3,743 research outputs found
Dao shu shi er zhong / [(Qing) Liu Yiming zhuan bian] 道書十二種 / [(清) 劉一明撰編]
Full text linkContents: Wu dao po yi 悟道破疑 -- Hui xin ji 會心集 -- Zhou yi chan zhen 周易闡真 -- Tong guan wen 通關文 -- Xiang yan po yi 象言破疑 -- Zhi nan zhen 指南針 -- Can wu zhi yan 參悟直言 -- Wu dao lu 悟道錄 -- Xiu zhen bian nan 修真辨難 -- Huang ting jing 黄庭經 -- Xiu zhen jiu yao 修真九要 -- Wu gen shu 無根樹
Lan Zhou lecture.
No full textT.H.H. Pian.Recording venue: 蘭州鐵道學院.Live recording.Electronic reproduction from Rulan Chao Pian U-matic collection.Spoken in Chinese.T.H.H. Pian.Recording venue: Lan Zhou tie dao xue yuan
Thermal Stress Emulation of Power Devices Subject to DFIG Wind Power Converter
Full text linkThe turbine system equipped with doubly-fed induction generation (DFIG) is widely used in wind power generation. Due to the increasing focus on its prolonged lifespan, it is particularly important to ensure the accurate thermal stress estimation and system reliability in the industrial field. This paper mainly focuses on the thermal stress and lifetime of power semiconductor devices used in DFIG back-to-back converters and its mission profile emulator H-bridge converter. By setting different loading profiles, the power consumption, as well as the junction temperature of the devices in the DFIG power converter is compared with the H-bridge emulator. Through lifetime model of the power device, the lifespan can be calculated according to the annual wind profile. PLECS simulation is applied to verify the comparison between the DFIG power converter and H-bridge converter.</p
Model-Based Thermal Stress and Lifetime Estimation of DFIG Wind Power Converter †
Full text linkTurbine systems equipped with doubly fed induction generation (DFIG) are becoming increasingly vital in wind power generation, with the reliability of the devices serving as a pillar in the industrial sector. Thermal stress and lifetime assessment are fundamental indicators in this regard. This paper primarily addresses the thermal stress and lifespan of power semiconductor devices utilized in a DFIG grid-side converter (GSC) and rotor-side converter (RSC). PLECS (Piecewise Linear Electrical Circuit Simulation) is employed to validate the electrical and thermal stress of the power devices. Additionally, Ansys Icepak, a finite element analysis (FEA) software, is utilized to confirm temperature fluctuations under various operations. The power consumption and junction temperature of the power devices in the GSC and RSC of a 2 MW DFIG are compared. It is evident that the most stressed power semiconductor is the IGBT for the GSC with a temperature swing of 3.4 °C, while the diode in the RSC is the most stressed with a temperature swing of 10.1 °C. This paper also presents a lifetime model to estimate the lifespan of the power device based on the annual wind profile. By considering the annual mission profile, we observe that the lifetime of the back-to-back power converter is limited by the diode of the RSC, whose B10 lifetime is calculated at 15 years.</p
Comparative Analysis of Power Semiconductor Thermal Stress in DC and AC Power Cycling
Full text linkPower semiconductors are gradually evolving towards lower cost, higher efficiency, higher power density, while they are considered to the most important component in the field of power electronics. Therefore, accelerated power cycling testing of power modules under different temperature stresses is required, where the accurate mapping of junction temperature becomes an important part. In this paper, theoretical analysis is carried out for both the DC and AC power cycling, in which the power dissipation and thermal stress of power semiconductor devices are in focused. Detailed derivation of the relationship between losses dissipation, junction temperature, and temperature swing are presented. At the same time, the differences, advantages and disadvantages of DC power cycling and AC power cycling are compared and analyzed. PLECS simulation is used to verify the correctness of the theoretical models
Influence of under-chassis-suspended equipment on high-speed EMU trains and the design of suspension parameters
No full textA numerical method for the calculation of the frequencies of vibration of a car body on a high-speed electric multiple unit train with under-chassis-suspended equipment is proposed. In addition, the design of the parameters of the suspension system for the equipment is presented; it is based on the principles of mode matching, transmissibility matching, and consideration of the optimal vibration of both car body and equipment. It is shown that by tuning the suspension stiffness, the first vertical bending frequency of the car body displays a frequency-hopping phenomenon. The first vertical bending frequency of the car body can be enhanced by optimizing the suspension parameters, so as to suppress the vibrations of both the car body and the suspended equipment
Chang dao wen 唱 道 文.
