基于PSO-BP神经网络的磨机传动系统模型修正

针对磨机传动系统结构的复杂性、部件间约束条件的不确定性以及非线性等因素,提出了一种基于PSO-BP神经网络的有限元模型修正方法。通过改进BP神经网络逼近设计参数和特征量间的非线性映射关系,结合实际结构响应,利用神经网络的泛化特性,得到了模型设计参数值。修正后频率误差从最高18%降到4%左右,修正系数误差范围均在0.5%以内,明显提高了有限元模型精度;同时,又不需要大量迭代求解步骤,避开了传统反问题模型修正法的复杂非线性优化过程,提升了效率,验证了PSO-BP神经网络法应用于大型磨机传动系统上的可行性,为后续传动系统整体分析奠定了基础。

纵扭复合型超声电机定子的非线性动力学特性研究

纵扭复合型超声电机的非线性动力学特性是影响电机运行的稳定性和可靠性的重要因素。基于广义Hamilton能量变分原理、Rayleigh-Ritz假设模态法以及非线性压电本构关系,建立纵扭复合型超声电机定子的非线性动力学模型,采用四阶Runge-Kutta法和Lyapunov指数等方法仿真分析纵向激励下电机定子的非线性振动响应特性。结果表明:电机定子的固有模态频率和实验值误差仅为1.8%,证明了所建立的纵扭复合型超声电机定子的非线性动力学模型的准确性。超声电机具有频率漂移、振幅跳跃等非线性行为特性,而实际工作时通常将定子的共振频率(即λ=1处)作为工作激励频率,此时位于稳定的周期运动区域。通过数值仿真分析得到不同频率激励下系统的发展趋势,以及系统稳定与不稳定运动的参数匹配区间,可为开展纵扭复合型超声电机的非线性动力学特性研究提供参考。

旋转行波型超声电机定子的非线性动力学分析

超声电机作为一种新型电机,独特的性能使其在如太空探索、精密仪器等一些特殊领域有着广阔的应用前景。然而,超声电机的强机电耦合非线性特性使其在工作过程中往往会产生频率漂移、跳跃等非线性现象,从而影响电机工作的稳定性。用四阶Runge-Kutta法、Lyapunov指数、Poincaré截面等方法获得了旋转行波超声电机定子在单相激励下的非线性振动响应特性,研究了定子振动响应的Hopf分岔以及由Hopf分岔通向周期解的变化过程,该结果对进一步改善行波型超声电机输出特性的研究具有一定的参考意义。

稀燃工况下天然气发动机燃烧不稳定性分析

为了研究稀燃工况下天然气发动机燃烧不稳定性的变化规律,在25%负荷、转速为1000 r/min工况下针对6组不同过量空气系数λ进行试验,采用统计分析方法研究了最大爆压、最大爆压对应的曲轴转角、指示平均有效压力(IMEP)的频率分布规律,并分析了各燃烧特征参数之间的关联性。结果表明:随着λ增大,天然气发动机燃烧不稳定性增强;最大爆压、最大爆压对应曲轴转角的频率分布范围逐渐增大,IMEP频率分布范围先减小后增大,循环间差异性均增加;各燃烧特征参数的关系图中,点的分布范围均增大,且存在线性关系,当混合气浓度过稀时线性关系减弱。稀燃工况下天然气发动机产生燃烧不稳定分析,为天然气发动机稀燃稳定性优化和控制提供了理论依据。

供应链金融增强企业组织韧性的影响机制

在复杂多变的商业环境中,组织韧性成为企业应对挑战并抓住机遇的关键能力。聚焦供应链金融这一依托实体经济交易活动的创新融资工具,旨在深入探究其在增强组织韧性中的独特作用及其内在机理。通过对2011年至2022年间沪深A股上市公司的年度报告与公告文本数据的分析,识别采用供应链金融的样本,考察供应链金融对企业组织韧性的影响,揭示内在过程的合作创新机制。实证分析支持了供应链金融能增强组织韧性的假设,验证了供应链金融是撬动企业合作创新从而提升组织韧性的重要杠杆,并且发现企业数字化转型和数字普惠金融环境的发展都会强化供应链金融的提升作用,东部地区企业供应链金融采用对组织韧性的提升作用显著大于非东部地区企业。研究结论拓展了构建企业组织韧性的机制范畴,丰富了供应链金融在现代企业治理与安全发展层面的作用。企业应充分认识供应链金融增强组织韧性的关键作用,重视合作创新对组织韧性的推动作用,不断利用数字技术提升供应链金融的运作效率,进一步加强组织合作,发挥供应链金融对组织韧性的积极影响。金融机构和政府相关机构应根据地区与场景异质性调整供应链金融策略,提高普惠金融供给制度的完善程度,运用各类制度协同多方主体,加大对数字基础设施的投入并不断完善升级,筑牢金融服务与合作创新的基础,全方位助力企业的组织韧性成长和高质量发展。

