The overall motion induced interruptions as operability criterion for fishing vessels

A new index, namely the overall motion induced interruptions (OMII), is proposed as a seakeeping criterion for fishing vessels, to compare ships having different hull forms and dimensions by means of an only parameter, in a human centred approach, mainly related to the onboard risk level. Therefore, the first aim of the paper is to investigate the factors affecting fishing vessels’ seakeeping performances to improve them to reduce the high number of injuries occurring during fishing operations, mainly related to both risk perception and harsh weather conditions. Despite the classical approach, where motion induced interruption is determined for a certain sea state with regard to several location points, the new index accounts for all crew members’ positions on the working deck, all heading angles the vessel may experience during fishing operations, based on relevant operating scenario, and all sea states the ship may encounter in the fishing area. The influence of position, heading angles and sea states on the attained risk level is fully investigated, analysing seakeeping performances of four fishing vessels with different hull forms and dimensions. Finally, a new operability criterion is proposed, based on OMII, to investigate the influence of ship size and operating scenario on the risk of injuries during fishing operations. Main factors affecting fishing vessels’ seakeeping performances are fully discussed, paying attention to relevant correlation with ship roll natural period.     

Shifting urban freight deliveries to the off-peak hours: a review of theory and practice

This paper presents a comprehensive review of the literature on off-peak hour deliveries (OPHD). The review identifies different approaches and policy levers used in the past, such as the laissez-faire approach, a road pricing approach, an incentives approach, and a regulatory approach. The paper also identifies different delivery reception schemes discussed in the literature. The authors complement the theory with a synthesis of pilot tests and the analysis of a set of interviews with practitioners (from the public sector and other organisations) in charge of OPHD programmes. The results from this review show the potential benefits that these programmes could bring about, the challenges faced in the early stages – along with potential solutions – and the significant progress that has been made in this domain in the last decade. According to the review, the results from the pilot tests tend to be positive, suggesting the importance of these programmes to reach more efficient and sustainable transportation systems.     

Development of a Remotely Controlled Testing Platform with Low-drag Air-ventilated Hull

This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promi...     

Sediment community biomass and respiration in the Northeast water polynya, Greenland: a numerical simulation of benthic lander and spade core data

Sediment community metabolism (oxygen demand) was measured in the Northeast Water (NEW) polynya off Greenland employing two methods: in situ benthic chambers deployed with a benthic (GOMEX) lander and shipboard laboratory Batch Micro-Incubation Chambers (BMICs) utilizing ‘cores’ recovered from USNEL box cores. The mean benthic respiration rate measured with the lander was 0.057 mM O₂ m⁻² h⁻¹ (n = 5); whereas the mean measured with the BMICs was 0.11 mM O₂ m⁻² h⁻¹ (n = 21; p < 0.01 that the means were the same). In terms of carbon fluxes (14 and 27 mg C m⁻² d⁻¹), these respiration rates represent ca. 5–15% of the average net primary production measured in the euphotic zone in 1992. The biomass of the bacteria, meiofauna and macrofauna were measured at each location to quantify the relationship between total community respiration and total community biomass (mean 1.42 g C m⁻²). Average carbon residence time in the biota, calculated by dividing the biomass by the respiration, was on the order of 50–100 days, which is comparable to relatively oligotrophic continental margins at temperate latitudes.The biomass and respiration data for the aerobic heterotrophic bacteria, the infaunal invertebrates (meiofauna and macrofauna), and the epifaunal megabenthos (two species of brittle stars) are summarized in a ‘steady-state’ solution of a sediment food chain model, in terms of carbon. This carbon budget illustrates the relative importance of the sediment-dwelling invertebrates in the benthic subsystem, compared to the bacteria and the epibenthos, during the summer open-water period in mud-lined troughs at depths of about 300 m. The input needed to drive heterotrophic respiratory processes was within the range of the input of organic matter recorded in moored, time-sequencing sediment traps.A time-dependent numerical simulation of the model was run to investigate the potential responses of the three size groups of benthos to abrupt seasonal pulses of particulate organic matter. The model suggests that there is a time lag in the increase in bottom community biomass and respiration following the POC pulse, and provides hypothetical estimates for the potential carbon storage in the summer (open water), followed by catabolic losses during each ensuing winter (ice covered).This sequence of storage and respiration may contribute to the process of seasonal CO₂ ‘rectification’ (sensu Yager et al., 1995) in some Arctic ecosystems.     

The female antennules of Paracyclops (Cyclopoida: Cyclopidae): their significance for systematics

The setation patterns of female antennules of some Paracyclops species are analysed with reference to the hypothetical 28-segmented antennule of ancestral copepod proposed by Huys and Boxshall in 1991. Comparison between Paracyclops species has revealed a setation pattern common to all species thus far examined. Several modifications of the female antennules have been identified as apomorphic states and can be used in phylogenetic studies. P. waiariki has 12-segmented antennules and exhibits more plesiomorphic characters than the reduced 8-segmented antennules of other species, such as P. fimbriatus. The results confirm that simple segment numbers are unusable as characters in cladistic analysis. Both P. affinis and P. yeatmani, for example, have 11-segmented antennules but analysis of segmental homologies has revealed that the 11-segmented state is convergent in these two species.     

