Distortion Minimization in Wireless Sensor Networks With Energy Harvesting

Pengfei Du,Qinghai Yang,Zhong Shen,Kyung Sup Kwak IEEE 2017 IEEE communications letters Vol.21 No.6

<P>In this letter, we investigate the distortion minimization problem by jointly optimizing the sleep-wake scheduling and the transmit power in energy harvesting wireless sensor networks. A mean square error minimization problem with a more efficient harvest-use-store architecture and limited available channels taken into account is formulated. To tackle this mixed-integer non-linear programming, we first transform it into a tractable convex problem through the integer relaxation. Subsequently, a low-complexity sleep-wake scheduling and power control algorithm is proposed to solve the transformed problem. Specifically, we uncover the special structure of the transformed problem and employ it to obtain the optimal sleep-wake policy and power allocation for each sensor node.</P>

Investigation of the Dynamic Characteristics of Muck during EPB Shield Tunnelling in a Full Chamber Model Using a CFD Method

Jiazheng Zhong,Shuying Wang,Pengfei Liu,Zhengri Liu,Tao Xu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

For the safety and efficiency of earth pressure balance (EPB) shield tunnelling, the dynamic characteristics of the muck in the excavation chamber and the screw conveyor should be considered. However, the velocity and pressure distribution of the muck in the EPB shield, reflecting muck flowability and face stability, are rarely observed at the jobsite. Therefore, a computational fluid dynamics (CFD) model with a modified inlet boundary was established to investigate the muck characteristics in the chamber and the screw conveyor during tunnelling in a full chamber mode. A compressible Bingham model was adapted to describe the muck compressibility and rheology. The time-dependent tunnelling parameters obtained from the simulation excellently matched the field-measured data. The simulation results show the non-uniform velocity distribution of the muck at the excavation face and the low-velocity zones where clogging potentially occurs. The muck pressure reaches a peak at the excavation face and then decreases along the cutterhead openings, chamber and screw conveyor for inflow. The simulation also captures the pressure imbalance at the cutterhead and bulkhead, which may destabilize the excavation face. The proposed discharge efficiency is 56.7% in the simulated condition, indicating that tunnelling with these muck properties has no risk of muck spewing.

The Prognostic Value of CD8+ and CD45RO+ T Cells Infiltration and Beclin1 Expression Levels for Early Postoperative Cholangitis of Biliary Atresia Patients after Kasai Operation

Hong Jiang,Pengfei Gao,Huadong Chen,Zhihai Zhong,Man Shu,Zhichong Zhang,Jinbiao She,Juncheng Liu 대한의학회 2018 Journal of Korean medical science Vol.33 No.30

Background: Postoperative cholangitis is a common but severe complication after Kasai portoenterostomy for biliary atresia (BA). This study aimed to identify its prognostic factors Methods: Two sets of liver paraffin-embedded tissue samples were collected from BA patients who received Kasai portoenterostomy (n = 25 and n = 31, respectively). Patients were divided into non-cholangitis and cholangitis groups. The infiltration of CD4+ , CD8+ , CD45RO+ , CD68+ cells and expression of Beclin1 were quantitatively evaluated in immunohistochemical analysis. Results: Cholangitis group had a significantly lower CD8+ T cell infiltration but a higher CD45RO+ cell infiltration, and a lower Beclin1 level than non-cholangitis group (all P < 0.01). Multivariate logistic regression analysis indicated that infiltration of CD8+ cells (odds ratio [OR], 0.112; 95% confidence interval [CI], 0.022–0.577) and CD45RO+ cells (OR, 3.88; 95% CI, 1.37–11.03), and Beclin1 level (OR, 0.088; 95% CI, 0.018–0.452) were independent influence factors for early postoperative cholangitis. Receiver operating characteristic (ROC) analysis showed that area under ROC curve (AUROC) values for CD8+ cells, CD45RO+ cells and Beclin1 were 0.857, 0.738 and 0.900, respectively. Conclusion: Our findings demonstrated the CD8+ cells, CD45RO+ cells and Beclin1 level possessed the prognostic value for early postoperative cholangitis following Kasai operation, which may be helpful to develop new prevention and treatment strategies for postoperative cholangitis.

