延续到内的经典Volvo系列车驾驶室

众所周知,“质量、安全、舒适”一直是Volvo集团公司不变的追求目标,为此,这位欧洲第一、世界第二的载重车业界重量级“老大哥”,对其自身产品升级、换代的脚步从未停歇过,特别是为了能够全面、有效地提升整车性能,Volvo公司对整车的一个主要部件——驾驶室的改进与创新,更是一直未曾懈怠。在同行业中,Volvo的三款驾驶室——低顶卧铺型、标准型、高顶卧铺型,堪称驾驶室系列产品中改进与升级的“与时俱进”版本。     

Observations on colony formation by the cosmopolitan phytoplankton genus Phaeocystis

Few marine phytoplankton have heteromorphic life cycles and also often dominate the ecosystems in which they occur. The class Prymnesiophyceae contains a notable exception: the genus Phaeocystis includes three species that form gelatinous colonies but also occur within their ranges as solitary cells. Phaeocystis antarctica and P. pouchetii are exclusively high latitude taxa, and are notable for regionally tremendous blooms of the colony stage. P. globosa occurs circumglobally, yet its colony blooms primarily are confined to colder waters within its range. Three additional species are warm water forms that have been reported only as solitary cells or loose aggregations that bear little resemblance to the organized colonies of the other taxa. Interpretation of existing data indicates that resource availability (light, temperature and nutrients) by itself is not sufficient to explain this distinction between cold-water colony-forming taxa and warm water solitary cell taxa, nor why colony development in P. globosa is essentially a spatially restricted phenomenon within a much broader geographic range. Colony development by P. globosa in situ has been observed at temperatures ≥20 °C, but only rarely and generally under conditions of seasonally or anthropogenically elevated nutrient supply. Data presented here demonstrate colony development at 20–22 °C in natural plankton communities from oligotrophic waters that were pre-screened through 63 μm mesh (i.e. lacking mesozooplankton and large microzooplankton), but not in unscreened communities containing microzooplankton and >63 μm zooplankton. Reduction of colony proliferation at higher temperatures by mesozooplankton grazing remains as an intriguing possibility that is consistent with available evidence to help explain differences in latitudinal extent of in situ colony development. These data are interpreted within a theoretical framework regarding the potential advantages and disadvantages of the two life cycle stages.     

A dynamic CSTT model for the effects of added nutrients in Loch Creran, a shallow fjord

Despite a tendency for the complexity of physical–biological models to increase, simple coupled models remain useful for some applications and can provide insights into crucial links between physical and biological processes. This argument is illustrated with an account of a simple 3-box model intended to help assess the capacity of fjords to assimilate nutrients from fish farms. The model, a dynamic version of the UK “Comprehensive Studies Task Team” (CSTT) steady-state model for eutrophication, was applied to Loch Creran (Scottish Western Highlands) and was implemented using Stella 8 and tested using historical data from 1975 (before the installation of a salmon farm) and field data collected in 2003, during the period of operation of the farm. The model's biological state variables are chlorophyll, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), and it includes a simple run-off model to convert rainfall into river discharge. The physical processes involved in exchange between the loch and the adjacent waters of the Firth of Lorne were parameterised as a constant daily exchange rate.Between 1975 and 2003, local inputs of nutrient increased but, despite this, there was little apparent increase in nutrient concentrations in the loch, and observed chlorophyll concentrations decreased substantially. Model simulations of chlorophyll and DIN agreed well with observations in 1975, as did DIN simulations in 2003. However, simulated chlorophyll was overestimated in 2003.Some of the agreement between observations and simulations come from the use of observed boundary conditions to force the model. However, even when boundary conditions are subtracted from simulations and observations, the simulations in most cases retain a significant correlation with observations, demonstrating that the model's ‘interior’ processes do add to its ability to replicate conditions in the loch.     

Exploring maritime ergonomics from a bottom line perspective

The present paper reports a study composed of three research activities exploring the economics of ergonomics in a shipping context. First, a literature study aimed to review previous studies on the economics of ergonomics in general and within the maritime domain in particular; and moreover, to ascertain the key ergonomic factors addressed in contemporary maritime ergonomic research. Second, the concept of ergonomics was probed from a stakeholder perspective through nine semi-structured qualitative interviews. Third, structured interviews were held with representatives of ten Swedish shipping companies to investigate if the shipowners are aware of and calculate the economic effects of ergonomics.     

U.S. import/export container flow modeling and disruption analysis

International containerized freight movement is a vital part of the supply chain for many companies, and a critical element of moving consumer goods to points of retail sale within the U.S. Containerized imports also present a clear security concern (e.g., terrorists attempting to ship “dirty bombs,” chemical, biological or even nuclear weapons, into the U.S. in a shipping container). The goal of the research presented here is to create a modeling tool for analyzing flows of U.S. imports and exports of containerized freight, and the potential changes in those flows under a variety of conditions (e.g., port disruptions, extensive security-related delays, etc.). Our focus is on movements through maritime container ports, and not overland movements between the U.S. and Canada or Mexico.The network model, referred to as the System for Import/Export Routing and Recovery Analysis (SIERRA), represents container movements between the U.S. and 46 other countries that account for the vast majority of U.S. imports and exports. The SIERRA model is a network equilibrium model that predicts flows between foreign countries and North American ports, the total volumes handled (import and export) by each port, the modal volumes (truck and rail) moving domestically into and out of each port, and volumes between each port and a set of transportation analysis zones within the U.S.     

