Effect of thinning intensity on understory herbaceous diversity and biomass in mixed coniferous and broad-leaved forests of Changbai Mountain

Background:Herbs are an important part of the forest ecosystem,and their diversity and biomass can reflect the restoration of vegetation after forest thinning disturbances.Based on the near-mature secondary coniferous and broad-leaved mixed forest in Jilin Province Forestry Experimental Zone,this study analyzed seasonal changes of species diversity and biomass of the understory herb layer after different intensities of thinning.Results:The results showed that although the composition of herbaceous species and the ranking of importance values were affected by thinning intensity,they were mainly determined by seasonal changes.Across the entire growing season,the species with the highest importance values in thinning treatments included Carex pilosa,Aegopodium alpestre,Meehania urticifolia,and Filipendula palmata,which dominated the herb layer of the coniferous and broad-leaved mixed forest.The number of species,Margalef index,Shannon-Wiener index and Simpson index all had their highest values in May,and gradually decreased with months.Pielou index was roughly inverted“N”throughout the growing season.Thinning did not increase the species diversity.Thinning can promote the total biomass,above-and below-ground biomass.The number of plants per unit area and coverage were related to the total biomass,above-and below-ground biomass.The average height had a significantly positive correlation with herb biomass in May but not in July.However,it exerted a significantly negative correlation with herb biomass in September.The biomass in the same month increased with increasing thinning intensity.Total herb biomass,above-and below-ground biomass showed positive correlations with Shannon-Winner index,Simpson index and Pielou evenness index in May.Conclusions:Thinning mainly changed the light environment in the forest,which would improve the plant diversity and biomass of herb layer in a short time.And different thinning intensity had different effects on the diversity of understory herb layer.The findings provide theoretical basis and reference for reasonable thinning and tending in coniferous and broad-leaved mixed forests.

Optimal search path planning of UUV in battlefeld ambush scene

Aiming at the practical application of Unmanned Underwater Vehicle(UUV)in underwater combat,this paper proposes a battlefield ambush scene with UUV considering ocean current.Firstly,by establishing these mathematical models of ocean current environment,target movement,and sonar detection,the probability calculation methods of single UUV searching target and multiple UUV cooperatively searching target are given respectively.Then,based on the Hybrid Quantum-behaved Particle Swarm Optimization(HQPSO)algorithm,the path with the highest target search probability is found.Finally,through simulation calculations,the influence of different UUV parameters and target parameters on the target search probability is analyzed,and the minimum number of UUVs that need to be deployed to complete the ambush task is demonstrated,and the optimal search path scheme is obtained.The method proposed in this paper provides a theoretical basis for the practical application of UUV in the future combat.

Analysis of System Value Evolution Trends of Energy Storage in Decarbonization Process

With the continuous expansion of the scale of renewable energy installation,the demand for energy storage has increased significantly.However,there are significant differences in the value of energy storage in different scenarios,and the phenomenon of diminishing marginal benefits of energy storage is becoming more apparent.Therefore,themulti-dimensional value evolution trend of energy storage has become a key issue.This study selects indicators from three dimensions of energy storage:low-carbon emission reduction,smoothing wind and solar power fluctuations,and saving generation costs,quantifying the economic,environmental,and technical values of energy storage.This forms a quantitative evaluation system for energy storage value.By comparing the calculated system values under different energy storage capacities,the marginal value evolution trend of energy storage is obtained.Meanwhile,considering factors such as the utilization rate of renewable energy,the change in energy storage value under different scenarios is analyzed.The results show that the value of long-duration energy storage is significantly affected by the energy storage capacity.Specifically,when the charge-discharge efficiency of longduration energy storage reaches 0.6 or above,the system value increases significantly.Additionally,appropriately reducing the cost of energy storage capacity also helps to improve its system value.

