A Hybrid Self-Powered System Based on Wind Energy Harvesting for Low-Power Sensors on Canyon Bridges

Hao Cao,Xiaoping Wu,Hao Wu,Yajia Pan,Dabing Luo,Ali Azam,Zutao Zhang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

Canyon cross wind has great potential to be transformed into electricity to power for low-power sensors of the health monitoring devices in bridge field. In this paper, a hybrid wind energy harvesting system (WEHS), integrating piezoelectric and electromagnetic mechanisms, is proposed to supply power for low-power sensors on canyon bridges. Firstly, the S-rotor embedded with a one-way bearing converts wind energy into rotational mechanical energy. Then, the piezoelectric cantilever beam and coils simultaneously convert mechanical energy into electricity under the excitation of the rotational magnet array. For the piezoelectric transducer, the symmetrical poles arrangement of tip magnet reduces the starting wind speed and resistance torque during energy harvesting. In addition, the relationship between different number of excitation magnets and the output of the piezoelectric transducer is explored. Finally, the output electricity is stored in the capacitors to supply power for low power sensors. The experimental results showed that the symmetrical poles arrangement of tip magnet could effectively reduce the starting resistance torque and improve the output power at low wind speeds. Given a wind speed of 6.5 m/s, the maximum output power of the WEHS can reach 19.24 mW with corresponding electrical energy of 75.714 mJ in one sweep period (6 s). The field test results demonstrated that the WEHS could effectively charge for the capacitors and power for a hundred LEDs. Furthermore, the mechanical durability and stability of the WEHS are verified by introducing a self-powered low power sensor system.

An experimental identification model of rotordynamic coefficients of seals using unbalanced synchronous excitation method

Hao Cao,Jian Gang Yang,Wan Fu Zhang,Rui Guo 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.7

This study presents an improved impedance method based on unbalanced synchronous excitation to identify the rotordynamic coefficients of labyrinth seals. The rotordynamic coefficient test is implemented near the cylinder resonance frequency to enlarge the influence of seal force. The force generated by the rotor unbalance is used to provide synchronous frequency excitation for the rotordynamic coefficient test. Four unique equations are set up under two sets of different rotor unbalance conditions to obtain four unknown complex rotordynamic coefficients. The factors that influence the rotordynamic coefficients of seals, namely, unbalance mass, inlet/outlet pressure ratio, and rotating speed, are considered. The dynamic coefficients are minimally affected by different rotor unbalances. The direct items are nearly equal with same signs, whereas the cross-coupled items are nearly equal with opposite signs. All coefficients increase with increasing inlet/outlet pressure ratio and rotating speed. The direct stiffness coefficients increase more quickly than the cross-coupled items. In addition, the effect stiffness and effect damping coefficients are analyzed; results indicate that both coefficients increase with increasing rotating speed.

中国音乐综艺叙事策略对音乐产业流通的影响研究 - 以《声生不息》为例

Cao Lu Hao 대한경영정보학회 2022 대한경영정보학회 학술발표대회 Vol.2022 No.11

中国音乐综艺叙事策略对音乐产业流通的影响研究 - 以《声生不息》为例

Cao Lu Hao 한국경영실무학회 2022 한국경영실무학회 학술발표대회 Vol.2022 No.11

A Calculation Method for the Nonlinear Crowbar Circuit of DFIG Wind Generation based on Frequency Domain Analysis

Hao Luo,Mingyao Lin,Yang Cao,Wei Guo,Li Hao,Peng Wang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The ride-through control of a doubly-fed induction generator (DFIG) for the voltage sags on wind farms utilizing crowbar circuits by which the rotor side converter (RSC) is disabled has being reported in many literatures. An analysis and calculation of the transient current when the RSC is switched off are of significance for carrying out the low voltage ride through (LVRT) of a DFIG. The mathematical derivation is highlighted in this paper. The zero-state and zero-input responses of the transient current in the frequency domain through a Laplace transformation are investigated, and the transient components in the time domain are achieved. With the characteristics worked out from the linear resolving without modeling simplification, the selection of the resistance in the linear crowbar circuit and the value conversion from a linear circuit to a nonlinear one is proposed to setup the attenuation rate. In terms of grid code requirements, the theoretical analysis for the time constant of the transient components attenuation insures the controllability when the excitation of the RSC is resumed and it guarantees the reserved time for the response of the reactive power compensation. Simulations are executed in MATLAB/SIMPOWER and experiments are carried out to validate the theoretical analysis. They indicate that the calculation method is effective for selection of the resistance in a crowbar circuit for LVRT operations.

