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101.
In cellular networks, cooperative relaying is an economic and promising way to enlarge the network capacity and coverage. In the case that multiple users and multiple relays are taken into account, efficient resource allocation is important in such networks. In this paper, we consider the joint relay power control with amplify- and-forward (AF) strategy and dynamic pricing for uplink cellular networks in order to maximize the network administrator's system revenue. The system revenue is associated with pricing strategies and mobile users' random data request, which is supported by the relay assisted transmission. To deal with the problem of the coupling in pricing and relay resource allocation, we utilize Lyapunov optimization techniques to design online pricing and relay power control without any statistic information of random events in networks. Theoretical analysis shows that the proposed algorithm can achieve a near-optimal performance and simulation results also validate its effectiveness and robustness. 相似文献
102.
Ronny Püschel Christos Evangelinos 《Transportation Research Part D: Transport and Environment》2012,17(8):598-604
This study estimates airport noise annoyance cost around Düsseldorf, Germany by examining rental apartment market data. Using data on regional apartment offers we estimate rent discounts of 1.04% per additional decibel of airport noise. Other sources of traffic noise induce significantly lower price effects. As a result, airport noise annoyance costs amount to about €7.5 million a year. While the noise protection fund recovers annoyance costs, the charging regime of the airport fails to fully internalize them. 相似文献
103.
Vilmar Fuchs Janto Gundlach Olaf Wünsch 《Journal of Marine Science and Technology》2013,18(3):276-293
Hydrodynamic impacts of free surface waves are a widely known issue in coastal and ship engineering. They can result in severe damage to important industry facilities (e.g. offshore wind turbines) or means of transport (e.g. oil tankers). This kinds of damage give rise to different difficulties due to economic losses and environmental pollution. On that account, the present paper deals with a special feature of a protective mechanism for offshore structures. We develop a numerical multiregional wave-structure impact model of a damping element prototype. The investigated prototype consists essentially of an elastic cover that is attached to the cylindrical mono-pile foundation at wave level. The chamber between the flexible structure and the mono-pile is filled with a liquid. A prototype of the damping element has been constructed as a mono-pile structure test object. In order to measure the hydrodynamic loads on the test object, we placed piezoelectric sensors on the stagnation points of the mono-pile. The multiregional simulation model created is able to imitate the wave impact and its consequences. These implications include the deformation and oscillation of the elastic shell, the resultant force affecting the pile and the dissipation power of the damping fluid. The dissipation power can be understood as the crucial factor preventing the shell from oscillating over long periods of time. It enables us to state the mechanical energy that is transfered due to the wave’s impact on the damping fluid region. 相似文献
104.
ABSTRACTDespite significant changes in work tasks performed on board, towards more sedentary monitoring and administrative work, the incidence of occupational injuries and disorders remains high among seafarers. In order to improve safety standards, industry stakeholders increasingly require written documentation of numerous routines, procedures and tasks performed on board. These increased demands have however added to the administrative burden. Some say, to the extent that administrative work has become a safety risk in itself. This paper presents the result of a survey investigating how Swedish seafarers perceive their own level of fatigue, stress and over-exertion related to work. The material consists of 1309 respondents originating from a random selection procedure, of which 651 reported to be employed in short sea shipping. Multiple regression analysis (OLS regression), allowing adjusted effects, were applied in several steps of the analysis. The highest levels of exertion were reported by employees in the catering department, positions not generally associated with high administrative burden. Perceived high levels of administrative work do increase the level of exertion, but cannot explain the observed pattern. Future ship and trade-specific studies on physical and mental well-being and complementary studies on the catering department’s working conditions and work environment are necessary. 相似文献
105.
106.
The free piston Stirling engine external combustion system was simulated to investigate the diesel-air combustion characteristics in order to demonstrate its feasibility by computational fluid dynamics (CFD). The different effects on combustion were distinguished by analyzing the combustion burner, the injection position of diesel oil, the front tube arrangement of Stirling heater head and the back fin. The results show that the tilted front tube arrangement of the heater head with the back fin is the best practicable technology while the distance between the diesel nozzle position and the swirler top is 0. Its total heat flux is 15.6 kW, and the average heat transfer coefficients of the front and back tubes are 127W/(m2 · K) and 192W/(m2 · K), respectively. The heat transfer is mainly through convection, and the proportion of radiative heat transfer is only 16.9%. The best combustion efficiency of the free piston Stirling engine external combustion system is 86%. 相似文献
107.
