables. The paired t-test was used while considering p value Result: Forty five patients completed follow up. There was a male preponderance (4:1), right humerus predominated (3:2). Motor vehicular accidents were the commonest cause of the fractures (62%). Most non-union fractures occurred at the level of the middle 3<sup>rd</sup> of the humeral shaft (60%). Failed TBS treatment was the commonest indication for the osteosynthesis (71%). More patients had plating (53%) compared to 47% who had LIMN. Most patients (93.4%) had union between 3 to 6 months irrespective of fixation type with no significant statistical difference between the union rate of DCP and LIMN (p value 0.06) with similar functional outcome and complication rates irrespective of the type of fixation. Conclusion: This study showed that the success rates in term of fracture union, outcome functional grades and complication rates were not directly dependent on the types of the fixation: plating or locked intra-medullary nailing.展开更多
The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long tim...The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long time delay,which makes it difficult to realize mode locking without additional phaselocking mechanisms.We have achieved,for the first time to our knowledge,a self-mode-locking OEO and generated stable microwave frequency combs by analyzing the characteristics of OEOs with an ultrashort time scale.In the experiment,the self-mode-locking OEOs with fundamental mode,second-order harmonic,and sixth-order harmonic were realized by adjusting the system parameters,all of which produced uniform square wave signals with tunable duty cycles,steep rising and falling edges,and periods of less than 20 ns.The self-fundamental-mode-locking OEOs with different time delays were also implemented and experimentally realized.Furthermore,the experiment revealed the self-hybrid mode-locking OEO,which is the coexistence and synchronization of the three measured self-locking modes in one OEO cavity,demonstrating the complex nonlinear dynamical behaviors of the OEO system and enabling the generation of periodic nonuniform hybrid square wave signals.The realization of the self-mode-locking OEO and the generation of flexible and stable square wave signals at ultrashort time scales enrich the study of OEO nonlinear dynamics in the realm of complex microwave waveform generation,offering promising applications in areas such as atomic clocks,radars,communications,and optoelectronic neural networks.展开更多
The widespread applications of single-cell technologies have generated a large amount of single-cell data,resulting in a growing need for single-cell data analysis and interpretation methods.While methods such as mach...The widespread applications of single-cell technologies have generated a large amount of single-cell data,resulting in a growing need for single-cell data analysis and interpretation methods.While methods such as machine learning allow for single-cell data analysis,they cannot interpret the data very well.展开更多
AIM To compare the outcomes of displaced distal radius fractures treated with volar locking plates and with immediate postoperative mobilisation with the outcomes of these fractures treated with modalities that necess...AIM To compare the outcomes of displaced distal radius fractures treated with volar locking plates and with immediate postoperative mobilisation with the outcomes of these fractures treated with modalities that necessitate 6 wk wrist immobilisation.METHODS A prospective, randomised controlled single-centre trial was conducted with 56 patients who had a displaced radius fracture were randomised to treatment either with a volar locking plate(n = 29), or another treatment modality(n = 27; cast immobilisation with or without wires or external fixator). Outcomes were measured at 12 wk. Functional outcome scores measured were the Patient-Rated Wrist Evaluation(PRWE) Score; Disabilities of the Arm, Shoulder and Hand and activities of daily living(ADLs). Clinical outcomes were wrist range of motion and grip strength. Radiographic parameters were volar inclination and ulnar variance.RESULTS Patients in the volar locking plate group had significantly better PRWE scores, ADL scores, grip strength and range of extension at three months compared with the control group. All radiological parameters were significantly better in the volar locking plate group at 3 mo. CONCLUSION The present study suggests that volar locking plates produced significantly better functional and clinical outcomes at 3 mo compared with other treatment modalities. Anatomical reduction was significantly more likely to be preserved in the plating group. Level of evidence: Ⅱ.展开更多
