Effects of Aschersonia aleyrodis on the life table and demographic parameters of Bemisia tabaci

The present study reports the sublethal effects of the entomopathogenic fungus, Aschersonia aleyrodis（Webber） on Bemisia tabaci（Gennadius）（Homoptera： Aleyrodidae）. A fungal suspension of A. aleyrodis isolate Aa005 containing 1×107 conidia mL^-1 was sprayed against B. tabaci on eggplant leaves under greenhouse conditions. The effects of fungal application on survival as well as life table parameters of the whitefly were observed at different post inoculation periods. The results indicated that A. aleyrodis can significantly affect the survival of 1st, 2nd, and 3rd nymphal instars of B. tabaci. Developmental periods of different instar nymphs were not affected by fungal application. A. aleyrodis spores persisted well and significantly affected the survivorship of young instar nymphs of B. tabaci at different post incubation periods. Life table results suggested that A. aleyrodis has no impact on general fecundity and longevity of B. tabaci. When the pathogen was exposed to the open environment and maintained for a relatively longer period, a reduction in the reproductive rate and intrinsic rate of increase was caused by the fungal spores, though the sublethal effects were not as good as the control treatment. The results suggest that the ability of spores to suppress an increase in whitefly population persists well after incubation of spores to the external environment（up to 9 days）.

Life Tables for the Experimental Population Phenacoccus solenopsis Tinsley at Different Temperatures

[Objective] The study was to investigate the effect of temperature on pop- ulation dynamics of Phenacoccus solenopsis Tinsley, so as to providing references for the control and prevention of this pest. [Method] The experimental populations were kept in laboratory and fed on cotton plants, and the major parameters of the population were recorded. [Result] By the construction of age specific life tables and reproductive life tables for the P. solenopsis experimental population at 24, 27, 30 ~C, more than 10 parameters were obtained, including mean generation time, survival rates of different stages and sexes, life expectancy, spawning period, fecundity amount per female, sexual ratio, net reproductive rate, intrinsic increase rate, finite increase rate, population trend index, curve of survival rate, and curve of daily fe- male oviposition, which revealed the effect of temperature on growth and develop- ment, life expectancy and fecundities of P. solenopsis. [Conclusion] The reproductive potential of the P. solenopsis population is very great at suitable temperature, making it easy to outbreak. The research provided scientific basis for population dynam- ics investigation, predication and integrated control of P. solenopsis.

Effects of temperatures on the development and reproduction of the armyworm, Mythimna roseilinea: Analysis using an age-stage, two-sex life table

The armyworm Mythimna roseilinea（Walker） is a major pest of grain crops in South China. So far little is known about its basic biology and ecology, making prediction of population dynamics difficult. This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30℃. The highest values of net reproductive rate（R_0） and fecundity were observed at 21 and 24℃, respectively. Both the intrinsic rate of increase（r） and finite rate of increase（λ） increased significantly and mean generation time（T） decreased significantly with increasing temperature. M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested. Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature. The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24℃, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively. These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.

The Influence of Some Key Parameters on Fatigue Life of Common Metallic Components

The effect of key parameters on fatigue life of common metallic components, e.g. steel, aluminium alloy, has been analysed quantitatively. The influential coverage and degree of these parameters have been investigated systematically, some phenomena which can′t be discovered with qualitative analysis method have been revealed, a series of valuable conclusions has been obtained, which would be very beneficial to fatigue resistant design and improvement of anti fatigue ability of metallic components.

Effects of rigid gas permeable contact lens on morphological parameters and vision-related quality of life in keratoconus patients

