An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization...An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization, inversion, all upside down, radix-S block upside down and shift combination, the proposed code is achieved. Theory analysis and simulation performance of the improved code are illustrated. And the results indicate that the suggested method gains a better performance than the traditional one by reasonable choices of the initial value and the S parameter in the im- proved method. Meanwhile the chaotic sequence＇ s characteristic of large addresses is inherited when the chaotic-map is used as the source. This advantage makes this improved code very suitable for the multiple access application in communication system.展开更多
In this paper, an explicitly analytical shock mapping relation is approximately deduced based on the theoretical modeling of the chemical nonequilibrium stagnation flow towards a slightly blunted nose. Based on the re...In this paper, an explicitly analytical shock mapping relation is approximately deduced based on the theoretical modeling of the chemical nonequilibrium stagnation flow towards a slightly blunted nose. Based on the relation, the complex reacting stagnation flow problem can be discussed under the framework of the simplest normal shockwave flow. Therefore, a quantita- tively meaningful criterion for dissociation nonequilibrium flow, that is a specific Damk hler number Da d , is naturally intro- duced as the ratio of the mapping length of the stagnation streamline and the characteristic nonequilibrium scale. Da d is found to be dependent on the flow's rarefaction criterion W r , that is a specific Knudsen number. Then, based on Da d , a normalized analytical formulation is obtained to quantitatively predict the actual degrees of dissociation at the outer edge of the stagnation point boundary layer (SPBL). At last, the direct simulation Monte Carlo (DSMC) method is employed to validate the analytical results, and the related flow mechanism is discussed. The present study not only shows nonequilibrium features of the flow problem, but also provides an indispensable basis for the following study on the nonequilibrium SPBL heat transfer.展开更多
Waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental pol...Waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental pollution.This paper investigates the characteristics of various kinds of waste heat energy,namely,waste heat in exhaust,cooling water and charge air,over the engine’s whole operating region.Based on the energy balance experiments,the energy distribution of a conventional heavy-duty diesel engine is obtained under mapping characteristics.According to exergy analysis,the energy recovery potential for waste heat is studied as well.The experimental results indicate that exhaust energy increases with engine speed and load,while cooling water energy is more sensitive to load,especially at low and middle speed.Charge air energy,on the other hand,mainly counts on speed rather than load.Exhaust energy possesses the highest recovery potential in terms of both quantity and quality.Through waste heat recovery,a dramatic improvement in engine efficiency is achievable,actually,the maximum value can amount to 60%or even more.展开更多
In this paper, a system of generalized symmetric vector quasi-equilibrium problems for set-valued mappings is introduced. By using a scalarization method and a fixed-point theorem, the existence result for its solutio...In this paper, a system of generalized symmetric vector quasi-equilibrium problems for set-valued mappings is introduced. By using a scalarization method and a fixed-point theorem, the existence result for its solution is established. The main result extends the corresponding results in Fu (J. Math. Anal. Appl. 285, 708–713, 2003) and Zhang, Chen and Li (OR Transactions 10, 24–32, 2006).展开更多
文摘An improved method of generating the self-balanced chaotic spread-spectrum code is presented. The chaotic-map pseudorandom sequence is used as the generated source. After a series of processing two-valued quantization, inversion, all upside down, radix-S block upside down and shift combination, the proposed code is achieved. Theory analysis and simulation performance of the improved code are illustrated. And the results indicate that the suggested method gains a better performance than the traditional one by reasonable choices of the initial value and the S parameter in the im- proved method. Meanwhile the chaotic sequence＇ s characteristic of large addresses is inherited when the chaotic-map is used as the source. This advantage makes this improved code very suitable for the multiple access application in communication system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 91116012 and 11202224)the Postdoctoral Science Foundation of China (Grant No. 2011M500415)
文摘In this paper, an explicitly analytical shock mapping relation is approximately deduced based on the theoretical modeling of the chemical nonequilibrium stagnation flow towards a slightly blunted nose. Based on the relation, the complex reacting stagnation flow problem can be discussed under the framework of the simplest normal shockwave flow. Therefore, a quantita- tively meaningful criterion for dissociation nonequilibrium flow, that is a specific Damk hler number Da d , is naturally intro- duced as the ratio of the mapping length of the stagnation streamline and the characteristic nonequilibrium scale. Da d is found to be dependent on the flow's rarefaction criterion W r , that is a specific Knudsen number. Then, based on Da d , a normalized analytical formulation is obtained to quantitatively predict the actual degrees of dissociation at the outer edge of the stagnation point boundary layer (SPBL). At last, the direct simulation Monte Carlo (DSMC) method is employed to validate the analytical results, and the related flow mechanism is discussed. The present study not only shows nonequilibrium features of the flow problem, but also provides an indispensable basis for the following study on the nonequilibrium SPBL heat transfer.
基金supported by the National Natural Science Foundation of China(Grant No.51206117)
文摘Waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental pollution.This paper investigates the characteristics of various kinds of waste heat energy,namely,waste heat in exhaust,cooling water and charge air,over the engine’s whole operating region.Based on the energy balance experiments,the energy distribution of a conventional heavy-duty diesel engine is obtained under mapping characteristics.According to exergy analysis,the energy recovery potential for waste heat is studied as well.The experimental results indicate that exhaust energy increases with engine speed and load,while cooling water energy is more sensitive to load,especially at low and middle speed.Charge air energy,on the other hand,mainly counts on speed rather than load.Exhaust energy possesses the highest recovery potential in terms of both quantity and quality.Through waste heat recovery,a dramatic improvement in engine efficiency is achievable,actually,the maximum value can amount to 60%or even more.
基金the National Natural Science Foundation of China (No.60574073)the Natural Science Foundation Project of Chongqing Science and Technology Commission (No.2007BB6117)
文摘In this paper, a system of generalized symmetric vector quasi-equilibrium problems for set-valued mappings is introduced. By using a scalarization method and a fixed-point theorem, the existence result for its solution is established. The main result extends the corresponding results in Fu (J. Math. Anal. Appl. 285, 708–713, 2003) and Zhang, Chen and Li (OR Transactions 10, 24–32, 2006).