Contact nonlinear theory was researched. Contact problem was transformed into optimization problem containing Lagrange multiplier, and unsymmetrical stiffness matrix was transformed into symmetrical stiffness matrix. ...Contact nonlinear theory was researched. Contact problem was transformed into optimization problem containing Lagrange multiplier, and unsymmetrical stiffness matrix was transformed into symmetrical stiffness matrix. A finite element analysis (FEA) model defining more than 300 contact pairs for long nut-short screw locking mechanism of a large-scale vertical gear-rack typed ship-lift was built. Using augmented Lagrange method and symmetry algorithm of contact element stiffness, the FEA model was analyzed, and the contact stress of contact interfaces and the von Mises stress of key parts were obtained. The results show that the design of the locking mechanism meets the requirement of engineering, and this method is effective for solving large stole nonlinear contact pairs.展开更多
Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in dif...Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.展开更多
To predict the attitude of satellite during the whole deployment process and evaluate the locking impact, a numerical flexible model of a certain satellite associated with four flexible honeycomb solar panels was esta...To predict the attitude of satellite during the whole deployment process and evaluate the locking impact, a numerical flexible model of a certain satellite associated with four flexible honeycomb solar panels was established. The flexible solar panel was modeled by the finite element analysis (FEA), and the motion equations were derived by Lagrangian formulation. The locking process was based on the method of Hertzian contact, which enables one to predict the locking impact on the satellite and the subsequent oscillation of solar panels. The results reveal that locking operation has great impact on the attitude of the satellite, and the angular acceleration of satellite reaches 22.03°/s2 at the locking moment; the flexible solar panels model is feasible to predict the accurate response of the satellite during deployment and the oscillation of solar panels; the instantly impulsive force occurred during locking process is about 1.5 kN and the changing time is nearly 0.32 s. It provides an effective approach to present the flexible solar panels' deployment process and evaluate the locking impact.展开更多
This paper presents an algorithm that aims to reduce the peak-to-average power ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) communication systems while maintaining frequency tracking.The algorit...This paper presents an algorithm that aims to reduce the peak-to-average power ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) communication systems while maintaining frequency tracking.The algorithm achieves PAPR reduction by applying the complex conjugates of the data symbol obtained from the frequency domain to cancel the phase of the data symbol.A likelihood estimator is used to obtain the sub-carrier phase error due to the residual carrier frequency offset(RCFO) using the same complex conjugates as a pilot signal.Furthermore,a joint time and frequency domain multicarrier phase locked loop(MPLL) is developed to compensate additional frequency offset.Simulation results show that this algorithm is capable of reducing PAPR without impacting the frequency tracking performance.展开更多
Dear editor,In this letter,we would like to discuss a method to avoid collisions and deadlocks in multi-robot systems based on a new concept of glued nodes.In terms of collision and deadlock avoidance,many methods are...Dear editor,In this letter,we would like to discuss a method to avoid collisions and deadlocks in multi-robot systems based on a new concept of glued nodes.In terms of collision and deadlock avoidance,many methods are based on zone control which has two disadvantages.First,unless all nodes are collision-free,the roadmap must be divided into disjoint zones,which increases the difficulty of applying the methods.Moreover,each zone should be able to accommodate a robot,which leads to imprecision and waste of space.This letter proposes the concept of glued nodes,which can dynamically determine the mutual influence between nodes based on the real-time sizes and paths of the robots.Based on the glued nodes,this letter proposes a collision and deadlock avoidance algorithm,which can be applied to multi-robot systems with variable-sized robots and roadmaps with any structure.The experimental results indicate that the method proposed in this letter is effective and efficient.展开更多
Abstract We study dynamics in two mutually coupling multi-quantum-well lasers. We carry out theoretical and numerical analysis of synchronization, anti-synchronization, in-phase locking in the two identical lasers but...Abstract We study dynamics in two mutually coupling multi-quantum-well lasers. We carry out theoretical and numerical analysis of synchronization, anti-synchronization, in-phase locking in the two identical lasers but detuning, in detain. It is proved that the coupling level determines stability of the lasers by analyzing the eigenvalue equation. Critical case of locking is discussed via the phase difference equation. Quasi-period and stable states in the two lasers are investigated via varying the current, detuning and coupling level.展开更多
The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rota...The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.展开更多
基金This work was partially supported by Shanghai Municipal Health Bureau(No.2011239)the National Science and Technology Supporting Program of China(No.2012BAI17B02).
