Surface Texture Transformation in Micro-Cutting of AA6061-T6 with the Rehbinder Effect

Jiayi Zhang,Yan Jin Lee,Hao Wang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.4

The Rehbinder effect (R-effect) on microcutting has been successful to augment machinability of ductile metals; however, there is a lack in understanding of its influence on texture evolution in the machined surfaces. This study validates the R-eff ect on AA6061-T6 and characterises the influence of the R-effect on the texture transformation in the machined surface. Microhardness tests reveal that the R-effect produces softer surfaces (87–96 HV) as compared with the surfaces produced conventionally (96–108 HV), which is attributed to the differences in grain types. A large fraction of substructured grains (96.4%) exists in the surfactant-affected subsurface while a higher proportion of deformed grains (42.8%) forms during conventional microcutting. In addition, the main texture components of the conventionally produced surface are Cube, Goss and S textures, which differ from the dominant volumes of Copper and R textures under the R-effect. The differences are results of the stress states induced during microcutting, which is exemplified through numerical simulations that consider the reduction in fracture toughness of the material with the R-effect. The advanced understanding of the R-effect better positions the use of surfactants as a cleaner near-dry metalworking fluid.

PD-type ℓ2-ℓ∞ Intermittent Pinning Synchronization Control of Discrete Time-delay Nonlinear Dynamical Networks

Jiayi Zhang,Guoliang Wei,Shuai Liu,Derui Ding 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.8

In this paper, the PD-type `2 − `∞ synchronization control problem is concerned for a class of discrete time-delayed nonlinear dynamical networks. A PD-type (proportional-derivative-type) pinning control protocol is proposed where only a small fraction of network nodes is controlled in order to achieve the global synchronization performance. Meanwhile, for the sake of decreasing the update frequency of the controller, the periodic intermittent control strategy is developed. The main purpose of the addressed problem is to design a PD-type intermittent pinning feedback controller such that the closed-loop system achieves both the exponential synchronization and the prescribed `2 −`∞ performance index. Subsequently, by means of the Lyapunov-Krasovskii functional method, a sufficient condition is established under which the addressed PD-type controller design problem is recast into a linear convex optimization one that can be easily solved via available software packages. Finally, a simulation example is given to show the applicability of the developed theoretical results.

Chitosan/hydroxyapatite composite coatings on porous Ti6Al4V titanium implants: in vitro and in vivo studies

Zhang, Ting,Zhang, Xinwei,Mao, Mengyun,Li, Jiayi,Wei, Ting,Sun, Huiqiang Korean Academy of Periodontology 2020 Journal of Periodontal & Implant Science Vol.50 No.6

Purpose: Titanium implants are widely used in the treatment of dentition defects; however, due to problems such as osseointegration failure, peri-implant bone resorption, and periimplant inflammation, their application is subject to certain restrictions. The surface modification of titanium implants can improve the implant success rate and meet the needs of clinical applications. The goal of this study was to evaluate the effect of the use of porous titanium with a chitosan/hydroxyapatite coating on osseointegration. Methods: Titanium implants with a dense core and a porous outer structure were prepared using a computer-aided design model and selective laser sintering technology, with a fabricated chitosan/hydroxyapatite composite coating on their surfaces. In vivo and in vitro experiments were used to assess osteogenesis. Results: The quasi-elastic gradient and compressive strength of porous titanium implants were observed to decrease as the porosity increased. The in vitro experiments demonstrated that, the porous titanium implants had no biological toxicity; additionally, the porous structure was shown to be superior to dense titanium with regard to facilitating the adhesion and proliferation of osteoblast-like MC3T3-E1 cells. The in vivo experimental results also showed that the porous structure was beneficial, as bone tissue could grow into the pores, thereby exhibiting good osseointegration. Conclusions: Porous titanium with a chitosan/hydroxyapatite coating promoted MC3T3-E1 cell proliferation and differentiation, and also improved osseointegration in vitro. This study has meaningful implications for research into ways of improving the surface structures of implants and promoting implant osseointegration.

Chinese zodiac of font dream

Zhang Jiayi 한국콘텐츠학회 2020 ICCC International Digital Design Invitation Exhib Vol.2020 No.11

Chinese zodiac of font dream

Zhang Jiayi 한국콘텐츠학회 2020 한국콘텐츠학회 ICCC 논문집 Vol.2020 No.11

Project Summary of Three Gorges' 840MVA Hydro-generator with Close-Loop-Self-Circulating Evaporative Cooling System

Yuan, Jiayi,Meng, Dawei,Gu, Guobiao,Song, Fuchuan,Zhang, Tianpeng Journal of International Conference on Electrical 2014 Journal of international Conference on Electrical Vol.3 No.1

In December 2011 and July 2012, two sets of 840MVA hydro-generator of Three Gorges on Yangtze River with Close-loop-self-circulating evaporative cooling (CLSCEC) system were put into commercial operation. In this paper, we make engineering summary of these two generators with CLSCEC system. We also make a comparison between the internal water cooling (IWC) hydro-generator and the CLSCEC hydro-generator used in Three Gorges power plant in fields of their operating characteristics, working performances, technical features, working safety and reliability. In addition, engineering structures, type tests' results and systematic emulating calculation of CLSCEC schemes are analyzed.

