EVC-TDMA: An Enhanced TDMA Based Cooperative MAC Protocol for Vehicular Networks

Tianjiao Zhang,Qi Zhu 한국통신학회 2020 Journal of communications and networks Vol.22 No.4

In order to optimize the communication mechanism inthe vehicular adHoc networks (VANETs), this paper presents anenhanced TDMA based cooperative MAC protocol called EVCTDMA. In EVC-TDMA, when the vehicles need to transmit multihop messages, they choose relay nodes dynamically according tothe relative speeds and buffer lengths. By monitoring the broadcasting messages, the other nodes can know the buffer lengths ofthe relay nodes, they will help transmit the relay messages whentheir buffer are idle or less. Considering the data arrive follows aPoison Point Process, this paper analyzes the nodes’ buffer lengthbased on a two-dimension Markov process. The simulation resultsshow that EVC-TDMA can reduce the dropping rate and improvethe throughput of the network.

Game-Based TDMA MAC Protocol for Vehicular Network

Zhang Tianjiao,Zhu Qi 한국통신학회 2017 Journal of communications and networks Vol.19 No.3

A vehicular ad hoc network (VANET) is a special network for vehicle-to-vehicle communication. The proper medium access control (MAC) protocol based on time division multiple access (TDMA) is the key to realizing efficient vehicle-to-vehicle communication. In a VANET, when two or more nodes occupy the same time slot and drive into each other's communication ranges, a reservation collision occurs, and all of the colliding nodes release their slots. This paper presents a game-based TDMA MAC protocol (GAH-MAC) to solve this problem. In this protocol, when a reservation collision occurs, the colliding nodes will play games with each other to decide whether to reserve the original slot or a new one. In this way, the time slots can be fully used, and the reservation speeds can be increased without being controlled by the base stations. The simulation results show that the performance of GAH-MAC is superior in high-density networks, raising the success rate of reservations and increasing network throughput.

An Accurate Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry Method for Serum C-Peptide and Its Use in Harmonization in China

Deng Yuhang,Zhang Chao,Wang Jing,Zeng Jie,Zhang Jiangtao,Zhang Tianjiao,Zhao Haijian,Zhou Weiyan,Zhang Chuanbao 대한진단검사의학회 2023 Annals of Laboratory Medicine Vol.43 No.4

Background: Serum C-peptide results from various routine methods used in China are highly variable, warranting well-performing methods to serve as an accuracy base to improve the harmonization of C-peptide measurements in China. We developed an accurate isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC–MS/MS) method for serum C-peptide measurement and explored its use in harmonization. Methods: After protein precipitation with ZnSO4 solution, C-peptide was extracted from serum samples by anion-exchange solid-phase extraction and quantified by ID-LC–MS/MS in positive ion mode. The precision and analytical recovery of the ID-LC–MS/MS method were assessed. Seventy-six serum samples were analyzed using the ID-LC–MS/MS method and six routine immunoassays. Ordinary linear regression (OLR) and Bland-Altman (BA) analyses were conducted to evaluate the relationship between the ID-LC–MS/MS method and routine immunoassays. Five serum pool samples assigned using the ID-LC–MS/MS method were used to recalibrate the routine assays. OLR and BA analyses were re-conducted after recalibration. Results: The within-run, between-run, and total precision for the ID-LC–MS/MS method at four concentrations were 1.0%–2.1%, 0.6%–1.2%, and 1.3%–2.2%, respectively. The analytical recoveries for the ID-LC–MS/MS method at three concentrations were 100.3%–100.7%, 100.4%–101.0%, and 99.6%–100.7%. The developed method and the immunoassays were strongly correlated, with all R2 >0.98. The comparability among the immunoassays was substantially improved after recalibration. Conclusions: The performance of the ID-LC–MS/MS method was carefully validated, and this method can be used to improve the harmonization of serum C-peptide measurements in China.