AIM: To evaluate the effect of rigid gas permeable contact lens(RGP-CL) on corneal morphological parameters and vision-related quality of life in keratoconus(KC) patients.METHODS: Totally 57 eyes of 30 KC patients who were followed-up for more than two years, including 17 RGP wearers(32 eyes) and 13 non-wearers(25 eyes) were retrospectively analyzed. Initial medical history and corneal topography were collected at baseline. Corneal topography, corneal aberration, optical coherence tomography, and vision-related quality of life questionnaires were performed at the last follow-up.RESULTS: According to corneal topography, increase of the flattest keratometric values was higher in RGP wearers than in non-wearers(P=0.038). The morphological parameters, including symmetry index of front corneal curvature(P=0.004) and Baiocchi-Calossi-Versaci index front(P=0.047), were lower in RGP wearers than in nonwearers. Vertical coma was smaller in RGP wearers than non-wearers in 3.0, 5.0, 6.0, and 7.0 mm pupil diameters, respectively(P<0.05). The environmental triggering domain of ocular surface disease index was worse in RGP wearers as compared to non-wearers(P=0.003). At the last followup, there were no significant differences in constituent ratios of KC progression, corneal thickness topography, epithelial thickness topography, morphological parameters of corneal topography, and other questionnaire scores between the two groups(all P>0.05).CONCLUSION: Long-term use of RGP does not worsen KC but may cause corneal epithelial remodeling to increase symmetry of corneal anterior surface, reduce corneal vertical coma and improve visual quality. However, RGP wearing causes a slight decrease in vision-related quality of life. The occurrence of ocular surface symptoms is mainly associated with environmental triggering factors.

Analyses of Numerical Responses and Main Life Parameters for Determining the Suppression of Amblyseius cucumeris on Panonychus citri

In this paper, the numeral response and main parameters of experimental population life table were analyzed for determining the suppressing ability of Amblyseius cucumeris on Panonychus citri. The result showed that: (1) Under 21-31°C and 1 - 9 prey densities/leaf fragment condition, the prey consumptions of A. cucumeris increased with the temperature or prey density; (2) In 1:3 predator-prey ratio treatment, the suppression of P. citri (Ro=34.0053; T=19.4369; t=3.8204) was rather weak, it was enhanced as the ratio over 5:30, and the populations of P. citri in these treatments can be fully controlled within 4-5 days; (3) Under 25±1°C, 80-85% RH and 15L: 9D illumination conditions, the net reproductive rate, mean generation duration and the time for population double increase of P. citri (Ro=34.0053; T=19.4369; t=3.8204) were higher than those of A. cucumeris (Ro=21.8750; T=16.8943; t=3.7954). While the intrinsic rate of increase and finite rate of increase of the former (rm=0.1814; λ=1.1989) were lower than those of the latter (rm=0.1826; λ=1.2004). These results indicated that A. cucumeris is a desirable bio-control agent to suppress P. citri at lower population stage in citrus orchard.

Relationships between Microbial Growth Parameters and Shelf Life of MAP Sliced Onions

Microbial counts （total aerobic psychrotrophic count （TPC）, lactic acid bacteria （LAB）, coliforms, pseudomonads, yeasts） and sensory properties of sliced onions stored at different temperatures and air compositions were investigated. Microbial counts were fitted to the modified Gompertz equation and the growth parameters of microorganisms (the initial cell number （N0）, maximum cell number (Nmax), maximum specific growth rate (μmax), lag-phase （（λ）） were obtained as derived parameters. The relationships between growth parameters of microorganisms and the microbial or sensory shelf life were built. The results showed that microbial counts increased and sensory qualities decreased during storage. TPC was predominant bacteria associated with spoilage of sliced onions under tested temperatures and air conditions. High correlation coefficients （r） were found between the lag time （λ） of TPC, coliforms, pseudomonads, yeasts and the microbial or sensory shelf life. The correlations between microbial or sensory shelf life and μmax of five microorganisms were between -0.69 and -0.86. The initial microbial counts （N0） of five microorganisms strains only showed a little correlation, and the maximum microbial counts (Nmax) showed no obvious correlation with shelf life except for LAB and yeasts.

THE POSSIBILITY ANALYSIS OF NATURAL POPLAR-BIRCH FOREST RECOVERY TO BROAD-LEAF KOREAN PINE FOREST THROUGH THE METHOD OF LIFE TABLE IN THE XIOAXING'AN MOUNTAINS

The basic principle of life table method is deseribed, and the method of tree height instead of tree age in static life table is suggested, and it is also discussed that the possibility of natural poplar -birch forest recover to broad-leaf Korean pine forest on low pitches in the Xiaoxing'an Mountains by this method. If there is no particular situation, Korean pines after high than 5m under natural Poplar-birch forest will basically survive and make their way into dominant callopy accompanied by climax broad-leaf species.