Rapid quantitative typing spectra model for distinguishing sweet and bitter apricot kernels

Xue Huang,Jiayi Xu,Feng Gao,Hongyan Zhang,Ling Guo 한국식품과학회 2022 Food Science and Biotechnology Vol.31 No.9

Amygdalin content in apricot kernels is an essential factor in the rapid and nondestructive identification of sweet or bitter apricot kernels through spectroscopy. Now, amygdalin content has been determined by high-performance liquid chromatography and near-infrared spectral database to construct a model so that the sweet or bitter apricot kernels could be identified and classified. Principal component analysis–K-nearest neighbor classification algorithm combined with multivariate scattering correction pretreatment method could distinguish sweet and bitter apricot kernels in the wavelength range of 1650–1740 nm with 98.3% accuracy and apricot kernel species with 96.3% recognition rate in the full wavelength spectrum. Furthermore, prediction of amygdalin content in bitter and sweet apricot kernels by partial least squares model was superior to that by back-propagation neural network model. This study provides a theoretical basis for quality identification of apricot kernel quality, as well as a method for nondestructive and rapid detection of sweet and bitter apricot kernels.

5G Network Slices Embedding with Sharable Virtual Network Functions

Chengli Mei,Jiayi Liu,Jinyan Li,Lei Zhang,Menghan Shao 한국통신학회 2020 Journal of communications and networks Vol.22 No.5

Network slicing (NS) is recognized as a key technology for the 5G mobile network in enabling the network to support multiple diversified vertical markets over a shared physicalinfrastructure with efficiency and flexibility. A 5G NS instance iscomposed of a set of virtual network function (VNF) instances toform the end-to-end (E2E) virtual network for the slice to operateindependently. The deployment of a NS is a typical virtual network embedding (VNE) problem. We consider a scenario in whichVNF instances can be shared across multiple slices to further enhance the utilization ratio of the underlying physical resources. ForNSs with sharable VNF instances, the deployment of the slice instances is essentially the embedding of multiple virtual networkscoupled by the VNFs shared among slices. Hence, we formulatethis sharable-VNFs-based multiple coupled VNE problem (SVMVNE) through an integer linear program (ILP) formulation, anddesign a back-tracking coordinated virtual network mapping algorithm. Simulation results demonstrate that VNF-sharing can enhance the slice acceptance ratio with the same physical network,which represents higher physical resource utilization. Moreover,our approach achieves higher acceptance ratio by comparing to abaseline algorithm.

Joint Beamforming and Power Allocation for Multiple Primary Users and Secondary Users in Cognitive MIMO Systems via Game Theory

( Feng Zhao ),( Jiayi Zhang ),( Hongbin Chen ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.6

We consider a system where a licensed radio spectrum is shared by multiple primary users (PUs) and secondary users (SUs). As the spectrum of interest is licensed to primary network, power and channel allocation must be carried out within the cognitive radio network so that no excessive interference is caused to PUs. For this system, we study the joint beamforming and power allocation problem via game theory in this paper. The problem is formulated as a non-cooperative beamforming and power allocation game, subject to the interference constraintsof PUs as well as the peak transmission power constraintsof SUs. We design a joint beamforming and powerallocation algorithm for maximizing the total throughput of SUs, which is implemented by alternating iteration of minimum mean square error based decision feedback beamforming and a best response based iterative power allocation algorithm. Simulation results show that the algorithm has better performance than an existing algorithm and can converge to a locally optimal sum utility.

Dietary and herbal supplements for fatigue: A quality assessment of online consumer health information

Jeremy Y. Ng,Catherine Jiayi Zhang,Saad Ahmed 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.4

Background The Internet is increasingly utilized by patients to acquire information about dietary and herbal supplements (DHSs). Previously published studies assessing the quality of websites providing consumer health information about DHSs have been found to contain inaccuracies and misinformation that may compromise patient safety.. The present study assessed the quality of online DHSs consumer health information for fatigue. Methods Six unique search terms were searched on Google, each relating to fatigue and DHSs, across four countries. Across 480 websites identified, 48 were deemed eligible and were quality assessed using the DISCERN instrument, a standardized index of the quality of consumer health information. Results Across 48 eligible websites, the mean summed score was 47.64 (SD = 10.38) and the mean overall rating was 3.06 (SD = 0.90). Commercial sites were the most numerous in quantity, but contained information of the poorest quality. In general, websites lacked discussion surrounding uncertainty of information, describing what would happen if no treatment was used, and how treatment choices affect overall quality of life. Conclusion Physicians and other healthcare professionals should be aware of the high variability in the quality of online information regarding the use of DHSs for fatigue and facilitate open communication with patients to guide them towards reliable online sources. Background The Internet is increasingly utilized by patients to acquire information about dietary and herbal supplements (DHSs). Previously published studies assessing the quality of websites providing consumer health information about DHSs have been found to contain inaccuracies and misinformation that may compromise patient safety.. The present study assessed the quality of online DHSs consumer health information for fatigue. Methods Six unique search terms were searched on Google, each relating to fatigue and DHSs, across four countries. Across 480 websites identified, 48 were deemed eligible and were quality assessed using the DISCERN instrument, a standardized index of the quality of consumer health information. Results Across 48 eligible websites, the mean summed score was 47.64 (SD = 10.38) and the mean overall rating was 3.06 (SD = 0.90). Commercial sites were the most numerous in quantity, but contained information of the poorest quality. In general, websites lacked discussion surrounding uncertainty of information, describing what would happen if no treatment was used, and how treatment choices affect overall quality of life. Conclusion Physicians and other healthcare professionals should be aware of the high variability in the quality of online information regarding the use of DHSs for fatigue and facilitate open communication with patients to guide them towards reliable online sources.