ON THE EXISTENCE OF PERIODIC SOLUTIONS FOR NONLINEAR SYSTEM WITH MULTIPLE DELAYS

The existence of T_periodic solutions of the nonlinear system with multiple delays is studied. By using the topological degree method, sufficient conditions are obtained for the existence of T_periodic solutions. As an application, the existence of positive periodic solution for a logarithmic population model is established under some conditions.

Multiple Periodic Solutions for Some Classes of First-Order Hamiltonian Systems

Considering a decomposition R2N=A⊕B of R2N , we prove in this work, the existence of at least (1+dimA) geometrically distinct periodic solutions for the first-order Hamiltonian system Jx'(t)+H'(t,x(t))+e(t)=0 when the Hamiltonian H(t,u+v) is periodic in (t,u) and its growth at infinity in v is at most like or faster than |v|a, 0≤ae is a forcing term. For the proof, we use the Least Action Principle and a Generalized Saddle Point Theorem.

Periodic Solutions for the Higher Order Differential Equations with Multiple Delays

By Fourier analysis techniques and Schauder fixed point theorem, we study the existence of periodic solutions for a class of even order differential equations with multiple delays. The result obtained is a generalization of the results developed by W. Layton to the case of multiple delays.

Multiple Period Repair Kit Problem with Capacity Considerations

The repair kit problem seeks an optimal stock of parts for a repair kit for purposes of remote repairs. This problem has often been studied when restocking is possible between each order, or when the number of orders is known between each restocking. This research evaluates a model for the repair kit stocking problem for which there is multiple-period demand with a known time interval between each restocking, but an unknown number of on-site repair visits is required during the restocking period. Most previous work focuses on minimum cost subject to some minimum service level;in the case where the value of technician time and customer service is relatively large, the space constraint of the kit and volume of parts comes into play. This work contributes to the literature by testing the robustness of a heuristic originally proposed by [1] in a field study. We conduct numerical experiments to evaluate the heuristic over a wide range of parameterizations. Our results indicate that the heuristic performs close to optimum, and its performance improves as the problem size grows.

MULTIPLE SOLUTIONS FOR HAMILTONIAN SYSTEMS WITH PERIODIC NONLINEARITY AND STRONG RESONANCE

I. Introduction In this paper we are looking for solutions of the following Hamiltonian system of second order: where x= （x1, x2） and V satisfies （V. 1） V: R×R2→R is a C1-function, 1-periodic In t, （V.2） V is periodic in x1 with the period T>0, （V. 3） V→O, Vx→O as |x2|→∞, uniformly in （t, x1）.

Measurement of overburden failure zones in close-multiple coal seams mining

In the Kaiping Coal field,mining of five coal seams,located within 80 m in the Kailuan Group,#5,#7,#8,#9 and#12 coal seam,is difficult due to small interburden thickness,concentrated stress distributions,high coal seam metamorphism,and complex geological conditions.By using the ZTR12 geological penetration radar(GPR)survey combined with borehole observations,the overburden caving due to mining of the five coals seams was measured.The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan,which provides a measurement basis for the control of rock strata in close multiple coal seam mining.For the first time,it was found that the overburden caving pattern shows a periodic triangular caved characteristic.Furthermore,it is proposed that an upright triangular collapsed pile masonry and an inverted triangular with larger fragments piled up alternately appear in the lower gob.The research results show that the roof structure formed in the gob area can support the key overlying strata,which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close coal seams.

Application of the Modality of Multiple Disciplinary Team for a Perioperative Patient with Suspected Novel Coronavirus Pneumonia and Cervical Spine Fracture in Nursing

With the explosive spread of novel coronavirus pneumonia, a major public major public health emergency has been declared around the world. Our country has come to a crucial stage of “external defense input, internal defense rebound” and strict quarantine measures are taken in all ports of entry throughout the country. Operations on patients with cervical spine during the quarantine, which not only increases the risk of surgical treatment, but also increases the difficulty of perioperative nursing. The objective is to explore the result of application of the modality of multiple disciplinary team for a perioperative patient with suspected novel coronavirus pneumonia and cervical spine fracture in nursing. The patient’s condition and nursing measures are studied and discussed from various specialist angle through the multidisciplinary team established by the isolation ward, orthopedics department, emergency department, anesthesiology department, operating room, rehabilitation department, psychology department and so on, and the overall and personalized surgical and nursing planning is formed through interdisciplinary advice. The nursing experience is summarized in this paper.

