搜索到638篇“ MULTI-SPECIES“的相关文章
从多树种古树群中优选造林乡土树种研究——以怀化市为例
2024年
对怀化市156个古树群(含3个树种、15株古树以上)进行研究,分析树种和古树群结构特征,选择适宜在怀化市造林的乡土树种及配置模式。实地调查古树群,按照平均胸径、平均树高、株数和重要值计算树种得分,按分值优选造林树种。古树群以树种数、株数、平均胸径、平均树高计算分值,选取前20个古树群研究树种配置。选出枫香树、青冈、香樟、马尾松、黄连木、朴树、钩栲、木荷、银杏、甜槠等23种适宜造林的乡土树种。树种配置不固定到种,采取6种以上树种混交,喜光树种作先锋种,根据经营目的搭配中性和耐荫树种的模式。选出的造林乡土树种和树种配置模式,实用性强,可以为当地建设长期稳定的森林群落提供树种选择理论依据。
陶德树
多品种种子干燥技术分析与应用
2024年
当前多品种种子干燥技术可满足不同品种及小批量种子的繁育需求,该研究旨在探讨分析多品种种子模块化干燥单元的能耗及其内部干燥介质的物理参数。基于多品种种子模块化干燥单元内部种子质量、干燥风温及干燥速度等因素,分析计算其热源及风机的相关参数。结果表明,多品种种子模块化干燥单元的电磁热风炉功率5 kW,风机流量412~859 m^(3)/h,全压507~310 Pa。研究结果以期为多品种种子干燥技术的后续发展提供技术参考及理论借鉴。
韩长生彭博温海江马文军李想崔潇
关键词:风压
赛博格能理解蘑菇吗?跨物种民族志视野下的媒介之思
2024年
人工智能技术的发展,促使媒介研究者们关注未来的赛博格和虚拟人,却忽视了人与现存生命之间的关系,尤其是围绕媒介所展开的关系。无论是动物、植物、真菌、细菌,抑或是作为整体的自然界,早就与人建立了一种双向乃至多向的驯化过程,由此形成跨越物种界限的关系丛。媒介是关系丛的核心要素,它构建场所、形成生产与再生产、促成流动、形成时间序列,同时也作为一种决断装置,在生命状况中制造不平等的区隔。在“人类世”的新图景中,人类学家的跨物种民族志研究重新确定人的地位,也重新思考人与多元物种之间的关系,从而为理解媒介带来新的潜力。本文梳理跨物种民族志对于媒介的启示,尤其关注一个关键问题,即物种关系是如何借助媒介展开的。本文提出了通用语言、视角转换和跨感官转码三个关键点,认为这是跨物种媒介展开的新维度,而正是在这个去人类中心主义的展开过程中,包括人在内的各物种都有可能走向新的生成关系。
张磊
关键词:人类世根茎
Multi-species probiotics enhance survival,growth,intestinal microbiota and disease resistance of rohu(Labeo rohita)larvae
2024年
Multi-strain probiotics provide the most dependable approaches to improve health,immune response,and disease resistance in farmed fishes.In the present study,we examined the effects of multi-species probiotics on the survival,growth,immune response,and disease resistance of rohu(Labeo rohita)larvae.Newly hatched larvae from the day of first feeding(average weight of 0.003 g)were reared with multi-species probiotics having a combination of Bacillus subtilis(109 colony forming units(cfu)/mL)and Lactobacillus spp.(Lactobacillus plantarum,Lactobacillus buchneri-1011 cfu/mL)in water containing doses of 0(control-C),0.5 mL/L(treatment 1-T1),and 1.0 mL/L(treatment 2-T2)in triplicates for 90 days.After the experiment,a challenge test was performed to assess the fish's resistance to pathogenic Aeromonas veronii.Significantly higher survival was recorded in larvae of treated groups(87%in T2 and 79%in T1)compared to the control(62%).Significantly higher growth performance(weight gain and specific growth rate—SGR)was shown by the probiotic-treated larval groups compared to the control.Probiotic supplementation resulted in significantly higher counts of total viable colony(TVC)and lactic acid bacteria(LAB)in the intestine.Some immunological parameters(mucosal fold fattening,goblet cell abundance,expansion of lamina propria and enterocytes)of the gut were significantly better in probiotic-treated fish.The liver of treated fish showed irregular shape nuclei turning into regular shape and reducing spaces between the hepatic cells.Probiotic-treated fish had the highest post-challenge survival rate(90%)against A.veronii infection.The erythrocytes of challenged fish treated with probiotics had significantly lower frequencies of various nuclear and cellular abnormalities.These findings suggest that multi-species probiotic supplements could improve the survival,growth,health status,and immune response of rohu in the early stages of its development.
