An investigation of forecast horizon and observation fit’s influence on an econometric rate forecast model in the liner shipping industry

This paper evaluates the influence of forecast horizon and observation fit on the robustness and performance of a specific freight rate forecast model used in the liner shipping industry. In the first stage of the research, a forecast model used to predict container freight rate development is presented by exploring the relationship between individual company’s rates and aggregated market rates, and thus assists in dealing with uncertainty and market volatility for a given business situation. In the second stage, a design of experiment approach is applied to highlight the influence of the forecast horizon and observation fit and their interactions on the forecast model’s performance. The results underline the complicated nature of creating a suitable forecast model by balancing business needs, a desire to fit a good model and achieve high accuracy. There is strong empirical evidence from this study; that a robust model is preferable, that overfitting is a true danger, and that a balance must be achieved between forecast horizon and the number of observations used to fit the model. In addition, methodological guidance has also been provided on how to test, design, and choose the superior model for business needs.     

俘获女人心Jeep Compass

JeepCompass是以2005年法兰克福车展中发表的JeepCompass概念车发展而成的全新产品,除了具有SUV的外形与特性之外,还结合了轿车的性能、操控、省油及适宜价格等优点。JeepCompass是Jeep旗下第一款以前轮驱动底盘为基础的产品,并且以四轮独立悬架系统提供一般道路的乘坐舒适度、操控与驾驶乐趣。     

A spatially explicit ecosystem model of seston depletion in dense mussel culture

A fully-coupled biological–physical–chemical model of a coastal ecosystem was constructed to examine the impact of suspended mussel culture on phytoplankton biomass in Tracadie Bay, Prince Edward Island, Canada. Due to the extent of mussel culture there, we hypothesised that shellfish filtration would control the concentration and distribution of phytoplankton and other suspended particles in the bay. Circulation was delineated with a tidally-driven 2D numerical model and used to drive an ecosystem model with a focus on pelagic components including phytoplankton production, nutrients, detritus, and mussels. The benthos were treated as a sink. Nutrients and seston were forced by tidal exchange and river input, with phytoplankton additionally forced by light. Boundary conditions of seston and nutrients were derived from field studies with an emphasis on the contrast between spring (high river nutrients, low temperature) and summer (low river inputs and high temperatures). Model output was used to map phytoplankton carbon over the bay for each season and in the presence of mussels and river nutrient input. Results indicate severe depletion effects of mussel culture on overall phytoplankton biomass, but no spatial pattern that can be attributed to grazing alone. Primary production generated by nutrient-rich river water created a mid-bay spike in phytoplankton that dominated the spatial pattern of chlorophyll-based carbon. Model results were validated with surveys from a towed sensor array (Acrobat) that confirmed the river influence and indicated bay-wide depletion of 29% between high and low water. Our model results indicate that the farm-scale depletion emphasised in previous studies cannot simply be extrapolated to seston limitation at the ecosystem level.     

观市2011

全球经济机遇与挑战并存2011年全球经济复苏呈现双轨态势.国际货币基金组织(IMP)预测2011年和2012年新兴经济体和发展中国家将保持在6.5%的增长水平,略低于2010年7%的增速,其中增速最快的仍是亚洲发展中国家的中国和印度.2011年和2012年发达国家经济将增长2.5%.     

Environmental impact assessment of sediment dumping in the southern Baltic Sea using meiofaunal indicators

An experimental sediment dumping was carried out in the southern part of the Mecklenburg Bight in June 2001. Foraminiferans and ostracods from superficial sandy sediment were studied in a time series from before dumping until March 2004 in order to assess changes in associations and recolonization patterns of both groups. Additionally, an area sampling covering the dumping site and its surroundings from 15.5 to 20.7 m water depth made it possible to compare associations inside and outside the dumping area as well as the water depth dependent distribution of foraminiferans and ostracods. Salinity values vary within the high alpha-mesohaline and low polyhaline range. The dominating species are Ammotium cassis (Foraminifera) and Sarsicytheridea bradii (Ostracoda). The diversity is low (Fisher alpha index from 0.4 to 3.2 for foraminiferans and 1.0 to 2.5 for ostracods), but higher within the dumping site samples. These higher values are explainable by input of allochthonous tests and valves representing additional species. After the sediment dumping it took two and a half years to re-establish the total foraminiferan association and the total foraminifer/ostracod ratio within the dumping site. Total foraminiferan abundance increases remarkably with water depth (mean 83 tests in 100 ml) driven by higher nutrient availability and more suitable salinity and temperature values within the zone of the oscillating halocline. The distribution of shallow water species such as Cribroelphidium excavatum, Eucythere argus and Hirschmannia viridis, within the transient water layer A. cassis, Nodulina dentaliniformis, S. bradii and Palmoconcha laevata and below Eggerella scabra indicate the depth position of the halocline. Water depth and sediment dumping influence are the main driving factors for the distribution of foraminifer and ostracod associations within the study area. However, a significant sedimentological difference between samples inside and outside the dumping area is not recognizable.     