MULTIPLICITY OF PERIODIC SOLUTIONS FOR SECOND ORDER HAMILTONIAN SYSTEMS WITH MIXED NONLINEARITIES

The multiplicity of periodic solutions for a class of second order Hamiltonian system with superquadratic plus subquadratic nonlinearity is studied in this paper.Obtained via the Symmetric Mountain Pass Lemma,two results about infinitely many periodic solutions of the systems extend some previously known results.

Internal Transactions for Multiple Risky Assets

Most of the articles about insider trading assume that there is only one risky asset in the market. On the basis of these papers, this thesis is mainly divided into three parts to study the situation of multiple risky assets in the market. In the first part, the situation of multiple risky assets in the market when two transactions are in progress is studied and then, the equilibrium when the market requires the internal traders to disclose the trading volume after each transaction is analyzed. In the second part, the equilibrium of multi-period based on the two phases of transaction is derived. The third part is the summary of the paper.

Simultaneous Bilateral Thoracoscopic Pneumonectomy for Early Multiple Primary Lung Cancer Feasibility Analysis

Objective:To analyze the feasibility of simultaneous bilateral thoracoscopic lung resection in the treatment of multiple primary lung cancers in the early stage.Methods:The study time range is between March 2019 and March 2021.A sample of 30 patients with early multiple primary lung cancer admitted to this hospital were included,and they were divided into a study group,a control group,and samples within the group using a random number table scheme n=15,patients in the control group underwent staged bilateral thoracoscopic pneumonectomy,and patients in the study group underwent bilateral thoracoscopic pneumonectomy at the same time.The indicators of the two groups were compared and analyzed.Results:There was no significant difference in the operation time and intraoperative blood loss between the two groups(P>0.05).There were significant differences in the VAS score,total length of hospital stay,and total surgical costs on the first day after surgery(P<0.05);there was no significant difference in the two groups'postoperative recovery indicators and the incidence of complications(P>0.05).Conclusion:It is safe and feasible to treat patients with multiple primary lung cancer in both lungs at the same time with simultaneous bilateral thoracoscopic surgery,and is suitable for promotion.

建筑基本周期多因素机器学习预测模型

建筑物基本周期是其最重要的动力特性参数,影响因素众多。受限于曲线拟合的传统建模手段,目前的基本周期预测模型表达式中仅能包含高度或层数等单一因素,而忽略其他因素的影响。数据驱动机器学习方法的出现,为建筑周期多因素预测模型的建立提供了新思路。研究从大量文献中收集整理了2561条建筑周期的实测数据,形成了包含建筑高度、层数、材料、功能、地区等多因素的建筑周期实测数据库。建立了具有自学习能力的建筑基本周期多因素机器学习预测模型,避免了一般机器学习模型中繁琐的参数调节过程,提升模型的鲁棒性和适用性。与传统模型结果的对比表明:所提预测模型的适用结构类型范围广、准确性更高,配合云端服务器可形成一种全新的、开放式自学习的建筑周期预测模式。

基于功率重构和时序特性约束的长预见期光伏集群功率预测

光伏装机容量的逐渐增大为大规模的光伏并网带来了巨大挑战,突破更长预见期的光伏功率预测有助于电力系统的安全稳定运行。现有研究及应用最长预见期为7 d,为将预见期延长至8~15 d,提出了一种基于功率重构和时序特性约束的长预见期光伏集群功率预测方法。首先,采用近似积分计算日电量和辐照能;其次,基于麻雀搜索算法优化变分模态分解以分解电量及辐照能序列,并采用多元线性回归模型对不同频率的分量进行预测叠加得到电量预测结果;然后,根据出力特性建立约束过程,将电量预测结果重构为光伏功率;最后,将所提方法应用于中国甘肃省某光伏集群,模型在不同季节典型月功率预测的均方根误差平均降低2.55%,验证了方法的有效性。

