Active power decoupling method for single‑phase PWM converters without LC branch sensors

Jian Xiong,Jianzhong Zhang,Zheng Xu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.7

The presence of ripple power in a converter system has a negative influence on both control performance and reliability. Active power decoupling (APD) is a practical technique to deal with such problems. However, the APD method requires extra sensors on the LC branch, which increases the complexity and cost of the control system. This paper puts forward a new APD method to handle undesirable ripple power for H-bridge PWM converters. When compared with previous APD methods, the proposed APD method eliminates the current and voltage sensors on the LC branch by utilizing a ripple voltage control loop. Then, both the cost and reliability of the converter system are improved. To improve the control performance, an APD method that only has a voltage sensor in the LC branch is also discussed. Simulation results show that the DC-link voltage ripples can be decreased due to the application of the proposed APD method. Finally, the effectiveness of the proposed method is verified by the experimental results.

High alcohol-soluble MoOx gel for interfacial layer in organic solar cells

Jian Xiong,Zhen He,Shiping Zhan,Bingchu Yang,Xiaowen Zhang,Ping Cai,Cong Xu,Xiaogang Xue,Jian Zhang 한국물리학회 2017 Current Applied Physics Vol.17 No.8

Water-free solvent soluble, low-temperature processed metal oxides are important for preparing efficient and stable electronic devices, as well as the convenience in simplifying the device production process. Here we reported a facile approach with the features of low-temperature and solution-based process for the formation of a MoOx (s-MoOx) film as interface layer in polymer solar cells (PSCs). The absorbability, elementary composition, electronic property and surface microstructure of the s-MoOx are investigated in detail by ultravioletevisible spectrophotometer (UVevis), X-ray photoelectron spectrometry (XPS), ultraviolet photo-electron spectrometer (UPS) and atomic force microscopy (AFM). These investigations confirmed that such MoOx xerogel has high solubility in the organic alcohol solvents, such as ethanol and methanol. Meanwhile, this s-MoOx can be applied as the interfacial layer in organic solar cells via a low-temperature treatment (about 100 C) due to its proper physical properties, and a power conversion efficiency (PCE) over 3% was achieved. In addition, the devices with s-MoOx shows excellent air-stability, and the PCE efficiency can maintain about 84% of its initial value after 100 h exposure in air, which is dramatically enhanced comparing with the common devices with PEDOT:PSS layer.

Research on The SWIPT System Throughput Based on Interference Signal Energy Collecting

( Jianxiong Li ),( Hailong Jiang ) 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.8

The general interference is the imperative trouble for simultaneous wireless information and power transfer (SWIPT) system. Although interference has bad influences on the performance of the system, it carries energy simultaneously. In this paper, the energy-constrained relay of the SWIPT system needs to spend much time on energy collecting (EC) in the information transmission (IT) period. Therefore, we propose the scheme of interference signal energy collecting (ISEC) when the interference is strong, and the SWIPT system does not carry out IT. The relay of the system continues to collect energy and stores it until the interference has minimal impact on IT. Then the system performs IT. We divide the collected interference energy equally into several parts, and each IT block receives one part. The proposed scheme is appealing because it can reduce the time of EC in IT period to make the relay spends more time forwarding the received signal in order to improve the performance of the system throughput. Furthermore, we propose a time-switching (TS) protocol based on EC at the relay. And it allows the relay forwarding signal at an appropriate power. Under the protocol, the time of EC can be flexible according to the forwarding power that we give so that the collected energy can be used more efficiently. We give the expressions of the system throughput according to the proposed scheme and protocol. Moreover, the influence of the interference power on the system throughput is also studied.

Junction Temperature Estimation Approach Based on TSEPs in Multichip IGBT Modules

Jianxiong Yang,Yanbo Che,Li Ran,Borong Hu,Mingxing Du 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9

Power semiconductor chips are parallelly packed in modules to achieve a specific current capacity and power level. An inhomogeneous degradation of the solder layer makes the junction temperature between chips unevenly distributed in multichip modules. The real matters of the junction temperature represented by the terminal electrical characteristics are not known when a junction temperature difference occurs in the internal chip of a multichip IGBT module. This paper analyzes the electrothermal coupling characteristics among the chips in multichip modules and establishes a mathematical model of the electrothermal relationship. To accurately control the different temperature distributions and uneven aging conditions of paralleled chips, two power modules or two discrete devices packaged in a TO-247 are connected in parallel to simulate a multichip power module. The correctness of the proposed electrothermal model and the feasibility of simulating multichip modules are verified through experiments. The findings indicate that the temperature evaluated by the threshold voltage approaches the maximum temperature of the chips inside the module. The junction temperature evaluated by the maximum change rate of the collector–emitter voltage and that of the collector current approach are used to obtain the average temperature.

