Planktonic community structure and carbon cycling in the Arabian Sea as a result of monsoonal forcing: the application of a generic model

The Arabian Sea exhibits a complex pattern of biogeochemical and ecological dynamics, which vary both seasonally and spatially. These dynamics have been studied using a one-dimensional vertical hydrodynamic model coupled to a complex ecosystem model, simulating the annual cycle at three contrasting stations. These stations are characterised by seasonally upwelling, mixed-layer-deepening and a-seasonal oligotrophic conditions, respectively, and coincide with extensively measured stations on the two JGOFS ARABESQUE cruises in 1994. The model reproduces many spatial and temporal trends in production, biomass, physical and chemical properties, both qualitatively and quantitatively and so gives insight into the main mechanisms responsible for the biogeochemical and ecological complexity. Monsoonal systems are typified by classical food web dynamics, whilst intermonsoonal and oligotrophic systems are dominated by the microbial loop. The ecosystem model (ERSEM), developed for temperate regions, is found to be applicable to the Arabian Sea system with little reparameterisation. Differences in in-situ physical forcing are sufficient to recreate contrasting eutrophic and oligotrophic systems, although the lack of lateral terms are probably the greatest source of error in the model. Physics, nutrients, light and grazing are all shown to play a role in controlling production and community structure. Small-celled phytoplanktons are predicted to be dominant and sub-surface chlorophyll maxima are robust centers of production during intermonsoon periods. Analysis of carbon fluxes indicate that physically driven outgassing of CO₂ predominates in monsoonal upwelling systems but ecological activity may significantly moderate CO₂ outgassing in the Arabian Sea interior.     

An evaluation of vehicle deceleration profiles

Vehicles stopping at signalized intersections were examined for the purpose of evaluating the validity of the common assumption of constant and uniform deceleration rates. The data set consisted of the first vehicles to stop upon the onset of the yellow signal interval with measurements of the initial approach speed, deceleration time, and deceleration distance. The deceleration rate may be computed using only two of the three measured values; thus the rate for each vehicle can be determined by three different equations. With nonuniform deceleration profiles, the equations will produce different values; and the degree of nonuniformity can be determined by comparing the differences in the computed deceleration rates. The analysis of the field observations indicated that 69 percent of the vehicles demonstrated deceleration profiles associated with nonuniform deceleration rates. Furthermore, the deceleration profile and the degree of nonuniformity were found to be a function of the initial approach speed.     

Unconventional Bogie Designs - Their Practical Basis and Historical Background

This paper deals with the design concepts for steerable bogies. A brief historical background is given and the modern design basis generated by the creep theory is summarised with regard to curving performance and dynamic stability of two- and three-axle bogies. The basic structural elements used for trailing and motorised steerable bogies are illustrated. Experience gained with some recent designs of self-steering and forced-steering bogies is discussed and achievable stability and curving performances are quoted.     

Ergonomic and biomechnical analysis of automotive general assembly using XML and digital human models

Automotive general assembly requires many manual assembly operations to be carried out by human workers. Ergonomic analysis is an important part of the design and evaluation of products, jobs, tools, machines and environments for safe, comfortable and effective human functioning. Most recent researches have involved the evaluation of working conditions to prevent work-related musculoskeletal disorders. The majority of previous research on automotive companies has mainly considered the results of ergonomic analyses such as RULA (Rapid Upper Limb Assessment), REBA (Rapid Entire Body Assessment) and OWAS (Ovako Working Posture Analysis System). Analysis of static posture including reachability, clearances for arm, hand and tool has also been used to evaluate working conditions. However, in addition to static posture analysis, a biomechanical analysis in dynamic conditions should also be conducted. There are no integrated frameworks or standard schema for ergonomic analysis using digital human models in digital environments. The purpose of this paper is to propose a new framework for the evaluation of working conditions by ergonomic and biomechanical analysis using digital models based on XML standard schema, including: products, processes, manufacturing resources and human workers. This paper presents the analysis results using the proposed framework for automotive general assembly operations. We propose a new framework for the evaluation of the assembly operations and their environments. Then we apply a digital human model to the dynamic simulation of general automotive assembly operations based on standard schemas in XML and PPRH (Product, Process, Resource and Human). Using PPRH information based on a standard XML schema to analyze the ergonomic and biomechanical results, the engineer can visualize, analyze and improve assembly operations and working environments in automotive general assembly shops using digital models.     