数字经济政策冲击推动能源效率提升的影响机制研究

基于2006—2021年全国281个地级市面板数据,将“宽带中国”示范城市政策视为一项准自然实验,运用多期双重差分法考察数字经济政策冲击对能源效率提升的影响及其作用机制。研究发现,“宽带中国”示范城市政策推动了能源效率提升,经过一系列稳健性检验,结论依然成立。机制研究发现,“宽带中国”示范城市政策主要通过加强绿色创新和促进金融发展来提升能源效率。异质性分析表明,“宽带中国”示范城市政策能有效推动老工业基地能源效率提升,但对非老工业基地的影响不显著;该政策能有效推动一二线城市能源效率提升,但对其他城市影响不显著。进一步研究表明,“宽带中国”示范城市政策对能源效率提升还存在一定的空间溢出效应,对周边区域的能源效率提升具有带动作用。

基于地区线性矩法的四川省24 h极值降雨频率分析

为探究四川省24 h极值降雨在不同重现期不同频率下的时空分布特征,采用地区线性矩法划分四川省水文气象一致区,确定最优拟合线型,并验证地区线性矩法在站点稀疏地区的适用性,随后估计四川省24 h不同重现期降雨频率值,分析其时空分布特征。研究结果表明:(1)四川省可划分为40个水文气象一致区,经线型拟合优度检验,主要线型为GLO、GEV和GNO,其中川西高原地区的最优线型大多为GLO,盆地区域的最优线型大多为GEV。(2)地区线性矩法在站点相对稀疏的川西高原地区具有良好的适用性。(3)四川省内不同地区24 h极值降雨空间分布十分不均,同一重现期下不同地区降雨频率估计值的最大值可达最小值的10倍。

局部超二次二阶哈密尔顿系统周期解的多重性

运用对称山路引理研究一类二阶哈密尔顿系统在局部超二次条件下周期解的多重性问题.得到了系统的能量泛函的无穷多个临界点.在此局部超二次条件下,二阶哈密尔顿系统有无穷多个周期解.

榆神矿区多层厚硬顶板强矿压显现及覆岩破断运动规律研究

针对榆神矿区多层厚硬顶板条件下工作面强矿压和邻空侧巷道变形严重问题,综合采用理论分析、数值计算和微震监测方法,分析了多关键层结构下顶板覆岩破断和邻空侧巷道围岩应力特征。研究结果表明:多层厚硬岩层条件下,顶板破断垂向位移和能量均呈现明显的“低、中、高”分区特征,中高位岩层破断明显滞后于低位岩层,这构成了工作面“大、小周期”的重要结构基础;本工作面开采时,相邻采空区破碎顶板大能量微震事件增多、破断强度较高,并可对邻空回风巷围岩形成强二次采动影响,这是邻空侧回风巷高应力、强变形的主要诱因。同时,高低位多关键层组合破断可导致“大周期”来压发生强度和风险上升,对关键层顶板破断运动规律进行控制是降低“大周期”强度和频率的有效途径之一。