No full textSha zhou 沙 州. Da Tang guo 大 唐 國. Chang dao wen 唱 道 文. Yong an si 永 安 寺Numérisation effectuée à partir d'un document original.Fin manque. Titre initial : Chang dao wen yi ben 一 本. Texte récité au monastère Yong an 永 安 寺 de Sha zhou 沙 州 du pays des grands Tang, Da Tang guo 大 唐 國, en l'an chou (929). Même texte que le Pelliot chinois 3228 et S. 5560. Seuls les noms des monastères et les dates varient. A 4 reprises, sur les col. 16, 17 et 21, mentions san shuo 三 說, en petits car. Cf. TKBG , p. 70. Écr. entre kai et xing. Encre assez foncée. 24 col., 20 à 23 car. par col. Marges tracées, pas toujours respectées, sup. et inf. 1,2 à 1,5 cm. Réglures
First Deployed DAO with True Full Decentralisation
No full textBlockchain technology has allowed for the emergence of a new type of organization, the Decentralized Autonomous Organization (DAO). They have gained significant traction in recent years, reaching market capitalizations of up to 60 billion USD in 2021. These organizations coordinate economic activity by an unbounded group of people within an adversarial environment. However, despite their potential, currently deployed DAOs face notable challenges related to centralization in governance and infrastructure. This work addresses these limitations by proposing a novel architecture for a fully decentralized DAO with no compromises. We introduce a scalable governance protocol utilizing multi-signature schemes to manage shared assets effectively. To demonstrate the feasibility of our approach, we implement, deploy, and evaluate a real-world DAO called Music DAO. Music DAO serves as a compelling use case, enabling listeners to collectively invest in and listen to their favorite artists. This research represents a significant advancement in the field of decentralized organizations, with the potential to revolutionize the way people collaborate and organize themselves.Computer Science | Data Science and Technolog
Experimental Data on Fire-Resistance Behavior of Reinforced Concrete Structures with Example Calculations
Full text linkThis thesis selects concrete, steel and their relation as research subjects, mainly commentary and discusses the property changes of steel and concrete materials under and after high temperature.The differences and comparisons of reasearch methods and ways between different researchers and different papers,particularly for chinese researches and chinese papers,and partly for comparison between chinese papers methods and Euro-Amercian papers methods about Fire Resistance Behavior of Reinforced Concrete will be summarized and analyzed.The researches on fire-resistance behavior of reinforced concrete become more and more important all over the world. And I would find differences between Chinese researches results, between Chinese researches results and other countries researches results
Method of multi-mode vibration control for the carbody of high-speed electric multiple unit trains
No full textA method of multi-mode vibration control for the carbody of high-speed electric multiple unit (EMU) trains by using the onboard and suspended equipments as dynamic vibration absorbers (DVAs) is proposed. The effect of the multi-mode vibration on the ride quality of a high-speed EMU train was studied, and the target modes of vibration control were determined. An equivalent mass identification method was used to determine the equivalent mass for the target modes at the device installation positions. To optimize the vibration acceleration response of the carbody, the natural frequencies and damping ratios of the lateral and vertical vibration were designed based on the theory of dynamic vibration absorption. In order to realize the optimized design values of the natural frequencies for the lateral and vertical vibrations simultaneously, a new type of vibration absorber was designed in which a belleville spring and conventional rubber parts are connected in parallel. This design utilizes the negative stiffness of the belleville spring. Results show that, as compared to rigid equipment connections, the proposed method effectively reduces the multi-mode vibration of a carbody in a high-speed EMU train, thereby achieving the control objectives. The ride quality in terms of the lateral and vertical vibration of the carbody is considerably improved. Moreover, the optimal value of the damping ratio is effective in dissipating the vibration energy, which reduces the vibration of both the carbody and the equipment
- …