Suspended sediment and erosion dynamics in Kugmallit Bay and Beaufort Sea during ice-free conditions

The Mackenzie River is the largest river on the North American side of the Arctic and its huge freshwater and sediment load impacts the Canadian Beaufort Shelf. Huge quantities of sediment and associated organic carbon are transported in the Mackenzie plume into the interior of the Arctic Ocean mainly during the freshet (May to September). Changing climate scenarios portend increased coastal erosion and resuspension that lead to altered river-shelf-slope particle budgets. We measured sedimentation rates, suspended particulate matter (SPM), particle size and settling rates during ice-free conditions in Kugmallit Bay (3–5 m depth). Additionally, measurements of erosion rate, critical shear stress, particle size distribution and resuspension threshold of bottom sediments were examined at four regionally contrasting sites (33–523 m depth) on the Canadian Beaufort Shelf using a new method for assessing sediment erosion. Wind induced resuspension was evidenced by a strong relationship between SPM and wind speed in Kugmallit Bay. Deployment of sediment traps showed decreasing sedimentation rates at sites along an inshore–offshore transect ranging from 5400 to 3700 g m^− 2 day^− 1. Particle settling rates and size distributions measured using a Perspex settling chamber showed strong relationships between equivalent spherical diameter (ESD) and particle settling rates (r² = 0.91). Mean settling rates were 0.72 cm s^− 1 with corresponding ESD values of 0.9 mm. Undisturbed sediment cores were exposed to shear stress in an attempt to compare differences in sediment stability across the shelf during September to October 2003. Shear was generated by vertically oscillating a perforated disc at controlled frequencies corresponding to calibrated shear velocity using a piston grid erosion device. Critical (Type I) erosion thresholds (u) varied between 1.1 and 1.3 cm s^− 1 with no obvious differences in location. Sediments at the deepest site Amundsen Gulf displayed the highest erosion rates (22–54 g m^− 2 min^− 1) with resuspended particle sizes ranging from 100 to 930 µm for all sites. There was no indication of biotic influence on sediment stability, although our cores did not display a fluff layer of unconsolidated sediment. Concurrent studies in the delta and shelf region suggest the importance of a nepheloid layer which transports suspended particles to the slope. Continuous cycles of resuspension, deposition, and horizontal advection may intensify with reduction of sea ice in this region. Our measurements coupled with studies of circulation and cross-shelf exchange allow parameterization and modeling of particle dynamics and carbon fluxes under various climate change scenarios.     

Marine Stingers: Review of an Under-Recognized Global Coastal Management Issue

Dangerous marine stingers (jellyfish) are an emotive issue in tropical Australia, where they are widely regarded as the number one marine health threat. However, numerous severe and fatal stings have been reported throughout the tropical and temperate seas of the world, indicating that marine stingers are a global health problem. Further, life-threatening jellyfish stings are more frequently reported globally now compared to earlier decades, possibly as a result of improved recognition and reporting, or increased spatial and/or temporal distribution or densities. As stinging incidents may also have significant financial implications (lost tourism revenues and liability settlements), and the treatment of envenomed patients comes at high cost to the taxpayer, this issue is also a management challenge. This article outlines suggested approaches, based largely on Australian experience, for dealing with this under-recognized global coastal management issue.     

Seaports and the structural implications of the economic crisis

The 2008 credit crunch and the subsequent economic crisis ended a period that lasted over two decades wherein international seaports around the globe experienced double-digit volume increases. This chapter provides an analysis of the structural effects that the crisis has on seaports, focusing mostly on developments in Europe. It does so via an examination of (a) the crisis implication for each of the four major types of transport flows that account for the vast majority of port throughput worldwide; (b) the prospects for future capacity organisation and development, given the realignment of the involvement strategies that the various stakeholders (i.e., governments, port authorities, service providers, users, investors) endorse in reaction to the financial tsunami; and (c) the adjustment opportunities, that the trade downturn unintentionally provides, allowing for correction of existing misallocations in the sector via the deployment of relevant adjustment strategies by the related actors. Recapping the identified structural consequences, the final section concludes on the changing role and responsibilities of port authorities and the ‘new issues’ that will require further investigation in the post-financial tsunami era.     

The impact of a port on its local economy: the case of Plymouth

It has been suggested in two potentially influential documents that the development of ports could be an important tool of regional economic growth in areas such as South West England. This proposition is analysed in this article by detailed examination of the case of Plymouth, one of the areas in the region for which port development has been mooted. It is concluded that the Plymouth evidence suggests that it is easy to exaggerate the existing and potential role of ports in the regional development process. Ports are not big employers of labour and are no longer the inter-related industrial complexes that they once were. In most cases, therefore, they serve industry in areas distant from their own.     

Editor's note on the comments from Eugene P. Odum,Howard T. Odum,Leonard Shabman,and Sandra Batie

Abstract

It was pointed out in a recent article on shorelines management in France that no overall coastal management legislation in that country exists.¹ Nevertheless, certain existing legislation has been adapted to take account of the peculiarities of the shoreline and coastal zone, and new institutions such as the “Shorelines Trust”; have been created.² As is the case with most countries in the Western world, the processes of urbanization, industrialization, and recreational development place tremendous pressure on shoreline use. Resulting conflicts are sometimes difficult to solve unless adequate institutional frameworks exist. Some form of institutional change is thus inevitable.