A Calculation Method for the Nonlinear Crowbar Circuit of DFIG Wind Generation based on Frequency Domain Analysis

Luo, Hao,Lin, Mingyao,Cao, Yang,Guo, Wei,Hao, Li,Wang, Peng The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The ride-through control of a doubly-fed induction generator (DFIG) for the voltage sags on wind farms utilizing crowbar circuits by which the rotor side converter (RSC) is disabled has being reported in many literatures. An analysis and calculation of the transient current when the RSC is switched off are of significance for carrying out the low voltage ride through (LVRT) of a DFIG. The mathematical derivation is highlighted in this paper. The zero-state and zero-input responses of the transient current in the frequency domain through a Laplace transformation are investigated, and the transient components in the time domain are achieved. With the characteristics worked out from the linear resolving without modeling simplification, the selection of the resistance in the linear crowbar circuit and the value conversion from a linear circuit to a nonlinear one is proposed to setup the attenuation rate. In terms of grid code requirements, the theoretical analysis for the time constant of the transient components attenuation insures the controllability when the excitation of the RSC is resumed and it guarantees the reserved time for the response of the reactive power compensation. Simulations are executed in MATLAB/SIMPOWER and experiments are carried out to validate the theoretical analysis. They indicate that the calculation method is effective for selection of the resistance in a crowbar circuit for LVRT operations.

「崔尉子傳」·「蘇知縣羅衫再合」과 「朱鳳傳」의 辨別性

曹昊(Cao, Hao) 국어문학회 2015 국어문학 Vol.58 No.-

唐 皇甫씨의 「崔尉子傳」, 明 馮夢龍의 「蘇知縣羅衫再合」과 朝鮮後期 유행했던 「朱鳳傳」은 이른 시기 두 나라에서 나타났던 작품으로 이야기의 구조가 크게 다르지 않다. 그러나 이 작품들은 후대로 올수록 등장인물이 많아졌고, 그들의 역할이 확대되었으며, 사건 전개가 복잡해졌다는 차이가 있다. 주인공이 임지로 가다가 피습 당하고 그 아내가 사로잡혔다가 도망한다든지, 도적이 양육했던 유복자가 과거에 급제한 후 복수한다는 기본 골격은 유사하다. 그렇지만 시대·지리적 배경 설정이 다르고 등장인물도 다양해졌으며, 특히 주인공이 과거에 급제한 후 벼슬생활을 하는 것이나 임지로 향하다가 수적에게 피습당한 후 부인들의 처세도 세 작품이 다르다. 백성을 향한 관리들의 태도에서도 차이가 크다. 이야기의 마지막에도 차이가 있다. 중국 작품에서는 수적을 치죄하는 것으로 이야기를 매듭지었다. 그러나 「朱鳳傳」의 작가는 복수를 감행한다는 이야기의 결과도 중요한 것이었지만 그보다는 그런 결과를 초래한 것에 대해 報恩이나 容恕와 和解, 事必歸正, 因果應報 사상을 보다 강조하였다. 그리고 어떻게 사는 것이 가장 인간다운 삶인가를 보여주고 있다는 차이점도 간과해서는 안 된다. 바로 이 점이 두 나라 민족의 정서에서 비롯되었던 결과라 본다. 가장 큰 차이라면 유교사상이나 불교신앙보다는 한국의 전통적 민간신앙 요소들을 작품 전개 과정 곳곳에 문학적 장치로 이용하고 있다는 점이다. Choiwejajeon(崔尉子傳) written by Huang Fu(皇甫) in Tang Dynasty, Sojihyeonnasamjaehap(知縣羅衫再合) written by Feng Menglong(馮夢龍) in Ming Dynasty and Jubongjeon(朱鳳傳) that was famous in Late Joseon are in common as work written in the early period of each relevant countries and have similar story structures. However, as approaching to the later time, the number of characters is increased with extended roles and the story progression is more complicated in the work. The basic structure of story is similar: The main character is attacked by a thief on the way to the appointed region. The wife escapes after being captured. The posthumous child is grown by the thief, and later, revenges the thief after qualified from the government official selection test. However, the timely and geographical background is different among the stories and the appearing characters become more various following the time of each story"s release. Especially, the main character"s work as the official after qualified by the government test and the wife"s attitude after the main character is attacked by the thief on the way to the appointed region largely differs among these stories. Chinese stories are ending with punishing the thief. However, the writter of Ju Bong Story shows that, while the revenge is important, forgiveness, reconciliation and ideas of "prevailing and punitive" justice" are more highlighted. Also, the difference from showing "what kind of life is the most humane life" shouldn"t ignored. The reason for such difference can be considered as coming from the emotional difference between the peoples in different countries. The most significant difference is found from that the factors of traditional folk belief of Korea are used as literary devices in various spots in the story rather than Confucius idea or Buddhism belief.

