Design and Control of Warehouse Order Picking: a literature review

Order picking has long been identified as the most labour-intensive and costly activity for almost every warehouse; the cost of order picking is estimated to be as much as 55% of the total warehouse operating expense. Any underperformance in order picking can lead to unsatisfactory service and high operational cost for its warehouse, and consequently for the whole supply chain. In order to operate efficiently, the orderpicking process needs to be robustly designed and optimally controlled. This paper gives a literature overview on typical decision problems in design and control of manual order-picking processes. We focus on optimal (internal) layout design, storage assignment methods, routing methods, order batching and zoning. The research in this area has grown rapidly recently. Still, combinations of the above areas have hardly been explored. Order-picking system developments in practice lead to promising new research directions.Order picking;Logistics;Warehouse Management

Fair Shares for All? The development of needs based governmental funding in education, health and housing

Furthering equity as an achievable public policy objective is based on the ability to assess needs accurately, and distribute resources accordingly. This paper plots the development of the formulae governing resouce allocation in education, health and social housing, and charts their course as a tool with which governments attempted to achieve various objectives. The paper begins by suggesting that allocation systems can be explained through a form of public choice theory. It then charts the development of needs-based resource allocation from its origin in the nineteenth century, through the pre- and post Second World War period, and into the major flowering of needs-based formulae since 1970 - when resources were constrained and attempts were made to push allocation even further down and apply the formulae to smaller units. The conclusion looks at equity, public choice and technical ability as over-riding features governing the development of resource allocation within the English state sector.Resource allocation, funding formulae, geographical equity

Crying over Spilt Milk: A Critical Assessment of the Ecological Modernisation of New Zealand’s Dairy Industry

Ecological modernization theory holds that capitalist economic structures can be transformed to avoid long-term environmental damage, through the introduction of modern environmental technologies and reforming modern institutions. Empirical evidence, drawing on ecological modernization practices in some European and North American contexts, lends support to this view. However, it is not clear yet whether the practices of ecological modernization can be applied with equal success to agricultural industries (such New Zealand's dairy sector), based on farmers as multiple producers. The New Zealand dairy industry faces political and commercial pressure to improve its environmental performance while maintaining commercial competitiveness in a global marketplace. In response to such pressures, the industry's main umbrella organization (Fonterra) has taken steps to improve the environmental management practices of the farmers who supply milk. The New Zealand dairy industry offers an example from which to assess the relevance of economical modernization theory

Optimal composition of hybrid/blended real estate portfolios

Purpose: The purpose of this paper is to establish an optimum mix of liquid, publicly traded assets that may be added to a real estate portfolio, such as those held by open-ended funds, to provide the liquidity required by institutional investors such as UK defined contribution pension funds. This is with the objective of securing liquidity while not unduly compromising the risk-return characteristics of the underlying asset class. This paper considers the best mix of liquid assets at different thresholds for a liquid asset allocation, with the performance then evaluated against that of a direct real estate benchmark index. Design/Methodology/Approach: The authors employ a mean-tracking error optimisation approach in determining the optimal combination of liquid assets that can be added to a real estate fund portfolio. The returns of the optimised portfolios are compared to the returns for portfolios that employ the use of either cash or listed real estate alone as a liquidity buffer. Multivariate Generalised Autoregressive models are used along with rolling correlations and tracking errors to gauge the effectiveness of the various portfolios in tracking the performance of the benchmark index. Findings: The results indicate that applying formal optimisation techniques leads to a considerable improvement in the ability of the returns from blended real estate portfolios to track the underlying real estate market. This is the case at a number of different thresholds for the liquid asset allocation and in cases where a minimum return requirement is imposed. Practical Implications: The results suggest that real estate fund managers can realise the liquidity benefits of incorporating publicly traded assets into their portfolios without sacrificing the ability to deliver real estate-like returns. However, in order to do so, a wider range of liquid assets must be considered, not just cash. Originality/value: Despite their importance in the real estate investment industry, comparatively few studies have examined the structure and operation of open-ended real estate funds. To the authors’ knowledge, this is the first study to analyse the optimal composition of liquid assets within blended or hybrid real estate portfolios

