Nb reinforced Fe-Mn-Si shape memory alloy composite coating fabricated by laser cladding on 304 stainless steel surface

Xiaochen Liu,Peng Xu,Like Yao,Xiang Li,Chi Pang,Long Yang,Yi Liang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

Laser cladding technology was adapted to fabricate Fe-based shape memory alloy/Nb composite coatings with 5 wt. % Nb doping amounts on 304 stainless steel to promote the microhardness and wear resistance. The SEM, XRD, optical profilometer and electrochemical workstation were used to characterize micromorphology, phase and microstructure. Meanwhile, wear and anti-resistance ability were detected. The results showed that Nb, NbC, ε-martensite, α’-martensite and γ-austenite were found in SMA/Nb coating. The microhardness was enhanced because of the solid solution strengthening and second phase strengthening. Also, the shape recovery rate and anti-corrosion property of the SMA/Nb coating are improved as well.

Robust Secure Transmit Design with Artificial Noise in the Presence of Multiple Eavesdroppers

( Xiaochen Liu ),( Yuanyuan Gao ),( Nan Sha ),( Guozhen Zang ),( Shijie. Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.6

This paper studies secure wireless transmission from a multi-antenna transmitter to a single-antenna intended receiver overheard by multiple eavesdroppers with considering the imperfect channel state information (CSI) of wiretap channel. To enhance security of communication link, the artificial noise (AN) is generated at transmitter. We first design the robust joint optimal beamforming of secret signal and AN to minimize transmit power with constraints of security quality of service (QoS), i.e., minimum allowable signal-to-interference-and-noise ratio (SINR) at receiver and maximum tolerable SINR at eavesdroppers. The formulated design problem is shown to be nonconvex and we transfer it into linear matrix inequalities (LMIs). The semidefinite relaxation (SDR) technique is used and the approximated method is proved to solve the original problem exactly. To verify the robustness and tightness of proposed beamforming, we also provide a method to calculate the worst-case SINR at eavesdroppers for a designed transmit scheme using semidefinite programming (SDP). Additionally, the secrecy rate maximization is explored for fixed total transmit power. To tackle the nonconvexity of original formulation, we develop an iterative approach employing sequential parametric convex approximation (SPCA). The simulation results illustrate that the proposed robust transmit schemes can effectively improve the transmit performance.

A Security Assessment Framework and Selection Method for Outsourcing Cloud Service

Xiaochen Liu,Chunhe Xia,Jiajin Cao,Jinghua Gao,Zhao Wei 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.6

Cloud services have become state of the art of resource sharing and interoperability among different service providers. The federated cloud seek to reduce costs and maximize efficiency, provide flexible and reliable services composed of various external cloud service and internal services, but this would introduce a risk of security due to outsourcing. For organization which provide an integrity cloud service must rely on SLA to illustrate the capacity of risk and performance, the various providers involved in the federations or services compositions should effectively distribute the organizational responsibilities and SLA. To solve the fears and deal with the threats associated with outsourcing, new method for selection of outsourcing cloud service providers(CSP) based on assessment of security and performance is urgently needed. This paper presents an approach on how to select the proper CSP to guarantee organizational SLA, which quantify the SLA terms and calculate a security weight, the organization can choose the appropriate CSP based on security weight, meanwhile minimize the business cost. This paper make contribution on modeling the capacity of the CSP, considering the business cost and historical performance. The proposed approach is validated through case study that shows selected CSP through our approach can best meet the organizational security and cost needs.

Clinical Application of MRI in an Animal Bone Graft Model

Xiaochen Liu,Wenxiao Jia,Gele Jin,Hong Wang,Jingxu Ma,Yunling Wang,Yi Yang,Wei Deng 한국자기학회 2013 Journal of Magnetics Vol.18 No.2

We aim to monitor vascularization of early bone perfusion following rabbit lumbar intertransverse bone graft fusion surgery using magnetic resonance imaging assessment. Correlation with graft survival status was evaluated by histological method. Experimental animals were randomly divided into three groups and the model was established by operating bilateral lumbar intertransverse bone graft with different types of bone graft substitute material. The lumbar intertransverse area of three groups of rabbits was scanned via MRI. In addition, histological examinations were performed at the 6<SUP>th</SUP> week after surgery and the quantitative analysis of the osteogenesis in different grafted area was carried out by an image analysis system. The MRI technique can be used for early postoperative evaluation of vascularized bone graft perfusion after transplantation of different bone materials, whereas histological examination allows direct visualization of the osteogenesis process.

