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Power Control in Uplink and Downlink CDMA Systems with Multiple Flow Types
Li Yun,Ephremides Anthony The Korea Institute of Information and Commucation 2006 Journal of communications and networks Vol.8 No.3
We consider a power controlled code division multiple access (CDMA) system with multiple flow types. At each of the N nodes, there are F flow types with different signal-to-interference-and-noise-ratio (SINR) requirements. To keep the complexity of the transmitter low, we assume that each node uses the same power level for all its flows. The single flow case has been fully solved and is well-understood. We concentrate on the multiple flow case, and use a novel and different approach. For the uplink problem with N = 2 and F arbitrary, the necessary and sufficient conditions to have a solution are found and proved. For the general N > 1 uplink problem, we provide a necessary condition for the problem to have a solution and an iterative algorithm to find the optimum solution. For the downlink case with F > 1 some properties of the optimal sequences are obtained.
李?(Li Yun),王川(Wang Chuan) 중국문화연구학회 2009 중국문화연구 Vol.0 No.15
From the perspective of modality, this paper proposes the term of Modal Adverbs Denoting Euphemism, which canbe further divided into four sub-types on the standard of uncertainty. Furthermore, the paper figures out the different syntactic features of the said four sub-types. The combination of semantics and syntax will shed some lights on the teaching of Chinese to speakers of other languages.
Analysis upon fuel injection quantity variation of common rail system for diesel engines
Liyun Fan,Yun Bai,Xiuzhen Ma,Enzhe Song 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7
Fuel injection quantity variation of common rail system has effect on the stability and reliability of diesel engines. For purpose of investigating the influence rule and mechanism of fuel injection quantity variation caused by parameters, taking account of the influence of fuel physical properties on dynamic injection characteristics of the system, a bond graph model of common rail injector has been proposed based on bond graph methodology and the state equations of the system are obtained. Comparisons between calculated fuel injection quantities by the numerical model and experimental measurements at different rail pressures and injection pulse widths indicate that the developed model can reasonably predict the fuel injection quantity characteristic of the system. Fuel injection quantity variation characteristics caused by the parameters of common rail injector have been analyzed in entire operating conditions. The selected parameters are delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter. The variation rules of quantitative percentages are obtained by quantitative analysis upon fuel injection quantity variation influential factors. It is concluded that ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter have the most significant effect on fuel injection quantity variation, and the followed are delivery chamber diameter and needle seat semi-angle. In addition, needle cone semi-angle also results in the variation of fuel injection quantity, but the effect is insignificant.
Liyun Xiang,Jing Ya,Lixia Li,Zhifeng Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.2
TiO2 nanotube arrays (TiO2NTs) were prepared by anodic oxidation, then soaked in thiourea solution, and finally transformed into modified anatase TiO2 structure by heat treatment. Through the test results of SEM, TEM, XRD, XPS, UV-vis diffuse reflectance spectroscopy, photo-current and so on, finding that S replaces Ti4+ in the form of S6+, and part of the Ti4+ is reduced to Ti3+. Ladder type energy band structure, producing by the appearance of S6+ and Ti3+, makes the electron–hole more easily and increases the carrier transfer speed to a certain degree. The photo-current size has increased from 1.07 mA/cm2 to 2.13 mA/cm2. By simulating decolorization test of sample to methylthionine chloride under visible light, the degradation rate of the modified sample to methylene blue increases from 32% to 63%, and increased by 1.97 times.
Liyun Li,Xiuli Du,Jing Zhou 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.10
In China, with the rapid development of subway construction, the site deformation induced by subway construction is an interesting and hot issue in civil engineering. Focusing on the mechanism and characteristics of site deformation induced by parallel shield tunnel construction in typical soil-rock composite strata of Changchun region, and relying on the subway tunnel between Northeast Normal University Station and Gongnong Square Station, which belongs to the Changchun Metro Line 1, the tunnel construction process is simulated using FLAC3D software. In this paper, the numerical modeling and parameters for shield tunneling are described in detail, and the mechanism and characteristics of site deformation induced by shield tunneling are discussed systematically. Furthermore, the influence of construction parameters on site deformation, including construction sequence, tunnel spacing and earth chamber pressure, are studied. The results can provide reference for similar projects in the future.