Research on the Living Room Behavior Pattern of the Elderly in Urban China

Hongchao Xu,YoungHwan Pan 한국디자인학회 2018 한국디자인학회 학술발표대회 논문집 Vol.2018 No.11

The Research Sports Management Monitoring System Based on WSN

Hongchao Xu 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.12

With the rapid development and improvement of public life and social economy, the whole society has entered into the age of information, which can use common computer assisted control system more and more widely. For the demand of the sports management with efficient and safe operation, the wireless sports management monitoring management system of a sports management is designed based on MCP2515/CAN bus in this paper. In order to monitor the operation state information of the sports management real-time, the system monitor front-end is designed by using the platform with Cortex A8 and WinCE6. MCP2515 driver and Wireless communication message is designed by using Modbus/TCP protocol and the remote sports management monitoring and unified management of the sports managements are realized by the two-way communication of GPRS and remote management center. The stable and reliable of the system is proved by the field operation and the system has good application prospect.

Feel The Time

Hongchao Yu 한국콘텐츠학회 2012 ICCC International Digital Design Invitation Exhib Vol.8 No.1

ESS Scheduling for a Microgrid Considering Peak Demand Charge

HongChao Gao(고홍초),Seon-Ju Ahn(안선주),Joon-Ho Choi(최준호),Sang-Yun Yun(윤상윤) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.7

Research on Synthesis and Rheological Properties of Silicone Oil-based Ferrofluid with Dual Surfactants

Hongchao Cui,Jiahao Xu,Jiajia Zhang,Jingjing Lu,Zhenkun li 한국자기학회 2023 Journal of Magnetics Vol.28 No.1

Ferrofluids as a new kind of nano-functional material, possessing both magnetism of solid material and fluidity of liquid material, thus, they have extensive scientific research and engineering application value. To avoid the defects of conventional non- or single silane coupling agent in silicone oil-based ferrofluid preparation, TEOS and KH-792 were introduced as surfactants to modify Fe3O4 magnetic nanoparticles (MNPs). Silicone oil modified by carboxylic acid was used as based liquid because of improved compatibility with surfactants. Silicone oil-based ferrofluid was prepared by high-energy ball milling method, and its rheological properties were studied. The saturated magnetization of the silicon oil based ferrofluid was 142.71 Gs. When external magnetic field was applied, the MNPs formed a chain structure in the microscope. The viscosity of ferrofluid increased with magnetic field and the shear stress rose with shear rate. The viscosity decreased steeply with increasing temperature and shear rate. The viscosity of silicone oil-based ferrofluid was 950 mPa·s at 25 °C and can vary from 2044 mPa·s at 5 °C to 465 mPa·s at 40 °C. The ferrofluid transformed from a Newtonian fluid at zero magnetic field to a shear-thinning pseudoplastic Bingham fluid when an external magnetic field was applied. The viscosity varied from 1.37 to 2.38 × 105 mPa·s at zero shear rate. While, when magnetic field varied from 0 kA/ rose to 160 kA/m, the viscosity increased obviously and this phenomenon became more pronounced as the shear rate decreased. When magnetic field intensity was higher than 64 kA/m, the viscosity increased slowly with increasing shear rates and viscosity curve was close to a straight line at 100 s-1. This study expands the idea of exploring the synthesis of ferrofluids with mixed surfactants. Silicone oil-based ferrofluid is expected to have unique application prospects in the aerospace field, especially in space damping, sealing and biomedicine.

A Novel High Performance SOI LDMOS with Buried Stepped Gate Field Plate

Hongchao Hu,Hongli Dai,Luoxin Wang,Haitao Lyu,Yuming Xue,Tu Qian 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.6

With the continuous development of science and technology, the power semiconductor devices are becoming more and more extensive. A novel silicon-on-insulator (SOI) lateral double-diffused metal–oxide–semiconductor (LDMOS) has been proposed in this paper. The new device is mainly characterized by introducing a stepped gate field plate in the low-K dielectric buried layer (SGFP-LK). On the one hand, the stepped gate field plate introduces extra lateral electric field peaks, which makes the distribution of potential lines more uniform and improves the breakdown voltage (BV). Moreover, the stepped gate fi eld plate decreases the specific on-resistance ( R on,sp ) by a promoted depletion. On the other hand, different from the traditional buried oxygen layer, the low-K dielectric layer strengthens the vertical electric field and signifi cantly increases BV. Ultimately, compared with the conventional device (C-SOI LDMOS), the BV of the SGFP-LK LDMOS is dramatically enhanced by 107% and the R on,sp is reduced by 24.8%. Furthermore, the figure of merit is enhanced by 472%. In addition, the maximum lattice temperature of the SGFP-LK LDMOS is dropped by 23.1 K, which relieves self-heating effects to some extent.

