Recent Progress in Flexible Perovskite Solar Cell Development

Ren, Xiaodong,Jung, Hyun Suk The Korean Ceramic Society 2018 한국세라믹학회지 Vol.55 No.4

Perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted significant attention due to their remarkable optoelectrical properties, including high absorption coefficients, high carrier mobilities, long carrier diffusion lengths, tunable bandgaps, low cost, and facile fabrication. PSCs have reached efficiencies of 22.70% and 18.36% on rigid fluorine-doped tin oxide and poly(ethylene terephthalate) substrates, respectively; these are comparable to those of single-crystal silicon and copper-indium-gallium-selenium solar cells. Over the past eight years, the photo conversion efficiency of PSCs has been significantly improved by device-architecture adjustments, and absorber and electron/hole transport layer optimization. Each layer is important for the performance of PSCs; hence, we discuss achievements in flexible perovskite solar cells (FPSCs), covering electron/hole-transport materials, electrode materials. We give a comprehensive overview of FPSCs and put forward suggestions for their further development.

NUND: Non-Uniform Node Distribution in Cluster-based Wireless Sensor Networks

( Ju Ren ),( Yaoxue Zhang ),( Xiaodong Lin ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.7

Cluster-based wireless sensor network (WSN) can significantly reduce the energy consumption by data aggregation and has been widely used in WSN applications. However, due to the intrinsic many-to-one traffic pattern in WSN, the network lifetime is generally deteriorated by the unbalanced energy consumption in a cluster-based WSN. Therefore, energy efficiency and network lifetime improvement are two crucial and challenging issues in cluster-based WSNs. In this paper, we propose a Non-Uniform Node Distribution (NUND) scheme to improve the energy efficiency and network lifetime in cluster-based WSNs. Specifically, we first propose an analytic model to analyze the energy consumption and the network lifetime of the cluster-based WSNs. Based on the analysis results, we propose a node distribution algorithm to maximize the network lifetime with a fixed number of sensor nodes in cluster-based WSNs. Extensive simulations demonstrate that the theoretical analysis results determined by the proposed analytic model are consistent with the simulation results, and the NUND can significantly improve the energy efficiency and network lifetime.

Patterning of CVD Diamond Films For MEMS Application

Wang, Xiaodong,Yang, Yirong,Ren, Congxin,Mao, Minyao,Wang, Weiyuan The Korean Vacuum Society 1998 Applied Science and Convergence Technology Vol.7 No.1

To apply diamond films in microelectromechanical systems(MEMS), it is necessary to develop the patterning technologies of diamond films in the micrometer scale. In this paper, three different kinds of technologies for patterning CVD diamond films carried out by us were demonstrated: selective growth by improved diamond nucleation in DC bias-enhanced microwave plasma chemical vapor deposition (MPCVD) system, selective growth of seeding using diamond-particle-mixed photoresist, and selective etching of oxygen ion beam using Al as the mask. It was show that high selectivity and precise patterns had been achieved, and all the processes were compatible with IC process.

Clearance Measurement Equipment for Gas Lubricated Dynamic Pressure Bearing of Gyro Motor

Tong-qun Ren,Zhi-rou Liu,Xiang-dong Xu,Yu Liu,Xiaodong Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.12

The clearance of gas lubricated dynamic pressure bearing of gyro motor refers specifically to small internal air gap between the rotor and stator. The clearance size is an important indicator of running performance of a motor. In this work, a dedicated clearance measurement equipment is developed. The clearance is converted to external micro displacement and measured by dual inductive probes with relative measurement principle. For this purpose, three main functional modules are designed together with corresponding electronic and pneumatic control systems. The clamp fixation module helps to support the measured bearing flexibly at the shaft end, which is conducive to protect the bearing and ensure the smoothness of force application. The force application module consists of a 3-D precision motion platform and a triaxial force sensor. It converts internal air gap to external micro displacement in cooperation with the clamp fixation module. The displacement measurement module is a 2-D precision motion platform carrying dual inductive probes. Based on theoretical analysis and practical experiments, the measurement accuracy is superior to 0.3 μm. Moreover, it realizes controllable and continuous force application, which is suitable for batch measurement.