Deletion of cg1360 Affects ATP Synthase Function and Enhances Production of L-Valine in Corynebacterium glutamicum

( Xiaochen Wang ),( Hongyu Yang ),( Wei Zhou ),( Jun Liu ),( Ning Xu ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.8

Bacterial ATP synthases drive ATP synthesis by a rotary mechanism, and play a vital role in physiology and cell metabolism. Corynebacterium glutamicum is well known as an industrial workhorse for amino acid production, and its ATP synthase operon contains eight structural genes and two adjacent genes, cg1360 and cg1361. So far, the physiological functions of Cg1360 (GenBank CAF19908) and Cg1361 (GenBank CAF19909) remain unclear. Here, we showed that Cg1360 was a hydrophobic protein with four transmembrane helices (TMHs), while no TMH was found in Cg1361. Deletion of cg1360, but not cg1361, led to significantly reduced cell growth using glucose and acetic acid as carbon sources, reduced F1 portions in the membrane, reduced ATP-driven proton-pumping activity and ATPase activity, suggesting that Cg1360 plays an important role in ATP synthase function. The intracellular ATP concentration in the Δcg1360 mutant was decreased to 72% of the wild type, while the NADH and NADPH levels in the Δcg1360 mutant were increased by 29% and 26%, respectively. However, the Δcg1361 mutant exhibited comparable intracellular ATP, NADH and NADPH levels with the wild-type strain. Moreover, the effect of cg1360 deletion on L-valine production was examined in the L-valine-producing V-10 strain. The final production of L-valine in the V-10-Δcg1360 mutant reached 9.2 ± 0.3 g/l in shake flasks, which was 14% higher than that of the V-10 strain. Thus, Cg1360 can be used as an effective engineering target by altering energy metabolism for the enhancement of amino acid production in C. glutamicum.

Early Plasma Circulating Tumor DNA as a Potential Biomarker of Disease Recurrence in Non-metastatic Prostate Cancer

Xiaochen Fei,Xinxing Du,Yiming Gong,Jiazhou Liu,Liancheng Fan,Jiayi Wang,Yanqing Wang,Yinjie Zhu,Jiahua Pan,Baijun Dong,Wei Xue 대한암학회 2023 Cancer Research and Treatment Vol.55 No.3

Purpose In non-metastatic prostate cancer (nmPCa) setting, it is important to early identify the patients at risk of biochemical recurrence (BCR) for immediate postoperative intervention. Our study aimed to evaluate the potential clinical utility of circulating tumor DNA (ctDNA) for predicting disease recurrence.Materials and Methods This real-world observational study evaluated 161 cases of nmPCa undergoing next-generation sequencing at our institution. A total of 139 ctDNA samples and 31 biopsied tumor tissue underwent genomic profiling. The study endpoint was BCR after radical prostatectomy. Relationships between the ctDNA status and the biochemical progression-free survival (bPFS) were analyzed by log-rank test and multivariate Cox regression.Results Of 161 enrolled patients, 19 (11.8%) harbored deleterious alterations in <i>NCOR2</i>, followed by <i>BRCA2</i> (3.7%), <i>ATR</i> (2.5%), and <i>CDK12</i> (2.5%). Of available pre-operative blood samples (n=139), ctDNA was detectable in 91 (65.5%). Until last follow-up, 56 of 68 patients (85.3%) with detectable ctDNA had achieved BCR, whereas only eight of 39 patients (20.5%) with undetectable ctDNA had achieved BCR. Patients who had undetectable ctDNA experienced significantly longer bPFS compared with those who had detectable ctDNA (not available vs. 8.2 months; hazard ratio, 0.14; p < 0.01). Pre-operative ctDNA status was a significant prognostic factor of disease recurrence.Conclusion Pre-operative ctDNA detection could identify patients at high risk of recurrence and has the potential to inform immediate postoperative interventions, but these approaches remain to be validated in prospective studies. ctDNA studies can provide insights into accurate monitoring and precise treatment rather than simply following routine clinical care.

