Experimental Research on a Hypersonic Configuration with Blunt Forebody Edges

Xiao, Hong,Xu, Zhe-Zhu,Kim, Lae-Sung,Li, Dong-yang,Lyu, Sung-Ki Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.10

A design method, for hypersonic forebody configuration with blunt edges, was developed by lift body and waverider. Experimental study was conducted. It was showed that the difference of pressure coefficient, at centre-line and side-line on forebody pre-compression surface, was between 2.5% and 16.7% within the Mach number 5 to 7 and attack angle 0 to 12. These differences were slightly bigger than those of non-blunt-edges forebody. However, experimental data also show that the present configuration can achieve the closed shockwave, and can also realize the automatic overflow of boundary layer on forebody pre-compression surface. It is also observed that the present forebody gets a good aerodynamic performance at high Mach numbers. But with increasing attack angle, the advantage was weakened gradually. And, at the degree of side-slip exceeding 8, the side-line pressure is higher than that of center-line, which indicates that the forebody boundary layer does not achiev automatically overflowing to side surface.

Analysis of South Korea's Direct Investment in China

Xiaohong Zhan Jungseok Research Institute of International Logis 2004 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.2 No.2

Using a dynamic perspective this article examines, the general situation of the development of south Korean direct investment in China since 1992, when the two countries established diplomatic relations. It probes many characteristics of South Korean direct investment in China; its late start yet rapid rise; the smaller average value of Korean project investments; the accelerated process of localization by large South Korean enterprises in China; the diversified industrial distribution; and the wide-ranging geographical distribution. It analyses the reasons for the rapid increase in South Korean investment in China: the use of china's low-priced production factors, the direct entry of South Korean enterprises into the Chinese market, and the stable investment environment with fewer labor disputes that China provides. Finally, this article also proves that south Korean enterprises have achieved satisfactory results from their direct investment in China.

The Regulation of Sugar Metabolism in Huangguan Pears (Pyrus pyrifolia Nakai) with Edible Coatings of Calcium or Pullulan during Cold Storage

Xiaohong Kou,Bianling Jiang,Ying Zhang,Jun Wang,Zhaohui Xue 한국원예학회 2016 원예과학기술지 Vol.34 No.6

Sugars play many important roles in plant metabolism and directly influence fruit quality. The effects of two edible coatings, 2% calcium chloride and 1% pullulan, on sugar metabolism in postharvest Huangguan pear fruit were investigated during cold storage. The respiration rate, sugar content and composition, sucrose metabolism enzyme activities [acid invertase (AIV), neutral invertase (NI), sucrose synthase (SS), and sucrose phosphate synthase (SPS)] and expression of the AIV gene were analyzed during storage at 0℃ for 210 days. Coating treatments slowed the decrease of sucrose and hexose, the respiration rate, and the activities of AIV, NI, SS and SPS, thus maintaining high total soluble solids (TSS) and titratable acid (TA) contents in the fruit. There were no significant differences in AIV expression or activity between the treated and control groups of fruits. Both of the coatings could inhibit the activities of sucrose-cleaving enzymes, thus slowing the decrease of sugar content and maintaining high fruit quality during cold storage.

A novel semi-IPN hydrogel: Preparation, swelling properties and adsorption studies of Co (II)

Xiaohong Wang,Haiqian Hou,Yujun Li,Yingying Wang,Chen Hao,Cunwang Ge b 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.41 No.-

A range of super-absorbent semi-IPN hydrogels—polyvinyl alcohol/poly (acrylic acid-co-acrylic amide)(PVA-P(AA-co-AM)) were synthesized via free radical polymerization method under ultrasound-assistedcondition. L16 (45) orthogonal experiments were designed to optimize the synthesis conditions and thesuccess was characterized by FTIR, SEM and TGA. Swelling capacities were studied in various pH solutionand saline solution whose results indicated that pH in solution shows an obvious influence on it and thesalt resistance is greater in salt solution of low valence relative to that of high valence. Meanwhile, itsswelling behavior was evaluated in water solution, which revealed that the swelling process conformedto the Schott model and the diffusion type was non-Fickian diffusion. Moreover, the adsorption on cobalt(II) from aqueous solutions was also investigated in the paper. The optimumpH value was found close to4 for the cobalt (II) adsorption and it was discovered that adsorption kinetics and adsorption isothermsfor cobalt (II) were in accordance with the pseudo-second-order model and the Freundlich modelrespectively. Besides, thermodynamic parameters were calculated for the cobalt (II) adsorption and thefindings revealed that the adsorption behavior is spontaneous and endothermic.

The Design and Reliability Analysis of Elevator Monitoring System Based on the Internet of Things

Xiaohong Pan 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.12

In order to solve the problems of high cost, complicated wiring and inconvenient operation of the elevator monitoring system, this paper designs an elevator safety monitoring system based on Internet of things technologies. In this system, the CC2530 acts as a processor and communication module, the DHT11 as a temperature and humidity sensor module, and the ADXL345 as an accelerometer sensor module. The power supply module uses the chip LM2576S to provide 3V and 3.3V voltage. The fault tree analysis method is employed to analyze the reliability of the system designed in this paper. The data acquisition module, power supply module and MCU I/O port are given relatively large weight, which demonstrates that they are more likely to cause system failure. In this paper, the environmental parameters of elevator in a certain residential area are tested. According to the test results, the average relative errors of temperature, air humidity and velocity are 0.47%, 1.40% and 1.36%, respectively. The experimental results show that this easy-to-operate system can monitor the environmental parameters of the elevator with high precision, and can achieve the real-time monitoring on the running state of the elevator.

