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301.
302.
Manolis G. Kavussanos Arne Juell-Skielse Matthew Forrest 《Maritime Policy and Management》2003,30(2):107-122
This paper compares the behaviour of shipping and shipping-related company stock returns to reveal whether systematic risk differs from the average in the market and across sub-sectors of the maritime industry. Following an extensive collection of information through a postal questionnaire survey, 108 publicly listed shipping and shipping-related companies, across stock exchanges of the world, are classified by sector according to their core business activity. The Capital Asset Pricing Model (CAPM) is employed for the period 1996-1999 to model stock returns and measure sector βs (systematic risk). Stock returns over the period are mostly negative. The systematic risks of the Drilling and Offshore sectors are significantly higher than those of all other sectors, but are not different from each other. There is no significant difference between the systematic risks of the Bulk, Tanker, Container and Ferry sectors. The systematic risk of the Cruise sector lies somewhere between these two groups. There is no difference in the systematic risk of companies that diversified within shipping or shipping-related industries when compared to companies that diversified in other areas. Over all companies in the sample, βis lower than the market average, and so are the βs of the Ferry, Tanker, Bulk, Container and Yard sectors. Only the βof the Drilling sector is statistically higher than one, while the Cruise, Diversified and Offshore sectors are statistically one. 相似文献
303.
The traffic signal settings for a single road junction have been often evaluated by mathematical programming techniques. This paper proposes a new approach to the problem which allows all the regulation variables to be incorporated into a Binary-Mixed-Integer- Linear-Programming model. This general model permits some of the limitative assumptions involved in other formulations of the problem based on the stage matrix to be removed. The model can be easily solved obtaining a fast computation of the globally optimal control system design. A detailed treatment is given for the particular structure of the mathematical programming schemes obtained by considering delay minimization, capacity reserve maximization, or cycle time minimization as the objective. 相似文献
304.
G. Levikov 《Maritime Policy and Management》1992,19(1):63-68
This paper highlights sources of finance for Soviet shipping companies. These include the fund for the development of production, science and technology, the shipping company's foreign currency fund, loans and centralized sources. Particular attention is paid to the structure of these funds and their purposes. Activities of the commercial shipping bank (Morbank) set up in 1989 are described. 相似文献
305.
J. Yang G. L. Wang Z. J. Wan C. Liang H. C. Zhou 《International Journal of Automotive Technology》2016,17(4):639-649
Two types of radial tire 11.00R20 and 385/65R22.5 are chosen as the research objects, and their carcass contours are redesigned by using Sakai Hideo’s, Frank’s and the new non-natural equilibrium contour design theories, which were based on analyzing the current non-equilibrium contour design theories of radial tire. Then the tire wear, rolling resistance and grip performance of the two radial tires designed by different non-natural equilibrium contour design theories are comprehensively analyzed with the finite element software ABAQUS. The results show that Frank’s contour design theory can reduce tire wear; the new non-natural equilibrium contour design theory can enhance tire wear, rolling resistance performance, etc. It is also found that the tire carcass contour has great influence on tire performance, especially on the tire rolling resistance. The new non-natural equilibrium contour theory provides a guidance to reduce the tire rolling resistance, and it can break through the target conflicts in tire performance. The tire with the new non-natural equilibrium carcass contour can enhance its comprehensive performance. 相似文献
306.
A novel hybrid optimal algorithm for DC motor of electro-mechanical Automated Manual Transmission (AMT) is presented. It combines non-linear time optimal controller and optimal Linear Quadratic Regulator (LQR) consequently used at different shifting stages. The working principle and dynamic characteristics of the AMT system are firstly presented, and the model of the DC motor is analyzed in detail. The non-linear time optimal controller is designed to explore the potential of the motor and minimize the gear shifting time. While the optimal LQR is then adopted at the final shifting stage to avoid overshoot and increase system robustness. Based on the position control algorithm of the actuators, the coordinated shifting control strategy is also proposed. Both simulation and vehicle test results demonstrate that, this control algorithm could decrease the shifting time and improve the shift quality effectively. 相似文献
307.