Crown Financial Asset Management: Objectives and Practice

This paper analyses key issues that may be relevant to setting the Crown's overall objectives and practices for financial asset and liability management. It examines implications of the nature of the Crown's balance sheet for asset and liability management and investigates the appropriate approach of the Crown towards managing risk (concluding that a risk averse approach is warranted). The issue of centralisation versus decentralisation of Crown asset and liability management is analysed both from a portfolio management perspective and from an organisational design perspective. Insights from private sector financial conglomerates are also incorporated. The paper concludes that individual Crown financial entities should each continue to be responsible for setting their own strategic asset allocation, after taking into account the nature of their liabilities. A central Crown body should, however, monitor and aggregate information from each of these entities and be delegated the responsibility and power to manage risks to the overall Crown balance sheet.Crown balance sheet; Public debt management

Model-predictive control for non-domestic buildings: a critical review and prospects

Model-predictive control (MPC) has recently excited a great deal of interest as a new control paradigm for non-domestic buildings. Since it is based on the notion of optimisation, MPC is, in principle, well-placed to deliver significant energy savings and reduction in carbon emissions compared to existing rule-based control systems. In this paper, we critically review the prospects for buildings MPC and, in particular, the central role of the predictive mathematical model that lies at its heart; our clear emphasis is on practical implementation rather than control-theoretic aspects, and covers the role of occupants as well as the form of the predictive model. The most appropriate structure for such a model is still an open question, which we discuss alongside the development of the initial model, and the process of updating the model during the building’s operational life. The importance of sensor placement is highlighted alongside the possibility of updating the model with occupants’ comfort perception. We conclude that there is an urgent need for research on the automated creation and updating of predictive models if MPC is to become an economically-viable control methodology for non-domestic buildings. Finally, more evidence through operating full scale buildings with MPC is required to demonstrate the viability of this method

Design and Control of Warehouse Order Picking: a literature review

Order picking has long been identified as the most labour-intensive and costly activity for almost every warehouse; the cost of order picking is estimated to be as much as 55% of the total warehouse operating expense. Any underperformance in order picking can lead to unsatisfactory service and high operational cost for its warehouse, and consequently for the whole supply chain. In order to operate efficiently, the orderpicking process needs to be robustly designed and optimally controlled. This paper gives a literature overview on typical decision problems in design and control of manual order-picking processes. We focus on optimal (internal) layout design, storage assignment methods, routing methods, order batching and zoning. The research in this area has grown rapidly recently. Still, combinations of the above areas have hardly been explored. Order-picking system developments in practice lead to promising new research directions

Organic production in the hills and uplands (OF0319)