Remaining useful life prediction of aero-engines based on random-coefficient regression model considering random failure threshold

Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomness of failure threshold.Firstly,a random-coefficient regression(RCR)model is used to model the degradation process of aeroengines.Then,the RUL distribution based on fixed failure threshold is derived.The prior parameters of the degradation model are calculated by a two-step maximum likelihood estimation(MLE)method and the random coefficient is updated in real time under the Bayesian framework.The failure threshold in this paper is defined by the actual degradation process of aeroengines.After that,a expectation maximization(EM)algorithm is proposed to estimate the underlying failure threshold of aeroengines.In addition,the conditional probability is used to satisfy the limitation of failure threshold.Then,based on above results,an analytical expression of RUL distribution of aero-engines based on the RCR model considering random failure threshold(RFT)is derived in a closed-form.Finally,a case study of turbofan engine is used to demonstrate the effectiveness and superiority of the RUL prediction method and the parameters estimation method of failure threshold proposed.

Life Table of Natural Population of Gastrolina depressa

[Objective]The paper was to understand the population development regularity of Gastrolina depressa in natural environment in Guizhou Province.[Method]The population dynamics of G.depressa was studied by establishing life table of natural population of G.depressa via field observation and calculating dynamic trend index of population.[Result]The mortality rates in egg stage,pupal stage and adult stage accounted for 26.42%,10.96%and 8.22%of the total mortality rate,respectively.The mortality rate in larval stage was the highest,accounting for 54.40%of the total mortality rate,higher than the total mortality rate in the other three stages.The population dynamic trend index I=9.25,I>1 indicated that the population showed an upward trend.[Conclusion]Under the natural conditions,the population of G.depressa shows upward trend,and human intervention is needed to control the population.The larval stage is the weak stage of the insect,which is the best time to control the insect.

Design of Fine Life Cycle Prediction System for Failure of Medical Equipment

The inquiry process of traditional medical equipment maintenance management is complex,which has a negative impact on the efficiency and accuracy of medical equipment maintenance management and results in a significant amount of wasted time and resources.To properly predict the failure of medical equipment,a method for failure life cycle prediction of medical equipment was developed.The system is divided into four modules:the whole life cycle management module constructs the life cycle data set of medical devices from the three parts of the management in the early stage,the middle stage,and the later stage;the status detection module monitors the main operation data of the medical device components through the normal value of the relevant sensitive data in the whole life cycle management module;and the main function of the fault diagnosis module is based on the normal value of the relevant sensitive data in the whole life cycle management module.The inference machine diagnoses the operation data of the equipment;the fault prediction module constructs a fine prediction system based on the least square support vector machine algorithm and uses the AFS-ABC algorithm to optimize the model to obtain the optimal model with the regularized parameters and width parameters;the optimal model is then used to predict the failure of medical equipment.Comparative experiments are designed to determine whether or not the design system is effective.The results demonstrate that the suggested system accurately predicts the breakdown of ECG diagnostic equipment and incubators and has a high level of support and dependability.The design system has the minimum prediction error and the quickest program execution time compared to the comparison system.Hence,the design system is able to accurately predict the numerous causes and types of medical device failure.

Positive Stable Frailty Approach in the Construction of Dependence Life-Tables

Dependence may arise in insurance when the insureds are clustered into groups e.g. joint-life annuities. This dependence may be produced by sharing a common risk acting on mortality of members of the group. Various dependence models have been considered in literature; however, the focus has been on either the lower-tail dependence alone or upper-tail dependence alone. This article implements the frailty dependence approach to life insurance problems where most applications have been within medical setting. Our strategy is to use the conditional independence assumption given an observed association measure in a positive stable frailty approach to account for both lower and upper-tail dependence. The model is calibrated on the association of Kenyan insurers 2010 male and female published rates. The positive stable model is then proposed to construct dependence life-tables and generate life annuity payment streams in the competitive Kenyan market.

江苏宝华山宝华玉兰种群结构与动态特征分析

为了揭示极危(CR)植物宝华玉兰〔Yulania zenii(W.C.Cheng)D.L.Fu〕野生种群的结构和动态特征,对江苏省句容市宝华山宝华玉兰野生资源进行全面调查,并运用静态生命表、存活曲线和生存分析等方法综合分析宝华玉兰种群结构和动态变化。结果表明:宝华山全境现存宝华玉兰野生开花植株115株,主要分布于宝华山北坡中部。宝华玉兰种群以中树和大树〔10 cm≤胸径(DBH)<25 cm〕为主,占比达66.1%,属于衰退型种群。从静态生命表看,宝华玉兰种群的生命期望随着径级的增加逐渐下降,种群存活曲线趋向于Deevey-Ⅱ型。生存分析结果显示:宝华玉兰种群趋势具有前期锐减、中期稳定、后期衰退的特点。种群动态量化分析结果表明:宝华玉兰种群动态总体呈增长趋势,但增长极为缓慢。基于上述研究结果,建议采取人工播种、补植实生苗等方式加强对宝华玉兰种群的保护和管理,促进其种群的更新和良性发展。