基于机器视觉的激光功率计字符识别系统

为实现激光设备功率自动校准,应用机器视觉和图像处理技术对激光功率计数字仪表自动读数识别进行研究,设计了激光功率计字符识别系统。针对传统穿线法对倾斜数码管数字图像识别准确率不高且无法识别小数点的情况,提出了一种改进型穿线法,实现了对带小数点数码管数字图像的准确识别,并利用Socket通信实现对识别数字结果的下发。实验结果表明,静态图像的识别率达到100%,平均识别时间为13 ms/张。在摄像头固定的动态识别中,经数字滤波后,下发给激光设备的数字准确率达98%,平均识别时间为50 ms/张。该系统已在实际工程中应用,有效提高了激光设备功率校准的效率。

Evaluation and Improvement of Roundabouts in Changchun

In Changchun, China, roundabouts are fairly common. They are often designed to connect the main roads because of their ability to reduce conflict points, making them safer than other intersections. They can also beautify the city when the central islands are landscaped. However, with increasing traffic, they may not function well and may even paralyze the road network. This means that it is important to evaluate the performance of roundabouts promptly, and to make necessary improvements if required. Using several roundabouts in Changchun as case studies, this article uses V/C ratio and delay to evaluate roundabout performance. Based on the result of evaluation, the micro-simulation model of the poorly-performing roundabout is built and enhancement is proposed.

Adaptive economic and ecological forest management under risk

Background： Forest managers must deal with inherently stochastic ecological and economic processes. The future growth of trees is uncertain, and so is their value. The randomness of low-impact, high frequency or rare catastrophic shocks in forest growth has significant implications in shaping the mix of tree species and the forest landscape. In addition, the fluctuations of wood prices influence greatly forest revenues. Methods： Markov decision process models （MDPs） offer a rigorous and practical way of developing optimum management strategies, given these multiple sources of risk. Results： Examples illustrate how such management guidelines are obtained with MDPs for combined ecological and economic objectives, including diversity of tree species and size, landscape diversity, old growth preservation, and carbon sequestration. Conclusions： The findings illustrate the power of the MDP approach to deal with risk in forest resource management. They recognize that the future is best viewed in terms of probabilities. Given these probabilities, MDPs tie optimum adaptive actions strictly to the state of the forest and timber prices at decision time. The methods are theoretically rigorous, numerically efficient, and practical for field implementation.

X-ray focusing using an x-ray lens composed of multi-square polycapillary slices

A new type of x-ray lens composed of multi-square polycapillary slices(ASPXRL)used in focusing parallel x-ray beam was presented in this paper.Compared with conventional x-ray polycapillary lens,ASPXRL can provide smaller and brighter focus.The effects of the manufacturing imperfections on focusing quality of ASPXRL were evaluated with the values of transmission efficiency and discussed.It is suggested that ASPXRL has application prospects as a condenser lens for x-ray microscopy and flux collectors for x-ray analytical instruments.

电力物资供应商履约风险预警评价模型及研究

针对电力物资供应链中存在的风险,提出了电力物资供应商履约风险预警评价模型,设计了电力物资供应商履约风险模型,采用ERP系统,利用WBS-RBS风险识别技术,实现对电力物资供应商履约风险的识别,然后利用层次分析法,对识别出的风险进行等级分析;利用风险评估LECC方法,对履约风险进行评估。还研究了基于ACO-SVM算法的电力物资供应商履约风险预警,对风险进行分级定级。实验表明,本研究系统对电力物资供应商履约风险预警的预警效果高达92%。

Scaffold-based tissue engineering strategies for soft-hard interface regeneration

