On the measurement of benefits from shipping services

This brief paper extends the author's comments on Conference pricing policy, and represents a reply to comments made by E. T. Laing.     

Attitudes towards public transport in New Zealand

Attitudes towards public transport (PT) in New Zealand’s three largest cities (Auckland, Wellington, and Christchurch) were examined in a cross-sectional survey of drivers. A measure of prejudice to PT was developed to assess the strength and nature of attitudinal differences. Auckland residents had the highest levels of PT prejudice while Wellington residents had the lowest, and these differences were not related to demographic differences between the samples. Direct contact with PT was associated with reduced levels of PT prejudice, but measures of indirect contact, beliefs about using PT, and environmental attitudes were stronger predictors of PT prejudice scores. Controlling for these variables resulted in the difference in PT prejudice levels between Wellington and Christchurch becoming non-significant, while the differences between Auckland and the other two cities remained. This suggests that the difference between Wellington and Christchurch was primarily based on social norms regarding PT prejudice, while quality of service was a factor in the difference between Auckland and the other two cities. It is suggested that campaigns promoting PT ridership should focus both on the quality of service and on presenting PT usage as socially normal.     

Risk assessment: An introduction and critique

Abstract

Risk assessment is a methodology which has been used to evaluate the safety of major public projects, notably aerospace programs, liquefied natural gas import facilities, and nuclear power plants.

This article begins with a review of public attitudes toward risk and then describes the basic components of a risk assessment. Subsequent critical analysis suggests the pitfalls inherent in the technique, especially in regard to the establishing of a criterion of safety against which the results of a risk assessment will be compared. The author identifies three such criteria and rejects two of them, including the one most commonly used in federal government agency decision‐making, as unreliable or philosophically unacceptable.

The article concludes with comments on the applicability of risk assessment in coastal zone management.     

Simulation tool for optimization and performance prediction of a generic hybrid electric series powertrain

Hybrid and electric vehicles are taking an increasingly important slice of the market, gaining much interest from major car manufacturers which have decided to invest in this sector, taking as example the pioneers like Toyota. The key factor to hybrid and electric vehicle success is a good overall mileage achieved from the battery back or powertrain. The purpose of this work is to provide a support to design, testing, and development of such vehicles through the implementation of a mathematical model in order to simulate the operation and predict the performance of a generic ground vehicle equipped with either a purely electric or a hybrid-electric type powertrain. The model should enable the user to estimate the impact of various control strategies on mileage range, efficiency, energy consumption, etc. The model should also allow for a significant time to market reduction with all the related benefits in terms of cost etc. A validation is also provided, based on the application of this tool on a so-called micro-car (0.5t GVW class). Thanks to a joint research project with the manufacturer it has been possible to compare model results with real-world data directly obtained during road testing with the help of a data acquisition system.     

The structure of the solution set to network optimisation problems

This paper argues that both heuristic and non-heuristic algorithms for the road network optimisation problem would benefit from a greater understanding of the structure of the set of feasible solutions to such problems. In order to provide this, a comparative study of a number of spatial combinatorial problems was undertaken. The results show that the road network optimisation problem is rich in good sub-optimal solutions. The implications of this finding for the development of optimising and heuristic algorithms are discussed, and some suggestions made as to where future research on network optimisation problems could most fruitfully be directed.     

Study of the Impact of Single-and Double-tube Tunnel Systems on Rockburst in Deep-buried Extra-long Tunnelling北大核心CSCD

Rockburst is one of the main disasters for tunnelling under high ground stress. Taking the rockburst section of Ping'an Tunnel with high ground stress, which is located on Chengdu-Lanzhou Railway, as the study object, this paper adopts combined methods of filed measurement, numerical analysis, and laboratory test, and with respect to rockburst development mechanism, energy density change and rockburst strength it comprehensively analyzes the impact of two construction schemes (single-tube double-track tunnel system and double-tube single-track tunnel system) on the rockburst in deep-buried extra-long tunnels with high ground stress. The study results show that the order relation of maximum energy density at various locations of the tunnel is Uside wall >Uhance >Utunnel face >Uvault, and rockburst easily occurs at the working face of the tunnel section to be excavated and both side walls of excavated and supported section; compared with vault, hance, side wall and other locations, more energy would be released at the tunnel face, and the stress release holes shall be reasonably installed in the process of excavation; the doubletube single-track tunnel system scheme can effectively reduce the rockburst intensity and the rockburst hazards, so as to better avoid the occurrence of rockburst. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Improvement of combustion efficiency and emission characteristics of IC diesel engine operating on ESC cycle applying Variable Geometry Turbocharger (VGT) with vaneless turbine volute

