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Powerful and compact coherent mid-infrared radiation source is crucial for a vast number of applications. A widely tunable 3- $15~\mu $ m optical parametric amplifier with BaGa2GeSe6 crystal pumped by a picosecond mode-locked 1064 nm laser was demonstrated for the first time. Type-I produced a maximum energy of $377~\mu $ J at $5.2~\mu $ m, while type-II achieved a maximum energy of $294~\mu $ J at $6.7~\mu $ m under the incident pump energy of 11.8 mJ, corresponding to the pump-to-idler energy efficiency of 3.2% and 2.5%, respectively. Furthermore, the corresponding phase-matching angles for 3– $15~\mu $ m were measured experimentally. Moreover, the conversion efficiency, typical pulse temporal shapes and beam spatial profiles of idler were calculated based on a BaGa2GeSe6-OPA numerical model. The results indicate the potential of BaGa2GeSe6 pumped at 1064 nm for realizing high-efficiency and high-energy mid-infrared laser radiation.

Based on the hypersonic plasma model and the random phase screen theory, this study aimed to calculate the intensity and phase distribution of the scattering field when a double vortex beam passes through atmospheric turbulence and plasma targets. The results demonstrate that the combined double vortex beam exhibits superior retention of orbital angular momentum (OAM) energy compared to a general vortex beam, owing to the influence of turbulence and plasma target scattering. Furthermore, the scintillation coefficient of the laser scattering field is affected by the topological charge difference of the vortex light itself and the splitting of the light spot. It decreases initially and then increases as the topological charge difference of the double vortex beam increases. Moreover, by utilizing the scintillation index (SI) to calculate and analyze the bit error rate of the scattered field, a double vortex optical beam with a lower topological charge difference exhibits improved target detection performance. These findings offer a theoretical foundation for studying the detection of hypersonic plasma turbulence targets and investigating the “blackout” issues related to plasma sheath.

Orbital angular momentum (OAM) has a unique mode division multiplexing model that can increase the communication capacity and density of laser communication without increasing the frequency spectrum while achieving high-density and high-capacity laser communication and greatly improving transmission capacity. This letter conducts the model in hypersonic target plasma turbulence and investigates the OAM multiplexing characteristics in line-of-sight multiple-input–multiple-output systems under a plasma turbulence environment. The singular value (SV) and spectrum efficiency (SE) of power exponential vortex beams are compared with those of normal vortex beams. In addition, the intensity and phase of the power exponential vortex light penetrating turbulence are analyzed. Results show that the SE and SV of power exponential vortex beams are higher than those of ordinary vortex beams in hypersonic plasma turbulence under certain conditions. This finding indicates that the communication performance of power exponential vortex beams in plasma turbulence is better than that of ordinary vortex beams. These results can provide a theoretical basis for the analysis of hypersonic plasma targets.

The cortical patterning principle has been a long-standing question in neuroscience, yet how this translates to macroscale functional specialization in the human brain remains largely unknown. Here we examine age-dependent differences in resting-state thalamocortical connectivity to investigate its role in the emergence of large-scale functional networks during early life, using a primarily cross-sectional but also longitudinal approach. We show that thalamocortical connectivity during infancy reflects an early differentiation of sensorimotor networks and genetically influenced axonal projection. This pattern changes in childhood, when connectivity is established with the salience network, while decoupling externally and internally oriented functional systems. A developmental simulation using generative network models corroborated these findings, demonstrating that thalamic connectivity contributes to developing key features of the mature brain, such as functional segregation and the sensory-association axis, especially across 12–18 years of age. Our study suggests that the thalamus plays an important role in functional specialization during development, with potential implications for studying conditions with compromised internal and external processing.

Plasma characteristic parameters are the basis for studying plasma properties and are important in engineering applications. A deep learning-based method, the P-U-net model, is proposed to meet the need for fast and efficient reconstruction of plasma parameters. The network is trained by improving the traditional U-net model and adding the previous information containing the target features into the scattered field. Several representative tests are carried out in the study, including both single-target plasma and multitarget plasma, to evaluate the performances of the proposed model. The simulation results demonstrate that the P-U-net model has obvious advantages in plasma parameter reconstruction compared with the classical iterative method and U-net model which only trains the real part of the scattered electric field. The mean absolute error of the reconstructed parameters of the P-U-net model is lower than other traditional methods. The proposed model is expected to provide more substantial theoretical support for further improving the real-time performance and detection accuracy of plasma parameters measurement.