饱和砂土液化Finn模型的关键参数

以闽江中细砂层为对象,开展三因素三水平正交设计的小型振动台试验,定性探讨闽江砂土液化特性;同时基于Finn模型,在FLAC3D数值平台上对典型试验过程开展动力时程数值模拟。结果表明:Finn模型可有效模拟地震动作用下饱和砂土孔压的增长与有效应力的降低,能较为准确地反映饱和砂土的液化效应,Finn模型中的关键参数C_(1)、C_(2)对计算结果影响显著。以超孔压比峰值及超孔压比稳定值为指标,通过大量数值模拟结果与试验结果的对比,对上述关键参数进行标定,建议闽江饱和砂土液化Finn模型的关键参数取值为C_(1)=1.30、C_(2)=0.31。饱和砂土激振过程中呈现出轻微剪胀趋势,大致与液化现象同步出现。

基于MATLAB的民航发动机涡轮叶片寿命建模

针对民航飞机维修工作中发动机涡轮叶片普遍存在故障率较高的问题,收集某型民用航空发动机涡轮叶片的可靠性数据,并运用三参数Weibull分布建立该型发动机涡轮叶片的可靠性寿命模型。在模型求解的数值计算过程中,为保证模型的计算精度,采用经典的牛顿迭代法及三参数相关系数优化法对涡轮叶片的寿命数据进行拟合分析及计算;同时为减少计算工作量及提高数值计算过程中人工智能的参与度,基于MATLAB软件对上述数值计算方法编写计算程序,最后对计算结果进行K-S假设检验。结果表明:对涡轮叶片寿命数据进行可靠性分析时,运用Weibull分布建立的数学模型符合客观规律;同时牛顿迭代法、三参数相关系数优化法及MATLAB计算程序的有效利用,保证了计算结果的精度。

共享单车锁用减速器输出级齿轮副疲劳寿命分析

共享单车的落地和普及促进了共享单车锁用减速器的发展和应用,而输出级齿轮副的疲劳寿命决定了减速器的有效寿命,针对传统试验测试齿轮疲劳寿命方法的不足,提出一种基于有限元仿真的输出级齿轮副寿命预测方法。在ANSYS软件中建立齿轮副有限元模型,并改进齿轮副结构参数以改善齿轮副间的受力情况。在ADAMS软件中对齿轮副进行动力学仿真获取齿轮副间的动态接触力,并以此作为载荷谱在nCode DesignLife软件中对齿轮副疲劳寿命做出预测,最后通过试验验证有限元仿真方法的正确性。结果表明:改进从动轮压力角后齿轮副主动轮应力减小了30.18%,从动轮应力减小了38.71%;改进压力角后齿轮副疲劳寿命增加了124.23%,满足设计要求;齿轮副试验寿命结果与仿真预测寿命结果误差小于10%,在可接受范围内。

基于DDPG的振动台控制参数整定方法

三参量控制是地震模拟振动台的底层控制算法,其参数整定过程中涉及的参数多,传统的参数整定方法存在效率低、过程繁琐等问题。为了提高整定效率和准确性,提出一种基于确定性策略梯度(DDPG)算法的振动台三参量控制参数整定算法。此方法通过将振动台三参量控制系统作为强化学习环境,利用DDPG算法对系统的状态-动作-奖励数据进行学习和训练;训练好的智能体则可以输出最优的控制参数,然后将整定完成的控制参数放在实际振动台系统模型中进行测试。结果表明:DDPG算法可以有效优化振动台控制性能,提高试验结果的准确性和可靠性,具有实际应用价值。

