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291.
292.
H. Beshir Selim 《Maritime Policy and Management》2013,40(2):115-125
The choices faced by shippers are generally complex. Typically, the shipper is presented with a range of alternative carriers, each of which has its individual strengths and weaknesses. A survey of companies purchasing shipping services in an overnight RO/RO ferry trade was conducted to identify their priorities and to help understand and the decision-making process. The shippers were found to be conservative decision makers with a strong emphasis on quality of service. 相似文献
293.
IntroductionThere are many methods to perform imagesegmentation and edge detection tasks that incor-porate region- growing and edge detection tech-niques,for example,it is applying edge detectiontechniques to obtain Difference In Strength( DIS)map then employ region growing techniques towork on the map as in Refs.[1 ,2 ]. In the others,combining both special and intensity information inimage segmentation approach based on multi- reso-lution edge detection,region selection and intensi-ty thre… 相似文献
294.
This paper presents a system for treating of the actual measured data for load histories. The approach consists of two steps: stress analysis and fatigue damage prediction. Finite element analysis is conducted for the component in question to obtain detailed stress-strain responses. A significant number of failures occurred in a brake end beam which led to economic losses and disruption of service. The cracks appeared to be fatigue cracks caused by the dynamic load produced in the loaded bogie frame. Strain gauge data were analyzed, and fatigue cycles were calculated from this data. Rainflow cycle counting was used to estimate cumulative damage of the end beam under in-service loading conditions. The fatigue life calculated with the rainflow cycle counting method, the P-S-N curve, and the modified Miner’s rule agreed well with actual fatigue life within an error range of 2.7%~31%. 相似文献
295.
Jin Shang Dihua Guan L. H. Yam 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2002,37(2):129-144
Based on the modeling of tire vertical characteristics and steady cornering properties, the model of tire nonsteady cornering is established in this paper using tire modal parameters extracted experimentally. In order to consider the influence of tire rolling effect on its cornering properties, the induced transfer function is introduced. The analytical formulae for calculation of transfer-function of lateral force and self-aligning torque with respect to lateral displacement and yaw angle are derived. The nonsteady cornering characteristics of tire under different loads can be calculated. The results of calculation are consistent with the experimental ones in the literature. The influence of rolling speed on tire cornering properties including the static case is analyzed. The nonsteady cornering properties in high frequency range are given by the model. The study demonstrates the consistency between steady and nonsteady tire modeling by using modal parameters. 相似文献
296.
Seung-Bok S. Choi Hyun-Jeong H. Song 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2002,37(3):193-216
This paper presents vibration control of a passenger vehicle using an electronically controllable electro-rheological (ER) engine mount. A mixed-mode ER engine mount operating under the flow and shear modes is devised and manufactured. After establishing the dynamic model of the proposed ER engine mount, both field-dependent displacement transmissibility and dynamic stiffness of the ER engine mount are empirically evaluated. The ER engine mount is then incorporated with a full-vehicle model in order to investigate vibration control performance at the driver's seat position. The governing equation of motion of the full-vehicle model is formulated by considering engine excitation force, followed by designing a skyhook controller to attenuate unwanted vibration. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at idle speed are evaluated in the frequency and time domains. 相似文献
297.
298.
Jennifer D. Ruiz-Ramírez Jorge I. Euán-Ávila Víctor H. Rivera-Monroy 《Coastal management》2019,47(1):23-43
We evaluated the potential economic impacts of increasing sea level rise (SLR) along the Mexican Caribbean where there are major gaps in our understanding of the mechanisms controlling flooding duration and frequency associated to future ecological and economic impacts. We determined the negative economic impact of SLR on infrastructure in the largest urban centers (Cancun, Isla Mujeres, Playa del Carmen, Puerto Morelos and Cozumel) in the state of Quintana Roo (Mexico) that are considered the largest tourism “hot spots” (resort cities) in the country. The tourism industry in this coastal area injects >8 billion dollars year?1 to the Mexican economy. Our conservative economic assessment regarding the impact of SLR, under a 1?m scenario for all coastal cities is $330 million USD. Further projections for worst scenarios (SLR >2 m) show a non-linear trend where the cost of inaction can reach up to $1.4 billion USD (2?m SLR scenario) and $2.3 billion USD (3?m SLR scenario). This potential loss of infrastructure, as construction cost, is staggering and represents a robust baseline to start evaluating with more detail future impacts of climate variability and change on the Mexican Caribbean coastline. 相似文献
299.
This paper focuses on the response of port authorities to the changing market environment in which they operate. It documents the changes taking place in the relationships between port authorities and terminal management companies and considers the strategic issues faced by these groups and other port interests. In particular, it investigates the potential conflicts of interest for a port authority in matters related to the level of competition amongst terminals within a port and the amount of competition amongst ports. 相似文献
300.
In this paper, a tramp ship routing model of fleet deployment in a hub-and-spoke network is presented. This model simultaneously determines the selection of hubs, the assignment of spokes to hubs, the deployment of feeder-containerships as well as containership routing between spokes and spokes, hubs and spokes, and hubs and hubs. Even though some parts have been studied, this complex combination of shipping problems has never been addressed. Because the problem is NP-hard, a genetic algorithm (GA) with local search is proposed. In the algorithm, a cut-off procedure is applied to fleet deployment in a sub-route strategy. A number of randomly generated problem instances are solved by both a mathematical program and the GA with local search. A simple but realistic heuristic algorithm is also developed. Both the GA with local search and the heuristic algorithm are used to solve a number of real case instances. A comparison of the results shows the efficiency of the GA with local search. The developed model can be used as a route-decision support tool for shipping companies that provide long-haul shipping services in a hub-and-spoke network. 相似文献