Representing and estimating interactions between activities in a need-based model of activity generation

Although several activity-based models made the transition to practice in recent years, modeling dynamic activity generation and especially, the mechanisms underlying activity generation are not well incorporated in the current activity-based models. For instance, current models assume that activities are independent, but to the extent that different activities fulfill the same underlying needs and act as partial substitutes, their interactions/dependencies should be taken into account. For example, recreational, leisure, and social activities tend to be partly substitutable since they satisfy a common need of relaxation, and when undertaken together with others, social needs will be satisfied as well. This paper describes the parameter estimation of a need-based activity generation model, which includes the representation of possible interaction effects between activities. A survey was carried out to collect activity data for a typical week and a specific day among a sample of individuals. The diary data contain detailed information on activity history and future planning. Estimation of the model involves a range of shopping, social, leisure, and sports activities, as dependent variables, and socioeconomic, day preference, and interaction variables, as explanatory variables. The results show that several person, household, and dwelling attributes influence activity-episode timing decisions in a longitudinal time frame and, thus, the frequency and day choice of conducting the social, leisure, and sports activities. Furthermore, interactions were found in the sense that several activities influence the need for other activities and some activities affect the utility of conducting another activity on the same day.     

Explaining differences in acceptability before and acceptance after the implementation of a congestion charge in Stockholm

A field experiment was conducted in Stockholm where a congestion charge trial was introduced in 2006. Respondents completed a questionnaire before and after the trial. Acceptance of the congestion charge was higher after the trial as opposed to its acceptability judgments before the trial. Respondents believed the charge had more positive consequences (viz., decreasing parking problems, congestion, and pollution) and less negative consequences (viz., financial cost increases) after the trial than they had expected beforehand. Furthermore, we examined the relative importance of various beliefs for the acceptability of the congestion charge before and after it was implemented. Results are that before the implementation of the charge acceptability was significantly related to beliefs about the expected consequences for one’s own car use and financial costs, whereas acceptance after the trial was related to beliefs about the perceived consequences for one’s own car use and parking problems. These results indicate that acceptance of the congestion charge had increased because people experienced positive consequences of the charge. This conclusion is discussed in the broader context in which the Stockholm trial took place.     

Assessing financial impact of maritime ergonomics on company level: a case study

The present paper reports a case study examining a conceptual framework for assessing financial impact of occupational maritime ergonomics in a Swedish shipping company. Specifically, the aim was to study the availability and applicability of suggested determinants for operational performance, routines for estimating the effects of ergonomics and the customer’s (sea transport buyer’s) demands for ergonomics management on the case company. The results show that the determinants and subcategories for operational performance in terms of productivity, efficiency and quality are present and applicable, albeit not measured to any large extent. No routines or specific methods for measuring or estimating cost and effects of ergonomics investments, accidents and operational disturbances were found. Further, the results show that the sea transport buyers increasingly express interest for and place demands related to maritime ergonomics, for instance, through compliance of specific standards and guiding principles linked to maritime ergonomics. It is concluded that in order to support and enable managers’ ability to make well-informed decisions and prioritizations, between investments, ergonomic or other, increased knowledge is needed of the financial effects of ergonomics on company core value processes. There is also a need to develop and implement usable tools to simplify these measuring procedures.     

Updating predictive accident models of modern rural single carriageway A-roads

Abstract

Reliable predictive accident models (PAMs) are essential to design and maintain safe road networks, and yet the models most commonly used in the UK were derived using data collected 20 to 30 years ago. Given that the national personal injury accident total fell by some 30% in the last 25 years, while road traffic increased by over 60%, significant errors in scheme appraisal and evaluation based on the models currently in use seem inevitable. In this paper, the temporal transferability of PAMs for modern rural single carriageway A-roads is investigated, and their predictive performance is evaluated against a recent data set. Despite the age of these models, the PAMs for predicting the total accidents provide a remarkably good fit to recent data and these are more accurate than models where accidents are disaggregated by type. The performance of the models can be improved by calibrating them against recent data.     

Modelling Complex Activity‐Travel Scheduling Decisions: Procedure for the Simultaneous Estimation of Activity Generation and Duration Functions

Abstract

Activity generation is a key factor in individual's choices of trip frequency and trip purpose. This paper describes the results of an experiment conducted to estimate functions of several temporal factors on individuals' propensity to schedule a given activity on a given day. The theory on which the experimental design is based states that the probability of scheduling an activity is a complex and continuous function of how long ago the activity was lastly performed, the duration constraints for the activity and the amount of available time in the activity schedule of the day considered. Aurora, an existing model of activity scheduling, assumes S‐shaped utility functions for the history as well as the duration functions, whereas most time‐use studies assume monotonically decreasing marginal utilities. The stated‐choice experiment involves a range of flexible activities and a large sample of individuals to measure the utility effects of a set of carefully chosen levels for the factors and tests these specific assumptions. The results suggest that the amount of discretionary time on a day has no significant impact on the scheduling decisions provided that enough time is available for the activity. The effects of other factors are as expected and show diminishing marginal utilities. We find mixed evidence for an initial phase of increasing marginal returns as assumed in an S‐shaped function.