基于静强度分布参数的复合材料剩余强度及寿命预测

为探讨剩余强度及疲劳寿命与初始静强度分布参数之间的关系,构建基于初始静强度分布参数的剩余强度和疲劳寿命计算模型。在模型构建过程中未涉及复合材料结构的层数、铺层厚度和铺层方向,适应性强。模型参数可通过静力试验和剩余强度试验获得,试验成本相对疲劳试验较低。剩余强度和疲劳寿命与初始静强度变异系数及其分布参数有关,当初始静强度服从威布尔分布时,疲劳寿命亦服从威布尔分布,可为开展疲劳可靠性提供借鉴和参考。算例表明,基于建立的模型,剩余强度计算结果最大误差为-1.58%,疲劳寿命与试验数据吻合较好。

7种榕属植物叶片的理化性质及对朱红毛斑蛾生长发育的影响

为探究相较于其余5种榕属植物,朱红毛斑蛾Phauda flammans偏好小叶榕Ficus concinna及垂叶榕F.benjamina的原因。本文通过测量比较7种常用的园林绿化榕属植物营养物质、次生代谢物质以及物理性状,采用室内饲养观察与调查统计的方法评估朱红毛斑蛾在小叶榕和垂叶榕上的发育历期和种群生命表参数。结果发现,与黄葛树、无花果、对叶榕、高山榕和印度榕相比,小叶榕和垂叶榕叶片可溶性糖含量分别为98.47μg/g与65.21μg/g;可溶性蛋白含量分别为4.18 mg/g与0.95 mg/g;含水量分别为0.84%与0.95%;叶片厚度分别为3.59 mm与2.65 mm;硬度分别为3.91 mN与3.49 mN;朱红毛斑蛾仅在小叶榕和垂叶榕上能完成生活史;与垂叶榕相比,取食小叶榕后的幼虫、蛹和成虫的生长发育历期更短,分别为50.25 d、11.48 d和4.28 d,种群存活率和繁殖率更高,且自然死亡排除控制指数为1.68,低于垂叶榕。说明小叶榕和垂叶榕叶片含有较高的营养物质、较低含量的次生代谢物质、较小的叶片硬度,导致朱红毛斑蛾偏好小叶榕和垂叶榕,并能完成生活史。因此在基于榕树植物的园林绿化造景过程中,应注意树种的搭配,降低朱红毛斑蛾对城市园林景观和生态效益的影响。

新疆库尔勒八字地老虎在不同温度下的种群生命表及灯下成虫种群动态

【目的】研究温度对新疆库尔勒八字地老虎Xestia c-nigrum生长发育和繁殖的影响,明确其对环境温度的适应能力。【方法】利用两性生命表方法比较15, 20, 25, 30和35℃下八字地老虎卵孵化率、幼虫存活率、化蛹率、羽化率、发育历期及繁殖力,分析不同温度对其种群生命表参数的影响,并计算不同发育阶段的发育起点温度和有效积温。利用灯诱监测数据分析2020-2022年期间新疆库尔勒农区八字地老虎种群动态与日平均温度变化的关系。【结果】15℃时八字地老虎幼虫存活率、化蛹率、羽化率均低于30%,30℃时幼虫存活率、化蛹率低于10%且蛹不能正常羽化,35℃时幼虫不能存活。八字地老虎各发育阶段历期随温度升高而缩短,15, 20, 25, 30和35℃时卵历期分别为15.52, 7.40, 5.47, 4.88和3.88 d;15, 20, 25和30℃时幼虫历期分别为109.43, 40.53, 26.48和24.55 d;15, 20和25℃时蛹历期分别为41.43, 18.00和12.54 d。15℃时种群呈负增长,20和25℃时种群呈正增长,其中25℃时内禀增长率(r_m)最大。八字地老虎卵、1-6龄幼虫和蛹的发育起点温度分别为9.81, 8.43,9.95, 10.26, 12.52, 13.58, 12.60和10.81℃,有效积温依次为79.62, 92.17, 56.09, 57.03, 39.35, 38.16, 80.72和172.39日·度。2020-2022年灯诱监测数据表明,八字地老虎在新疆库尔勒每年发生3代,成虫高峰期分别在5月中旬、7月下旬和9月上旬,对应的日平均温度在19.5~26.5℃之间。【结论】低于15℃时八字地老虎种群呈负增长,超过30℃时不能完成生活史,而20~25℃比较适合八字地老虎的生长与繁殖,该结果为明确新疆库尔勒八字地老虎的温度适应能力及其发生规律提供了科学依据。