It is Government policy to provide a framework in which organic farming can develop, promoting more sustainable and environmentally sound systems of livestock production. Scientific information is required on the development, performance and limitations of organic systems, to facilitate informed decision-making and to aid policy formulation. Using the established organic unit at Redesdale, the overall objective of this project was to evaluate and demonstrate the long-term potential of organic livestock production in the hills and uplands. The experiment was a systems study sited on one discrete farm unit covering 518 ha. Approximately 400 ha had been put into conversion in 1991, so that the experimental period (2002 - 2005) represented years 9 to 12 years of full organic production. Approximately 600 Scottish Blackface ewes were involved in the study, in four self-replacing flocks. At the start of conversion, one original heft (Dargues Dipper) was split to form two sub-hefts of equal stock carrying capacity. One sub-heft (Organic Dipper) was converted to organic production, while the second (Conventional Dipper) continued to be managed conventionally. The two other hefts (Cairn and Burnhead) were both converted to organic production. Beef production was based on spring calving suckler cows, managed in three sub-herds - two a direct comparison of organic and conventionally managed Angus cross cows put to a continental sire; the third consisting of organically managed Angus cows put to an Angus sire. Grassland management was based on a modified ‘Two Pasture’ hill system, integrating native hill, improved hill and inbye land for beef and sheep production. On the native hill, detailed long-term monitoring of vegetation change showed that botanical composition was more affected by previous and current stocking levels, and events such as heather beetle infestation, than by organic and or conventional management. On improved hill land, the underlying trend was regression to rush pasture, leading to reduced productivity on both organic and conventionally managed areas. On the more intensively managed inbye fields, soil fertility levels were adequately maintained on the organic areas, which received only farmyard manure and slurries. Soil pH was more stable than on conventional fields, which received soluable nitrogen fertiliser. Organic inbye fields were sown predominately with short term leys, based on Italian ryegrass and Red or Alsike clover, to provide greater competition for weeds. Production levels were approximately 70% that of fertilised conventional fields. Self sufficiency in winter forage averaged 107% and 93% for the organic and conventional livestock (both sheep and cattle enterprises) respectively. Established infestations of docks production proved difficult to control. Historically, the greatest success was obtained where dock numbers were sufficiently low to enable the plants to be removed manually, or semi-mechanically using a tractor/digger. Data collected as an observation study suggested that for heavy infestations a fallow period and grazing by pigs could have good potential for dock control. Consistent with earlier the phases of the study, sheep production levels were higher in the conventionally managed sheep. Organically managed ewes were significantly lighter and had lower body condition scores at most stages of the production cycle. Average lamb rearing percentages over the three years of the study were 124, 108,108 and 111 for Conventional Dipper, Organic Dipper, Cairn and Burnhead flocks respectively. Average lamb weaning weights (kg) were 31.8, 29.5, 31.3 and 32.9 respectively. Of the total crop, 65% of Conventional Dipper lambs were sold finished at a mean liveweight of 38.1 kg, returning an average of £40.03 (£1.05/kg). The balance (35%) were ewe lambs retained within the flock or sold for breeding. Depending on the flock, the majority of the organic lamb crop (55%-61%) were sold after weaning as stores for further finishing, at a price of approximately £1.15 per kg liveweight. Store hill lambs performed well finishing on an organic lowland farm, returning typical carcass weights of 18.5 kg and a mean sale date of mid-March. An arrangement was entered into to spread the financial risk, sharing the feeders margin between the store lamb producer and lowland finisher. This could be a useful model for wider application, between different farmers or regions with complementary resources. Across all four flocks, the three year average for ewe and hogg mortality was less than 5%. Lamb mortality averaged less than 10%, which compares well with quoted industry figures of 15%-20%. Parasite burdens were low and anthelmintic input was limited to a few individual lambs. No adverse effects were recorded as a result of the long-term withdrawal of clostridial and pasteurella vaccination from one of the three organic flocks (Cairn). Lower levels of performance in the organic flocks could be a multi-component effect of reduced forage availability, lower veterinary inputs, higher levels of subclinical disease etc. However, the most likely factor was the difference in how the improved hill and inbye land was managed under an alternate grazing regime, which allows access by sheep to only half the area of improved hill in any given year. There was little difference in the physical performance of directly comparable organic and conventional sub-herds producing continental cross calves. Conception rates were consistently high, averaging 94%. Calf weaning weights (kg) averaged 292, 297 and 298 for conventional halfbred, organic halfbred and organic Angus sub-herds respectively. Prices achieved (p/kg live weight) for store prices cattle were 102, 127 and 133 respectively. Despite higher prices for organic cattle sold as stores, carcass data from animals sold finished indicated poorer