Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function

This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.

Control and data acquisition system for collinear laser spectroscopy experiments

A control and data acquisition system was implemented for the recently developed collinear laser spectroscopy setup.This system is dedicated to data recording,storage,processing,monitoring of the beam intensity and energy,and visualization of various spectra.In comparison to the conventional resonance nuclear reaction system,the key technique is the precise synchronization of the detected counts with the actual scanning voltage(or probing laser frequency).The functions of the system were tested by measuring the hyperfine structure spectra of stable calcium(e.g.,^(40)Ca^(+))and radioactive potassium(e.g.,^(38)K)in the bunched and continuous modes,respectively.This system will be routinely applied and further improved in subsequent laser spectroscopy experiments on unstable isotopes at the Beijing Radioactive Ion-beam Facility(BRIF).

非共线多裂纹结构的剩余强度分析与评估

针对老龄飞机的广布疲劳损伤(Widespread Fatigue Damage,WFD)评估问题,通过试验方法研究了不同结构参数对非共线多裂纹结构剩余强度的影响,修正原有剩余强度评估方法中的缺陷,提出改进的净截面屈服准则和改进的Irwin塑性区连通准则,获得更准确的评估结果。改进的净截面屈服准则评估结果误差小,适用范围广,可以评估铆钉孔间距和铆钉孔直径对结构剩余强度的影响;改进的Irwin塑性区连通准则在铆钉孔间距大于10mm时,有较准确的评估结果,还可以评估裂纹分布位置对剩余强度的影响。

45号钢腐蚀程度的超声非线性检测实验研究

腐蚀会显著降低金属零件的使用性能,检测金属零件的腐蚀程度对确保其安全使用具有重要意义。超声非线性技术已被应用于检测材料微损伤、残余应力和黏结状态等方面,其能否用于检测腐蚀程度倍受关注。本文搭建了基于超声非线性技术的临界折射纵波(criticalrefraction longitudinal wave,简称LCR波)混频检测系统,检测不同腐蚀程度的45号钢试件的非线性系数,随后根据超声非线性效应的机理结合材料的微观形貌对差频非线性系数的变化原因进行分析。实验结果表明:差频非线性系数对材料腐蚀程度十分敏感,随着45号钢试件腐蚀程度增加,差频非线性系数随之增加。超声非线性技术可以有效地实现对金属材料腐蚀程度的表征。

大麦HvMBF1c耐盐机制分析

大麦HvMBF1c基因参与调控植物盐胁迫表达,为探究其对盐胁迫的响应模式,本文对大麦HvMBF1基因进行生物信息学分析,并以中川大麦(耐盐型)、GN18(盐敏感型)及WT与转HvMBF1c基因拟南芥为材料,分别取200 mmol L^(-1) NaCl胁迫0 h、6 h、12 h、24 h、48 h及72 h样品,对其进行qRT-PCR分析和生理指标的测定。结果显示,大麦HvMBF1c基因与小麦TaMBF1c亲缘关系最近,位于7H染色体上。HvMBF1c的外显子比HvMBF1a和HvMBF1b的大,且HvMBF1a和HvMBF1b两者具有典型的motif 4结构域,而HvMBF1c基因具有独特的motif 5结构域。HvMBF1c基因的启动子序列含有光响应、根特定调节元件和缺氧特异性诱导增强元件,与小麦2号、3号和7号染色体存在同源性。qRT-PCR分析表明,随着盐处理时间的延长,大麦HvMBF1c基因在2份种质材料苗期、拔节期、抽穗期和灌浆期的表达量呈上升趋势,且中川大麦中该基因的表达量高于GN18中的表达量;转HvMBF1c拟南芥中其表达量随着盐处理时间的延长而升高。盐胁迫下,中川大麦苗期、拔节期、抽穗期及灌浆期的SOD、POD、CAT、MDA和可溶性蛋白低于GN18,转基因拟南芥中各生理指标的变化量低于WT。本研究结果为进一步探索HvMBF1c的功能提供参考。

Three-point bending behavior of aluminum foam sandwich with steel panel

Static three-point bending tests of aluminum foam sandwiches with glued steel panel were performed. The deformation and failure of sandwich structure with different thicknesses of panel and foam core were investigated. The results indicate that the maximum bending load increases with the thickness of both steel panel and foam core. The failure of sandwich can be ascribed to the crush and shear damage of foam core and the delamination of glued interface at a large bending load, The crack on the foam wall developed in the melting foam procedure is the major factor for the failure of foam core. The sandwich structure with thick foam core and thin steel panel has the optimal specific bending strength. The maximum bending load of that with 8 mm panel and 50 mm foam core is 66.06 kN.