Adsorption,in vitro digestion and human gut microbiota regulation characteristics of three Poria cocos polysaccharides

Poria cocos(PC)is a famous traditional Chinese medicine(TCM)and a widely used healthcare ingredient,which has antiobesity,enhancing immunity and improving sleep effects.Traditionally,only water-soluble poria polysaccharide(WSP)is extracted and applied for clinical application,while insoluble polysaccharide(alkali-soluble poria polysaccharide,ASP)is discarded as herb residue.However,the whole PC has also been historically utilized as functional herbal food.Considering the beneficial role of dietary fiber and the traditional use of PC,ASP may also contribute substantially to the therapy function of PC.Compared to WSP,little attention has been paid to ASP and ASP modified product carboxymethyl poria polysaccharide(CMP)which has been used as an antitumor adjuvant drug.In this study,the oil,cholesterol,metal ions and polyphenols adsorption ability,in vitro simulated digestive and the gut microbiota fermentation characteristics of WSP,ASP and CMP were studied to evaluate the functional values of three P.cocos polysaccharides(PCPs).The results showed that all three PCPs had good adsorption capacity on cholesterol,polyphenols and metal ions(Cd^(2+)/Zn^(2+)/Mg^(2+)),among which ASP showed the highest capacity than WSP and CMP.The adsorption capacity of all three PCPs on heavy metal ions(Cd^(2+)/Zn^(2+))was stronger than that of non-heavy metal ions(Mg^(2+));The in vitro digestibility of all three PCPs was very low,but WSP was slightly higher than ASP and CMP;Moreover,the indigestible residue of all three PCPs could improve the richness and diversity of gut microbiota,among which ASP had the greatest influence.In general,ASP and CMP could significantly promote the proliferation of some probiotics and inhibit the growth of some harmful bacteria.The gut microbiota diversity of CMP was reduced,but the richness of probiotics,especially Parabacteroides distasonis was significantly enhanced compared with the ASP group,and the growth of harmful bacteria Klebsiella pneumoniae was inhibited after CMP treatment.The short-chain fatty acids(SCFAs)analysis results showed that all three PCPs could significantly promote the production of acetic acid,propionic acid and the total acid content compared with blank control group,and SCFAs producing activity was positively correlated with the proliferative capacity of probiotics.Taken together,the good adsorption characteristics and gut microbiota regulatory activity of ASP may lay foundation for its lipid-lowering and immune-improving function.Additionally,the probiotic effect of CMP and ASP indicated that except for only use the water extract of PC in clinic,CMP and ASP also can be used in healthcare to take full advantage of this valuable medicine.

供应链金融如何助力中小企业韧性建设?——基于悖论管理的过程

供应链金融助力中小企业韧性建设,成为中国经济高质量发展的新动能。如何管理各类持续相悖又相互依赖的价值主张成为关键问题。基于“供应链金融服务悖论—悖论管理—中小企业韧性建设”框架,运用纵向案例研究方法,深入分析了浙江网商银行股份有限公司的供应链金融实践。研究发现:在不同的供应链金融服务导向下,金融服务提供商需要通过“亚层次分割—高层次整合”的机制形成有效的悖论管理能力,即通过更微观的层级分割、更高的层级整合的方式,将应对悖论的策略转化为持续嵌入的悖论管理能力。研究结果有助于丰富企业韧性研究、拓展供应链金融理论、揭示悖论管理内在机制,有助于更好地运用金融手段助力中小企业韧性建设。

Predictive value of neutrophil-to-lymphocyte ratio in coronary chronic total occlusion patients