Based on experimental data, the present study investigates the influence of turbine adjustment in a turbocharger with vaneless turbine volute on diesel combustion efficiency indices and emission characteristics. Experimental investigations were conducted on engine modes as set out by the European Stationary Cycle (ESC). The adjustment algorithms selected for the experiment under ESC modes included adjustment to achieve minimal values of specific fuel consumption (SFC), NOx, CO and particulate matter (PM). In present research only VGT adjustment was investigated, the factors like fuel injection timing and EGR were not investigated. As a result we were able to make a comparison of the engine combustion efficiency and emission indices for VGT and a common turbocharger running on ESC cycle modes.     

Some insights into competition between low-cost airlines

The phenomenon of the wide world growth in low-cost airlines has resulted in a focus on their pricing strategies, on issues of cost recovery and on their impact on the traffic and market shares of legacy carriers or other low-cost carriers when they are in competition, either directly or at adjacent airports.This paper provides a brief overview of the characteristics of these low-cost carriers as well as their history and geography. It goes on to outline ways in which these carriers compete and manage demand, ranging from price competition to advertising; some of these methods directly reflect their special characteristics. Some empirical evidence is presented which indicates a correlation in fare setting behaviour between competitors and insights are offered on cost recovery.The impact of the start-up of low-cost carriers is also analysed, focusing on their impacts on other low-cost carriers. The case of Ryanair competing with easyJet on London-Venice is examined along with Southwest and Frontier on Denver-Las Vegas.     

Spatial heterogeneity and temporal dynamics of particles, bacteria, and pEPS in Arctic winter sea ice

Abundances of particles, total bacteria, and particulate extracellular polymeric substances (pEPS) in Arctic sea ice were tracked through a winter season to examine the impact of combined extremes of low temperature and high salinity on the prokaryotic microbial community. Three horizons, centered at depths of 25, 45, and 65 cm from the ice surface, with mean seasonal temperatures of − 20, − 17, and − 13 °C, respectively, were sampled 16 times over the course of 12 weeks. Microscopic counts of bacteria (stained with DAPI) and particles (stained with acridine orange) reflected the dynamic conditions of the growing ice sheet, with greater abundances and variability in the upper ice horizons compared to the lower. The trend of higher particle and bacterial abundances in the upper ice was corroborated by several full-depth profiles taken during the expedition, which also displayed significantly decreasing cell abundance with depth. Bacterial abundance declined slowly and significantly with time in the upper and middle ice horizons, but not in the lowest, suggesting that much of the prokaryotic microbial community is resilient to extreme environmental conditions. We found that pEPS concentrations increased significantly with time and with decreasing temperatures in all depth horizons, which may lend support to the argument that sea ice bacteria produce EPS in situ as a cryoprotectant.     

Comprehensive Evaluation of the Intelligent Degree of the Mining Face Based on Grey Relational Analysis北大核心CSCD

In order to further evaluate the intelligent degree of the coal mining face scientifically and reasonably, this paper constructs a gray relational analysis based comprehensive evaluation model for the intelligent degree of mining face by deeply analyzing the influencing factors on the intelligent degree of mining face, such as surrounding rock detection, mining equipment, production system, supporting production system, organization and management, etc. By quantifying and scoring factors affecting the intelligence degree of mining face, using the hierarchical analysis method to obtain the weights and determine the correlations, the intelligence degrees of mining face are classified into four levels: excellent, good, medium and poor. Using the comprehensive evaluation model to empirically verify the 802 working face of Shaanxi Huangling Mining Co., Ltd., the calculated correlation is 0.765 8, which indicates that the intelligent degree of 802 working face is excellent according to the rating criteria, and it is consistent with the actual situation. Therefore, the comprehensive evaluation model based on gray relational analysis can accurately and objectively evaluate the intelligent degree of the mining face. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.