小麦TaPOD家族的全基因组鉴定及表达分析

过氧化物酶(Peroxidase,POD)家族成员在调节植物生长发育和响应逆境胁迫中起重要作用。为系统探究小麦(Triticum aestivum L.)TaPOD基因家族的功能及其表达模式,本研究利用生物信息学的方法鉴定了小麦TaPOD基因家族成员,对其理化性质、启动子顺式作用元件、进化特征做了预测分析,并通过小麦转录组和实时荧光定量PCR(Real Time Quantitative,RT-qPCR)分析了其在不同组织、外源激素及逆境胁迫下的表达模式。结果表明,目前基因组测序小麦中包含659个TaPOD基因家族成员,蛋白质序列长度在206~518个氨基酸之间;系统发育分析表明,小麦TaPOD家族成员分为I~VII组且每组成员数量不等;序列比对显示小麦TaPOD家族成员具有5个保守基序,且基因结构等方面存在很大差异,预示着功能存在多样性;染色体定位发现其数量在小麦的21条染色体上分布不均匀,其中2B染色体上数量最多;通过种内共线性分析发现,小麦TaPOD基因共有396个重复事件,同源性较高且进化过程非常保守,主要通过片段复制和串联复制进行扩增,且Ka/Ks比率显示仅有4对家族成员受到了正向的自然选择压力;顺式作用元件分析表明,上游2 kb区域中存在23种与生长发育和抗逆性相关的结合元件;基因表达模式分析显示,86.5%TaPOD基因在小麦根系中表达量较高;通过RT-qPCR检测发现TaPOD基因表达量与激素诱导和非生物胁迫密切相关。上述结果为深入研究TaPOD基因在调控小麦生长发育与逆境胁迫中的功能提供初步的理论基础。

卵萼花锚STR基因家族的生物信息学分析

【目的】对卵萼花锚(Halenia elliptica)的异胡豆苷合成酶(strictosidine synthase,STR)基因家族成员进行鉴定和生物信息学分析,为进一步研究卵萼花锚STR家族基因的功能奠定基础。【方法】基于卵萼花锚基因组数据,采用生物信息学方法鉴定STR基因,分析其家族的进化关系、理化性质、基因结构和蛋白质保守基序,并与大花花锚(H.grandiflora)、花锚(H.corniculata)、四数獐牙菜(Sinoswertia tetraptera)和达乌里秦艽(Gentiana dahurica)的STR基因进行比较。【结果】卵萼花锚STR基因家族共有10个成员,基因数量与其他龙胆科物种相似。卵萼花锚STR基因与大花花锚具有较高的同源性,将所有HeSTR基因分为6组,同一组成员具有相似的基因结构和蛋白保守基序。HeSTR蛋白的氨基酸数量介于189~388个之间,除HeSTR14.1外,其他均为亲水蛋白。HeSTR基因的外显子数量为3或4个。卵萼花锚STR基因家族成员与四数獐牙菜、花锚和大花花锚的共线性较高。【结论】研究结果为深入探究STR基因功能及进一步解析卵萼花锚单帖吲哚生物碱龙胆苦苷的合成途径提供了理论依据。