BACKGROUND The neutrophil to lymphocyte ratio(NLR)has been reported as a novel predictor for atherosclerosis and car-diovascular outcomes.This study aimed to determine the effects of NLR on long-term clinical outcomes of chronic total occlusion(CTO)patients.METHODS A total of 670 patients with CTO who met the inclusion criteria were included at the end of the follow-up period.Patients were divided into tertiles according to their baseline NLR levels at admission:low(n=223),intermediate(n=223),and high(n=224).The incidence of major adverse cardiac events(MACEs)during the follow-up period,including all-cause death,nonfatal myocardial infarction(MI),or ischemia-driven revascularization,were compared among the three groups.RESULTS Major adverse cardiac events were observed in 27 patients(12.1%)in the low tertile,40(17.9%)in the intermediate tertile,and 61(27.2%)in the high NLR tertile(P<0.001).Kaplan-Meier analysis demonstrated a significantly higher incidence of MACE,ischemia-driven coronary revascularization,non-fatal MI,and mortality in patients within the high tertile than those in the low and intermediate groups(all P<0.001).Multivariable COX regression analysis showed that the high tertile of baseline NLR level showed a strong association with the risk of MACE(hazard ratio[HR]=2.21;95%confidence interval[CI]:1.21-4.03;P=0.009),ischemia-driven coronary revascularization(HR=3.19;95%CI:1.56-6.52;P=0.001),MI(HR=2.61;95%CI:1.35-5.03;P=0.043)and mortality(HR=3.78;95%CI:1.65-8.77;P=0.001).CONCLUSION Our findings suggest that NLR is an inexpensive and readily available biomarker that can independently pre-dict cardiovascular risk in patients with CTO.

Correlation of preoperative inflammatory factors and emotional disorders with postoperative delirium in patients with craniocerebral trauma

BACKGROUND Traumatic brain injury(TBI)imposes a substantial societal and familial burden due to its high disability and fatality rates,rendering it a serious public health problem.Some patients with TBI have poor treatment outcomes and are prone to postoperative delirium(POD),which affects their quality of life.Anxiety has been linked to increased POD incidence in some studies,while others have found no correlation.AIM To investigate the correlation of POD risk factors,preoperative inflammatory factors,and mood disorders in patients with TBI.METHODS We retrospectively collected data on the treatment of 80 patients with TBI from November 2021 to September 2023.Patients were grouped as POD and non-POD,according to their POD status,and the general data of the two groups were compared.Inflammatory factor levels were detected preoperatively,and the Hamilton Depression Scale(HAMD)and Hamilton Anxiety Scale(HAMA)were used to investigate the risk factors associated with POD in these patients.Logistic regression was used to identify the independent risk factors.RESULTS Twenty-one patients(26.25%)developed POD,including 7,10,and 4 cases of the excitatory,inhibitory,and mixed types,respectively.There were 59 cases(73.75%)in the non-POD group.Compared with the non-POD group,the POD group had a significantly higher proportion of patients with low Glasgow Coma Scale(GCS)scores before admission,unilateral mydriasis,preoperative hemorrhagic shock,intraventricular hemorrhage(IVH),and postoperative hyperglycemic hyperosmolar disease(P<0.05).In the POD group,interleukin-6(IL-6),human tumor necrosis factor-α(TNF-α),myeloperoxidase levels,HAMA,and HAMD scores were higher than those in the non-POD group(all P<0.05).Logistic multivariate analysis showed that GCS score at admission,IVH,IL-6,TNF-α,HAMA,and HAMD were independent risk factors for POD in patients with TBI(P<0.05).CONCLUSION Low GCS score at admission,IVH,elevated IL-6 and TNF-α,other inflammatory indicators,anxiety,and depression,can increase the risk of POD in patients with TBI after surgery.