The Five Buddha Districts on the Yunnan-Burma Frontier: A Political System Attached to the State

Jianxiong Ma 고려대학교 민족문화연구원 2013 Cross-Currents Vol.- No.8

The Five Buddha Districts system prevailed from the 1790s to the 1880s on the frontier between Yunnan, in Southwest China, and the Burmese Kingdom, in the mountainous areas to the west of the Mekong River. Through more than a century of political mobilization, the Lahu communities in this area became an integrated and militarized society, and their culture was reconstructed in the historical context of ethnic conflicts, competition, and cooperation among the Wa, Dai, and Han Chinese settlers. The political elites of the Five Buddha Districts, however, were monks who had escaped the strict orthodoxy of the Qing government to become local chieftains, or rebels, depending on political changes in southern Yunnan. As a centralized polity, the Five Buddha Districts system was attached to the frontier politics of the Qing state before the coming of European colonial powers. The Qing state provided a sociopolitical space for local groups to develop their political ideals between various powerful Dai-Shan chieftains. The negotiation, competition, and cooperation between the Five Buddha leadership and the Qing, Dai chieftains, and neighboring political powers had been thoroughly integrated into the frontier politics of this interdependent society for more than two hundred years. As the history of the Yunnan-Burma frontier formation shows that no mountain space existed to allow the natives to escape from the state through their shifting agriculture, and anarchism was not practiced by the mountain people who were separated from the state, the author argues that a stateless region like James Scott’s “Zomia” did not historically exist in this region.

A semi-analytical method of time-varying mesh stiffness in concentric face gear split-torque transmission system

Jianxiong Dong,Jin-Yuan Tang,Zehua Hu,Yi Wang 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2

Concentric face gear split-torque transmission system (CFGSTTS) has great applied value in the field of aeronautical transmission due to the characteristic of high integration. Mesh stiffness, as one of the most primary sources of vibration, is vitally important for the dynamic performances of gear transmission system. The existing finite element method (FEM) and analytical method (AM) are not suitable for tackling the mesh stiffness calculation of closed-loop multi-branch system such as CFGSTTS. Thus, a semi-analytical method (SAM) is presented and verified, which combines the high precision of FEM with the high efficiency of AM. Additionally, the differences between the mesh stiffness of independent face gear drive and that of the same gear pair in CFGSTTS under accordant load is researched by applying SAM. The influence rules of distribution angle and load condition on the mesh stiffness of gear pairs considering system structure are also studied. Results demonstrate that the mesh stiffness of gear pairs in CFGSTTS is time-varying and tends to be consistent with each other by adjusting load parameters.

Sertad1 Induces Neurological Injury after Ischemic Stroke via the CDK4/p-Rb Pathway

Jianxiong Li,Bin Li,Yujie Bu,Hailin Zhang,Jia Guo,Jianping Hu,Yanfang Zhang 한국분자세포생물학회 2022 Molecules and cells Vol.45 No.4

SERTA domain-containing protein 1 (Sertad1) is upregulated in the models of DNA damage and Alzheimer’s disease, contributing to neuronal death. However, the role and mechanism of Sertad1 in ischemic/hypoxic neurological injury remain unclear. In the present study, our results showed that the expression of Sertad1 was upregulated in a mouse middle cerebral artery occlusion and reperfusion model and in HT22 cells after oxygen-glucose deprivation/reoxygenation (OGD/R). Sertad1 knockdown significantly ameliorated ischemia-induced brain infarct volume, neurological deficits and neuronal apoptosis. In addition, it significantly ameliorated the OGD/R-induced inhibition of cell viability and apoptotic cell death in HT22 cells. Sertad1 knockdown significantly inhibited the ischemic/hypoxic-induced expression of p-Rb, B-Myb, and Bim in vivo and in vitro. However, Sertad1 overexpression significantly exacerbated the OGD/R-induced inhibition of cell viability and apoptotic cell death and p-Rb, B-Myb, and Bim expression in HT22 cells. In further studies, we demonstrated that Sertad1 directly binds to CDK4 and the CDK4 inhibitor ON123300 restores the effects of Sertad1 overexpression on OGD/R-induced apoptotic cell death and p-Rb, B-Myb, and Bim expression in HT22 cells. These results suggested that Sertad1 contributed to ischemic/hypoxic neurological injury by activating the CDK4/p-Rb pathway.

A dependent stress–strength interference model based on mixed copula function

Jianxiong Gao,Zongwen An,Bo Liu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10

In the traditional Stress–strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.

A Peer-to-Peer Communication Model using Software-based Access Point Techniques

Jianxiong Yin,Elmurod Talipov,Hojung Cha(차호정) 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.2

Volatile Organic Compounds of Black Locust Logs Heated at 250℃

Jianxiong Lu,Sang-Bum Park,Hee-Young Lee,Ho-Yang Kang 한국가구학회 2009 한국가구학회지 Vol.20 No.3

Less used small diameter logs of black locust were heated at 250℃ for improving utilization. The volatile compounds emitted by the heated logs were analyzed. Their effect of formaldehyde absorption was evaluated with PB. Ester and acid compounds were dominant in content. Especially, methyl acetate and acetic acid showed the highest contents. The total content of aromatic compounds decreased as heating time increased. Amoung ketone compounds, The contents of 2-propanone, 2-pentanone, 3-petanone, 3-hexanone and cyclopentenone decreased with the increase of heating time, but the others did not. The contents of the chemicals, furfural and 3-pentanol, increased with heating time, while that of 2-methyl butanal decreased. It was hard to say that formaldehyde was absorbed by the heated black locust samples. Some decorative goods were designed with the heated logs.