Real-time emergency event processing for mega-constellation management requires an approach that can quickly obtain a satisfactory satellite range rescheduling scheme. In this article, a deep reinforcement learning (DRL) approach is proposed for rapid rescheduling on the basis of established satellite range scheduling schemes. Three rescheduling principles with different impacts on established scheduling schemes are first analyzed. A mathematical model for both maximizing the completion profits of dynamic missions and minimizing their impacts on scheduled missions is formulated. An efficient DRL-based approach to satellite range rescheduling is then developed. A mask processing mechanism is integrated into the reinforcement learning framework to effectively eliminate the conflicts accurately expressed by the conflict space, and a modified pointer network (Ptr-Net) based on the mask processing mechanism is employed to approximate the action-value function for optimal decision-making. Experimental results show that the proposed approach significantly outperforms the rule-based heuristic and another DRL-based method in terms of computational efficiency and optimization performance, and the total time spent during the training and testing phases of the proposed approach is approximately 13% of the total running time required by the search-based methods.

The electromagnetic (EM) scattering properties of a high-speed moving and time-varying plasma target are simulated in this work. The calculation model is first established for moving and time-varying dispersive medium with the Lorentz transformation and shift-operator finite-difference time-domain (SO-FDTD) method. Subsequently, the Lorentz-FDTD method is applied to calculate the EM scattering properties of the time-varying and moving plasma in a two-dimensional (2-D) case. Furthermore, the impact of the time-varying plasma parameters on the EM scattering properties is investigated. Finally, the bistatic radar cross section (RCS) of the time-varying plasma target is analyzed for various moving velocities and the results indicate that the EM wave is modulated by the time-varying and moving plasma, and the EM scattering of the time-varying and moving plasma is influenced by the moving velocity, time-varying properties, and plasma parameters.

A high power quasi-continuous-wave (QCW) efficiently-cooled ceramic slab laser oscillator is reported. The maximum output power can reach 9.85 kW with the optical-to-optical efficiency of 60% with respect to the absorbed pump power as well as the slope efficiency up to 65.3%. To the best of our knowledge, this is the highest output power for any Yb:YAG ceramic laser oscillator. Beam aberration of the efficiently-cooled Yb:YAG ceramic slab laser is detected by a parallel probe beam along the optical path of laser beam. The peak-to-valley (PV) value of the wavefront distortion is $2.8~\mu \text{m}$ under full output power. The beam quality factor $\beta $ is estimated to be about 3.7 times diffraction limit while without additional correction system. A numerical model of temperature field is constructed to analyze the wavefront distortion of the probe beam, and the calculated results are in agreement with the experimental data.

We describe a high-peak-power macro/micro pulse 1319 nm laser operation, which is produced by the acousto-optic Q-switched Nd:YAG oscillator that is side-pumped with quasi- continuous-wave laser diode. Under remaining a fixed macro pulse repetition frequency of 400 Hz, the lasing characteristics for different micro pulse schemes are investigated. To realize 1319 nm single wavelength oscillation, a birefringence-plate is employed to suppress the adjacent 1338 nm line. Under 390 W of pump power with $200 ~\mu \text{s}$ of pulse duration, an average Q-switched 1319 nm power is increased from 32.5 W to 51.5 W by increasing the repetition rate of micro pulse from 400 Hz to 1600 Hz, and the corresponding micro pulse width can be stretched from 124 ns to 154 ns. The calculated maximum peak power is 0.655 MW with a pulse energy of 81.2 mJ, which is the highest-result reported to date for Q-switched 1319 nm lasers.