文摘The current study is to observe the effect of the locking system strengthened by biomimetic mineralized collagen putty for the treatment of senile proximal humeral osteoporotic fractures.From January 2012 to December 2015,80 cases of senile patients with osteoporotic proximal humeral fractures were randomly divided into an observation group and a control group,each group with a total of 40 cases.The control group was simply treated with locking plate.The observation group was treated with locking plate in combination with biomimetic mineralized collagen putty.The therapeutic effect thereby was observed.The excellent and satisfactory rate was 90%in observation group and was 72.5%in control group.The difference between the two groups was statistically significant(χ^(2)=5.3312,P<0.05).The fracture healing time was 11.8263.62 weeks in observation group and 19.7865.46 weeks in control group.The shoulder joint function score was 89.6368.12 in observation group and 76.9268.18 in control group.There was significant difference between the two groups(t=7.1272;12.7834,P<0.05).The complication rate was 10%in the observation group and 32.5%in the control group(χ^(2)=7.3786,P<0.05).Locking system strengthened by biomimetic mineralized collagen putty has advantages such as accelerating healing of senile proximal humeral fracture,improving the therapeutic effect,reducing the complications.As one of the optimal internal fixation method,it provides a new option for better treatment of senile osteoporotic fracture.
基金supported by the Foundation of the State Key Laboratory of Tribology at China(No.SKLT2014C01)the National Nature Science Foundation of China(No.51475262)the Autonomous Scientific Research Project of Tsinghua University at China(No.20151080363)
文摘We present a novel homodyne frequency-shifting interference pattern locking system to enhance the exposure contrast of interference lithography and scanning beam interference lithography(SBIL). The novel interference pattern locking system employs a special homodyne redundant phase measurement interferometer(HRPMI) as the sensor and an acousto-opto modulator(AOM) as the actuator. The HRPMI offers the highly accurate value as well as the direction recognition of the interference pattern drift from four quadrature interference signals. The AOM provides a very fine resolution with a high speed for phase modulation. A compact and concise system with a short optical path can be achieved with this new scheme and a small power laser head in tens of microwatts is sufficient for exposure and phase locking, which results in a relatively low-cost system compared with the heterodyne system. More importantly, the accuracy of the system is at a high level as well as having robustness to environmental fluctuation. The experiment results show that the short-time(4 s) accuracy of the system is 0.0481 rad e3σT at present. Moreover, the phase of the interference pattern can also be set arbitrarily to any value with a high accuracy in a relatively large range, which indicates that the system can also be extended to the SBIL application.
基金supported by the National Natural Science Foundation of China(Grant Nos.62235019,61875220,61927813,62035005,61991430,and 62105351)the“From 0 to 1”Innovation Program of the Chinese Academy of Sciences(Grant No.ZDBSLY-JSC009)+4 种基金the Scientific Instrument and Equipment Development Project of the Chinese Academy of Sciences(Grant No.YJKYYQ20200032)the CAS Project for Young Scientists in BasicResearch(Grant No.YSBR-069)the National Science Fund for Excellent Young Scholars(Grant No.62022084)the Shanghai Outstanding Academic Leaders Plan(Grant No.20XD1424700)the Shanghai Youth Top Talent Support Program.The authors have no conflicts to disclose.
文摘Stable operation is one of the most important requirements for a laser source for high-precision applications.Many efforts have been made to improve the stability of lasers by employing various techniques,e.g.,electrical and/or optical injection and phase locking.However,these techniques normally involve complex experimental facilities.Therefore,an easy implementation of the stability evaluation of a laser is still challenging,especially for lasers emitting in the terahertz(THz)frequency range because the broadband photodetectors and mature locking techniques are limited.In this work,we propose a simple method,i.e.,relative phase locking,to quickly evaluate the stability of THz lasers without a need of a THz local oscillator.The THz laser system consists of a THz quantum cascade laser(QCL)frequency comb and a single-mode QCL.Using the single-mode laser as a fast detector,heterodyne signals resulting from the beating between the singlemode laser and the comb laser are obtained.One of the heterodyne beating signals is selected and sent to a phase-locked loop(PLL)for implementing the relative phase locking.Two kinds of locks are performed by feeding the output error signal of the PLL,either to the comb laser or to the single-mode laser.By analyzing the current change and the corresponding frequency change of the PLL-controlled QCL in each phase-locking condition,we,in principle,are able to experimentally compare the stability of the emission frequency of the single-mode QCL(f s)and the carrier envelope offset frequency(f CEO)of the QCL comb.The experimental results reveal that the QCL comb with the repetition frequency injection locked demonstrates much higher stability than the single-mode laser.The work provides a simple heterodyne scheme for understanding the stability of THz lasers,which paves the way for the further locking of the lasers and their high-precision applications in the THz frequency range.