A Combination of a Microemulsion and a Phospholipid Complex for Topical Delivery of Oxymatrine

Fa-Hao Cao,Wu-Qing OuYang,Yan-Ping Wang,Peng-Fei Yue,Shu-Peng Li 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.4

Oxymatrine (OMT), a water-soluble drug, has a very low oral bioavailability because of its low membrane permeability and its biotransformation in the gastrointestinal tract. Formulated as an oxymatrine-phospholipid complex (OMT-PLC) can improve the lipid solubility and effectiveness of OMT. The purpose of this study was to explore the utility of the combination of a microemulsion and an OMT-PLC as a topical delivery vehicle for enhancing the absorption and efficacy of OMT. The solubility of OMT-PLC was determined and phase diagrams of microemulsions were constructed. Various microemulsion formulations were developed and characterized by their physicochemical properties, and their in vitro and in vivo permeability through skin. An optimal microemulsion (ME4), which presented as spherical droplets and consisted of 10.0% OMT-PLC, 8.0% isopropyl myristate, 30.0% Cremophor RH40/polyethylene glycol 400 (1:1) and 52.0% water, was selected. It possessed an average droplet size of 32.4 nm, a low viscosity of 113.7 mPa · s, and a high cloud point of 88°C. Compared to the control solution, ME4 provided better skin permeability in vitro and a higher retention ratio of OMT in skin in vivo. Moreover, ME4 significantly enhanced the antiproliferative activity of OMT on scar fibroblasts. These results indicate that the combination of a microemulsion and a phospholipid complex represents an effective vehicle for topical delivery of OMT.

Research on the Factors Influencing the Reading Volume of WeChat Official Account at Chinese Universities

Lu-Hao Cao,Xi-Yuan Wu K기업경영연구원 2023 KBM Journal(K Business Management Journal) Vol.7 No.2

By the end of 2022, the number of WeChat 5.0 users has reached more than 1000 million, 800 million of whom stay active, and WeChat public platform also had acquired 2 million public accounts. Among the numerous WeChat official accounts, the official accounts of colleges and universities have always been the focus of media attention. With the development of We Media, the presentation mode of WeChat official account has changed from simple information transmission mode to various other modes, and the information presentation mode has become more diversified. By studying the characteristics of content on university WeChat official accounts and reference items for audience reactions such as likes, this study aims to explore the relationship between audience reactions on WeChat official accounts, effectively understand the factors influencing the reading volume of university WeChat official accounts, and explore the communication strategies of WeChat public accounts. This paper uses the content analysis method to rank the number of weekly push articles read by Qingbo's big data on college WeChat public accounts from 2016 to 2017. These ranked articles are selected as samples, and random sampling is conducted from these samples. A total of 1200 valid samples will be analyzed to draw conclusions: The higher the popularity, the more likes and reading volume; The correlation between the originality of the posted article and the reading volume is not strong. I hope this paper can provide some reference meaning for the development of the Wechat official accounts.

Physicochemical characterization and cytotoxicity of chitosanmodified single walled carbon nanotubes as drug carriers

Qing‑Ri Cao,Xiao‑Xue Zhang,Hao‑Yan Huang,Li‑Qing Chen,Hehua Jin,Beom‑Jin Lee,Jing‑Hao Cui 한국약제학회 2019 Journal of Pharmaceutical Investigation Vol.49 No.1

The application of single-walled carbon nanotubes (SWCNTs) as drug carriers is limited by their poor dispersal in aqueous medium. This study aimed to prepare chitosan (CS)-modified SWCNTs (CS-SWCNTs) and to evaluate their physicochemical properties and cytotoxicity. Oxidized SWCNTs (O-SWCNTs) were prepared with the use of strong acid, and the effects of acidizing conditions on the oxidation degree of the O-SWCNTs were investigated. CS was then non-covalently modified on the surfaces of O-SWCNTs. O-SWCNTs and CS-SWCNTs were characterized through ultraviolet spectroscopy, Fourier transform-infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy. The cytotoxic effects of the functionalized SWCNTs were determined through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. O-SWCNTs with relatively complete structure were successfully synthesized through 5 h of treatment with 5 M acid. The amine group of the CS and the carboxyl group of O-SWCNTs interacted in CS-SWCNTs. The functionalized SWCNTs did not aggregate or precipitate in water and exerted no cytotoxic effects on A549 and MCF-7 tumor cells. The CS-SWCNTs possess the advantages of a simple preparation process, excellent water dispersibility, and biocompatibility for drug loading.