conformation and higher levels of fatness in Angus sired calves. Gross returns were £683 and £648 for continental and Angus calves respectively, representing a difference of £0.10/kg carcass weight (£2.24 Vs £2.34). The main technical issue associated with the organic suckler herd was ensuring an adequate supply of conserved fodder for a 200-day winter. Disease challenges were low and the only veterinary treatment given on a herd basis was a single treatment for lice during the winter period. Average gross margins (£/ewe) before forage costs were £56, £44, £46 and £49 for Conventional Dipper, Organic Dipper, Cairn and Burnhead flocks respectively. Whole flock gross margins averaged £7635, £4609, £5561 and £4315. Lower performance in the organic flocks resulted from a combination of lower sheep numbers, reduced lambing percentages, and the sale of store rather than finished animals. Countryside Stewardship Scheme payments could potentially have increased gross margin in the Burnhead flock to £7915. Gross margins (£/cow), before forage costs, for rearing and finishing enterprises combined were £755, £636 and £527 for conventional halfbred, organic halfbred and organic Angus sub-herds respectively. Forage costs (£/adjusted hectare) averaged £11 and £21 for organic and conventional sub-units respectively. The biggest single contributor to gross margin was stocking rate, which for the organic unit as a whole, was 54% that of the conventional (1.3 LU/adjusted ha Vs 0.7 LU/adjusted ha). For sheep and cattle enterprises combined, gross margins per Livestock Unit (LU), including forage costs, were £451 and £479 for conventional and organic sub-units respectively. The organic unit as a whole returned a gross margin per adjusted hectare 44% less than the conventional (£590 Vs £335). It could be suggested that in reducing stocking rate in pursuit of environmental gain, and adjusting management for better parasite control, the organic system at Redesdale has had to carry a disproportionate financial burden. To offset these effects would require an improvement in output, for example retaining a greater proportion of organic animals for finishing, or entry into an agri-environmental scheme. The period of the study coincides with the last three years of subsidy payments based primarily on the numbers of livestock carried. Historically, stocking rates have been a prime determinant of profitability when measured on a per hectare basis. Under organic management it was not possible to support sheep numbers at previous levels and maintain the same level of individual performance. The advent of support based on Single Farm Payment, further devolves stocking rate from overall profitability. More farmers may be tempted to convert, given that the opportunity cost of conversion is reduced. Decisions will be driven more by the relative strength of the organic market, technical or attitudinal constraints such as feeding 100% organically produced diets, and relative impacts on overall fixed costs. The case for organic farming conferring environmental benefit is clearer in lowland situations than in the hills. In theory, the difference between organic and conventional systems should be less stark under less intensive production prevalent in the hills and uplands. As yet, little has been done to determine the extent to which organic and conventional farmers have adopted practices with positive or negative impact on biodiversity or the agri-environment. Much depends on the attitude of the individual landowner. From a survey conducted by ADAS in Wales, the greatest benefits tend to occur where an organic farm is also participating in another agri-environmental scheme. The extent to which organic, and evolving conventional, systems complement or conflict with cross compliance or Water Framework Directive requirements has yet to be determined. At Redesdale, long-term studies of vegetation change on the native hill, showed a continuing decline in heather cover at the higher stocking rates. Where stocking rates were reduced significantly to accommodate a more balanced organic system there were indications of a positive, albeit slow response in botanical composition. Key to this is the ability to manage moorland in a more proactive way, and to have cattle available to graze Molinia and Nardus. This complementary effect of cattle not only controls the competitive effects of these grassy species with heather, but as demonstrated in other research projects, also benefits sheep performance. If the economics of cattle production becomes very adverse organic farmers may be forced to reduce cattle numbers, which could make some sheep-dominated systems less sustainable. The results indicate that for many hill and upland units, converting to an organic system is not likely to be a matter of minimal changes to existing management. In particular, stocking rate and balance of sheep and cattle at the start of conversion will have a major impact on the management required to achieve acceptable levels of animal performance, financial performance, input reduction and environmental gain. Recommendations were made for further research in the following areas:- Current behaviours and management practices for organic and conventional farmers; the interface of organic farming practice, and that of other agri-environmental schemes; environmental impact at the whole farm, or aggregated farm level; practices to enhance environmental benefit which can be used more widely on organic farms; control of weeds (rushes, thistles, bracken and docks); tightening regulations on non-organic feed allowances; internal and external parasite control; nutrient budgeting; wider cropping options for energy, protein and mineral nutrition; the potential to exploit co-operative effort to overcome technical issues and limitations, and increase environmental benefit