Comparative analysis of two digestive tract reconstruction methods in total laparoscopic radical total gastrectomy

BACKGROUND The incidence of gastric cancer has significantly increased in recent years.Surgical resection is the main treatment,but the method of digestive tract reconstruction after gastric cancer surgery remains controversial.In the current study,we sought to explore a reasonable method of digestive tract reconstruction and improve the quality of life and nutritional status of patients after surgery.To this end,we statistically analyzed the clinical results of patients with gastric cancer who underwent jejunal interposition double-tract reconstruction(DTR)and esophageal jejunum Roux-en-Y reconstruction(RY).AIM To explore the application effect of DTR in total laparoscopic radical total gastrectomy(TLTG)and evaluate its safety and efficacy.METHODS We collected the relevant data of 77 patients who underwent TLTG at the Fourth Hospital of Hebei Medical University from October 2021 to January 2023.Among them,35 cases were treated with DTR,and the remaining 42 cases were treated with traditional RY.After 1:1 propensity score matching,the cases were grouped into 31 cases per group,with evenly distributed data.The clinical characteristics and short-and long-term clinical outcomes of the two groups were statistically analyzed.RESULTS The two groups showed no significant differences in basic data,intraoperative blood loss,number of lymph node dissections,first defecation time after operation,postoperative hospital stay,postoperative complications,and laboratory examination results on the 1st,3rd,and 5th days after operation.The operation time of the DTR group was longer than that of the RY group[(307.58±65.14)min vs(272.45±62.09)min,P=0.016],but the first intake of liquid food in the DTR group was shorter than that in the RY group[(4.45±1.18)d vs(6.0±5.18)d,P=0.028].The incidence of reflux heartburn(Visick grade)and postoperative gallbladder disease in the DTR group was lower than that in the RY group(P=0.033 and P=0.038).Although there was no significant difference in body weight,hemoglobin,prealbumin,and albumin between the two groups at 1,3 and 6 months after surgery,the diet of patients in the DTR group was better than that in the RY group(P=0.031).CONCLUSION The clinical effect of DTR in TLTG is better than that of RY,indicating that it is a more valuable digestive tract reconstruction method in laparoscopic gastric cancer surgery.

变压应力条件下铁镓合金棒材高频磁特性测试与模型构建

高频大功率磁致伸缩换能器件的输出特性与其所受的压应力密切相关,施加一定的压应力可以提高其核心元件磁致伸缩棒材的磁致伸缩系数,增大器件输出功率,而不合适的压应力会使得器件性能恶化。该文搭建了磁致伸缩材料高频磁特性测试系统,测量了磁致伸缩材料铁镓合金棒材在不同激励条件下(变压应力σ、变励磁频率f和不同磁场强度H)的动态磁特性曲线。结果表明,当频率与磁场强度一定时,随着压应力的增加,高频磁特性中振幅磁导率减小、动态磁滞回线纵向变扁、磁能损耗减少。针对传统磁滞模型无法计及压应力影响的问题,在现有静态J-A磁滞模型的基础上,计及涡流损耗和剩余损耗,并采用分数阶导数修正高频涡流场表达式,建立了高频动态磁滞模型,再引入压应力相关项修正模型参数,得到与外施压应力相关的改进高频动态磁滞模型。将实验数据与模型计算结果进行对比分析,结果表明,在变压应力和高频激励条件下,模型计算结果与实测值吻合较好,最大误差为5.86%,平均误差为3.29%,验证了模型的准确性与可行性。

棒状铁镓合金磁特性测试装置的设计与实验

磁致伸缩水声换能器作为电-机械-声能量转换器件是声呐系统中重要的大功率电磁装置,其核心驱动元件铁镓合金棒需工作在高频(f>1 kHz)激励条件下,为对此类高频大功率磁致伸缩器件的优化设计提供指导,需要准确测试棒材的高频磁特性。以往的测试装置由于高频激励时导磁回路铁损大、励磁回路电阻抗高以及棒材磁导率低等特点,难以保证铁镓合金棒内获得均匀且数值较高的磁通密度。该文基于电磁场理论设计了一种棒状铁镓合金高频高磁通密度磁特性测试装置,首先根据电磁损耗机理选择高频磁心材料并利用参数化扫描的方法优化其尺寸参数,在此基础上,建立三维有限元模型仿真计算棒材内部磁场大小及分布;然后以提高电磁转化效率为目标,设计测试装置的电路部分并依据串联谐振原理进行阻抗匹配;最后制作样机并进行实验测试。结果表明,该测试装置在1 kHz下,磁通密度幅值最高可达0.89 T,比常用的AMH-1M-S动态磁特性测试仪(最高可提供0.1 T磁通密度幅值)提高约9倍,且操作简单、稳定可靠。