Hydraulic and Mechanical Coupling Analysis of Rough Fracture Network under Normal Stress and Shear Stress

Tianjiao Yang,Shuhong Wang,Pengyu Wang,Ze Zhang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

The hydraulic and mechanical coupling characteristics of fracture networks under normal stress and shear stress were studied in this paper. The hydraulic and mechanical coupling model of the fracture network comprehensively considers the normal stress, shear stress, seepage pressure and roughness characteristics. Based on the boundary conditions and reasonable assumptions, COMSOL Multiphysics software was used to develop the hydraulic and mechanical coupling finite element model of the fracture network with different intersection points under normal stress and shear stress, focusing on the study of the effect of normal stress and shear stress on the fracture permeability. The degree of permeability change caused by the normal stress and shear stress is different. The shear stress has a significant influence on the fracture permeability, and when the normal stress is low, the relationship between the fracture permeability and shear stress can be described by a linear relationship. Then, the influence of the number of intersection points in the fracture network on the average fracture width, average water pressure, average seepage velocity and seepage passage of the fractured rock mass was analyzed. The number of intersections in the fracture network has little influence on the average fracture gap width and average water pressure but has a great influence on the flow velocity. The analysis in this paper is very helpful to understand the seepage characteristics in rough fractures under normal stress and shear stress.

Commutability Assessment of Candidate External Quality Assessment Materials for Aminotransferase Activity Measurements Based on Different Approaches in China

Long Qichen,Qi Tianqi,Zhang Tianjiao,Wang Jing,Zeng Jie,Ying Yan,Meng Wang,Wei Huang,Haijian Zhao,Wenxiang Chen,Chuanbao Zhang 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.1

Background: Using commutable external quality assessment (EQA) materials is important for monitoring successful harmonization efforts. We assessed the commutability of four human serum pool (HSP) preparations to identify candidate EQA materials for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity measurement. Methods: One set each of 85 clinical samples (CSs) was collected for ALT and AST activity measurement. The 15 candidate EQA materials included four types of HSP preparations (A to D): materials A, C, and D contained human original recombinant (HOR) aminotransferases; materials B was mixed leftover samples. The CSs and 15 candidate EQA materials were analyzed using seven routine assays, and the ln-transformed results were analyzed in 21 assay pairs. Commutability was assessed using Deming regression, with a 95% prediction interval (CLSI approach) and the difference in bias with an error component model (International Federation of Clinical Chemistry and Laboratory Medicine [IFCC] approach). Results: For ALT, all materials were commutable for 14–21 assay pairs according to the CLSI and IFCC approaches. For AST, B01-03 showed commutability for 14-21 assay pairs, and C01-03 and D01-03 showed commutability for no less than 10 assay pairs according to the two approaches. A01-06 were commutable for 9-16 assay pairs according to the CLSI approach, but for 6-9 assay pairs according to the IFCC approach. Conclusions: Mixed leftover samples showed desirable commutability characteristics as candidate EQA materials for routine aminotransferase activity measurements. Human serum bases supplemented with HOR were commutable for most routine ALT activity measurements.

Varilactones and wortmannilactones produced by Penicillium variabile cultured with histone deacetylase inhibitor

Xueqian He,Zhenzhen Zhang,Qian Che,Tianjiao Zhu,Qian-Qun Gu,Dehai Li 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.1

Seven polyketides, including four new onesnamed as varilactones A–B (1–2) and wortmannilactonesM–N (3–4), as well as three biogenetically related knownwortmannilactones E, F and H (5–7), were isolated fromthe fungus Penicillium variabile HXQ-H-1, cultivated inpotato-based medium with the histone deacetylase inhibitorsuberoylanilide hydroxamic acid (SAHA). Their structures(1–7) were established by analysis of NMR and MS data,and the absolute configuration of oxabicyclo[2.2.1]heptaneunit was deduced from 1H-NMR analyses on MPA estersafter chemical reduction reaction. Among them, varilactonesA and B (1 and 2), features a novel skeleton with atriene unit linking an oxabicyclo[2.2.1]heptane and anoxabicyclo[3.3.0]octane rings.