基金The project is supported by Naural Science Foundation Committee of China
文摘We have developed two 474 THz(633 nm)new iodine stabilized He-Ne lasers with compatible system of third and fifth harmonic locking.The frequency stability is 1.0×10-11/ 1s and 3.5×10-12 / 10s with third harmonic locking,and corresponding values are 1.3×10-11/1s and 4.0×10-12/ 10s with fifth harmonic locking.We found that the frequency difference between the same component with third and fifth harmonic locking are from 5 kHz to SO kHz.Our experiment and analysis indicate that the center of fifth harmonic signals is closer to the Lorentzian center in iodine absorption component than one of the third harmonic signals,and the reproducibility with fifth harmonic locking is also better than one with third harmonic locking.
基金supported by the National Natural Science Foundation of China under Grant No.61003032/F020207
文摘Graphic processing units (GPUs) have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due to the lack in framework for real-time analysis. In order to guarantee real-time requirements while maintaining system utilization ~in modern heterogeneous systems, such as multicore multi-GPU systems, a novel suspension-based k-exclusion real-time locking protocol and the associated suspension-aware schedulability analysis are proposed. The proposed protocol provides a synchronization framework that enables multiple GPUs to be efficiently integrated in multicore real-time systems. Comparative evaluations show that the proposed methods improve upon the existing work in terms of schedulability.
文摘It is demonstrated how superconducting iced particles of the protoplanetary cloud of Saturn are coming to magnetic equator plane and create the stable enough rings disk. There are two steps. First, after appearance of the Saturn magnetic field due to Meissner phenomenon, all particles orbits are moving to the magnetic equator plane. Finally they become distributed as rings and gaps like iron particles around magnet on laboratory table. And they are separated from each other by the magnetic field expelled from them. It takes up to few tens of thousands years with ten meters rings disk thickness. Second, because of quantum locking all particles become to be locked within magnetic well at the magnetic equator plane due to Abrikosov vortex for superconductor. Finally each particle is locked within three-dimensional magnetic well. It works even when particles have small fraction of superconductor. During the rings evolution some contribution to the disk also could come from the collision-generated debris of the current moon, coming meteorites and from the geysers like it happened due to magnetic coupling of Saturn and Enceladus. The rings are relict of the early days of the magnetic field of Saturn system.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3203400)the National Natural Science Foundation of China(Grant Nos.U21A20141,62273314,and 51821003)+1 种基金the Fundamental Research Program of Shanxi Province(Grant No.202303021223001)Shanxi Province Key Laboratory of Quantum Sensing and Precision Measurement(Grant No.201905D121001)。
文摘Mode locking can be effectively achieved by using the thermo-optic effects in the whispering gallery mode(WGM)optical microcavity,without the help of external equipment.Therefore,it has the advantages of small size,low integration costs,and self-locking,which shows great potential for application.However,the conventional single-channel microcavity thermal-locking method that relies solely on internal thermal balance will inevitably be disturbed by the external environment.This limitation affects the locking time and stability.Therefore,in this paper,we propose a new method for closed-loop thermal locking of a dual-channel microcavity.The thermal locking of the signal laser and the thermal regulation of the control laser are carried out respectively by synchronously drawing a dual-path tapered fiber.The theoretical model of the thermal dynamics of the dual-channel microcavity system is established,and the influence of the control-laser power on the thermal locking of the signal laser is confirmed.The deviation between the locking voltage of the signal laser and the set point value is used as a closed-loop feedback parameter to achieve long-term and highly stable mode locking of the signal laser.The results show that in the 2.63 h thermal-locking test,the locking stability is an order of magnitude higher than that of the single tapered fiber.This solution addresses the issue of thermal locking being disrupted by the external environment,and offers new possibilities for important applications such as spectroscopy and micro-optical sensor devices.
文摘According to the United Nations,a moderately aging society refers to a country where those aged 65 and above exceed 14%of the total population.Data released by the Ministry of Civil Affairs showed that there were 296.97 million people aged 60 and above in China by the end of 2023,accounting for 21.1%of the total population.Among them,216.76 million were aged 65 and above,making up 15.4%of the total population.This indicates that China has officially crossed the threshold into a moderately aging society.