Co-design of Anti-windup Compensator and a Novel Saturation-based Dynamic Event-triggered Mechanism for Asymmetric Saturated System

Hongchao Li,Huimin Deng,Nan Zhang,Mengfan Li 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2

This paper addresses the co-design of anti-windup compensator and a novel saturation-based dynamic event-triggered condition for asymmetric saturated system. Asymmetric saturation frequently appears in practical systems, which may seriously degrade the system performance. For the systems with undetectable state, dynamic output feedback controller is employed in this paper. A saturation-based dynamic event-triggered mechanism related to the upper and lower bounds of asymmetric saturation is proposed in this paper, which has better performance in reducing the event-triggered number than static event-triggered condition. In addition, the minimum triggering time interval is calculated to avoid Zeno behavior. An optimization problem is formulated to maximize estimated stable region for the closed-loop system. Finally, the proposed results are illustrated by a numerical example.

Experimental Study on Mechanical Properties of Q690 High Strength Steel in Marine Corrosive Environment

Hongchao Guo,Tianqi Lei,Jinguang Yu,Defa Wang,Xiaolei Li 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.2

In order to study the mechanical property degradation rule of Q690 high-strength steel in the ocean wave splash area, the rusted specimen is obtained by indoor damp heat surrounding soaking environment corrosion test. The scanning electron microscopy, uniaxial tensile and cyclic loading tests of corroded steel are performed. This paper analyzes the steel from elastic modulus, yield strength, ductility and law of hysteresis degradation under diff erent corrosion cycles and establishes the constitutive model of HSS. The results show that the appearance of HSS is obviously aff ected by the corrosion cycle. With the increase of the corrosion cycle, reddish-brown fl aky corrosion products are formed on the surface of the steel and there are obvious corrosion pits. After 100 days of corrosion, the corrosion rate of steel reached 7.21%; the elastic modulus and yield strength under uniaxial tension load decreased by 10.2% and 4.9%. Under the eff ect of cyclic reciprocating load, the hysteretic energy is reduced by 15.3%; at the same time, the test curve is fi tted by the secondary plastic fl ow model and the Ramberg–Osgood model and it is found that the shape parameter S 1 and the cyclic strengthening coeffi cient K’ are reduced by 20.1% and 10.2%, While the shape parameter S 2 and the cycle strengthening index n’ have no obvious changes.

Diagnosis of rolling element bearing based on multifractal detrended fluctuation analyses and continuous hidden markov model

Hongchao Wang,Zhiqiang Guo,Wenliao Du 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

The conventional signal processing based methods are difficult to achieve satisfactory results for rolling element bearings (REBs)’ weak fault due to the serious influence of interference signal. Intelligent classification technology and the arising popular monitoring technology-performance evaluation assessment (PDA) are the research hotspots of fault diagnosis of REB in recent years, which could resolve the above problem to some extent. Especially the latter could reflect the operating status of the equipment more comprehensively. Effective feature extraction basing on signal processing methods and intelligent algorithm are the two key aspects for the above two technologies which will determine their effectiveness to great extent. Multifractal detrended fluctuation analyses (MDFA) is an effective non-stationary signal processing method which could reveal the multifractality buried in nonlinear and nonstationary vibration signals of REB, and continuous hidden markov model (CHMM) is a mature intelligent algorithm with solid theoretical basis and rich mathematical structure. So a diagnosis method basing on combination of MDFA with CHMM is proposed in the paper, and it could deal with both fault classification and PDA tasks for the diagnosis of REBs. Effectiveness of the proposed method is validated by two different diagnosis experiments, one for fault classification and another for lifecycle performance evaluation of REBs. Compared to state-of-the-art peer methods, the proposed method has the best performance when dealing with fault diagnosis tasks for REBs.

High Thermoelectric Performance of a Heterogeneous PbTe Nanocomposite

Wang, Hongchao,Hwang, Junphil,Snedaker, Matthew Loren,Kim, Il-ho,Kang, Chanyoung,Kim, Jungwon,Stucky, Galen D.,Bowers, John,Kim, Woochul American Chemical Society 2015 Chemistry of materials Vol.27 No.3

<P>In this paper, we propose a heterogeneous material for bulk thermoelectrics. By varying the quenching time of Na doped PbTe, followed by hot pressing, we synthesized heterogeneous nanocomposites, a mixture of nanodot nanocomposites and nanograined nanocomposites. It is well-known that by putting excess amounts of Na (i.e., exceeding the solubility limit) into PbTe, nanodots with sizes as small as a few nanometers can be formed. Nanograined regions with an average grain size of ca. 10 nm are observed only in materials synthesized with an extremely low quenching rate, which was achieved by using a quenching media of iced salt water and cold water. Dimensionless thermoelectric figures of merit, <I>zT</I>, of those heterogeneous nanocomposites exhibited a <I>zT</I> around 2.0 at 773 K, which is a 25% increase compared to <I>zT</I> of a homogeneous nanodot nanocomposite with the largest quenching time in our experiment, i.e. furnace cooled. The power factor increase is 5%, and the thermal conductivity reduction is 15%; thus, <I>zT</I> increase mainly comes from the thermal conductivity reduction.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-3/cm5042138/production/images/medium/cm-2014-042138_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5042138'>ACS Electronic Supporting Info</A></P>