浅析某深基坑工程支护方案优化措施

本文结合具体工程项目对狭窄场地下的深基坑支护技术进行分析,重点是工程项目所采用的钻孔混凝土灌注桩、锚杆、锚喷护壁和挡土墙联合支护结构体系;提出针对狭窄场地情况下,改进和优化支护技术的几项措施,谨供大家作参考之用。     

CDMA2000 1x EV-DO网络的室分优化

文章针对中国电信CDMA2000 1xEV-DO网络的室分优化工程,探讨了多种数据分析及故障定位方法,并提出了基于不同场景的网络性能优化的解决方案。     

中国各产业的就业拉动能力分析——基于完全就业新视角的投入产出分析

利用2002年的42*42投入产出表,计算出各个产业单位产值所需的完全劳动与资本消耗,并使用修正的要素投入指标(单位产值所需劳动、劳动资本比),对各产业的就业拉动能力进行排序。和未考虑完全劳动消耗的产业排序相对比,考虑完全劳动消耗的产业排序并未形成统计意义上的背离。但是,考虑完全劳动消耗后,一些产业的就业吸纳能力在排序上发生了非常显著的变化。因此,从产业的完全就业拉动角度来考虑产业政策,更有助于解决就业问题。     

Deciphering robust portfolios

Robust portfolio optimization has been developed to resolve the high sensitivity to inputs of the Markowitz mean–variance model. Although much effort has been put into forming robust portfolios, there have not been many attempts to analyze the characteristics of portfolios formed from robust optimization. We investigate the behavior of robust portfolios by analytically describing how robustness leads to higher dependency on factor movements. Focusing on the robust formulation with an ellipsoidal uncertainty set for expected returns, we show that as the robustness of a portfolio increases, its optimal weights approach the portfolio with variance that is maximally explained by factors.     

Portfolio management with robustness in both prediction and decision: A mixture model based learning approach

We develop in this paper a novel portfolio selection framework with a feature of double robustness in both return distribution modeling and portfolio optimization. While predicting the future return distributions always represents the most compelling challenge in investment, any underlying distribution can be always well approximated by utilizing a mixture distribution, if we are able to ensure that the component list of a mixture distribution includes all possible distributions corresponding to the scenario analysis of potential market modes. Adopting a mixture distribution enables us to (1) reduce the problem of distribution prediction to a parameter estimation problem in which the mixture weights of a mixture distribution are estimated under a Bayesian learning scheme and the corresponding credible regions of the mixture weights are obtained as well and (2) harmonize information from different channels, such as historical data, market implied information and investors׳ subjective views. We further formulate a robust mean-CVaR portfolio selection problem to deal with the inherent uncertainty in predicting the future return distributions. By employing the duality theory, we show that the robust portfolio selection problem via learning with a mixture model can be reformulated as a linear program or a second-order cone program, which can be effectively solved in polynomial time. We present the results of simulation analyses and primary empirical tests to illustrate a significance of the proposed approach and demonstrate its pros and cons.     

顾客行为对物流企业营销的作用研究

在相关文献回顾与研究方法归纳的基础上，分析了顾客行为对物流企业营销方式的影响，并根据目前市场现状，对二者间存在的问题进行了优化研究。     

再服务理念视角下的旅游物流优化研究

详细地分析了中国旅游物流发展的基本状况，界定了再服务理念含义，分析了在旅游物流中应用再服务理念的重要作用和功能，因此明确应该将其作为指导原则。在以上分析的基础上，重点提出了在旅游物流中应用再服务理念的建议。     

利用网络环境加强大学英语词汇自主学习

笔者在本文中将针对如何利用网络增强词汇的学习做简要的探讨,对如何利用网络环境下的学习平台刺激大脑记忆潜能,加大英语词汇的输入和输出的教学研究,并提出相应学习策略的教学应用性参考意见。     

A neural‐network‐based decision‐making model in the peer‐to‐peer lending market

This study proposes an investment recommendation model for peer‐to‐peer (P2P) lending. P2P lenders usually are inexpert, so helping them to make the best decision for their investments is vital. In this study, while we aim to compare the performance of different artificial neural network (ANN) models, we evaluate loans from two perspectives: risk and return. The net present value (NPV) is considered as the return variable. To the best of our knowledge, NPV has been used in few studies in the P2P lending context. Considering the advantages of using NPV, we aim to improve decision‐making models in this market by the use of NPV and the integration of supervised learning and optimization algorithms that can be considered as one of our contributions. In order to predict NPV, three ANN models are compared concerning mean square error, mean absolute error, and root‐mean‐square error to find the optimal ANN model. Furthermore, for the risk evaluation, the probability of default of loans is computed using logistic regression. Investors in the P2P lending market can share their assets between different loans, so the procedure of P2P investment is similar to portfolio optimization. In this context, we minimize the risk of a portfolio for a minimum acceptable level of return. To analyse the effectiveness of our proposed model, we compare our decision‐making algorithm with the output of a traditional model. The experimental results on a real‐world data set show that our model leads to a better investment concerning both risk and return.     

上海园林土壤标准及管理现状与 对策研究

上海园林土壤的标准化管理发端于《园林栽植土质 量标准》(DBJ 08-231—98),在一定历史时期对上海的园 林土壤管理具有重要作用。但是,随着生态文明建设的持续推 进,现有园林土壤的标准化管理已无法适应目前的工作需要。 系统梳理上海现行园林土壤标准体系,发现园林土壤标准主要 存在部分标准内容相互重复和冲突、国标与地标间层次关系不 明确,以及技术标准未及时更新等问题。提出完善上海园林土 壤标准体系的优化方案,包括针对技术指标进行细化和优化, 以及统一土壤指标测定方法避免标准间的冲突。此外,需要提 出符合中国园林土壤特点的技术标准,并予以及时修订和完 善。在标准化管理对策方面,要进一步重视园林土壤质量,在 园林绿化工程设计中,首先针对土壤质量进行控制,同时分类 管理园林土壤及土壤改良材料,并进一步提高园林绿化行业财 政支撑力度,加强园林土壤的相关科技研发。