Coronary heart disease (CHD) is the most common cardiovascular disease facing human beings. Cardiac remodelling is an important pathological factor for the progression of heart failure (HF) after CHD. At present, Chinese medicine is widely used in the treatment of HF, but there are still some drugs lack of evidence-based and mechanism evidence. Multi-omics techniques can deep explore candidate pathogenic factors and construct gene regulatory networks.This trial is intended to evaluate the effect on Huoxin pill (HXP) in the treatment of HF after programmable communication interface (PCI). Meantime, multi-omics analysis technique will be used to target the fundamental pathological links of cardiac remodelling, so as to study the mechanism of HXP in the treatment of HF after PCI.

We present a kilowatt-level quasi-continuous-wave (QCW) cryogenically cooled 946-nm slab laser oscillator for the first time, to the best of our knowledge. The laser system is based on a double-face-pumped large-size single-slab Nd:YAG design, delivering a record-high average power of 1.06 kW without additional amplification. This laser oscillator operates at repetition rate of 400 Hz with a pulse duration of 175 µs, resulting in a single pulse energy of 2.65 J. To the best of our knowledge, these results represent the highest output power and pulse energy for any all-solid-state 946-nm laser ever reported to date. Our scheme paves a new path for the development of the compact high-power solid-state 946-nm laser.

A compact and robust all-solid-state mid-infrared (MIR) laser at 6.45 µm with high average output power and near-Gaussian beam quality is demonstrated. A maximum output power of 1.53 W with a pulse width of approximately 42?ns at 10 kHz is achieved using a ZnGeP_2 (ZGP) optical parametric oscillator (OPO). This is the highest average power at 6.45 µm of any all-solid-state laser to the best of our knowledge. The average beam quality factor is measured to be M^2?=?1.19. Moreover, high output power stability is confirmed, with a power fluctuation of less than 1.35% rms over 2 h, and the laser can run efficiently for more than 500 h in total. Using this 6.45 µm pulse as a radiation source, ablation of animal brain tissue is tested. Furthermore, the collateral damage effect is theoretically analyzed for the first time, to the best of our knowledge, and the results indicate that this MIR laser has excellent ablation ability, making it a potential replacement for free electron lasers.

Background and Objectives: Vancomycin is one of the most commonly used antibiotics for intra-articular (IA) infusion in the treatment of prosthetic joint infection (PJI). This study aimed to preliminarily investigate the serum and synovial vancomycin concentrations in patients with PJI after IA infusion. Methods: In total, 16 patients who developed PJI were enrolled in this study; 14 of the patients were treated with IA infusion of vancomycin postoperatively, while the other 2 patients received intravenous (IV) infusion of vancomycin alone. Chemiluminescent immunoassay assay (CLIA) and high-performance liquid chromatography (HPLC) were used to determine the serum and synovial vancomycin concentrations, respectively. Results: Administration of vancomycin 0.5 g once daily (qd) IA maintained a high vancomycin trough concentration in synovial fluid before the next IA dose, regardless of whether it was given in combination with IV administration. The combination vancomycin 0.5 g qd IA + vancomycin 1 g every 12 h (q12h) IV yielded relatively good trough concentrations of vancomycin in both serum and synovial fluid. The mean trough serum vancomycin concentration of patients who used vancomycin 1 g q12h IV therapy was above 10 μg/mL; however, no vancomycin was detected in their synovial fluid. Conclusions: The rational use of IA vancomycin infusion may help to achieve effective therapeutic concentrations of vancomycin in the serum and synovial fluid of patients with PJI.

A high-power continuous-wave (CW) ultraviolet (UV) laser at 378 nm from an intracavity frequency-doubled Alexandrite laser has been demonstrated with 638 nm fiber-coupled laser diodes as the pump source. A maximum output power of 2.55 W was obtained, which is the highest power for CW frequency-doubled Alexandrite lasers, to the best of our knowledge, corresponding to the optical-to-optical conversion efficiency of 7.9% from 638 nm pump laser to 378 nm UV laser. The beam quality factors M^2 were measured to be 2.19 and 2.47 in x and y directions at UV output power of 1 W, respectively.

We call the solution of a kind of weighted Laplace equation complex-valued kernel α-harmonic mappings. In this paper, some geometric properties of the complex-valued kernel α-harmonic mappings, such as area, fully starlikeness and fully convexity of order γ, γ∈[0,1), are explored. Furthermore, for a class of given boundary function, the Radó–Kneser–Choquet-type theorem is obtained.

