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91.
Niclas A. Krüger 《Transportation Research Part A: Policy and Practice》2012,46(8):1359-1371
This paper is concerned with the implications of public–private partnership agreements for the execution of expansion options in road infrastructure. More specifically, it analyzes the expansion of an existing two-lane road in Sweden, and examines the real options created by an intermediate type of road with three lanes. Interpreting the results from real option analysis in the light of incomplete contract theory, this paper finds that external congestion costs might necessitate public ownership to ensure a social optimal outcome in public–private partnerships. 相似文献
92.
Autonomous Underwater Vehicles (AUVs) are capable of spending long periods of time for carrying out various underwater missions and marine tasks. In this paper, a novel conflict-free motion planning framework is introduced to enhance underwater vehicle’s mission performance by completing maximum number of highest priority tasks in a limited time through a large scale waypoint cluttered operating field, and ensuring safe deployment during the mission. The proposed combinatorial route-path planner model takes the advantages of the Biogeography-Based Optimization (BBO) algorithm toward satisfying objectives of both higher-lower level motion planners and guarantees maximization of the mission productivity for a single vehicle operation. The performance of the model is investigated under different scenarios including the particular cost constraints in time-varying operating fields. To show the reliability of the proposed model, performance of each motion planner assessed separately and then statistical analysis is undertaken to evaluate the total performance of the entire model. The simulation results indicate the stability of the contributed model and its feasible application for real experiments. 相似文献
93.
An improved numerical method is used to simulate the dynamic behavior of a two part towing cable systems during turnings. In U turns and full turns, periodical heave motions are found both for the towed vehicle and for the depressor. Periodic motions of the subsea units and of the cable surface tension are closely related to the turning parameters, such as turning velocity and turning radius. System parameters, such as length of the second cable and the vehicle hydrodynamics, also damp turning instability. 相似文献
94.
While connected, highly automated, and autonomous vehicles (CAVs) will eventually hit the roads, their success and market penetration rates depend largely on public opinions regarding benefits, concerns, and adoption of these technologies. Additionally, the introduction of these technologies is accompanied by uncertainties in their effects on the carsharing market and land use patterns, and raises the need for tolling policies to appease the travel demand induced due to the increased convenience. To these ends, this study surveyed 1088 respondents across Texas to understand their opinions about smart vehicle technologies and related decisions. The key summary statistics indicate that Texans are willing to pay (WTP) $2910, $4607, $7589, and $127 for Level 2, Level 3, and Level 4 automation and connectivity, respectively, on average. Moreover, affordability and equipment failure are Texans’ top two concerns regarding AVs. This study also estimates interval regression and ordered probit models to understand the multivariate correlation between explanatory variables, such as demographics, built-environment attributes, travel patterns, and crash histories, and response variables, including willingness to pay for CAV technologies, adoption rates of shared AVs at different pricing points, home location shift decisions, adoption timing of automation technologies, and opinions about various tolling policies. The practically significant relationships indicate that more experienced licensed drivers and older people associate lower WTP values with all new vehicle technologies. Such parameter estimates help not only in forecasting long-term adoption of CAV technologies, but also help transportation planners in understanding the characteristics of regions with high or low future-year CAV adoption levels, and subsequently, develop smart strategies in respective regions. 相似文献
95.
Nabanita Datta 《船舶与海洋工程学报》2017,16(4):458-464
This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, analyzed using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation (lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency. 相似文献
96.
Legal affair simulation is on the basis of information technology, and can simulate legal scene. College students do legal experiments with virtual reality scene. This helps to train college students. Petri net has not only strict math definition to analyze the dynamic behavior of models, but also intuitive graphic expression. Petri net is used to model for legal process. Reduction rules of Petri net are used to analyze the correctness of the system. At last Java Business Process Management (JBPM) technology is used to realize legal affair simulation models, models are transformed into flow charts. Simulation software deduces processes of legal affair. Many college students have improved their ability with the software, the fact proves that the method is effective. 相似文献
97.
Community-based management (CBM) could be an essential tool to prevent the depletion of marine resources in the Western Indian Ocean region. In Kenya, political pressure to strengthen local governance, has led to adoption of CBM as a way of reducing over-exploitation and managing the competing uses and impacts on the marine environment. Several communities in Kenya have embraced CBM and have set aside or closed previously fished areas to enhance recovery of fisheries and biodiversity. These community fisheries closures (locally called tengefu), despite being degraded, may recover to finfish abundances and biodiversity levels similar to established MPAs or above thresholds for maintaining some ecological services. Communities see their direct involvement and control of these tengefu as more likely to result in benefits flowing directly to them. Community closures are also important for articulating and resolving community values and strengthening their management capacity. Here, we describe the evolution of the tengefu movement in Kenya and combine information from focus group discussions, interviews, underwater surveys and boundary marking to evaluate the current status, opportunities and challenges facing these tengefu. We show that in some cases community closures suffer from slow and incomplete national and local legislative processes, challenges to compliance, and weak management. 相似文献
98.
This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling. 相似文献
99.
Jianhu Zhao Yajing Zou Hongmei Zhang Yongting Wu Shouchuan Fang 《Journal of Marine Science and Technology》2016,21(2):216-226
To decrease the time consumption and the labor intensity in the absolute datum transfer of traditional seafloor control network measurement, a new method, namely sailing-circle positioning method, is put forward in this paper. First, the traditional intersection positioning model is improved by considering the equivalent sound velocity profile error as an unknown parameter in the adjustment model. Second, the effect of geometric dilution of precision (GDOP) on positioning accuracy is analyzed. By seeking for the minimum of GDOP, it is concluded that the absolute datum transfer can achieve the highest accuracy in the condition of sailing along a circle relative to other sailing paths. Moreover, the optimal radius of the circle for the accurate datum transfer is also given out. Besides, the correlation between the accuracy of datum transfer and the sound velocity error in this method is analyzed. Finally, the new method was tested and verified by the experiments in Songhua lake with the water depth of 60 m and in South China sea with the water depth of 2000 m, respectively. These experiment results show that the new method can improve the accuracy and efficiency of traditional datum transfer method significantly. 相似文献
100.
HAMADE Thomas A. 《上海交通大学学报(英文版)》2018,(1)
High voltage electrostatics and corona discharge are utilized for various applications in pollution and environmental control. The traditional applications have many flaws due to improper construction of electrode design and assembly that cause system failure, in particular when electrically stimulated devices are exposed to high humidity. A new innovative-patented design by Hamade, electrically stimulated catalytic converter(ESCC),eliminates such flaws and shows the wide practical applications of the new design. The new design utilized previous patented designs and work of the same inventor but retrofitted for catalytic auto exhaust emission control. The current and previous patents include: employing electrically stimulated filtration(ESF) to replace high efficiency particulate air(HEPA) filters, treatment of biological and infectious diseases, electret fabrication, and, most notably, the invention of a new electrically stimulated catalytic converter(ESCC). The electrically stimulated catalytic converter invention includes an exhaust conduit fed from the engine exhaust port with a housed corona charger apparatus. The opposite end is opened to the atmosphere outside of the vehicle or connected to a reduced-size catalytic converter. The corona charger is intrusively or non-intrusively associated with a main flow path defined by the exhaust conduit. The corona charger includes at least one electrode, which may be recessed away from, the main flow path. A plurality of corona chargers may be used in various combinations, optimally a two dimensional grid. The electrically stimulated catalytic converter is adapted to treat and eliminate auto exhaust pollution emission to air. 相似文献