文摘Background: Fractures of humeral shaft in adults are common injuries. Humeral shafts non-union either from late presentation after initial treatment by traditional bone setters or failed non-operative orthodox care is a major problem in this part of the world. This non-union is a major treatment challenge with increased cost of care and morbidity in this part of the world. Humeral shaft non-union can be treated with locked intra-medullary nailing (LIMN) or dynamic compression plating (DCP). Study on comparison of these methods of fixation in this part of the world is scarce in literature search, hence the reason for this study. Objective: The objectives of this study are: (1) to compare early clinical outcome following fixation of humeral shaft fracture nonunion with DCP versus LIMN;(2) to compare the time of radiologic fracture union of DCP with LIMN;(3) to compare complications following fixation of humeral shaft fracture nonunion with DCP versus LIMN. Patients and Methods: This was a randomized control study done for 2 years in which fifty adult patients with humeral shaft non-union were recruited. The patients were grouped into 2 (P = DCP & N = LIMN). Forty five of the patients completed the follow up periods of the study and then analyzed. The P group had ORIF with DCP while the N group had ORIF with LIMN. Both groups had grafting with cancellous bones. Each patient was followed up for a period of 6 months at the time which radiographic union is expected. Any patient without clinical and/or radiographic evidence of union after six months of surgery was diagnosed as having recurrent non-union. The data generated was analyzed using SPSS Version 23. The results were presented in charts and tables. The paired t-test was used while considering p value Result: Forty five patients completed follow up. There was a male preponderance (4:1), right humerus predominated (3:2). Motor vehicular accidents were the commonest cause of the fractures (62%). Most non-union fractures occurred at the level of the middle 3<sup>rd</sup> of the humeral shaft (60%). Failed TBS treatment was the commonest indication for the osteosynthesis (71%). More patients had plating (53%) compared to 47% who had LIMN. Most patients (93.4%) had union between 3 to 6 months irrespective of fixation type with no significant statistical difference between the union rate of DCP and LIMN (p value 0.06) with similar functional outcome and complication rates irrespective of the type of fixation. Conclusion: This study showed that the success rates in term of fracture union, outcome functional grades and complication rates were not directly dependent on the types of the fixation: plating or locked intra-medullary nailing.
基金supported by the National Natural Science Foundation of China(Grant No.62301495)the Project of the National Key Laboratory of Microwave Photonics(Nanjing University of Aeronautics and Astronautics),Ministry of Education(Grant No.NJ20220007).
文摘The optoelectronic oscillator(OEO)is a typical time-delay system with rich nonlinear dynamical characteristics.Most of the previous research on OEOs has been focused on analyzing the properties of OEOs with a long time delay,which makes it difficult to realize mode locking without additional phaselocking mechanisms.We have achieved,for the first time to our knowledge,a self-mode-locking OEO and generated stable microwave frequency combs by analyzing the characteristics of OEOs with an ultrashort time scale.In the experiment,the self-mode-locking OEOs with fundamental mode,second-order harmonic,and sixth-order harmonic were realized by adjusting the system parameters,all of which produced uniform square wave signals with tunable duty cycles,steep rising and falling edges,and periods of less than 20 ns.The self-fundamental-mode-locking OEOs with different time delays were also implemented and experimentally realized.Furthermore,the experiment revealed the self-hybrid mode-locking OEO,which is the coexistence and synchronization of the three measured self-locking modes in one OEO cavity,demonstrating the complex nonlinear dynamical behaviors of the OEO system and enabling the generation of periodic nonuniform hybrid square wave signals.The realization of the self-mode-locking OEO and the generation of flexible and stable square wave signals at ultrashort time scales enrich the study of OEO nonlinear dynamics in the realm of complex microwave waveform generation,offering promising applications in areas such as atomic clocks,radars,communications,and optoelectronic neural networks.
文摘The widespread applications of single-cell technologies have generated a large amount of single-cell data,resulting in a growing need for single-cell data analysis and interpretation methods.While methods such as machine learning allow for single-cell data analysis,they cannot interpret the data very well.
文摘AIM To compare the outcomes of displaced distal radius fractures treated with volar locking plates and with immediate postoperative mobilisation with the outcomes of these fractures treated with modalities that necessitate 6 wk wrist immobilisation.METHODS A prospective, randomised controlled single-centre trial was conducted with 56 patients who had a displaced radius fracture were randomised to treatment either with a volar locking plate(n = 29), or another treatment modality(n = 27; cast immobilisation with or without wires or external fixator). Outcomes were measured at 12 wk. Functional outcome scores measured were the Patient-Rated Wrist Evaluation(PRWE) Score; Disabilities of the Arm, Shoulder and Hand and activities of daily living(ADLs). Clinical outcomes were wrist range of motion and grip strength. Radiographic parameters were volar inclination and ulnar variance.RESULTS Patients in the volar locking plate group had significantly better PRWE scores, ADL scores, grip strength and range of extension at three months compared with the control group. All radiological parameters were significantly better in the volar locking plate group at 3 mo. CONCLUSION The present study suggests that volar locking plates produced significantly better functional and clinical outcomes at 3 mo compared with other treatment modalities. Anatomical reduction was significantly more likely to be preserved in the plating group. Level of evidence: Ⅱ.