Current irrigation water use (IWU) estimation methods confront uncertainties warranting further attention, primarily stemming from constraints within model structure and data quality. This study proposes a hybrid framework that integrates multiple machine learning (ML) methods with theory‐guided strategies to calculate IWU for three principal cereal crops within the Chinese agricultural landscape. We generated high resolution time series data sets of evapotranspiration and surface soil moisture (SM) using remote sensing resources. ML techniques, along with the Bayesian three‐cornered hat ensemble, were employed to drive multiple remote sensing‐derived data sets in IWU calculation. We applied two theory‐guided mechanisms to quantify irrigation signals: first, converting original SM values into logarithmic terms, and second, extracting process‐based SM residuals. Proposed framework has been validated at 12 field stations across China, yielding coefficient of determination (R2) ranging from 0.54 to 0.70, and root mean square error (RMSE) spanning 278–335 mm/yr. Our framework demonstrates considerable strength in IWU estimation when compared to reported IWU values form 341 cities across China. Specifically, for rice, wheat, and maize, the R2values range from 0.78 to 0.83, 0.68 to 0.76, and 0.53 to 0.64, respectively, with corresponding RMSE measuring 0.22–0.25, 0.10–0.12, and 0.11–0.13 km3/yr, respectively. These findings highlight the effectiveness of theory‐guided strategies in discerning irrigation‐related information, thereby improving overall model performance. Attention should be directed toward the uncertainties in evapotranspiration and precipitation products on model performance, which remained modest, with a relative change of less than 5%. Hybrid framework is developed to estimate irrigation water use (IWU) for three staple cereal crops in ChinaMachine learning is employed to drive multiple remote sensing‐derived products for precise IWU estimationProposed framework accurately estimates IWU and incorporates theory‐guided module to reveal implicit irrigation signal Hybrid framework is developed to estimate irrigation water use (IWU) for three staple cereal crops in China Machine learning is employed to drive multiple remote sensing‐derived products for precise IWU estimation Proposed framework accurately estimates IWU and incorporates theory‐guided module to reveal implicit irrigation signal

High-power solid-state lasers with good beam quality are attracting great attention on account of their important applications in industry and military. However, the thermal effects generated in the laser host materials seriously limit power scaling and degrade the beam quality. Thermal lensing and thermally induced wavefront deformation are the main causes of the beam quality deterioration. Here we investigate the performance of a zero thermal expansion (ZTE) solid-state laser gain material. In a proof-of-principle experiment, an ${a}$-cut rod ${\rm Nd}\!:\!{{\rm YAlO}_3}$ (Nd:YAP) perovskite crystal is chosen to be the gain medium for ZTE around 180 K. The laser performance spanning the temperature range from 80 to 290 K is studied. The maximum output power and minimum threshold pump power were obtained at a temperature of 180 K. Moreover, the measured thermal focal power and peak-to-valley value of the wavefront distortion also reach a minimum at this temperature, an additional benefit from the crystal’s ZTE coefficient. We envisage that these results will open a new route towards the development of high-power and high-beam-quality lasers through the use of ZTE gain materials.

Sustained pain is a major characteristic of clinical pain disorders, but it is difficult to assess in isolation from co-occurring cognitive and emotional features in patients. In this study, we developed a functional magnetic resonance imaging signature based on whole-brain functional connectivity that tracks experimentally induced tonic pain intensity and tested its sensitivity, specificity and generalizability to clinical pain across six studies (total n= 334). The signature displayed high sensitivity and specificity to tonic pain across three independent studies of orofacial tonic pain and aversive taste. It also predicted clinical pain severity and classified patients versus controls in two independent studies of clinical low back pain. Tonic and clinical pain showed similar network-level representations, particularly in somatomotor, frontoparietal and dorsal attention networks. These patterns were distinct from representations of experimental phasic pain. This study identified a brain biomarker for sustained pain with high potential for clinical translation.