Overview of CSNS tantalum cladded tungsten solid Target-1 and Target-2

Shaohong Wei,Ruiqiang Zhang,Quan Ji,Changfeng Li,Bin Zhou,Youlian Lu,Jun Xu,Ke Zhou,Chongguang Zhao,Ning He,Wen Yin,Tianjiao Liang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5

A solid tungsten target was used at the China Spallation Neutron Source (CSNS) with 100 kW protonbeam power. To improve the lifetime, hot isostatic pressing (HIP) process was selected to bond tantalumcladding with tungsten plates. Radioactive isotope 182Ta, an activation product of tantalum, was found inthe cooling water after a period of operation, however, no radioactive isotopes of 187W was found, whichshows the tantalum layer remained mostly intact. The CSNS Target-1 had been operating safely for threeyears and was replaced by Target-2 in August 2020

Polycyclotriphosphazene Derivative Grafted and NanometerY₂O₃ Doped SPEEK Composite Membrane for DMFC

Li, Xia,Guo, Qiang,Zhang, Tianjiao,Qian, Junzhi,Tan, Xiaolin Korean Chemical Society 2013 대한화학회지 Vol.57 No.5

A type of polycyclotriphosphazene derivative (PCTPD), hexasulfanilic acid polycyclotriphosphazene (HSACP) and HSACP grafting SPEEK, sulfonated poly[2-(petachloropolycyclotriphosphazene-oxy)] etheretherketone (SPPSACPEEK) were synthesized, which were characterized by FTIR and $^{31}P$ NMR. Then three types of composite membranes such as HSACP grafting SPEEK, HSACP blending SPEEK, and nano $Y_2O_3$ doping and HSACP grafting SPEEK, respectively, were continuously prepared by solution-casting method. Comparing to SPEEK membranes with different amount of HSACP grafted or blended, grafting 15 wt% HSACP and doping 10 wt% nano $Y_2O_3$ SPEEK membrane conducted outstanding overall behavior of proton conductivity reaching $3.18 {\times}10^{-2}$ S/cm at $90^{\circ}C$ which was merely junior to SPEEK with 15 wt% HSACP grafted, methanol permeability coefficient getting $9.46{\times}10^{-8}cm^2{\cdot}s^{-1}$, swelling degree of 20.9% and solid residue of 98.98% which was superior to all specimen.

ZnO/TiO2 core–shell heterojunction for CdS and PbS quantum dot-cosensitized solar cells

Fangfang Gao,Qian Chen,Xiaoshan Zhang,Huan Wang,Tianjiao Huang,Liya Zhou 한국물리학회 2018 Current Applied Physics Vol.18 No.5

ZnO nanorods (NRs) with regular morphology were prepared through hydrothermal method, and the TiO2 shell was assembled onto the surface of ZnO NRs by spin coating to the ZnO/TiO2 core–shell heterojunction. CdS and PbS quantum dots (QDs) were used to cosensitize the ZnO/TiO2 nanostructure by direct adsorption (DA) and successive ionic layer adsorption and reaction, respectively. SEM, TEM, and HRTEM images show that the samples possessed a rough surface and four lattice fringes indicating the successful synthesis of the ZnO/TiO2/ CdS/PbS composite structure. The ZnO/TiO2(10T)/CdS/PbS sample showed a high absorption intensity at a broad range of wavelength to visible light region. The ZnO/TiO2(10T)/CdS/PbS photoelectrode with QDSSCs showed the highest IPCE of 36.04% and photoelectric efficiency (η) of 1.59%; these values increased by approximately 550% and 150% compared with those of unsensitized ZnO (0.29%) and ZnO/TiO2(10T) (1.04%) and about 146% and 120% compared with those of ZnO/TiO2(10T)/CdS and ZnO/TiO2(10T)/PbS, respectively. The fill factor was 0.36, and the photocurrent density (Jsc) and open circuit voltage (Voc) reached the maximum values of 9.73 mA cm−2 and 0.46 V, respectively.