第三方物流参与限时蔬菜配送问题研究

根据我国第三方物流的发展现状,结合蔬菜运输企业的实际运营情况,建立一种有第三方物流企业参与的限时蔬菜配送模型。考虑配送成本及蔬菜配送的特殊性,对比有第三方物流企业参与的统一蔬菜配送与现阶段蔬菜配送的形式,采用RSG—GA混合算法对建立的模型进行求解。通过对比运算结果和运输时间的稳定性,分析第三方物流参与蔬菜配送问题的价值所在,探讨第三方物流在蔬菜配送问题中的影响及意义。     

Externalizing Behavior Among Adopted Boys with Preadoptive Histories of Child Sexual Abuse

This study examined the severity of externalizing symptomology among adopted boys with preadoptive histories of child sexual abuse, physical abuse, neglect/abandonment, or no abuse. The study was based on data collected across a three-year period from parents who adopted children from Florida's child welfare system. The sample consisted of 1,136 adopted boys aged 6 to 18 years. In repeated cross-sectional multivariate analyses, the results revealed that adopted boys with preadoptive child sexual abuse were prone to significantly higher levels and clinically severe externalizing symptomotology as compared to adopted boys without such histories. The findings highlight the need for postadoption services and empirically validated interventions for families adopting boys with preadoptive child sexual abuse.     

共球有限点集的广义欧拉超球面及其性质

应用向量方法,定义了一般n维共球有限点集的广义欧拉超球面概念,并揭示了它的一系列优美性质     

（2＋1）维长短波方程整体吸引子的存在性

研究了无穷维动力系统中（2＋1）维长短波方程整体吸引子的存在性．运用Galekin方法构建了该系统的弱吸引子,并证明了所构建的弱吸引子是强吸引子．     

高等教育国际化模式研究——以项目联结为视角

高等教育国际化已然是不可逆转的趋势,但同时也面临合作模式趋同困境.浙江传媒学院着眼于文化创意产业在全球经济中逐渐显现的支柱作用,创立了基于产品设计项目的国际合作案例的螺旋式创意模式.该模式重视政府、大学和产业三者分别作为创新主体之间的关系,团队合作与个体多样性并重,以项目联结政府、企业、高校和国外高校,形成可持续发展的创新合作模式,为高等教育国际化寻找新的增长点.     

基于GARCH-EWMA原理的期货交易保证金随动调整模型

在EWMA模型和GARCH模型思想的基础上,结合SPAN系统的思想,以保证金在期货交易中可以弥补最大损失额和保证交易的正常进行等作用为考虑因素,运用数理统计和VaR等风险管理方法,建立了保证金随动调整模型。在满足给定风险系数和置信水平的前提下,制定合理的保证金的收取比例,为期货交易的保证金水平的确定提供了新的计算方法。本模型的特点一是利用GARCH模型对EWMA模型中的关键参数-衰减因子进行测定,解决了以往使用EWMA模型时,对该参数人为赋值而导致模型人为因素过强的问题。二是在模型中引入波动函数,用来确定随时点t而不断变化的波动系数值。并采用大量的历史数据对大豆、豆粕两种期货品种的波动函数进行线性拟合,得到时点t与波动系数之间的连续线性函数,以代替以往波动系数与时点t之间所采用的极为粗糙的分段函数,从而大大提高了模型的灵敏性。三是采用近4500个合约价格的历史数据,对大豆和豆粕两种期货合约价格的涨跌停情况进行统计分析,得到这两类期货品种的涨跌停情况的概率分布。并分别考虑各种可能发生的情况综合计算最终单位保证金,使得保证金的计算更具全面性。     

Inter‐agency joint protocols for safeguarding children in social care and adult mental‐health agencies: a cross‐sectional survey of practitioner experiences

Parental mental illness, substance misuse and domestic violence are common risk factors for the maltreatment and neglect of children. Safeguarding children is everyone's responsibility, including professionals working primarily with adults. In the UK, Local Safeguarding Children Boards (LSCBs) were established to ensure that all agencies work together to safeguard children. Many LSCBs developed multi‐agency joint protocols to enhance collaboration, but there is limited evidence of their effectiveness. This paper reports findings from a cross‐sectional survey of practitioner self‐reported experiences of joint protocols, which was conducted in one inner London borough, to evaluate their impact on professional practice. A self‐complete questionnaire administered to all professionals in adult mental‐health and children's social care services in the borough yielded a response from 119 practitioners. The survey found that the protocols had been widely disseminated and provided clear guidance to practitioners. Practitioners perceived that they had increased awareness of the risk factors for safeguarding children and some had used the protocols to help them gain access to services for their clients. Practitioners also perceived that they had improved inter‐agency working between children's social care and adult mental‐health services. However, respondents indicated that positive interpersonal contact with practitioners from other agencies was equally important in promoting joint working and inter‐agency collaboration.     

Early traces of the Second Demographic Transition in Bulgaria: A joint analysis of marital and non-marital union formation, 1960–2004

We explore trends in first-union formation in Bulgaria from 1960, using data from the national Gender and Generations Survey of 2004. We analyse jointly the transition into cohabitation and directly into marriage. The standardized marriage rate falls dramatically from the early 1980s; the corresponding rate of entry into cohabitation has already increased from the early 1960s but (surprisingly) falls moderately toward the end of our period. Cohabitation also tends to last progressively longer in more recent periods. The analysis shows that a pregnancy leads to a dramatic increase in the rate of both kinds of union formation: the increase is by a factor of almost 20 for marriage formation and about 10 for entry into cohabitation, ceteris paribus. Our findings suggest that, in Bulgaria at least, some manifestations of the Second Demographic Transition can be detected as early as the 1980s.     

贵金属期货价格预测方法及实证研究

本文融合了二次分解与极限学习机的优势,提出了VMD-Res.-EEMD-ELM贵金属期货价格预测模型,选择变分模态分解(VMD)作为主要的分解技术,生成模态分量序列(VMFi)和残差序列(Res.),采用集合经验模态分解(EEMD)对残差序列进行二次分解,并使用具有良好泛化能力的极限学习机(ELM)对各分量进行预测,最后叠加各模态分量和残差的预测值形成收益率的最终预测结果。所提出的模型不仅充分发挥了二次分解技术的优势,而且解决了传统变分模态分解组合预测模型未考虑残差影响因素的问题。实证研究表明,本文所提出的组合模型能够全面捕捉黄金、白银期货价格日收益率序列的特征,方向性预测准确率分别为83.33%和93.33%,误差指标MAE分别为0.15和0.11,经比较本文所提出的模型具有良好的预测性能。