城市公园特征对游憩活力影响的时空异质性研究

以上海市外环线以内10个城市公园为研究对象,通过OLS与GTWR回归模型,建立了游憩活力与公园内部空间特征及外部环境特征的联系,探索了游憩活力的影响因素和时空异质性。结果表明:1)城市公园游憩活力在时间层面上存在差异性,而在空间层面上存在聚集性,城市公园特征对游憩活力的影响具有明显的时空异质性;2)游憩设施密度、草坪覆盖率等指标呈现出稳健的正向影响,但水体覆盖率、归一化植被指数等的影响情况随着时空变化而改变;3)道路条数与居住商业用地比对公园活力具有显著正向影响,而地铁线路条数与公交站数量的影响并不稳健,随空间变化而产生较大差异。结论为高密度城市公园的有机更新和活力提升提供理论依据和实证参考。

不同直径Cr∶Al_(2)O_(3)圆柱晶体的制备及其光学性能研究

采用光学浮区法制备了不同Cr^(3+)掺杂浓度的Cr∶Al_(2)O_(3)晶体,并根据需要制备了不同直径(2 mm至13 mm)的长度大于100 mm的圆柱状Cr∶Al_(2)O_(3)晶体。测量了在制备Cr∶Al_(2)O_(3)晶体不同阶段所获得的粉末料棒、陶瓷料棒和晶体的密度,分别为0.928、2.230和4.051 g/cm 3。XRD图谱显示,Cr∶Al_(2)O_(3)晶体为α-Al_(2)O_(3)相。透射光谱表明,Cr∶Al_(2)O_(3)晶体可见光非特征吸收波段透过率大于80%。吸收光谱和光致激发光谱(监测669 nm光)均显示,Cr∶Al_(2)O_(3)晶体在418及559 nm处有较强吸收带,分别对应Cr^(3+)从^(4)A_(2)至4 T 1和从^(4)A_(2)至^(4)T_(2)的跃迁。以波长为559 nm的光激发Cr∶Al_(2)O_(3)晶体,其光致发射谱在669 nm处出现较强的发射峰;当Cr^(3+)浓度较低时,发射峰强度随Cr^(3+)浓度的增加而增强,Cr_(0.0060)Al_(1.9940)O_(3)的发射强度达到最大,然后随Cr^(3+)浓度增加而降低。

Foundations and Applications of Information Systems Dynamics

Although numerous advances have been made in information technology in the past decades,there is still a lack of progress in information systems dynamics(ISD),owing to the lack of a mathematical foundation needed to describe information and the lack of an analytical framework to evaluate information systems.The value of ISD lies in its ability to guide the design,development,application,and evaluation of largescale information system-of-systems(So Ss),just as mechanical dynamics theories guide mechanical systems engineering.This paper reports on a breakthrough in these fundamental challenges by proposing a framework for information space,improving a mathematical theory for information measurement,and proposing a dynamic configuration model for information systems.In this way,it establishes a basic theoretical framework for ISD.The proposed theoretical methodologies have been successfully applied and verified in the Smart Court So Ss Engineering Project of China and have achieved significant improvements in the quality and efficiency of Chinese court informatization.The proposed ISD provides an innovative paradigm for the analysis,design,development,and evaluation of large-scale complex information systems,such as electronic government and smart cities.

Upregulation of histone H3 caused by CRYAA may contribute to the development of age-related cataract