Physically-Based Constitutive Modelling of As-Cast CL70 Steel for Hot Deformation

Fei Chen,Xiaodong Zhao,Jinyu Ren,Huiqin Chen,Xiaofeng Zhang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

In order to conduct numerical simulation of plasticity forming and confirm the processing parameters of heat deformationfor as-cast CL70 steel, the hot deformation behaviors of as-cast CL70 steel were studied by isothermal compression testswhich used a Gleeble-1500D thermal mechanical simulation tester for the deformation temperatures ranging from 1173 to1523 K and the strain rates ranging from 0.001 to 1 s−1. Flow stress curves of the steel were obtained under high temperature. The flow stress constitutive models of the work hardening-dynamical recovery period and dynamical recrystallizationperiod were established for as-cast CL70 steel. In work hardening-dynamic recovery period, the flow stress was predicted byemploying the evolution rule of dislocation density in the constitutive model. In dynamic recrystallization period, the flowstress after the critical strain was predicted by employing the dynamic recrystallization kinetics in the constitutive model. To improve the prediction accuracy of the model, the dynamic recovery coefficient is modified in the traditional physicallybasedconstitutive model. The results indicate that the proposed physically-based constitutive model has high accuracy inpredicting the flow stress under hot deformation for as-cast CL70 steel.

Characterization of MSTN/GDF11 gene from shrimp Macrobrachium nipponense and its expression profiles during molt cycle and after eyestalk ablation

Wenying Shen,Gang Ren,Yaorong Zhu,Xiaodong Zhang 한국유전학회 2015 Genes & Genomics Vol.37 No.5

Myostatin (MSTN), also known as the growth differentiation factor-8 (GDF-8), belongs to the transforming growth factor-b superfamily. MSTN is a negative regulator of muscle development in vertebrates. However, the transcriptional regulation of MSTN in freshwater crustaceans is still unclear. In this study, a cDNA encoding for MSTN/GDF11 (Mn-MSTN/GDF11) was cloned from the oriental freshwater shrimp, Macrobrachium nipponense. The full-length cDNA sequence of Mn-MSTN/ GDF11 was composed of 1733 nucleotides, including a 50 UTR of 119 nucleotides, an open read frame of 1359 nucleotides, and a 30 UTR of 255 nucleotides. The predicted peptide of Mn-MSTN/GDF11 has 452 amino acids with the conserved RXXR cleavage site and nine cysteines. Tissuespecific expression pattern showed that Mn-MSTN/GDF11 is mainly expressed in abdominal muscle. During the course of embryonic development, expression level of Mn- MSTN/GDF11 could be detected after gastrul stage, and reached at the highest level at embryonized-zoea stage. During molt cycle, expression level of Mn-MSTN/GDF11 mRNA was up-regulated significantly at early postmoult stage, but down-regulated gradually in the following molt stages. In the period of 14 days after eyestalk ablation, Mn- MSTN/GDF11 transcripts were significantly decreased in abdominal muscle and heart, but increased in thoracic muscle. The results of this study indicated that Mn-MSTN/ GDF11 may play a role in molt cycle and be regulated by hormone secreted in eyestalk.

Genome-wide scan for runs of homozygosity identifies candidate genes in Wannan Black pigs

Wu Xudong,Zhou Ren,Zhang Wei,Cao Bangji,Xia Jingjing,Wang Caiyun,Zhang Xiaodong,ChuMing-Xing,Yin Zongjun,Ding Yueyun 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.12

Objective: Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that can reveal inbreeding levels, selection pressure, and mating schemes. In this study, ROHs were evaluated in Wannan Black pigs to assess the inbreeding levels and the genome regions with high ROH frequency.Methods: In a previous study, we obtained 501.52 GB of raw data from resequencing (10×) of the genome and identified 21,316,754 single-nucleotide variants in 20 Wannan Black pig samples. We investigated the number, length, and frequency of ROH using resequencing data to characterize the homozygosity in Wannan Black pigs and identified genomic regions with high ROH frequencies.Results: In this work, 1,813 ROHs (837 ROHs in 100 to 500 kb, 449 ROHs in 500 to 1,000 kb, 527 ROHs in >1,000 kb) were identified in all samples, and the average genomic inbreeding coefficient (FROH) in Wannan Black pigs was 0.5234. Sixty-one regions on chromosomes 2, 3, 7, 8, 13, 15, and 16 harbored ROH islands. In total, 105 genes were identified in 42 ROH islands, among which some genes were related to production traits.Conclusion: This is the first study to identify ROH across the genome of Wannan Black pigs, the Chinese native breed of the Anhui province. Overall, Wannan Black pigs have high levels of inbreeding due to the influence of ancient and recent inbreeding due to the genome. These findings are a reliable resource for future studies and contribute to save and use the germplasm resources of Wannan Black pigs. Objective: Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that can reveal inbreeding levels, selection pressure, and mating schemes. In this study, ROHs were evaluated in Wannan Black pigs to assess the inbreeding levels and the genome regions with high ROH frequency. Methods: In a previous study, we obtained 501.52 GB of raw data from resequencing (10×) of the genome and identified 21,316,754 single-nucleotide variants in 20 Wannan Black pig samples. We investigated the number, length, and frequency of ROH using resequencing data to characterize the homozygosity in Wannan Black pigs and identified genomic regions with high ROH frequencies. Results: In this work, 1,813 ROHs (837 ROHs in 100 to 500 kb, 449 ROHs in 500 to 1,000 kb, 527 ROHs in >1,000 kb) were identified in all samples, and the average genomic inbreeding coefficient (FROH) in Wannan Black pigs was 0.5234. Sixty-one regions on chromosomes 2, 3, 7, 8, 13, 15, and 16 harbored ROH islands. In total, 105 genes were identified in 42 ROH islands, among which some genes were related to production traits. Conclusion: This is the first study to identify ROH across the genome of Wannan Black pigs, the Chinese native breed of the Anhui province. Overall, Wannan Black pigs have high levels of inbreeding due to the influence of ancient and recent inbreeding due to the genome. These findings are a reliable resource for future studies and contribute to save and use the germplasm resources of Wannan Black pigs.