Auto-ignition and micro-explosion behaviors of droplet arrays of water-in-fuel emulsion

The characteristics of auto-ignition and micro-explosion behaviors of one-dimensional arrays of fuel droplets suspended in a chamber with high surrounding temperature were investigated experimentally with various droplet spacings, numbers of droplet and surrounding temperatures. The fuels used were pure n-decane and emulsified n-decane with varied water contents ranging from 10 to 30%. All experiments were performed under atmospheric conditions with high surrounding temperatures. An imaging technique using a high-speed camera was adopted to measure ignition delay, flame lifetime, and flame spread speed. The camera was also used to observe micro-explosion behaviors. As the droplet array spacing increased, the ignition delay also increased, regardless of water content. However, the lifetime of the droplet array decreased as the droplet spacing increased. The micro-explosion starting time remained unchanged regardless of the number of the droplets or the droplet spacing; however, it tended to be delayed slightly as the water percentage and droplet spacing increased.     

温拌技术的发展与现状

该文介绍了温拌沥青技术的发展与现状,有关经验可供专业人员参考。     

The federal republic of Germany: the federal ministry of transport

The continued liberalization of the airline market in the European Community offers the prospect of competition in terms of price, frequency of service and many other attributes. Understanding these factors that influence passenger demand and incorporating them into a demand function poses a substantial theoretical and empirical challenge. A basis for estimating demand functions is the logit model. This paper examines the value of a logit share model in explaining how the share of airlines between airports varies as a function of measured and unmeasured attributes. It shows how demand functions are necessary for understanding a competitive market and evaluates the progress to date in identifying accurate coefficients of the logit function.     

The use of demand correlation in the modeling of air carrier departure delays as first‐order autoregressive random processes

A method for modeling air carrier departure delays at commercial‐service airports as autoregressive random processes is presented. This method employs the correlation of a priori demand data to significantly reduce prediction error in the optimal least‐squares estimator for additive white noise. The reduction factor of the prediction error is demonstrated to be on the order of 10² over that of the unbiased estimator. Copyright © 2011 John Wiley & Sons, Ltd.     

Non‐compatible chemicals as cargoes in industry,on road,rail, and water

Toronto is to have an urban transit system with a passenger carrying capacity which fills the gap between the capacity of the subway and the capacity of the car and bus. Correspondingly, in the words of the Premier of Ontario, the system will “make possible an attractive alternative to high‐rise, high‐density living and urban sprawl. . . .” Furthermore, the new system is sufficiently economical to provide “. . . an encouragement to growth in appropriate areas, rather than merely responding to growth as it occurs . . .”

The decision to have such a system is the culmination of some years of major transportation activities in the Province, which included the Metropolitan Toronto and Region Transportation Study (MTARTS) of 1962. This study pursued both urban expressways and public transport solutions to the movement of people in Metropolitan Toronto.

The urban expressways programmes ran into difficulties, on environmental terms, when strong opposition from community groups was met on proposed routes. A climax came when the Ontario Government halted the construction of the controversial Spadina expressway in June 1971. However, the programmes of public transport solutions met with great success. The Toronto subway and its extensions, together with the change in land values along the route, has become a classic success story. So, too, has the introduction of the GO Train Service (Government of Ontario train service). This pioneered a combination of commuter rail service and integrated feeder buses and today replaces some 14,000 cars each day along the lakeshore highways.

The success of the subway and the GO train coupled with the difficulties experienced by the urban expressways programme, gave rise to the realisation that a better city through public transport rather than the car, was practicable. However, subways were too expensive and they needed a large patronage in a narrow corridor. Accordingly, an intermediate capacity transit system was sought.

The paper describes the programme of activities involved in the choice of the system and describes the technical specification which the system will enjoy. In particular, the demonstration installation which is to be set‐up in Toronto is described in detail, together with the plans to instal some 56 miles over five routes in Metropolitan Toronto.