Single-stage formulations for synchronised two-stage lot sizing and scheduling in soft drink production

This study deals with industrial processes that produce soft drink bottles in different flavours and sizes, carried out in two synchronised production stages: liquid preparation and bottling. Four single-stage formulations are proposed to solve the synchronised two-stage lot sizing and scheduling problem in soft drink production synchronising the first stage's syrup lots in tanks with the second stage's soft drink lots on bottling lines. The first two formulations are variants of the General Lot Sizing and Scheduling Problem (GLSP) with sequence-dependent setup times and costs, while the other two are based on the Asymmetric Travelling Salesman Problem (ATSP) with different subtour elimination constraints. All models are computationally tested and compared to the original two-stage formulation introduced in Ferreira et al. (2009), using data based on a real-world bottling plant. The results show not only the superiority of the single-stage models if compared to the two-stage formulation, but also the much faster solution times of the ATSP-based models.     

Trends and tensions in UK public house management

The management role in UK managed public houses has increased in relative importance over the years since 1970. Using material derived from both secondary sources and fieldwork in a major leisure retail company, the role of house manager is examined through the inter-related notions of landlord, manager and employee. There is a particular focus on shifts towards the employment of younger managers and the relationship between this and branding strategies. The implications of this relationship is examined through the notion of the ‘locus of interpretation’, and stress is placed on the need to view managing as a relationship.     

Structural Breaks and the Relationship between Barley and Wheat Futures Prices on the London International Financial Futures Exchange

Co-movement between futures prices can arise when commodities are substitutes. Counterintuitively, Dawson and White fail to find a significant long-run link between feed barley and wheat prices on the London International Financial Futures Exchange. This relationship is re-examined using  Johansen, Mosconi, and Nielsen's co-integration procedure that permits structural breaks. Results show evidence of co-integration and hence price discovery. There is a significant break in October 2000 following Common Agricultural Policy intervention price reductions, the barley–wheat futures market is perfectly integrated, and the barley price Granger-causes the wheat price. Modeling structural breaks in price relationships appears important.     

Megaw and the public sector: A union response

One Civil Service union ‐ the Institute of Professional Civil Servants ‐ welcomed the Megaw Report on the grounds that it would help restore internal relativities. Unions representing the great majority of civil servants, however, came out strongly against it. The general secretaries of the Civil and Public Servants Association and the Society of Civil and Public Servants prepared a note for the TUC's public service committee on the implications of Megaw for the public sector as a whole. The following is based on that note.     

Fertiliser availability in a resource-limited world: Production and recycling of nitrogen and phosphorus

Without the input of fertiliser nitrogen it is estimated that only about half of the current global population can be supplied with sufficient food energy and protein. The anticipated increase in the population to 2050 will increase the dependency on fertiliser inputs. The paper examines the different potential sources of energy and hydrogen required for this essential fixation of atmospheric nitrogen into plant-available nitrogenous fertiliser and concludes that methane from natural gas is clearly the most suitable source. In the absence of a cost-effective alternative source of hydrogen it is recommended that an on-going requirement for methane is acknowledged and that consideration be given to strategic reserves for the production of food. Phosphorus is also an essential and unsubstitutable nutrient for plants and animals, but while the global reserves of atmospheric nitrogen are effectively unlimited, the reserves of phosphate rock are finite. Recent estimates of the reserve suggest that at the current rate of use this resource will become exhausted within some hundreds of years. The annual increment of phosphorus contained in the human population is estimated to be in the order of 1 Mt/yr, which is a small proportion of the quantity mined. There is a clear requirement to ensure that phosphorus is recycled to a large extent, so that the rate of exhaustion of the reserves of phosphate rock is significantly reduced. Legislation relating to the management of phosphorus appears entirely associated with its potential to upset natural ecosystems, with apparently no regulations yet requiring the efficient use and reuse of a scarce resource.     

‘CHOOSE TO BE OPTIMISTIC,IT FEELS BETTER?’ EVIDENCE OF OPTIMISM ON EMPLOYMENT UTILITY

Individual's expected wages exceed predicted market wages. Rational expectations imply the divergence should be zero. If individuals over‐estimate the return from their attributes and view the paid‐employment return distribution too favourably, then conditional on market wages, subsequent employment utility is likely to be low through disappointment.     

Bankers' compensation and fair value accounting

This paper examines the role of certain fair value accounting (FVA) outcomes in compensation of US bank CEOs. The use of FVA in compensation invites an agency cost—the clawback problem—if cash compensation is based on unrealized profits that may reverse in the future. At the same time FVA may be a good measure of current managerial effort and so be cash compensated. We find evidence consistent with a positive link between CEO cash bonus and fair value (FV) valuation of trading assets, managed for short-term profit, as well as (amongst banks with limited trading exposure) a positive link between CEO pay and FV valuations of available for sale (AFS) assets. We find no evidence that trading income is incrementally compensation relevant, indicating that compensation committees avoided the clawback problem for unrealized trading gains. The paper also provides evidence on the link between FVA outcomes and equity-based pay.     

LABOUR ON THE FAMILY FARM: A THEORY AND SOME POLICY IMPLICATIONS

This paper seeks to examine the labour-input decisions on family farms at a theoretical level and to demonstrate some policy implications of this theory. Where the family has the opportunity to work on the land, utility maximisation, rather than profit maximisation, would seem to be a more appropriate criterion for decision-making. Accordingly, the decision-making process is analysed under this alternative assumption. We then consider some of the policy implications of this model. In particular, we consider the effects of policies on the labour-inputs since the optimal allocation of labour is at the heart of most agricultural policies.     

An Economic View of the Debate on Farm Size in Saskatchewan: A Comment

In a recent paper in this Journal, Jensen (1984) continues the debate on farm size in Saskatchewan. In particular, he considers the relationship between farm size and efficiency "… to determine if it is necessary to have fewer and larger farms in order to gain cost efficiency …" Attention is focused on the notion of returns to size and the vehicle for analysis is estimates of long-run average cost (LAC) curves. Individual farm data are used for different farm types in the two years, 1977 and 1980. Equations are fitted to each farm type in each year. Hence, each estimated equation is based on cross-section data. The conclusion drawn from this analysis is that, "… at the frontier, constant returns to size are the norm in Saskatchewan agriculture" (p. 199). Moreover, "Governments could consider removing policies which favor large units …" (p. 198).     

倾销与比较优势

简单贸易模型的一个重要假设是市场完全竞争，并且贸易是源于比较优势。然而，现实中很少存在完全竞争的市场，不完全竞争市场使传统的贸易模型呈现出有趣的结果。这引起关注的一方面是不完全竞争企业在不同市场上给出不同的价格，即通常所说的“价格歧视”。在国际贸易中，最基本的价格歧视方式是“倾销”，即对于同一商品，出口商在国际市场上价格低于国内市场上的价格。如果国内企业是完全竞争的，并且在国内市场上以边际成本价格卖出，倾销就是指在国外市场上已低于边际成本价格出售。在多数的贸易模型中，商品按进口品和出口品分组，货币被认为是交换的中性媒介。对基于比较优势进行贸易的倾销的指控，主要是由于运用了与贸易不联系的汇率。我们认为，根据汇率来衡量基于比较优势的贸易获利在逻辑上是错误的，因为这种衡量往往导致明显的倾销，如果汇率市场是均衡的话。恰当的衡量方法是以贸易为基础的影子汇率。进一步来说，贸易障碍使得外汇交换和贸易不完全替代，使得汇率按接受到的价格相互高估。我们认为，只有在出口与基于比较优势的利润最大化不一致时，才能说明是倾销。