A Geometric Method for Kinematics of Delta Robot and its Path Tracking Control

Xuewen Yang,Zuren Feng,Chenyu Liu,Xiaodong Ren 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

This paper presents a geometric method for solving the inverse and forward kinematics of Delta robot, and then investigated the problem of path tracking control. The forward kinematics is most commonly solved by various iterative methods, which may suffer from slow convergence rate and strict initial value conditions. In this paper, this problem is simplified as solving the intersection point of two circles and then transforming the coordinates system to get the final solution. This method has advantages in its simplicity, accuracy and efficiency. Based on the solution to kinematics and the derivation of Jacobian matrix, the path tracking control is studied from two parts: the superior trajectory planning and the lower control system. Trajectory planning aims to define a temporal motion law along a given geometric path. A method for trajectory planning is presented which is based on a modified trapezoidal velocity profile (TVP) of which initial and final velocities could be nonzero depending on its movement model, whether continuous path (CP) or point to point (PTP). A velocity control method is proposed using a nonlinear PD controller to ensure the end effector tracking the desired path with high precision. At last, a demo trajectory is generated to verify the feasibility of the method experimentally.

Effect of bidentate and tridentate additives on the photovoltaic performance and stability of perovskite solar cells

Chen, Jiangzhao,Kim, Seul-Gi,Ren, Xiaodong,Jung, Hyun Suk,Park, Nam-Gyu The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.9

<P>Fabrication of high-quality perovskite films with a large grain size and fewer defects is always crucial to achieve efficient and stable perovskite solar cells (PSCs). Here, we report a simple and effective method for crystal growth and defect passivation <I>via</I> additive engineering. It is found that bidentate ligand 2,2′-bipyridine (Bpy) and tridentate ligand 2,2′:6′,2′′-terpyridine (Tpy) show a positive effect on the power conversion efficiency (PCE) while a negative effect is observed for monodentate pyridine (Py). Bpy or Tpy additives increase the grain size and carrier lifetimes, which indicates that the degree of interaction between Lewis acid species in the precursor solution and pyridine derivatives plays a critical role in modulating grain growth and passivating defects. Moreover, device stability is improved upon introduction of Bpy or Tpy additives, which is mainly ascribed to suppressed trap-assisted non-radiative recombination as a consequence of reduced defect density. This work highlights the importance of rational engineering of additives for the purpose of simultaneous realization of morphological improvement and defect passivation in efficient and stable PSCs.</P>

Aerodynamic optimization of a high-expansion ratio organic radial-inflow turbine

Yan Li,Xue-song Li,Xiaodong Ren 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.12

Given that the radial-inflow turbine is a critical component of the Organic Rankine cycle system, its performance substantially influences system capacity. This paper established an optimization framework for the radial-inflow turbine is established with the combination of a computational fluid dynamics software, a non-uniform rational B-spline parameterization method, and an optimization strategy. The nozzle, meridional flow path, and blade profile of a 500 kW turbine were optimized. Results show that nozzle blade and impeller optimization leads to a 0.34 % and about 0.71 % increase in turbine efficiency, respectively. After optimization, the flow state in the turbine was good, and the flow separation almost disappeared.