Veysi Öztürk Ömer Faruk Arar Ferhat Şükrü Rende Ercan Öztemel Semih Sezer 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2017,55(1):41-71
Training simulators play an important role for sustaining safety, efficiency and cost effective railway transportation. Dynamic modelling of train systems is one of the main modules of training simulators. Validation of the dynamic models with collected real data ensures the fidelity of the simulator utilising the respective models. In this study, a validation process (Dynamic Modelling Validation Process (DyMVaP)) which is developed to support the validation of railway dynamic models is introduced. However, the proposed process can also be used in validating other dynamic models as well. The developed process is based on five steps including the preparation of validation scenarios, sensor deployment, real data collection, data preparation, and comparison of simulated and measured data. Note that the proposed DyMVaP was used for the validation of a full-mission training simulator so called TRENSIM, which was developed for Turkish State Railways. During the study it is realised that the current speed, travelled distance, acceleration (in x, y, z directions), rotation angles (around x, y, z axes), air pressure, in-train pressure/tension forces, traction motor currents, catenary voltage, positions of controllers must be collected synchronously by using proper sensors in order to ensure simulation validation. The required data was collected from locomotive body, bogies, wheel sets and connection of railway cars. The data (~200?GB) collected from the field by applying 27 different scenarios and transformed into appropriate data for utilising the generated dynamic models within the simulator. The measured and simulated data were also compared visually using graphical representation of the parameters as well as performing computations regarding the magnitude, phase and comprehensive error factors. 相似文献
108.
Nowadays, the selective catalytic reduction (SCR) is a promising solution to fulfill stringent nitrogen oxide (NOX) emission standards enforced by worldwide regulation bodies for lean burning engines. However, in the practical operation, urea deposits occur under unfavorable conditions, which bring about a failure of urea dosing strategy, affect the SCR system de-NOx performance and lowering the fuel economy by increasing the engine back pressure. This paper will present 3D deposit model, which can be used to predict the deposit position. Furthermore, a model-based controls strategy and calibration are designed. The comparison test results of both engine emission tests and vehicle field tests shows there is significant deposits improvement with the embedded model. 相似文献
109.
In this paper, we consider a method to create an engine emission simulation model for cycle and customer driving of a vehicle. The emission model results from an empiric approach, also taking into account the effects of engine dynamics on emissions. We analysed transient engine emissions in driving cycles and during representative customer driving profiles and created emission meta models. The analysis showed a significantly higher correlation in emissions when simulating realistic customer driving profiles using the created verified meta models (< 1 % model error) compared to static approaches, which are commonly used for vehicle simulation. Therefore, a transient modelling approach is conducted, which shows a great increase in accuracy in customer driving operation. 相似文献
110.
D.?Savitski V.?IvanovEmail author B.?Shyrokau T.?Pütz J.?De?Smet J.?Theunissen 《International Journal of Automotive Technology》2016,17(2):327-338
Functions of anti-lock braking for full electric vehicles (EV) with individually controlled wheel drive can be realized through conventional brake system actuating friction brakes and regenerative brake system actuating electric motors. To analyze advantages and limitations of both variants of anti-lock braking systems (ABS), the presented study introduces results of experimental investigations obtained from proving ground tests of all-wheel drive EV. The brake performance is assessed for three different configurations: hydraulic ABS; regenerative ABS only on the front axle; blended hydraulic and regenerative ABS on the front axle and hydraulic ABS on the rear axle. The hydraulic ABS is based on a rule-based controller, and the continuous regenerative ABS uses the gain-scheduled proportional-integral direct slip control with feedforward and feedback control parts. The results of tests on low-friction road surface demonstrated that all the ABS configurations guarantee considerable reduction of the brake distance compared to the vehicle without ABS. In addition, braking manoeuvres with the regenerative ABS are characterized by accurate tracking of the reference wheel slip that results in less oscillatory time profile of the vehicle deceleration and, as consequence, in better driving comfort. The results of the presented experimental investigations can be used in the process of selection of ABS architecture for upcoming generations of full electric vehicles with individual wheel drive. 相似文献