Objective:Age-relate cataract(ARC)is a disease of the eyes with no effective drugs to prevent or treat patients.The aim of the present study is to determine whether histone H3,αA-crystallin(CRYAA),β-galactosidase(GLB1),and p53 are involved in the pathogenesis of ARC.Methods:A total of 99 anterior lens capsules(ALCs)of patients with ARC of various nuclear grades,ultraviolet models of ALCs,and two human lens epithelial cell lines(FHL-124 and SRA01/04)were used,and the expression of histone H3,CRYAA,GLB1,and p53 were detected by immunoblotting and reverse transcription and real time-quantitative polymerase chain reaction.The association between CRYAA with histone H3,GLB1,and p53 was assessed in FHL-124 and SRA01/04 cells following CRYAA overexpression.Results:Histone H3 and p53 in ALCs of patients with ARC were up-regulated in a grade-dependent manner,and the expression of CRYAA showed a positive association with histone H3,p53,and GLB1.In UV models of ALCs and human lens epithelial cell lines,the expression levels of histone H3,cell apoptosis factors(Bax/Bcl-2,cleaved caspase-3),and inflammation factors(interleukin-6,tumor necrosis factor-α)were all up-regulated.Furthermore,transfection of CRYAA in FHL-124 cells induced overexpression of histone H3.Conclusion:CRYAA-mediated upregulation of histone H3 may be involved in the pathogenesis of ARC.p53 may also have a role in ARC development,but not via the CRYAA-histone H3 axis.The results of the present study may assist in improving our understanding of the pathogenesis of ARC and in identifying potential targets for treatment.

位移过电压抑制转接地故障消弧的柔性电源控制方法

柔性电源具备中性点位移过电压抑制和接地故障消弧功能,对配电网安全稳定运行至关重要,但是位移过电压抑制在线切换到故障消弧时,存在柔性电源输出过流问题。针对切换瞬间的过流问题,提出了一种幅值差分越限主动闭锁的控制方法,实现柔性电源运行模式的可靠切换。首先,介绍柔性电源运行机理,提出一种共用电流内环的闭环控制方法。其次,建立2种运行模式下的等效电路模型,分析切换过程中的过电流原理,通过位移过电压抑制模式下电压突变量是否越限来判定切换状态,进而闭锁交流输出直至收到上层故障消弧指令,柔性电源转为接地故障消弧模式。然后,仿真分析了2种运行模式及其切换控制方法的合理性。最后,研制样机并在中国某66 kV电网得到应用,现场实测结果验证了该方法的可靠性和先进性。

基于柔性励磁功率控制的载波同步策略

基于绝缘栅双极型晶体管(IGBT)电力电子元件的柔性励磁功率控制系统响应速度快,满足现今发电机大电感励磁回路的场合,但因功率回路并联引发的环流问题会导致输出电流畸变,增加系统损耗甚至造成系统崩溃。为此提出一种柔性载波同步策略抑制并联型功率控制器的环流问题。在功率控制并联模型的基础上,设置一个同步信号输出单元和若干个并联的功率控制器模块。同步信号输出单元向功率控制器模块内部的模拟载波发生器发出同步脉冲信号,模拟载波发生器同步清零,产生从零开始的锯齿波信号;实际载波发生器与模拟载波发生器同步清零,产生从零开始的三角波信号;通过模拟载波发生器的同步达到实际载波发生器的同步。此外,上述方法无需增加额外的硬件,提高了系统效率。实验验证了载波同步方法能够在不同功率点下实现很好的环流抑制效果,同时输出电流波形质量得到很大改善。

应用于光伏电站的快速功率跟踪控制策略

提出一种光伏(PV)快速功率跟踪控制策略,先将站内所有的PV逆变器划分成样本型和普通型,样本型逆变器以最大自然发电功率运行,并将自身的电气参数传递给上层快速功率控制装置以获取潜在最大功率。普通型逆变器处于限功率状态,当收到上层装置发送的功率提升目标值后,将功率和直流电压指令值作为内部程序中电压环和电流环的参考值,到达对应的次最大功率点处再继续追踪运行。通过实验验证,该方法解决了常规算法功率调节速率慢的问题,实现了逆变器30 ms以内的功率双向调节,避免了逆变器因直流电压下降而脱网的风险,满足现场PV电站的快速性需求。

响应面法在磨机传动系统分层修正中的应用

准确的有限元模型对结构的动态设计至关重要.针对结构复杂的大型磨机传动系统,基于分层思想以传动系统的子结构为研究对象,以试验模态频率数据为目标值,使用基于响应面的有限元模型修正技术识别结构中的不确定性参数,修正子结构模型.修正结果显示:频率误差小于0. 03%,振型相关系数值在0. 89以上,仿真模型与模态试验所得频率响应曲线接近,表明有限元模型精度明显得到提高,验证了响应面法应用于大型磨机传动系统设计及动态特性分析的可行性,并且为后续系统整体分析奠定了坚实的基础.