A 100 W level kilohertz repetition-rate microsecond (µs)-pulse all-solid-state sodium beacon laser at 589 nm is demonstrated for the first time, to the best of our knowledge, via combining two independent µs-pulsed lasers. Each beamlet is generated by the sum-frequency mixing of pulsed 1064 and 1319 nm lasers in a lithium triborate (LBO) crystal, which operate at 500 Hz pulse repetition frequency with 61 W $p$p-polarized and 53 W $s$s-polarized output, respectively. An incoherent sequence combining technology of polarized laser beams is employed to add the two beamlets. The average power of the combined beam is up to 107.5 W with a combining efficiency of 94.3%. The combined beam has a 1 kHz repetition rate with ${\sim}{120}\;\unicode{x00B5} {\rm s}$∼120µs pulse duration and beam quality ${M^2} = {1.41}$M^2=1.41. The central wavelength with a linewidth of ${\sim}{0.3}\;{\rm GHz}$∼0.3GHz is locked to a sodium ${{\rm D}_{2a}}$D_2a absorption line. To the best of our knowledge, this is a record-high power operating at kilohertz for µs-pulsed solid-state sodium beacon lasers.

We present a power-scalable high-power single-frequency continuous-wave 1342 nm master oscillator power amplifier (MOPA) system that consists of a polarized single-frequency 1342 nm LD seed laser, a Raman fiber preamplifier, and a three-stage ${\rm Nd}:{{\rm YVO}_4}$Nd:YVO_4 power amplifier. The single-frequency output power of 30 W at 1342 nm is achieved with the beam quality factors ${{\rm M}^{2\:}} = {1}.{26}$M^2=1.26, and the power stability for 1 h is better than ${\pm }\;{0}.{5}\% $±0.5%.

A 24.6 kW quasi-continuous-wave (QCW) Nd-doped yttrium aluminum garnet (Nd:YAG) slab laser is proposed in this Letter. The laser is based on a stable–unstable hybrid cavity. A stable and an unstable resonator were constructed along orthogonal directions in the aperture of the slab. Due to features of the hybrid cavity, the slab laser achieves both high efficiency of power extraction with excellent beam quality and compactness with simplicity. Average output power of 24.6 kW with 47% optical-to-optical efficiency is achieved in the experiment. The beam quality of the output beam is 1.5 times diffraction limits after correction of adaptive optics. The repetition frequency and pulse width of the laser are 400 Hz and 200 μs.

The solution set of the Sun-perturbed optimal two-impulse trans-lunar orbit is helpful for overall optimization of the lunar exploration mission. A model for computing the two-impulse trans-lunar orbit, which strictly satisfies the boundary constraints, is established. The solution set is computed first with a circular restricted three-body model using a generalized local gradient optimization algorithm and the strategy of design variable initial continuation. By taking the solution set of a circular restricted three-body model as the initial values of the design variables, the Sun-perturbed solution set is calculated based on the dynamic model continuation theory and traversal search methodology. A comparative analysis shows that the fuel cost may be reduced to some extent by considering the Sun’s perturbation and choosing an appropriate transfer window. Moreover, there are several optimal two-impulse trans-lunar methods for supporting a lunar mission to select a scenario with a certain ground measurement and to control the time cost. A fitted linear dependence relationship between the Sun’s befitting phase and the trans-lunar duration could thus provide a reference to select a low-fuel-cost trans-lunar injection window in an engineering project.

A void-free bonding technique was demonstrated for a large slab Nd: YAG crystal with a bonding surface dimension of $\sim{160}\;{\rm mm} \times {70}\;{\rm mm}$∼160mm×70mm. By using the novel fluxless oxide layer removal technology, the indium-oxide barrier problem was resolved. With the help of electrochemical-polished indium solder and a plasma-cleaned heat sink, the solderability of the indium was enhanced; in particular, the contact angle of the solder was improved from 51° to 31°. With the largest-bonding-size slab, a single-slab laser created a maximum output power of 7.3 kW under an absorbed pump power of 12.8 kW, corresponding to an optical to optical efficiency of 57% and a slope conversion of 67.8%. By detecting the wavefront of the interferometer before and after bonding, the RMS of wavefront was ${0.192}\lambda $0.192λ and ${0.434}\lambda $0.434λ ($\lambda = {633}\;{\rm nm}$λ=633nm), respectively. To the best of our knowledge, this is the largest void-free bonding size for a laser slab and the highest output power achieved from a single-slab crystal laser oscillator.