Zannatul FerdousMd Kabir HossainMd HadiuzzamanSMRafiquzzamanKM Abdul HalimTanvir RahmanMd Ali Reza FarukZulhisyam Abdul KariMd Shahjahan
关键词:AQUACULTUREPROBIOTICS
基于改进YOLOv7-tiny算法的多种类不均衡样本水稻害虫检测
2024年
为实现基于机器视觉的田间水稻害虫检测,本研究结合IP102农业害虫数据集及网络资源,建立了含有26类标签的不均衡样本水稻害虫数据集;改进YOLOv7-tiny单阶段目标检测算法,以部分卷积PConv作为主要卷积核,结合极化自注意力机制(Polarized Self-Attention),将提取到的特征进行复杂双向多尺度特征融合,建立了适合多种类不均衡样本的水稻害虫检测模型。结果表明,在加入迁移学习和多尺度训练的条件下,改进后的YOLOv7-tiny检测算法在自建水稻害虫数据集的平均检测精度达到96.4%,单张图片的检测时间为8.8 ms,模型大小为9 055 kb,可实现对田间水稻害虫的快速准确识别,为水稻害虫的智能化检测和防治提供了技术支持。
李鑫南新元
基于计算机视觉技术的多品种急救包折叠手势库设计
2024年
急救包作为医疗器械生产领域的通用产品之一,具有品种多、用途广、需求量激增的特点。针对急救包生产过程中手工折叠劳动负荷大、品质波动明显、生产效率低、操作标准缺乏等技术问题,分析各类急救器械和辅料码放工艺特征,并映射为折叠手势的技术工序组合。创新点包括:引入Leap Motion双目计算机视觉技术,构建双手空间模型和手势模型;采用卷积神经网络(CNN)建立手势关键点识别模型,形成急救包折叠手势的有序集合。采用图形数据库技术,设计存储各型号急救包的折叠手势库。通过某型号急救包生产案例,验证了设计的可行性。所设计的急救包折叠手势可转化为指挥机器人折叠操作的指令集合,实现急救包生产领域机器换人的智能制造模式。
赵继祥杜宝江
关键词:急救包手势识别
变异链球菌反义vicK RNA对口腔链球菌多菌种生物膜致龋性的抑制作用
2024年
目的研究变异链球菌(Sm)反义vicK RNA(ASvicK)对3种常见口腔链球菌[Sm、血链球菌(Ss)和戈登链球菌(Sg)]构建的多菌种生物膜致龋性的调控作用。方法通过重组质粒构建ASvicK过表达株,以Sm标准菌株UA159和ASvicK过表达株分别与Ss及Sg构建的多菌种生物膜(分别为UA159+Ss+Sg组、ASvicK+Ss+Sg组)为研究对象,扫描电镜观察生物膜结构;结晶紫染色法检测细菌生物膜总量的差异;通过乳酸试剂盒及蒽酮法评估生物膜产酸产糖能力;利用TaqMan荧光定量PCR及实时荧光定量PCR检测生物膜中3种菌的比例及Sm致龋相关基因的改变;进一步构建人牙釉质片生物膜脱矿模型,用显微硬度仪检测牙釉质表面硬度变化。结果 ASvicK过表达后,Sm+Ss+Sg多菌种生物膜结构疏松。相较于UA159+Ss+Sg组,ASvicK+Ss+Sg组生物膜总量、乳酸产量分别显著降低78.93%及62.23%(均P<0.001),而生物膜水不溶性和不溶性胞外多糖产量分别显著降低39.13%及68.00%(均P<0.001)。与UA159+Ss+Sg组相比,ASvicK+Ss+Sg多菌种生物膜中致龋菌Sm比例显著降低33.00%(P<0.01),Sm致龋相关基因vicK/X、gtfB、gtfC、gtfD和ftf表达显著下调(P<0.05),牙釉质片脱矿后显微硬度值显著上升至183.84%(P<0.001)。结论 ASvicK过表达可降低口腔链球菌生物膜中致龋菌Sm的比例,并减弱口腔链球菌生物膜致龋毒力及致龋性,可能减缓龋病的进展。
陈虹许萌萌孙雨婷余霜杨德琴
关键词:血链球菌
A discrete unified gas-kinetic scheme for multi-species rarefied flows
2023年
A discrete unified gas kinetic scheme(DUGKS)is developed for multi-species flow in all flow regimes based on the Andries-Aoki-Perthame(AAP)kinetic model.Although the species collision operator in the AAP model conserves fully the mass,momentum,and energy for the mixture,it does not conserve the momentum and energy for each species due to the inter-species collisions.In this work,the species collision operator is decomposed into two parts:one part is fully conservative for the species and the other represents the excess part.With this decomposition,the kinetic equation is solved using the Strang-splitting method,in which the excess part of the collision operator is treated as a source,while the kinetic equation with the species conservative part is solved by the standard DUGKS.Particularly,the time integration of the source term is realized by either explicit or implicit