樟树TIFY转录因子家族鉴定与表达分析

TIFY转录因子对植物生长发育与次生代谢有重要调控作用。本研究利用生物信息学技术鉴定了樟树(Cinnamomum camphora(L.)Presl.)基因组中的21个CcTIFYs基因,并基于转录组数据分析了其表达特性。结果显示,21个成员分属于TIFY、JAZ、PPD与ZML等4个亚家族,且JAZ亚家族又进一步形成了6个进化分枝。染色体定位与共线性分析显示,CcTIFYs不均匀地分布于9条染色体上,存在14对CcTIFY共线性基因对。种间共线性分析结果表明樟树TIFY家族与毛果杨(Populus trichocarpa Torr.&Gray.)TIFY家族亲缘关系更近。此外,表达分析表明14个成员具有组织表达特异性,CcJAZ11、CcTIFY1与CcJAZ4/5等分别在花、根与籽中优势表达;在不同化学型的叶组织中,5个成员发生了差异表达,其中,CcJAZ10与CcPPD1在柠檬醛型中优势表达,CcJAZ9在甲基丁香酚型中优势表达。研究结果为分析樟树组织发育和次生代谢调控机理提供了参考。

种子注入式太赫兹波参量产生源研究

种子注入式太赫兹波参量产生源(is-TPG)基于非线性晶体中的受激电磁偶子散射,具有线宽窄、相干性好、室温运转、可调谐等优点。本文基于5%摩尔百分比氧化镁掺杂的同成分铌酸锂晶体(MgO:CLN),对连续/脉冲种子注入式太赫兹波参量产生源(is/ips-TPG)调谐范围、输出能量、阈值等方面进行了研究。相比于is-TPG系统,ips-TPG系统调谐范围范围扩大约80%。is-TPG系统与ips-TPG系统3dB带宽分别为1THz与1.41THz,占各自调谐范围的51%和39%。ips-TPG系统相比is-TPG系统3dB带宽范围扩大了41%。在相近的平均功率密度下,由于ips-TPG具有更高的峰值功率密度降低了阈值,产生了更强的THz波输出,最大转换效率为1.01×10^(-5)。不同形式种子光的注入对太赫兹波参量辐射源有着显著的影响,实验结果表明ips-TPG系统的输出特性更为突出在实际应用中具有更高的价值。本文最后对其未来发展进行了分析和展望。

Ultrafast dynamics of femtosecond laser-induced high spatial frequency periodic structures on silicon surfaces

Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.

大西洋黄鳍金枪鱼资源丰度不同预报模型的比较分析

为探讨海洋环境因子对黄鳍金枪鱼(Thunnus albacares)资源丰度的影响,利用中水集团13艘延绳钓渔船2016—2019年的渔业数据,结合海表面风速(WS)、叶绿素a浓度(Chl a)、涡动能(EKE)、0~500 m水层温度(T)和盐度(S)等19个环境因子,经过相关性分析筛选出叶绿素a浓度等11个海洋环境因子;采用卷积神经网络(CNN)、BP神经网络、长短期记忆网络模型(LSTM)、双向长短期记忆网络模型(BiLSTM)、卷积神经网络结合双向长短期记忆网络模型(CNN-BiLSTM)分别对筛选的海洋环境因子和黄鳍金枪鱼资源丰度关系进行研究并对比模型的预测性能。结果表明,在筛选后的11个海洋环境因子中,100 m水层温度、200 m水层盐度、300 m水层温度和纬度相对重要性指数之和约占55%,为影响黄鳍金枪鱼单位捕捞努力量渔获量(CPUE)的关键环境因子;使用CNN-BiLSTM模型预测的均方根误差和平均绝对误差比其他4个模型低。研究表明,CNN-BiLSTM模型对黄鳍金枪鱼资源丰度有较高的预测准确度,可用于预测黄鳍金枪鱼的资源丰度。

一维六方压电准晶狭长体中双半无限共线裂纹问题的D-B模型

基于解析函数理论与保角映射方法,通过构造一维六方压电准晶狭长体中双半无限共线裂纹问题的D-B(Dugdale-Barenblatt)模型,研究了一维六方压电准晶狭长体中双半无限共线裂纹的弹塑性断裂力学问题,得到了塑性区尺寸及场强度因子的解析解,推广了材料中裂纹问题的已有结果,扩大了准晶压电材料弹塑性断裂力学问题的研究范围。

Elevating Localization Accuracy in Wireless Sensor Networks:A Refined DV-Hop Approach