Repairing injured tendon or ligament attachments to bones(enthesis)remains costly and challenging.Despite superb surgical management,the disorganized enthesis newly formed after surgery accounts for high recurrence rates after operations.Tissue engineering offers efficient alternatives to promote healing and regeneration of the specialized enthesis tissue.Load-transmitting functions thus can be restored with appropriate biomaterials and engineering strategies.Interestingly,recent studies have focused more on microstructure especially the arrangement of fibers since Rossetti successfully demonstrated the variability of fiber underspecific external force.In this review,we provide an important update on the current strategies for scaffold-based tissue engineering of enthesis when natural structure and properties are equally emphasized.We firstly described compositions,structures and features of natural enthesis with their special mechanical properties highlighted.Stimuli for growth,development and healing of enthesis widely used in popular strategies are systematically summarized.We discuss the fabrication of engineering scaffolds from the aspects of biomaterials,techniques and design strategies and comprehensively evaluate the advantages and disadvantages of each strategy.At last,this review pinpoints the remaining challenges and research directions to make breakthroughs in further studies.

Evaluation of Knees in Asymptomatic Amateur Ice Hockey Players Using 3.0-T Magnetic Resonance Imaging：A Case-Control Study

Background：Research on the changes to knee structures in asymptomatic amateur ice hockey players （AAIHPs） has been limited.We aimed to assess the performance of the knees in AAIHPs using 3.0-T magnetic resonance imaging （MRI）.Methods：A total of 71 asymptomatic knees （32 AAIHPs and 39 age-and sex-matched controls） were imaged using a 3.0-T MRI scanner at the Affiliated Zhongshan Hospital of Dalian University in April 2017.Two experienced musculoskeletal radiologists were blinded to assess all MRI findings,including bursae around the knee,bone marrow edema （BME）,meniscal signal changes,and articular cartilage and ligament damage.Any disagreements were resolved by a third professor of musculoskeletal radiology.Categorical variables were compared using the Chi-square test and continuous variables using the Student＇s t-test or Mann-Whitney U-test.Results：The most common finding was fluid-filled bursae surrounding the knee.In the AAIHP group,which totaled 32 knees and 416 bursae,155 （37％） fluid-filled bursae were present.In the control group,there were a total of 39 knees and 507 bursae,and 91（18％） fluid-filled bursae were present.There was a significant difference in the number of fluid-filled bursae between the two groups （P ＜ 0.05）.However,in AAIHPs,the prevalence of meniscal signal changes （16 knees,50％） was higher than in the control group （2 knees,5％;P ＜ 0.001）.Importantly,15 of the 19 were grade Ⅱ signals.Other changes were only found in AAIHPs.Articular cartilage lesions were detected in 47％ of their knees,predominantly at the patellofemoral joint,and BME was found in 34％ of their knees.Conclusion：The MRI findings of knees in AAIHPs mainly manifested as self-protection reaction,and proper ice hockey exercise could be advocated.

Infection of wild-type mice by SARS-CoV-2 B.1.351 variant indicates a possible novel cross-species transmission route

COVID-19 is identified as a zoonotic disease caused by SARS-CoV-2,which also can cross・transmit to many animals but not mice.Genetic modifications of SARS-CoV-2 or mice enable the mice susceptible to viral infection.Although neither is the natural situation,they are currently utilized to establish mouse infection models.Here we report a direct contact transmission of SARS-CoV-2 variant B.1.351 in wild-type mice.The SARS-CoV-2(B.1.351)re plicated efficiently and induced significant pathological changes in lungs and tracheas,accompanied by elevated proinflammatory cytokines in the lungs and sera.Mechanistically,the receptor-binding domain(RBD)of SARS-CoV-2(B.1.351)spike protein turned to a high binding affinity to mouse angiotensin-converting enzyme 2(mACE2),allowing the mice highly susceptible to SARS-CoV-2(B.1.351)infection.Our work suggests that SARS-CoV-2(B.1.351)expands the host range and therefore increases its transmission route without adapted mutation.As the wild house mice live with human populations quite closely,this possible transmission route could be potentially risky.In addition,because SARS-CoV-2(B.1.351)is one of the major epidemic strains and the mACE2 in laboratory-used mice is naturally expressed and regulated,the SARS-CoV-2(B.1.351)/mice could be a much convenient animal model system to study COVID-19 pathogenesis and evaluate antiviral inhibitors and vaccines.