基于无人机影像多时相的小麦品种氮效率分类识别

【目的】探索无人机遥感在氮效率分类识别中的潜力,构建小麦品种氮效率分类方法,为氮高效品种筛选提供理论依据和技术支持。【方法】通过6个成熟期与氮效率密切相关的农学指标(产量、植株氮积累、氮素生理利用效率、植株干生物量、籽粒总吸氮量、N收获指数)构建主成分综合值,并对其进行K-Means聚类分析,将121个小麦品种划分为氮高效型、氮中效型和氮低效型3种类型。利用无人机遥感平台搭载多光谱相机,在小麦拔节期、孕穗期和开花期获取无人机遥感影像,并提取34种植被指数,分析植被指数与氮效率综合值的相关性;对比支持向量机(SVM)、随机森林(RF)和K最近邻(KNN)分类方法的氮效率分类模型精度,使用总体分类精度(OA)和Kappa系数比较不同生育时期下小麦品种氮效率分类识别的能力;并使用3种不同的特征集筛选方法(ReliefF算法、Boruta算法和RF-RFE算法)对优化的特征子集进行综合评价,确立适宜的小麦品种氮效率分类识别方法。【结果】随着小麦生育时期的不断推进,植被指数与氮效率综合值的相关性逐渐提高,开花期最高(r=0.502);利用植被指数全特征集对小麦品种氮效率进行分类,对于单生育时期数据而言,以开花期的SVM模型分类效果最好(OA=77.1%,Kappa=0.591),拔节期最差(OA=65.6%,Kappa=0.406);总体而言,多生育时期数据融合的品种氮效率分类精度高于单生育时期,其中以拔节期+孕穗期+开花期3个生育时期数据融合的SVM模型的分类效果最优(OA=80.6%,Kappa=0.669)。为减少多生育时期数据融合的特征集变量数量,比较分析RF-RFE、Boruta和ReliefF 3种算法的特征优化效果,基于RF-RFE算法得到的优化特征子集分类精度最高,其OA和Kappa系数比全特征集分类模型分别提高了4.0%和10.1%,其中,以3个生育时期数据融合的分类效果最好(OA=85.4%,Kappa=0.749)。【结论】确立6个氮效率指标—主成分分析—K-Means氮效率评价方法;RF-RFE算法有效优化多生育时期组合的特征子集数量,且获得较高的分类精度,确立基于多生育时期组合—RF-RFE—SVM技术融合的小麦品种氮效率分类模型,为小麦氮高效品种的快速准确分类鉴定提供理论依据和技术支撑。

多宽带雷达协同目标微动周期估计方法

微动周期是区分弹头和仿形诱饵的重要特征.针对当前主要的雷达微动周期估计方法存在时间资源消耗大、对单雷达测量精度要求高、需要多宽带雷达同步观测等缺点,提出一种多宽带雷达协同目标微动周期估计方法.首先利用最小均方(LMS)算法进行目标真实尺寸估计;然后利用变尺度差频处理通过尺寸序列提取目标微动周期;最后通过仿真验证了本文方法的有效性,并探索了应用边界条件.该方法无需多宽带雷达同步观测,且在单雷达常规尺寸测量精度和时间资源消耗条件下即可准确估计目标微动周期.

1例严重多发伤合并急性呼吸窘迫综合征患者围手术期ECMO治疗的护理

创伤是全球面临的突出问题,目前,在我国已成为青壮年第1位死亡原因[1]。约50%的创伤患者合并有严重的胸部外伤[2],10%~20%严重创伤患者(损伤严重度评分(injury severity score,ISS)≥16分)可进展为呼吸功能衰竭甚至急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS),病死率高达50%~80%[3-4]。

求解最小公倍数问题的量子安全多方计算协议

最小公倍数是解决很多数学问题的基础工具,在隐私保护的情况下如何对其进行多方协同计算具有一定的研究价值.部分经典安全多方计算协议虽然能够求解该问题,但计算复杂度为指数级.本文通过将最小公倍数问题转化为求多个周期函数的连接函数的周期,提出了一个基于量子周期查找算法的最小公倍数协议,将复杂度降为多项式级.在协议中,发起方对每个参与方发送一个粒子.每个参与方对粒子施加一个Oracle操作,其中Oracle函数的周期即各自的私有整数.然后,发起方通过运行量子周期查找算法来计算出连接函数的周期,即各自整数的最小公倍数.为了防御共谋和伪造攻击,采用星-环混合拓扑结构对粒子发送方进行诚实性检验.由于量子周期查找算法存在一定的失败概率,设计了一个量子匿名输出检验协议来检验最小公倍数结果的正确性.安全性分析表明了该协议在恶意模型下具有无条件安全性,且协议的计算复杂度和通信复杂度分别为O(n^(3)m^(2)log(nm))和O(n^(2)mlog(nm)),均为多项式级.此外,该协议具有较好的扩展性,可应用于安全多方最大公约数计算、有理数求和、最值计算等问题.