Sequential optimization approach for the multi‐class user equilibrium problem in a continuous transportation system

We consider a city region with several facilities that are competing for customers of different classes. Within the city region, the road network is dense, and can be represented as a continuum. Customers are continuously distributed over space, and they choose a facility by considering both the transportation cost and market externalities. More importantly, the model takes into account the different transportation cost functions and market externalities to which different customer classes are subjected. A logit‐type distribution of demand is specified to model the decision‐making process of users' facility choice. We develop a sequential optimization approach to decompose the complex multi‐class and multi‐facility problem into a series of smaller single‐class and single‐facility sub‐problems. An efficient solution algorithm is then proposed to solve the resultant problem. A numerical example is given to demonstrate the effectiveness and potential applicability of the proposed methodology.     

Sensitivity Analysis of the Shipboard Integrated Power System

Stochastic sensitivity analysis is a valuable tool in ranking inputs and in investigating the degree of interaction of its components. In this paper, we present stochastic simulation results for a shipboard integrated power system and study its sensitivity. Specifically, we apply sensitivity analysis to two high-fidelity models of shipboard subsystems, investigating open- and closed-loop control of the propulsion system. The results show that different inputs are most important for the open- and closed-loop control, with sensitivities that change dramatically in time as they reflect the transition from the fast electrical scales to slower mechanical scales. We also demonstrate how sensitivity analysis can be used to establish the robustness of the AC drive.     

新开发的受电弓弓头碳滑板安装法

从运用的观点来看,受电弓弓头碳基滑板的安装方法是非常重要的.碳滑板一般用带贴紧钢套包层的楔型榫制成,或用能夹紧整个碳滑板的金属装配架制作,用螺栓固定在受电弓弓头上.作者开发了其他3种新的安装方法.并阐述了日本在过去20多年里对碳基滑板材料所进行的开发,以及对所开发的安装方法进行试验室试验或现场试验的结果.     

Primary productivity of the Palmer Long Term Ecological Research Area and the Southern Ocean

A major objective of the Palmer Long Term Ecological Research (Palmer LTER) project is to obtain a comprehensive understanding of the various components of the Antarctic marine ecosystem. Phytoplankton production plays a key role in this so-called high nutrient, low chlorophyll environment, and factors that regulate production include those that control cell growth (light, temperature, and nutrients) and those that control cell accumulation rate and hence population growth (water column stability, grazing, and sinking). Sea ice mediates several of these factors and frequently conditions the water column for a spring bloom which is characterized by a pulse of production restricted in both time and space. This study models the spatial and temporal variability of primary production within the Palmer LTER area west of the Antarctic Peninsula and discusses this production in the context of historical data for the Southern Ocean. Primary production for the Southern Ocean and the Palmer LTER area have been computed using both light-pigment production models [Smith, R.C., Bidigare, R.R., Prézelin, B.B., Baker, K.S., Brooks, J.M., 1987. Optical characterization of primary productivity across a coastal front. Mar. Biol. (96), 575–591; Bidigare, R.R., Smith, R.C., Baker, K.S., Marra, J., 1987. Oceanic primary production estimates from measurements of spectral irradiance and pigment concentrations. Global Biogeochem. Cycles (1), 171–186; Morel, A., Berthon, J.F., 1989. Surface pigments, algal biomass profiles and potential production of the euphotic layer—relationships reinvestigated in view of remote-sensing applications. Limnol. Oceanogr. (34), 1545–1562] and an ice edge production model [Nelson, D.M., Smith, W.O., 1986. Phytoplankton bloom dynamics of the western Ross Sea ice edge: II. Mesoscale cycling of nitrogen and silicon. Deep-Sea Res. (33), 1389–1412; Wilson, D.L., Smith, W.O., Nelson, D.M., 1986. Phytoplankton bloom dynamics of the Western Ross Sea ice edge: I. primary productivity and species-specific production. Deep-Sea Res., 33, 1375–1387; Smith, W.O., Nelson, D.M., 1986. Importance of ice edge phytoplankton production in the Southern Ocean. BioScience (36), 251–257]. Chlorophyll concentrations, total photosynthetically available radiation (PAR) and sea ice concentrations were derived from satellite data. These same parameters, in addition to hydrodynamic conditions, have also been determined from shipboard and Palmer Station observations during the LTER program. Model results are compared, sensitivity studies evaluated, and productivity of the Palmer LTER region is discussed in terms of its space time distribution, seasonal and interannual variability, and overall contribution to the marine ecology of the Southern Ocean.     

Validation of a MATLAB Railway Vehicle Simulation Using a Scale Roller Rig

A 1/5 scale roller rig has been constructed for use in analysing the dynamic behaviour of railway vehicles. The roller rig includes a servo hydraulic system to allow a realistic input of track irregularities at the rollers and instrumentation is fitted to allow measurement of the position and acceleration of the bodies. This paper reports on the first stage in validating the behaviour of the roller rig using a relatively simple, linear computer model constructed in MATLAB. Initial results show good correlation between the behaviour seen on the roller rig and that predicted by the model.