The Road Detection Technology of Vision Navigation for Picking Robot

Xiong Juntao,Zhong Pengfei,Zou Xiangjun 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.9

Vision navigation technology of the autonomous walking robot has been conducted in the research. Based on the characteristics of picking robot working environment, the visual system for the independent walking car is designed, which applies monocular camera to obtain images of marking lines on the surface of road for pre processing. Using the image gray contrast constraints determines the information of the effective area on the surface of road. Then the Hough linear detection combined with constraint will be used for the recognition and detection of the indication line on the surface, and the information of visual examination path will be fed back to the car control system as following. Through the ultrasonic sensors on the head of the walking car, the walking car can detect the obstacle at the same time. According to the real-time feedback data of ultrasonic sensor, fuzzy propulsion and calculation determine the information of the obstacles on the road surface ahead of time in order to achieve the function of real-time obstacle avoidance. The result of visual navigation test shows that maximum deviation of the car walking straight line based on visual navigation system is 1.5cm and the maximum deviation of curve walking is 6cm. The success rate of obstacle avoidance is 96.67%, which can meet the requirement of the vision navigation of picking robot and provide technical support for the autonomous navigation and intelligent operation of picking robot.

Preparation and investigation of Dy³⁺-doped Ca₉LiGd_2/3(PO₄)₇ single-phase full-color phosphor

Liu, Shihua,Liu, Simei,Wang, Jingjing,Sun, Pengfei,Zhong, Yifan,Jeong, Jung Hyun,Deng, Bin,Yu, Ruijin Elsevier 2018 Materials research bulletin Vol.108 No.-

<P><B>Abstract</B></P> <P>Novel single-phased white-light-emitting Ca<SUB>9</SUB>LiGd<SUB>2/3</SUB>(PO<SUB>4</SUB>)<SUB>7</SUB>:<I>x</I>Dy<SUP>3+</SUP> (<I>x</I> = 0.02, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30) β-Ca<SUB>3</SUB>(PO<SUB>4</SUB>)<SUB>2</SUB>-type phosphate phosphors were synthesized. The phase structure, luminescence, and thermal stability of the phosphors were characterized by X-ray powder diffraction analysis, photoluminescence excitation and emission spectra, thermal quenching, and decay curves. XRD analysis confirmed the phase formation of Ca<SUB>9</SUB>LiGd<SUB>2/3</SUB>(PO<SUB>4</SUB>)<SUB>7</SUB>:Dy<SUP>3+</SUP> materials. Under the excitation of 352 nm, the emission of the Ca<SUB>9</SUB>LiGd<SUB>2/3</SUB>(PO<SUB>4</SUB>)<SUB>7</SUB>:0.20Dy<SUP>3+</SUP> sample centered at blue (488 nm) and yellow (580 nm), which corresponded to <SUP>4</SUP>F<SUB>9/2</SUB>–<SUP>6</SUP>H<SUB>15/2</SUB> transition and <SUP>4</SUP>F<SUB>9/2</SUB>–<SUP>6</SUP>H<SUB>13/2</SUB> transition. The optimum dopant concentration of Dy<SUP>3+</SUP> ions was around 20 mol%, and the critical transfer distance of Dy<SUP>3+</SUP> was calculated as 18 Å. The thermal-quenching temperature was above 500 K for Ca<SUB>9</SUB>LiGd<SUB>2/3</SUB>(PO<SUB>4</SUB>)<SUB>7</SUB>:0.20Dy<SUP>3+</SUP>. The developed phosphor has a great potential as a single-component white-light-emitting phosphor for UV-light-emitting diodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel single-phased Ca<SUB>9</SUB>LiGd<SUB>2/3</SUB>(PO<SUB>4</SUB>)<SUB>7</SUB>:<I>x</I>Dy<SUP>3+</SUP> phosphor was firstly synthesized. </LI> <LI> Its structure, luminescent properties are well studied and characterized. </LI> <LI> It was promising as a single-component white-light-emitting phosphor for w-LEDs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Research of Face Recognition System Based on Visual Intelligent Monitoring

He Zhiliang,Xiong Juntao,Mai Zhiheng,Zhong Pengfei,Tang Linyue 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.5

The key technology of intelligent face recognition based on the visual monitoring was researched. Firstly, obtained the real-time scene by video camera, and the background difference method was used to judge whether there is a character goal in monitoring region, in view of the existing target, the color space of YCgCr and YCgCb were chosen to detect skin color, the geometric constraints that the aspect ratio of facial contour is 0.8 to 1.85 was used to realize the positioning of face region. Then the improved 2DPCA algorithm was used for face recognition, and data matching with the established database of face to determine the validity character identity. Finally the identification results were sent to the mobile terminal through the control system. System test results show that the processing speed of face recognition is 7 s/times, and the accuracy of face recognition results was 85%, which can provide technical support for the identity intelligent recognition of visual monitoring.