Enhanced Global Asymptotic Stabilization Criteria for Delayed Fractional Complex-valued Neural Networks with Parameter Uncertainty

Xiaohong Wang,Zhen Wang,Yingjie Fan,Jianwei Xia,Hao Shen 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.4

This paper addresses the global asymptotic stabilization of delayed fractional complex-valued neural networks(FCVNNs) subject to bounded parameter uncertainty. The problem is proposed for two reasons: 1) The availablemethods for uncertain dynamical systems may be too conservative; 2) The existing algebraic conditions willlead to huge computational burden for large-scale FCVNNs. To surmount these difficulties, the delayed FCVNNswith interval parameters are transformed into a tractable form at first. Then, a simple and practical controller–linearstate feedback controller is designed to achieve the global asymptotic stabilization. By constructing different Lyapunovfunctions and utilizing the fractional-order comparison principle and interval matrix method, two sufficientglobal asymptotic stabilization criteria expressed in LMI forms, are established. The obtained results in this paperimprove and extend some previous published results on FCVNNs. Finally, two numerical examples are provided toillustrate the correctness of the theoretical results.

Efficient Message Scheduling for WDM Optical Networkswith Minimizing Flow Time

Xiaohong Huang,Maode Ma 한국통신학회 2004 Journal of communications and networks Vol.6 No.2

Adaptive Controller Design for a Synchronous Generator with Unknown Perturbation in Mechanical Power

Xiaohong Jiao,Yuanzhang Sun,Tielong Shen 대한전기학회 2005 International Journal of Control, Automation, and Vol.3 No.2

Transient stabilization with voltage regulation is investigated for a synchronous generator when the mechanical power is perturbed to any unknown value within its physical bounds so that the operating point of the system shifts to an unknown point. An adaptive excitation controller is designed based on the backstepping method with tuning functions. It will be shown that the adaptive control law proposed can achieve the convergence of the system states to the new equilibrium point in correspondence with the real value of the unknown mechanical power and the regulation of the terminal voltage to the required value. Simulation results are given to demonstrate the effectiveness of the proposed controller for the transient stabilization and voltage regulation.

First-principles calculations of the effect of Ge content on the electronic, mechanical and acoustic properties of Li17Si4-xGex

Xiaohong Li,Hong-Ling Cui,Rui-Zhou Zhang 한국물리학회 2019 Current Applied Physics Vol.19 No.6

The electronic, mechanical and acoustic properties of Li17Si4-xGex (x=0, 2.3, 3.08, 3.53, and 4) have been investigated by using first-principles calculations based on the density functional theory (DFT). The research shows that the bulk modulus B, Young's modulus E, shear modulus G, and hardness Hv gradually decrease with the increasing Ge content. Li17Si4-xGex have the brittle nature from the analysis of B/G ratio and Cauchy pressure. The maximum Young's moduli are all along [1 1 0] plane, and the sequence of degree of anisotropic property is Li17Ge4 > Li17Si0.48Ge3.52 > Li17Si0.92Ge3.08 > Li17Si1.7Ge2.3 > Li17Si4. The analysis of acoustic velocity shows that all the sound velocities decrease with the increasing Ge content for Li17Si4-xGex (x=0, 2.3, 3.08, 3.53, and 4), and the longitudinal wave along [111] direction is fastest for the studied compounds. Debye temperature ΘD, vt and vl decrease with the increasing Ge content. The minimum thermal conductivity decreases with the increasing Ge content, and Li17Si4-xGex have low thermal conductivities and are not potential thermal conductors. The analysis of electronic properties indicates that Li17Si4-xGex have the metal nature and anisotropic electrical conductivity. The electric conduction is improved with the increasing Ge content.

Intracranial Artery Calcifcation and Its Clinical Signifcance

Xiaohong Wu,Xiang-Yan Chen,Li Juan Wang,Ka Sing Wong 대한신경과학회 2016 Journal of Clinical Neurology Vol.12 No.3

Intracranial arterial calcifcation (IAC) is an easily identifable entity on plain head computed tomography scans. Recent studies have found high prevalence rates for IAC worldwide, and this may be associated with ischemic stroke and cognitive decline. Aging, traditional cardiovascular risk factors, and chronic kidney disease have been found to be associated with IAC. Te severity of IAC can be assessed using diferent visual grading scales or various quantitative methods (by measuring volume or intensity). An objective method for assessing IAC using consistent criteria is urgently required to facilitate comparisons between multiple studies involving diverse populations. Tere is accumulating evidence from clinical studies that IAC could be utilized as an indicator of intracranial atherosclerosis. However, the pathophysiology underlying the potential correlation between IAC and ischemic stroke—through direct arterial stenosis or plaque stability—remains to be determined. More well-designed clinical studies are needed to explore the predictive values of IAC in vascular events and the underlying pathophysiological mechanisms.