Localization is crucial in wireless sensor networks for various applications,such as tracking objects in outdoor environments where GPS(Global Positioning System)or prior installed infrastructure is unavailable.However,traditional techniques involve many anchor nodes,increasing costs and reducing accuracy.Existing solutions do not address the selection of appropriate anchor nodes and selecting localized nodes as assistant anchor nodes for the localization process,which is a critical element in the localization process.Furthermore,an inaccurate average hop distance significantly affects localization accuracy.We propose an improved DV-Hop algorithm based on anchor sets(AS-IDV-Hop)to improve the localization accuracy.Through simulation analysis,we validated that the ASIDV-Hop proposed algorithm is more efficient in minimizing localization errors than existing studies.The ASIDV-Hop algorithm provides an efficient and cost-effective solution for localization in Wireless Sensor Networks.By strategically selecting anchor and assistant anchor nodes and rectifying the average hop distance,AS-IDV-Hop demonstrated superior performance,achieving a mean accuracy of approximately 1.59,which represents about 25.44%,38.28%,and 73.00%improvement over other algorithms,respectively.The estimated localization error is approximately 0.345,highlighting AS-IDV-Hop’s effectiveness.This substantial reduction in localization error underscores the advantages of implementing AS-IDV-Hop,particularly in complex scenarios requiring precise node localization.

共线公交线路协调发车间隔优化模型及实践

针对公交线路重复率过高问题,考虑多条公交线路中存在共线情况,将共线公交线路的发车间隔进行协调优化,减少了乘客和企业的加权成本和。构建了以乘客出行时间成本、公交运营成本加权和最小为目标的协调发车间隔优化模型,并采用熵值法计算权重,运用GeoGebra图形计算器计算最优解。结果表明:高峰小时节约成本共计268.85元,节约成本占实际运行成本的4.18%.在节约乘客候车成本的基础上,提高公交吸引量,提升乘客出行满意度,提高公交企业营运效率.

An Aerial Target Recognition Algorithm Based on Self-Attention and LSTM

In the application of aerial target recognition,on the one hand,the recognition error produced by the single measurement of the sensor is relatively large due to the impact of noise.On the other hand,it is difficult to apply machine learning methods to improve the intelligence and recognition effect due to few or no actual measurement samples.Aiming at these problems,an aerial target recognition algorithm based on self-attention and Long Short-Term Memory Network(LSTM)is proposed.LSTM can effectively extract temporal dependencies.The attention mechanism calculates the weight of each input element and applies the weight to the hidden state of the LSTM,thereby adjusting the LSTM’s attention to the input.This combination retains the learning ability of LSTM and introduces the advantages of the attention mechanism,making the model have stronger feature extraction ability and adaptability when processing sequence data.In addition,based on the prior information of the multidimensional characteristics of the target,the three-point estimation method is adopted to simulate an aerial target recognition dataset to train the recognition model.The experimental results show that the proposed algorithm achieves more than 91%recognition accuracy,lower false alarm rate and higher robustness compared with the multi-attribute decision-making(MADM)based on fuzzy numbers.

Breeding of Mycoplasmal pneumonia-negative Swine Population Using Combination Therapy,Segregated Early Weaning(SEW) and Three-point Production System

In order to explore a breeding method for mycoplasmal pneumonia-negative swine population, the purifying effects of combination therapy, SEW and three-point breeding and management system on Mycoplasma hyopneumoniae were investigated in this study. After the processes of screening pregnant sows, programmed therapy for sows, SEW, three-point breeding and management in the barrier isolation system and programmed therapy for piglets, the newly-bred piglets were monitored as long as four months by serum antibody detection of Mycoplasma hyopneumoniae and fluorescent quantitative PCR of nose swabs. The results showed that when the newlybred five batches of piglets were older than 35 d, they were all negative by serum antibody detection and nose swab antigen detection. Therefore, the combination therapy, SEW and three-point production and management system can effectively purify Mycoplasma hyopneumoniae, providing theoretical basis and clinical experience for the control and purification of domestic mycoplasmal pneumonia.