A. V. Tumbal N. R. Banapurmath P. G. Tewari 《International Journal of Automotive Technology》2016,17(1):35-50
Increasing petroleum prices, increasing threat to the environment from exhaust emissions and global warming have generated intense international interest in developing renewable and alternative non-petroleum fuels for engines. Evolving feasible technology and recurring energy crisis necessitated a continued investigation into the search for sustainable and clean-burning renewable fuels. In this investigation, Honge oil methyl ester (HOME) was used in a four stroke, single cylinder diesel engine. Tests were carried out to study the effect of fuel injection timing, fuel injector opening pressure (IOP) and injector nozzle geometry on the performance and combustion of CI engine fuelled with HOME. Injection timing was varied from 19°bTDC (before top dead centre) to 27°bTDC in incremental steps of 4°bTDC; injector opening pressure was varied from 210 bar to 240 bar in steps of 10 bar. Nozzle injectors of 3, 4 and 5 holes, each of 0.2, 0.25 and 0.3 mm size were selected for the study. It was concluded that retarded injection timing of 19°bTDC, increased injector opening pressure of 230 bar and 4 hole nozzle injector of 0.2 mm size resulted in overall better engine performance with increased brake thermal efficiency (BTE) and reduced HC, CO, smoke emissions. Further air-fuel mixing was improved using swirl induced techniques which enhanced the engine performance as well. 相似文献
308.
G. C. Pereira M. M. F. Oliveira L. P. Andrade R. P Espíndola K. G. van Hecke N. F. F. Ebecken 《Journal of Marine Science and Technology》2016,21(4):651-662
Coastal zones are among the most productive areas in the world, offering a wide variety of valuable habitats and ecosystems services. Despite the low population density in the Brazilian coastal zone, their distribution is quite concentrated near some coastal cities and state capitals. This concentration places enormous pressure on coastal resources. Therefore, the main objective of this paper is to present an overview on the current status of SiMoCo (Sistema de Monitoramento Costeiro, or Coastal Monitoring System in English) project as a possible early warning system that can be integrated to the Brazilian Coastal Management Information System. This prototype platform provides a real-time access to the composition, organization and simulation of planktonic communities. First, our results demonstrate such a system detecting a target dinoflagellate; second, we apply structural and functional indexes to compare and characterize the ecological networks from two different coastal areas. Conclusions are made about SiMoCo’s feasibility and its possible contribution to the decision-making process within integrated coastal zone management (ICZM) strategies. 相似文献
309.
A. Harifi A. Aghagolzadeh G. Alizadeh M. Sadeghi 《Transportation Research Part C: Emerging Technologies》2008,16(6):731-741
Antilock brake system (ABS) has been designed to achieve maximum negative acceleration by preventing the wheels from locking. Research shows that the friction between road and tire is a nonlinear function of wheel slip. Therefore, maximum negative acceleration can be achieved by designing a suitable control system for wheel slip regulation at its optimum value. Since there is a lot of nonlinearity and uncertainty (uncertainty in mass and center of gravity of the vehicle and road condition) in vehicle dynamics, a robust control method should be used. In this research, a sliding mode controller for wheel slip control has been designed based on a two-axle vehicle model. Important considered parameters for vehicle dynamic include two separated brake torques for front and rear wheels as well as longitudinal weight transfer caused by the acceleration or deceleration. One of the common problems in sliding mode control is chattering phenomenon. In this paper, primary controller design has been improved using integral switching surface to reduce chattering effects. Simulation results show the success of integral switching surface in elimination of chattering side effects and by high performance of this controller. At the end, the performance of the designed controller has been compared with three of the prevalent papers results to determine the performance of sliding mode control integrated with integral switching surface. 相似文献
310.
In order to prevent the uncontrolled release of seatbelt buckles due to high acceleration caused by pretensioners, anti-g
buckles that have pendulum-shaped g-masses to block the releasing motion are commonly adopted in seatbelt systems. However,
even with the wide applications of anti-g buckles, the underlying operational principles of anti-g buckles have yet to be
investigated. This work studies conditions for the engagement of the g-mass to prevent inertial release, and conditions for
maintaining a blocked state under very high acceleration. Using a multibody model of an anti-g buckle, the effects of various
design parameters on the performance of the anti-g buckle have been examined. It turns out that design variables associated
with the geometry of the g-mass and its contacting surface configuration play important roles. In order to account for the
dynamic interaction between driver and seatbelt, a multibody model of a seatbelt system is combined with a dummy model to
form a single dynamic system. Using the measured displacement of the buckle during the explosion of a pretensioner as the
driving condition for simulation, dynamic analysis of the seatbelt with driver interaction has been carried out. Through comparison
with measured and computed accelerations of webbing, which shows good agreement, the validity of the model has been demonstrated.
The dynamic model for seatbelt and driver can be used as a design tool for the development of anti-g buckles. 相似文献