Euler scheme.By this means,it is easy to extend the scheme to gas mixtures composed of Maxwell or hard-sphere molecules,while the previous DUGKS[Zhang Y,Zhu L,Wang R et al,Phys Rev E 97(5):053306,2018]of binary gases was only designed for Maxwell molecules.Several tests are performed to validate the scheme,including the shock structure under different Mach numbers and molar concentrations,the Couette flow under different mass ratios,and the pressure-driven Poiseuille flow in different flow regimes.The results are compared with those from other reliable numerical methods based on different models.And the influence of molecular model on the flow characteristics is studied.The results also show that the present DUGKS with implicit source discretization is more stable and preferable for gas mixture problems involving different flow regimes.
Ziyang XinYue ZhangZhaoli Guo
A novel method of utilizing static mixer to obtain mixing homogeneity of multi-species powders in laser metal deposition被引量:2
2023年
Real-time mixing of multi-species powder challenges Laser Metal Deposition(LMD)of Functionally Graded Materials(FGMs).The current work proposes a novel method of using a static mixer to realize rapid,uniform multi-species powder mixing.Firstly,copper powder and 316L stainless steel powder are selected to complete the powder mixing observation experiment with Scanning Electron Microscope(SEM)and Energy Dispersive Spectrometer(EDS).Secondly,computational fluid dynamics and particle mixing simulation models are used to analyze the flow field and particle motion characteristics in the static mixer.Finally,LMD experiment and metallo-graphic observation are carried out with 316L stainless steel powder and WC powder to verify the feasibility of the static mixer.This study provides a theoretical and practical basis for powder mixing in laser processing with a static mixer.The conclusions can also be applied to other processing fields requiring real-time and uniform mixing of multi-species powders.
Jipeng CHENShouchun XIEHe HUANG
关键词:HOMOGENEITYMIXING
荷载作用下开裂混凝土中多离子传输的数值研究被引量:8
2023年
临海地区的混凝土结构因氯离子侵蚀会导致严重的耐久性问题,尤其是在同时承受荷载作用的情况下。服役中的混凝土往往存在初始缺陷,荷载的持续作用会使得混凝土内部的孔隙结构进一步粗化并引起开裂,进而加剧氯盐侵蚀。同时,混凝土孔隙液中存在的多种离子也会影响到氯离子的传输。为了深入研究荷载-氯盐影响下的混凝土结构耐久性劣化,本工作针对前述机理开展多相数值研究,通过全面考虑荷载引起的混凝土开裂和孔隙损伤,以及异种离子间的电化学耦合效应的共同影响,提出了经过第三方试验验证的荷载-多离子传输耦合模型。研究发现,荷载大小和荷载施加方式的改变不仅会影响孔隙结构和裂缝形态,也会使静电势的分布产生差异,进而共同影响离子浓度的变化。荷载作用下的多离子电化学耦合效应会显著影响离子的传输规律,仅考虑单一离子会导致氯离子摄入量的预测偏低。荷载的作用同时还会放大环境条件(如盐溶液浓度)对氯传输的影响。
胡哲刘清风
关键词:荷载氯离子开裂孔隙率

相关作者

余国栋
作品数:17被引量:13H指数:2
供职机构:贵州教育学院
研究主题:绝对稳定性 周期解 LURIE型 不动点定理 RICCATI型方程