陆梁油田薄层底水油藏水平井井筒模拟研究

新疆陆梁油田呼图壁河组油藏发育一类特殊的薄层底水型油藏，其特点是油层厚度薄，构造幅度低，底水能量大，利用水平井开采，表现出无水采油期短、含水率上升速度快、产量递减大的特点。针对这些问题，采用水平井数值模拟方法，建立了考虑摩擦压力损失的水平井井筒模型，明确了摩擦压力损失对水平井的压力分布以及水平段产量的影响，在此基础上，分析研究了水平井底水锥进的水脊特征，判断了水平井出水位置，提出了封堵出水井段并结合油藏工程方法确定了水平井合理产液量，从而达到抑制底水快速锥进，减小压力损失，降低含水率上升速度的目的。     

Do information,price, or morals influence ethical consumption? A natural field experiment and customer survey on the purchase of Fair Trade coffee

We address ethical consumption using a natural field experiment on the actual purchase of Fair Trade (FT) coffee in three supermarkets in Germany. Based on a quasi-experimental before-and-after design the effects of three different treatments – information, 20% price reduction, and a moral appeal – are analyzed. Sales data cover actual ethical purchase behavior and avoid problems of social desirability. But they offer only limited insights into the motivations of individual consumers. We therefore complemented the field experiment with a customer survey that allows us to contrast observed (ethical) buying behavior with self-reported FT consumption. Results from the experiment suggest that only the price reduction had the expected positive and statistically significant effect on FT consumption.     

远海岛礁冷链物流体系优化模型及其集成算法

为研究远海岛礁渔获冷链物流的运行方案，本文选择了岛礁冷库储存中转和海上直接收购等两种不同的渔获运输方式，同时考虑了中转冷库选址、中转运输和直接收购船舶配备、航线配置、在渔场停留时间和渔获运输损耗等诸多复杂问题，构建了远海冷链物流体系组合优化模型。求解时，提出了一种以遗传算法（GA）为外部框架，以改进的模拟植物生长算法（PGSA）为内部模块，通过信息传递实现内外连接交互的集成算法。最后，以我国南海远海岛礁及渔场为实例进行分析，取得了较好效果。通过与传统遗传算法对比，本文优化结果、稳定性及计算速度等均有明显提高，从而证明了本文所建模型与算法的合理性和有效性。     

Translating cross-lagged effects into incidence rates and risk ratios: The case of psychosocial safety climate and depression

Longitudinal studies are the gold standard of empirical work and stress research whenever experiments are not plausible. Frequently, scales are used to assess risk factors and their consequences, and cross-lagged effects are estimated to determine possible risks. Methods to translate cross-lagged effects into risk ratios to facilitate risk assessment do not yet exist, which creates a divide between psychological and epidemiological work stress research. The aim of the present paper is to demonstrate how cross-lagged effects can be used to assess the risk ratio of different levels of psychosocial safety climate (PSC) in organisations, an important psychosocial risk for the development of depression. We used available longitudinal evidence from the Australian Workplace Barometer (N?=?1905) to estimate cross-lagged effects of PSC on depression. We applied continuous time modelling to obtain time-scalable cross effects. These were further investigated in a 4-year Monte Carlo simulation, which translated them into 4-year incident rates. Incident rates were determined by relying on clinically relevant 2-year periods of depression. We suggest a critical value of PSC?=?26 (corresponding to ?1.4 SD), which is indicative of more than 100% increased incidents of persistent depressive disorder in 4-year periods compared to average levels of PSC across 4 years.     

A non‐stationary bivariate INAR(1) process with a simple cross‐dependence: Estimation with some properties

This paper considers modelling of a non‐stationary bivariate integer‐valued autoregressive process of order 1 (BINAR(1)) where the cross‐dependence between the counting series is formed through the relationship of the current series with the previous‐lagged count series observations while the pair of innovations is independent and marginally Poisson. In addition, this paper proposes a generalised quasi‐likelihood (GQL) estimating equation based on the exact specification of the mean score and the auto‐covariance structure. The proposed approach is also compared with other popular techniques such as conditional maximum likelihood (CML), generalised least squares (GLS) and generalised method of moment (GMM) based on simulated data from the proposed BINAR(1). Moreover, the model is applied to weekly series of day and night road accidents arising in some regions of Mauritius and is compared with other existing BINAR(1) models.     

Optimal investment and life insurance strategies in a mixed jump-diffusion framework

Abstract

This article investigates an optimal investment and life insurance strategies in a mixed jump-diffusion framework. The individual life insurance policyholder who has CRRA preferences. The market consists of riskless asset, a zero-coupon bond, a stock and life insurance. The instantaneous interest rate is modeled as the O-U model, while a zero-coupon bond with credit risk follows a BSDE and a risky asset be driven by MJD-fBm model. The problem is solved by the mixed jump diffusion fractional HJB SDE which satisfied the admissible strategy, then the closed form solution and optimal strategies are derived and the simulation of the various parameters are also given.     

Theoretical results on the discrete Weibull distribution of Nakagawa and Osaki

In this paper, we discuss some theoretical results and properties of the discrete Weibull distribution, which was introduced by Nakagawa and Osaki [The discrete Weibull distribution. IEEE Trans Reliab. 1975;24:300–301]. We study the monotonicity of the probability mass, survival and hazard functions. Moreover, reliability, moments, p-quantiles, entropies and order statistics are also studied. We consider likelihood-based methods to estimate the model parameters based on complete and censored samples, and to derive confidence intervals. We also consider two additional methods to estimate the model parameters. The uniqueness of the maximum likelihood estimate of one of the parameters that index the discrete Weibull model is discussed. Numerical evaluation of the considered model is performed by Monte Carlo simulations. For illustrative purposes, two real data sets are analyzed.     

超大城市人口—自然资源系统可持续发展水平研究——基于Laplace混合政策模拟

人口增长与集聚为超大城市的发展提供动力,也给其自然资源系统带来极大扰动,使之呈现脆弱性特征;为实现超大城市人口—自然资源可持续发展,近年来政府实施了大量调控政策,但因对城市人口—自然资源系统的复杂互动难以精确量化,导致超大城市人口与自然资源关系治理困难重重。基于此,以北京市为例构建人口—自然资源系统可持续性评价框架,从政策干预视角,分析不同类型调控政策(如人口调控、技术改进、资源管制等)与人口、自然资源的因果关系,并利用Laplace准则结合决策者风险喜好,模拟混合政策干预对人口—自然资源系统可持续性带来的影响。结果显示:政策干预是保证北京市人口—自然资源系统可持续发展的重要手段,其中,人口调控政策是北京市人口—自然资源系统可持续性变动的主要影响因素,资源管制和技术改进是次要影响因素;随着政策干预强度的增加,由于人口系统安全性和自然资源系统脆弱性的互动博弈,北京市人口—自然资源可持续性逐渐趋于稳定;在Laplace情景下,人口安全性减弱了1.82%,损失不大;而自然资源脆弱性减弱了12.13%,收益较高;最终使得人口—自然资源系统可持续性增强了6.23%。因此,对于超大城市的政策干预需...     

Exploring gaps between MSW students’ experiences and expectations of field supervision in a Chinese setting

The quality of field supervision is essential to prepare social work students for professional practice. This qualitative study explored the experiences and expectations of 22 MSW students who received their field supervision at social work professional organizations in mainland China. Findings indicate that there are significant differences between the actual supervision that students received and their expectations with regard to the structure and content of supervision. This study contributes to the literature by clarifying further what the lack of time for supervision and the lack of professional supervision mean in China’s context.