To design a free-return orbit for manned lunar mission based on low earth orbit (LEO) rendezvous, an adaptive LEO-phase free-return orbit design method based on high-precision dynamics model is proposed. First, the radius of perilune and the absolute value of perilune velocity are decoupled using a coordinate system rotation, which is derived from moon-centric local vertical and local horizontal instantaneous coordinate system at the time of perilune. The two Euler rotation angles and the absolute value of perilune velocity are used as independent design variables because their initial values are easy to guess. Next, a two-segment numerical integration strategy is proposed to calculate orbital elements at the moments of trans-lunar injection and free-return vacuum perigee. Subsequently, an optimization algorithm software package for solving large-scale nonlinear sequential quadratic programming problems (SQP_snopt) is employed to search the objective free-return orbit with a fixed trans-lunar injection inclination and the other two constraints on radiuses of perigee at the times of trans-lunar injection and vacuum perigee. After that, an iteration algorithm is devised to adjust trans-lunar injection window for adaptive LEO-phase. Finally, numerical results show a fast and accurate performance of the direct optimization method, which can provide valuable references to manned lunar missions based on LEO rendezvous.

Graphical Abstract:

A dual-wavelength ${{\rm TEM}_{01}}$TEM_01 mode synchronous continuous wave passively mode-locked (CWML) Nd:YAG laser has been demonstrated for the first time to the best of our knowledge with a semiconductor saturable absorber mirror (SESAM) at 1319 and 1338 nm. The maximum average output power of 10.84 W was obtained at a 113.8 W absorbed pump power, corresponding to an optical-to-optical conversion efficiency of 9.5%. The dual-wavelength CWML pulses had a pulse duration of 35.1 ps at a repetition rate of 76 MHz. The beam quality was measured to be ${{\rm M}^2} = {2.51}$M^2=2.51.

We report a compact, long nanosecond (ns) pulse duration stretched laser source by a multi-pass cavity (MPC). Based on the combination of the MPC and pump power, a high-power high beam quality 1064 nm Q-switched Nd:YAG laser with a pulse duration adjustable over the range of 160–1000 ns was obtained at a pulse repetition frequency of 10 kHz for the first time, to the best of our knowledge. At a typical pulse width of 560 ns, an average output power of 10.6 W was successfully achieved. The beam quality factor M^2 was measured to be 1.45 with a good Gaussian mode.

Slab gain media with large aspect ratios were difficult to be adopted in ultrafast regenerative amplifiers (RAs) due to the obstacle of mode matching with the seed beam. We proposed that an unstable cavity could be employed to solve this difficulty by taking the advantage of its large fundamental mode volume. In this way, an Nd:YVO_4 slab-based picosecond RA has been successfully demonstrated using a stable-unstable hybrid cavity. The maximum average output power of 10.5 W was achieved at the repetition rate of 10 kHz. The beam quality factor M^2 was measured to be 1.54 in the stable direction and 2.26 in the unstable direction.

We report a high-energy single-frequency deep-ultraviolet (DUV) solid-state laser at 167.079 nm by the eighth-harmonic generation of a diode-pumped Nd:LGGG laser. A maximum DUV laser output energy of 1.5 μJ at a 5 Hz repetition rate with a 200 μs pulse duration is achieved. The central wavelength of the DUV laser is located at 167.079 nm and can be finely tuned from 167.075 to 167.083 nm. The linewidth is estimated to be 0.025 pm. To the best of our knowledge, this is the first Letter reporting a high-energy single-frequency solid-state DUV laser below 170 nm. The successful demonstration of the high-energy single-frequency DUV laser source with the unique wavelength is useful for direct detection of a Al^+27 ion via resonance fluorescence in a multi-ion optical clock.

