An Enhanced Concave Program Relaxation for Choice Network Revenue Management

The network choice revenue management problem models customers as choosing from an offer set, and the firm decides the best subset to offer at any given moment to maximize expected revenue. The resulting dynamic program for the firm is intractable and approximated by a deterministic linear program called the CDLP which has an exponential number of columns. However, under the choice‐set paradigm when the segment consideration sets overlap, the CDLP is difficult to solve. Column generation has been proposed but finding an entering column has been shown to be NP‐hard. In this study, starting with a concave program formulation called SDCP that is based on segment‐level consideration sets, we add a class of constraints called product constraints (σPC), that project onto subsets of intersections. In addition, we propose a natural direct tightening of the SDCP called , and compare the performance of both methods on the benchmark data sets in the literature. In our computational testing on the data sets, 2PC achieves the CDLP value at a fraction of the CPU time taken by column generation. For a large network our 2PC procedure runs under 70 seconds to come within 0.02% of the CDLP value, while column generation takes around 1 hour; for an even larger network with 68 legs, column generation does not converge even in 10 hours for most of the scenarios while 2PC runs under 9 minutes. Thus we believe our approach is very promising for quickly approximating CDLP when segment consideration sets overlap and the consideration sets themselves are relatively small.     

Factors Affecting Choice and Satisfaction: Social Work in Turkey

ABSTRACT

The study examines the relationship between professional choices and employment expectations of social worker trainees in the country of Turkey. Professional choices are examined according to gender and the relationship between employment expectations and satisfaction. This study examined responses with a comparative relational scanning model with a sample of 692 social service (social worker) trainees studying at four different universities in Turkey. Students were surveyed and answered 25 open- and closed-ended questions identifying aspects related to their career choice. Study findings reveal that gender, university entrance scores, and employability were high among the career selection factors. Additional factors identified included family-related factors, personality traits, and compatibility. Examination of the findings is discussed, and recommendations for further research are made.     

Till Death Us Do Part? A Critical Analysis of Obligation and Choice for Spousal Caregivers

Research demonstrates a significant number of carers identify obligation or lack of other alternatives as the reasons they undertake informal care. By utilizing critical discourse analysis, this research explores choice for informal caregivers in contemporary Australian social policy. Analysis demonstrates increasing shifts in policy toward choice in consumer-directed care, a feature absent for those who provide care. Familial care is a central pillar of Australian social policy, as it is in many liberal and conservative welfare regimes. Analysis reveals that these core social policies are fundamentally incongruent, with significant implications for individuals and social work practice.     

Does the amount of school choice matter for student engagement?

School choice may increase student engagement by enabling students to attend schools that more closely match their needs and preferences. But this effect on engagement may depend on the characteristics of the choices available. Therefore, we consider how the amount of educational choice of different types in a local educational marketplace affects student engagement using a large, national population of 8th grade students. We find that more choice of regular public schools in the elementary and middle school years is associated with a lower likelihood that students will be severely disengaged in eighth grade, and more choices of public schools of choice has a similar effect but only in urban areas. In contrast, more private sector choice does not have such a general beneficial effect.     

“Risky Business”

Over the last few decades the number of women becoming pregnant later on in life has markedly increased. Medical experts have raised concerns about the increase in the number of women having babies later, owing to evidence that suggests that advancing maternal age is associated with both a decline in fertility and an increase in health risks to both mother and baby. In recognition of these risks, experts have warned that women should aim to have their children between the ages of twenty and thirty-five. As a consequence, women giving birth past the age of thirty-five have typically been positioned as “older mothers.” In this paper we used a social constructionist thematic analysis in order to analyse how “older mothers” are represented in newspaper articles in the British press. We examined how the topics of “choice” and “risk” are handled in discussions of delayed motherhood, and found that the media position women as wholly responsible for choosing the timing of pregnancy and, as a consequence, as accountable for the associated risks. Moreover, we noted that newspapers also constructed a “right” time for women to become pregnant. As such, we discuss the implications for the ability of women to make real choices surrounding the timing of pregnancy.     

公众参与城乡规划的实现路径

公众参与城乡规划在我国是一项法定制度,有其特殊的政治、经济、社会和文化背景。随着我国公民民主法制意识的逐渐觉醒和城乡规划知识的广泛宣传,公众参与城乡规划已成为提高城乡规划决策水平的有效途径。要保障公众参与城乡规划的知情权、参与权、表达权和监督权,除在立法上明确公众参与城乡规划的内容、范围、方式、途径、责任追究和救济制度等以外,还要加强公众参与城乡规划的教育,提高规划师的整体素能,完善公众参与城乡规划配套制度等。     

理性与实践的互动——海洋科学技术的选择与应用问题研究

人类理性的有限性,决定了科学技术的发展是一种逐渐贴近现实的试错过程。尽管海洋科学技术有了非常大的进步,但人类对于广袤的海洋依然有着太多的不知。社会实践的需要是推动海洋科学技术发展的根本力量。那么,如何在日益庞大的海洋科学技术群中选择与应用就成为非常现实的问题。本文力图从受益范围的角度,按照经济学的方法把海洋科学技术分为三大类：公益性、准公益性和私益性,并针对不同类别的海洋科学技术的特点提出相应的选择、验证与资助的标准。人类理性与社会实践的互动,是推动海洋科学技术的发展、促进海洋经济的繁荣的根本途径。     

齐鲁工匠精神的内涵、培育困境与培育路径

山东正处于新旧动能转换的关键时期,无论是制造业转型升级还是创新驱动发展,均离不开工匠精神的传承与培育。齐鲁工匠精神具有齐鲁文化的精神特质,与山东地方性的文化基因具有高度一致性。同时,齐鲁工匠精神也在西方工业文明入侵、民族工业崛起以及国家建设和改革的过程中,随着外部环境的变化进一步凝练。然而,当前齐鲁工匠精神培育也面临诸多问题,如人才向省外流失、向其他行业分流等都使得工匠精神培育的主体数量不足;山东是儒家文化的发源地,对职业先天性的歧视危害至今;整个社会风气急功近利,不断追逐短期利益;市场监管制度还不够完善,这些都成为工匠精神坚守的阻碍因素。借鉴国外先进经验,在齐鲁工匠精神培育的路径选择上应加强舆论引导,夯实制度基础,完善培训体系,同时要发挥企业的主观能动性。     

交通方式选择与旅客时间价值研究--以北京-太原客运通道为例

从旅客出行交通方式选择入手,在综合考虑旅客收入、出行费用、出行时间、安全舒适度、服务水平等因素基础上,提出一个简化且合理的时间价值计算模型。以北京-太原客运通道为例,通过对不同收入旅客出行交通方式选择进行调查,计算出不同收入阶层旅客的时间价值。结果发现,不同收入的旅客时间价值是不同的,但不同收入旅客的每小时时间价值约等于该群体每小时人均可支配收入的50%左右。这一结论对各种交通运输工具的定价及交通资源的配置具有一定的借鉴意义。     

Property of bivariate poisson distribution and its application to stochastic processes

Assuming that the random vectors X ₁ and X ₂ have independent bivariate Poisson distributions, the conditional distribution of X ₁ given X ₁?+?X ₂?=?n is obtained. The conditional distribution turns out to be a finite mixture of distributions involving univariate binomial distributions and the mixing proportions are based on a bivariate Poisson (BVP) distribution. The result is used to establish two properties of a bivariate Poisson stochastic process which are the bivariate extensions of the properties for a Poisson process given by Karlin, S. and Taylor, H. M. (1975). A First Course in Stochastic Processes, Academic Press, New York.