Common fixed points for a pair of mappings satisfying contractive conditions of integral type

Liu, Zeqing,Zou, Xiaochen,Kang, Shin,Ume, Jeong Springer (Biomed Central Ltd.) 2014 Journal of inequalities and applications Vol.2014 No.1

Fatigue study on additional cutout between U shaped rib and floorbeam in orthotropic bridge deck

Xiaochen Ju,Zhibin Zeng,Xinxin Zhao,Xiaoguang Liu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.3

The field around additional cutout of the floor beam web in orthotropic bridge deck was subjected to high stress concentration, especially the weld toe between floor beam and U shaped rib and the free edge of the additional cutout. Based on different considerations, different geometrical parameters of additional cutout were proposed in European, American and Japanese specifications, and there remained remarkable differences among them. In this study, considering influence of out-ofplane deformation of floor beam web and U shaped rib, parameter analysis for additional cutout under typical load cases was performed by fine finite element method. The influence of additional cutout shape and height to the stress distribution around the additional cutout were investigated and analyzed. Meanwhile, the static and fatigue test on this structure details was carried out. The stress distribution was consistent with the finite element analysis results. The fatigue property for additional cutout height of 95mm was slightly better than that of 61.5 mm.

Parallel Algorithm of Improved FunkSVD Based on Spark

( Xiaochen Yue ),( Qicheng Liu ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.5

In view of the low accuracy of the traditional FunkSVD algorithm, and in order to improve the computational efficiency of the algorithm, this paper proposes a parallel algorithm of improved FunkSVD based on Spark (SP-FD). Using RMSProp algorithm to improve the traditional FunkSVD algorithm. The improved FunkSVD algorithm can not only solve the problem of decreased accuracy caused by iterative oscillations but also alleviate the impact of data sparseness on the accuracy of the algorithm, thereby achieving the effect of improving the accuracy of the algorithm. And using the Spark big data computing framework to realize the parallelization of the improved algorithm, to use RDD for iterative calculation, and to store calculation data in the iterative process in distributed memory to speed up the iteration. The Cartesian product operation in the improved FunkSVD algorithm is divided into blocks to realize parallel calculation, thereby improving the calculation speed of the algorithm. Experiments on three standard data sets in terms of accuracy, execution time, and speedup show that the SP-FD algorithm not only improves the recommendation accuracy, shortens the calculation interval compared to the traditional FunkSVD and several other algorithms but also shows good parallel performance in a cluster environment with multiple nodes. The analysis of experimental results shows that the SP-FD algorithm improves the accuracy and parallel computing capability of the algorithm, which is better than the traditional FunkSVD algorithm.

Electrochemical codeposition of graphene/polypyrrole composites on carbon paper for electrochemical capacitors

Yanhui Liu,Ke Xu,Xiaochen Zhang,Chunhua Qi,Qingchun Lv,Houjun Feng 한국물리학회 2016 Current Applied Physics Vol.16 No.5

A simple electrochemical codeposition technique has been introduced to fabricate graphene oxide/ polypyrrole (GO/PPy) composites. To increase the adsorption of colloidal GOs at the liquideliquid interface, the organic supporting electrolyte like benzenesulfonate sodium (BS) is added in GO/pyrrole micelle solution, which does not induce the flocculation sedimentation of GO at elevated ionic strength. The narrow size distribution of GO/pyrrole/BS micelles is benefit for uniform codeposition of GO/PPy on the carbon fiber surface. Moreover, the GO nanosheets and benzensulfonate have been incorporated into composites as mixture dopants, which increased the growth orientation of PPy in electropolymerization process and result in more loose structure for ionic transportation. The composites electrodes exhibit high specific capacitance, good cyclic stability after electrochemical reduction of graphene oxide (RGO). The specific capacitance of composite electrode with low mass density still reaches 358 F/g at scan rate of 10 mV/s within an electrochemical windows of 1.0 V. The strong interaction effect between two components resists the mechanical deformation effect and exhibits only 7.1% decay at a charge/discharge current of 3 A/g after 1000 cycles. At increasing the mass density of composites to 8.4 mg/cm2, the areal capacitance of electrode almost grow linearly to 1.286 F/cm2, which is more than triple that of BS-doped PPy with the same mass density. The high capacity of the composite electrode exerts the potential applications in capacitive deionization, microbial fuel cell or even capacitive energy storage.