The straightness is an important indicator in measuring the quality of shaft parts. Laser peening straightening (LPS) is a new mechanical method to straight the shaft through inducing residual compressive stress into the shaft surface. Compared with the traditional method, the process of laser peening correction is high efficiency and can be controlled precisely. In the present work, the mechanism of laser peening straightening for shaft straightness is revealed and a three-dimensional finite model is developed to investigate the effects of laser parameters for shaft straightness correction. The results show that the peak pressure and pulse duration should be more than 4 GPa and 8 ns when laser peening straightening is used to correct the shaft straightness. The straightening amount increases with laser power density, laser pulse duration, multiple laser peening. The maximum correction amount for shaft straightness with LPS is no more than 0.01mm.

TC4 titanium alloy plate was processed under multiple laser shocks and bending deformation was studied. A method was proposed to determine the curvature radius of bending deformation of metal plate under multiple laser shocks based on the theoretical model of curvature radius of bending deformation and the eigenstrain field was calculated by a modified finite element analysis method. Effect of shock wave peak pressure and the number of impacts on the curvature radius was studied. Results show that bending deformation increases rapidly at the beginning and then it stops growing. Bending deformation increases rapidly with the increase of the number of impacts and it cannot increase after three impacts.

In order to study the effect of laser spot superposition on aluminum alloy sheet forming by laser peening, the finite element analysis method was introduced to simulating the forming of 7075 aluminum alloy with different spot superposition case. The results showed that the forming effect and stress distribution of the metal sheet was effected by the laser spot superposition modes. The forming effect of transverse spot superposition mode was better than the other three spot superposition modes.

We have proposed a novel approach to realize a high-energy ultrafast optical parametric oscillator (OPO) by intracavity pumping in a regenerative amplifier. In this way, we have experimentally demonstrated an unprecedented pulse energy of 30.5 μJ from a 1.5-μm singly resonant synchronously pumped OPO at a pulse repetition rate of 10 kHz with a pulse width of 7.0 ps. To the best of our knowledge, this is the highest pulse energy from an ultrafast laser OPO.

A pulse width adjustable 1064 nm Q-switched cavity dumped Nd:YVO_4 laser was realized for the first time, to the best of our knowledge, by rotating an intracavity quarter-wave plate (QWP) and a Pockels cell (PC). The pulse width adjustment range was 4.8–7.8 ns with a constant output power of 3.6 W, and it reached 4.8–13.5 ns for a lower output power of 1.3 W. The pulse width was dependent mostly on the rotating angle of the QWP and PC, but independent of the gain and pulse repetition rate.

A rapid gas chromatography-tandem mass spectrometric (GC-MS) method was developed for the analysis of alkaline and neutral volatile metabolites of feces from human and rats. Feces were extracted by 75% methanol solution (V/V). After addition of ammonia solution (pH 10, final concentration of 1%), the supernatant was subjected to GC-MS analysis. The interesting compounds were separated on a CP-Sil 5 (25 m × 0.25 mm × 0.12 μm) capillary column. Helium was employed as a carrier gas at a constant flow rate of 1 mL min−1. Oven temperature was programmed as follows: the initial temperature was set at 50 °C and held for 1 min, then increased at 25 °C min−1to 150 °C, sustained for 1 min; increased at 20 °C min−1to 200 °C, held for 2 min; and finally increased at 10 °C min−1to 270 °C, maintained for 5 min. The MS was operated in the electron impact ionization mode at −70 eV. The injector, ion source and transfer line temperatures were maintained at 220 °C, 230 °C and 280 °C, respectively. Mass data were acquired in full scan mode of m/z10–600. The solvent delay time was set 3 min. A total of eleven volatile components were identified in the feces samples from human and seven in the feces samples from rats by retrieving the NIST library, comparing with the standards and analyzing the MS data. The method was simple and sensitive, and could be used to detect alkaline and neutral volatile metabolites of feces from human and rats.

In this paper, for the convolution and convex combination of harmonic mappings, the radii of univalence, full convexity and starlikeness of order $\unicode[STIX]{x1D6FC}$are explored. All results are sharp. By way of application, the univalent radius and the Bloch constant of the convolution of two bounded harmonic mappings are obtained.