Multi-Objective Optimization of Aluminum Alloy Electric Bus Frame Connectors for Enhanced Durability

The widespread adoption of aluminumalloy electric buses,known for their energy efficiency and eco-friendliness,faces a challenge due to the aluminum frame’s susceptibility to deformation compared to steel.This issue is further exacerbated by the stringent requirements imposed by the flammability and explosiveness of batteries,necessitating robust frame protection.Our study aims to optimize the connectors of aluminum alloy bus frames,emphasizing durability,energy efficiency,and safety.This research delves into Multi-Objective Coordinated Optimization(MCO)techniques for lightweight design in aluminum alloy bus body connectors.Our goal is to enhance lightweighting,reinforce energy absorption,and improve deformation resistance in connector components.Three typical aluminum alloy connectors were selected and a design optimization platform was built for their MCO using a variety of software and methods.Firstly,through three-point bending experiments and finite element analysis on three types of connector components,we identified optimized design parameters based on deformation patterns.Then,employing Optimal Latin hypercube design(OLHD),parametric modeling,and neural network approximation,we developed high-precision approximate models for the design parameters of each connector component,targeting energy absorption,mass,and logarithmic strain.Lastly,utilizing the Archive-based Micro Genetic Algorithm(AMGA),Multi-Objective Particle Swarm Optimization(MOPSO),and Non-dominated SortingGenetic Algorithm(NSGA2),we explored optimized design solutions for these joint components.Subsequently,we simulated joint assembly buckling during bus rollover crash scenarios to verify and analyze the optimized solutions in three-point bending simulations.Each joint component showcased a remarkable 30%–40%mass reduction while boosting energy absorption.Our design optimization method exhibits high efficiency and costeffectiveness.Leveraging contemporary automation technology,the design optimization platform developed in this study is poised to facilitate intelligent optimization of lightweight metal components in future applications.

Effects of Temperature and Liquid Nitrogen(LN2)on Coal’s Mechanical and Acoustic Emission(AE)Properties

Liquid nitrogen has shown excellent performances as a good fracturing medium in the extraction of unconventional natural gas,and its application in coalbed methane extraction is currently a research hotspot.This study focuses on the acoustic emission properties of coal specimens treated utilizing liquid nitrogen with varying initial temperatures in a three-point bending environment.Through examination of the load-displacement curves of the considered coal samples,their mechanical properties are also revealed for different initial temperatures and cycling frequencies.The findings demonstrate a gradual decline in the maximum load capacity of coal rock as the temperature rises.Similarly,when subjected to the same temperature,an escalation in the cycling frequency leads to a reduction in the peak load of coal rock.This suggests that both temperature and cycling frequency exert a notable impact on the fracturing efficacy of liquid nitrogen.Freeze-thaw cycling treatments and exposure to high-temperature conditions can activate preexisting damage in the coal rock,and,accordingly,influence its mechanical properties.In particular,throughout the progressive loading of coal rock samples,the failure mechanisms are predominantly characterized by the occurrence of tensile cracks,succeeded by the development,spread,and fracture of shear fissures.

青海省北川河径流量与水文地貌特征的关系分析

以北川河流域5个水文站径流量观测资料为基础,利用30 m分辨率的DEM数据提取了与径流量相关的水文地貌特征因子,通过对多年平均径流量与水文地貌特征因子之间的相关分析,经过共线性诊断筛选水文地貌特征因子,建立了线性回归方程.结果表明:北川河流域从上游到下游地形趋于平坦,水系发育程度更高,汇流能力更强;影响多年平均径流量主要的宏观地形因子贡献率分别是地形湿度指数(50.66%)和地表粗糙度(44.33%),主要的微观地形因子贡献率分别是剖面曲率(36.25%)、高程(27.26%)和坡向变率(24.31%),主要的水系形态指标贡献率分别是节点连接率(54.16%)和面积高程积分(32.95%).上述结果为深入理解北川河流域的水文地貌关系提供依据,为研究其他小流域的不同水文节点,特别是上下游的水文地貌特征以及径流量与水文地貌特征的关系分析提供思路参考.