基金Supported by the Key Research Project of StatePower Corporation (SPKJ 0l6-06)the Key Scientific ResearchProject of Hubei Province ( 2004AC101D31)
文摘Contact nonlinear theory was researched. Contact problem was transformed into optimization problem containing Lagrange multiplier, and unsymmetrical stiffness matrix was transformed into symmetrical stiffness matrix. A finite element analysis (FEA) model defining more than 300 contact pairs for long nut-short screw locking mechanism of a large-scale vertical gear-rack typed ship-lift was built. Using augmented Lagrange method and symmetry algorithm of contact element stiffness, the FEA model was analyzed, and the contact stress of contact interfaces and the von Mises stress of key parts were obtained. The results show that the design of the locking mechanism meets the requirement of engineering, and this method is effective for solving large stole nonlinear contact pairs.
文摘Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.
文摘To predict the attitude of satellite during the whole deployment process and evaluate the locking impact, a numerical flexible model of a certain satellite associated with four flexible honeycomb solar panels was established. The flexible solar panel was modeled by the finite element analysis (FEA), and the motion equations were derived by Lagrangian formulation. The locking process was based on the method of Hertzian contact, which enables one to predict the locking impact on the satellite and the subsequent oscillation of solar panels. The results reveal that locking operation has great impact on the attitude of the satellite, and the angular acceleration of satellite reaches 22.03°/s2 at the locking moment; the flexible solar panels model is feasible to predict the accurate response of the satellite during deployment and the oscillation of solar panels; the instantly impulsive force occurred during locking process is about 1.5 kN and the changing time is nearly 0.32 s. It provides an effective approach to present the flexible solar panels' deployment process and evaluate the locking impact.
基金supported by the National Natural Science Foundation of China(60872026)the Natural Science Foundation of Tianjin(09JCZDJC16900)
文摘This paper presents an algorithm that aims to reduce the peak-to-average power ratio(PAPR) of orthogonal frequency division multiplexing(OFDM) communication systems while maintaining frequency tracking.The algorithm achieves PAPR reduction by applying the complex conjugates of the data symbol obtained from the frequency domain to cancel the phase of the data symbol.A likelihood estimator is used to obtain the sub-carrier phase error due to the residual carrier frequency offset(RCFO) using the same complex conjugates as a pilot signal.Furthermore,a joint time and frequency domain multicarrier phase locked loop(MPLL) is developed to compensate additional frequency offset.Simulation results show that this algorithm is capable of reducing PAPR without impacting the frequency tracking performance.
文摘Dear editor,In this letter,we would like to discuss a method to avoid collisions and deadlocks in multi-robot systems based on a new concept of glued nodes.In terms of collision and deadlock avoidance,many methods are based on zone control which has two disadvantages.First,unless all nodes are collision-free,the roadmap must be divided into disjoint zones,which increases the difficulty of applying the methods.Moreover,each zone should be able to accommodate a robot,which leads to imprecision and waste of space.This letter proposes the concept of glued nodes,which can dynamically determine the mutual influence between nodes based on the real-time sizes and paths of the robots.Based on the glued nodes,this letter proposes a collision and deadlock avoidance algorithm,which can be applied to multi-robot systems with variable-sized robots and roadmaps with any structure.The experimental results indicate that the method proposed in this letter is effective and efficient.
文摘Abstract We study dynamics in two mutually coupling multi-quantum-well lasers. We carry out theoretical and numerical analysis of synchronization, anti-synchronization, in-phase locking in the two identical lasers but detuning, in detain. It is proved that the coupling level determines stability of the lasers by analyzing the eigenvalue equation. Critical case of locking is discussed via the phase difference equation. Quasi-period and stable states in the two lasers are investigated via varying the current, detuning and coupling level.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074078)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)+1 种基金the Key Program for Scientific and Technological Innovations of Higher Education Institutes in Guangdong Province,China(Grant No.cxzd1011)the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant No.C10183)
文摘The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simpie model has been established to explain the experimental observation.