We demonstrate a compact, high-power, quasi-continuous-wave (QCW) end-pumped 1319 nm Nd:YAG slab amplifier laser with good beam quality. The laser is based on a QCW pulse Nd:YAG master oscillator and Nd:YAG slab amplifier with multi-pass zigzag architecture. The amplifier operates at a pulse repetition frequency of 500 Hz and pulse width of ∼105  μs, delivering a maximum output power of 51.5 W under absorbed pump power of 217.8 W and corresponding to an extraction efficiency of 14.2%. The beam quality factor is measured to be Mx2=1.61 and My2=1.81 in the orthogonal directions. To the best of our knowledge, this is the first compact, high-power, high-beam-quality QCW Nd:YAG amplifier at 1319 nm based on a multi-pass zigzag slab structure.

An optimization method of trajectory design is established in this paper for manned lunar landing circumlunar free-return flight mission. The problem of designing free-return trajectory with multiple constrains under the high precise dynamic model is converted to the nonlinear bounded optimization problems. A solving strategy consisting of hybrid and two-level optimization algorithm is then proposed. Under the double two-body model, the initial trajectory with the weak constrain conditions is obtained by hybrid optimization algorithm which consists of differential evolution (DE) method and sequence quadratic program (SQP) method based on the patched-conic approach. Then a two-level initial trajectory corrective measure based on the sequence quadratic program is applied to obtain the final solution satisfying the strong engineering constrains under the high precise dynamic model. Finally, the reliability and effectiveness of the approach proposed in this paper are demonstrated by the simulation tests, and the results indicate that the proposed method has excellent convergence performance and high precision, thus can be a useful tool for manned lunar orbit design. [ABSTRACT FROM AUTHOR]

AbstractWe present a high-energy, hundred-picosecond (ps) pulsed mid-ultraviolet solid-state laser at 266 nm by a direct second harmonic generation (SHG) in a barium borate (BaB2O4, BBO) nonlinear crystal. The green pump source is a 710 mJ, 330 ps pulsed laser at a wavelength of 532 nm with a repetition rate of 1 Hz. Under a green pump energy of 710 mJ, a maximum output energy of 253.3 mJ at 266 nm is achieved with 250 ps pulse duration resulting in a peak power of more than 1 GW, corresponding to an SHG conversion efficiency of 35.7% from 532 to 266 nm. The experimental data were well consistent with the theoretical prediction. To the best of our knowledge, this laser exhibits both the highest output energy and highest peak power ever achieved in a hundred-ps/ps regime at 266 nm for BBO-SHG.

The application of a sodium laser guide star is the key difference between a modern adaptive optics system and traditional adaptive optics system. Especially in system such as multiconjugate adaptive optics, a sodium laser guide star asterism that is formed by several laser guide stars in a certain pattern is required to probe more atmospheric turbulence in different directions. To achieve this, a sodium laser guide star asterism launching platform is required. In this paper, we introduce the sodium laser guide star asterism launching platform built and tested on the 1.8 m telescope of Gaomeigu Observatory. The platform has two functions: one function is to compare the performance of sodium laser guide stars generated by different lasers at the same place, and the other function is to generate a sodium laser guide star asterism with an adjustable shape. The field test results at the beginning of 2021 verified the important role of the platform, which is also the first time that a sodium laser guide star asterism was realized in China.

A 65 W quasi-continuous-wave microsecond-pulse solid-state sodium beacon laser tuned to the sodium D_2a line has been developed with a linewidth of 0.3 GHz, beam quality of M^2=1.38, and pulse width of 120 μs at a repetition rate of 500 Hz by sum-frequency mixing 1319 and 1064 nm diode-pumped Nd:YAG master-oscillator power-amplifier systems. The laser wavelength stability is less than ±0.15  GHz through feedback controlling. The laser spiking due to relaxation oscillations is suppressed by inserting frequency doublers in both 1319 and 1064 nm oscillators. Sodium D_2b re-pumping is accomplished by tuning the frequency of the electro-optic modulator with the right D_2a−D_2b offset. A bright sodium laser guide star with a photon return of 1820  photons/cm^2/s was achieved with the laser system when a 32 W circular polarized beam was projected to the sky during our field test at the Xinglong Observatory.