Inertia Emulation through Supercapacitor Energy Storage Systems

Ruiqi Zhang,Jingyang Fang,Yi Tang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

To establish a more reliable, sustainable and high-efficiency smart grid, renewable energy sources (RESs) have been increasingly integrated into modern power systems. Since RESs are normally coupled to electrical grids through grid-connected power converters, which do not possess any rotational inertia as conventional synchronous generators do, modern power systems will face frequency control challenges as the power system inertia continues to decrease. To address the lack of inertia concern, supercapacitor energy storage systems (SESSs) are implemented in this paper to generate virtual inertia by proportionally linking the grid frequency to the voltage references of supercapacitors. In this way, the improvements of inertia and frequency control can be achieved. More importantly, this paper discloses that the basic inertia control scheme introduces inertia emulation errors under large frequency disturbances. As a solution, this paper presents a nonlinear inertia control scheme, which ensures fair inertia emulation even under large frequency disturbances. Simulation and experimental results are finally presented to verify the effectiveness of the virtual inertia and the control schemes.

An Enhanced Searching Electromagnetism-like Mechanism Algorithm for Global Optimization Problem

Zhang Ruiqi,Yin Feng 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.8

A global optimal algorithm derived from electromagnetism-like mechanism (EM), called as enhanced searching electromagnetism-like (ESEM) algorithm, was developed in this paper. The original EM is a meta-heuristic algorithm utilizing an attraction-repulsion mechanism (called as force F) to move sample points towards optimality in global optimization problems. Compared to the original algorithm, the best historical visited positions of each point were added into the search process in the improved algorithm. In ESEM, the search direction and step length of points were determined together by its best previously visited position, best point in current swarm and total force F. Preliminary experiments showed that additional best historical positions can help to improve the convergence property. More importantly, the improved searching mechanism can effectively solve the problem of stagnation of the original algorithm caused by too small values of force F.

High-Pitch Coronary CT Angiography at 70 kVp Adopting a Protocol of Low Injection Speed and Low Volume of Contrast Medium

Ruiqi Feng,Jiajie Tong,Xiaofei Liu,Yu Zhao,Liang Zhang 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.5

Objective: To evaluate the feasibility and image quality (IQ) of prospectively high-pitch coronary CT angiography (CCTA) with low contrast medium injection rate at 70 kVp. Materials and Methods: One hundred and four patients with suspected coronary artery disease (body mass index < 26 kg/m2, sinus rhythm and heart rate < 70 beats/min) were prospectively enrolled and randomly divided into two groups. In group A and group B, 28 mL and 40 mL of 370 mgI/mL iodinated contrast media was administrated at a flow rate of 3.5 and 5 mL/s, respectively. CT values, noise, signal-to-noise ratio, contrast-to-noise ratio (CNR) of the proximal segments of coronary arteries and subjective IQ were evaluated. Results: The CT values and noise in group A were significantly lower than those in group B (434–485 Hounsfield units [HU] vs. 772–851 HU, all p < 0.001; 17.8–22.3 vs. 23.3–26.4, all p < 0.005). The CNRs of the right coronary artery and left main artery showed no statistical difference between the two groups (42.1 ± 13.8 vs. 36.8 ± 16.0, p = 0.074; 38.7 ± 10.6 vs. 38.1 ± 17.0, p = 0.819). No statistical difference was observed between the two groups in IQ scores (3.04 ± 0.75 vs. 3.0 ± 0.79, p = 0.526) and diagnostic ratio (96.1% [50/52] vs. 94.2% [49/52], p = 0.647). Conclusion: Prospective high-pitch CCTA at 70 kVp with 28 mL of contrast media and injection rate of 3.5 mL/s could provide diagnostic IQ for normal-weight patients with heart rate of < 70 beats/min.

Transition metal modified manganese-based catalysts for soot oxidation promoted by noncompetitive adsorption of oxygen: Experiments and DFT calculations

Congcong Li,Ruiqi Li,Yuhang Wang,Runhan Niu,Qilong Guo,Changsen Zhang 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

A series of manganese-based oxide catalysts were synthesized by the hydrothermal method. By adjustingthe doping amounts of W and Cu in the system to study the catalytic performance of transition metaldopedmanganese oxides on soot combustion. They were deeply studied through various characterizationsand theoretical calculations. The results show that Wand Cu doping modifications can significantlyimprove the activity of manganese-based oxides in soot oxidation. W-Cu0.1/MnOx prepared by comodificationofWand Cu at 395 C can convert 90% of soot into CO2. The multiple characterization resultsshow that by adjusting the doping amount of copper and tungsten, the nano-flower-like morphology canbe obtained and the crystal plane can be reconstructed, which is helpful to increase the specific surfacearea, Mn3+ content, and oxygen vacancy content. The theoretical calculation results show that the oxygenvacancy on the surface of the catalyst shows the ability to activate O2 and H2O, and they show noncompetitiveadsorption. In addition, W-Cu0.1/MnOx has a good application prospect in the catalytic oxidationof soot because of its excellent catalytic stability. This work provides a reference for the designand preparation of non-noble metal-based catalysts for the elimination of soot particles from dieselengine exhaust.

Overexpression of ARO10 in pdc5ΔMutant Resulted in Higher Isobutanol Titers in Saccharomyces cerevisiae

Jingzhi Li,Ruiqi Feng,Zhihui Wen,Aili Zhang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4

To investigate effects of different pyruvate decarboxylases on isobutanol titers in Saccharomyces cerevisiae, single-gene deletion of the three PDCs genes encoding pyruvate decarboxylases were constructed in this study. In addition, we over-expressed Ilv2, which catalyzed the first step in the valine synthetic pathway, and Bat2, which was the cytoplasmic branched-chain amino-acid aminotransferase that catalyzed L-valine to 2-ketoisovalerate, to increase isobutanol production in the genetically modified strains. Our results showed that knockout of PDC5 were one of the main factors among the three PDC genes for improving isobutanol titers in S. cerevisiae. Additionally, we found that deletion of PDC5 in strain carrying overexpressed ILV2 and ARO10 resulted in 8-fold higher isobutanol productivity as compared to the control strain in micro-aerobic fermentations. Our results also suggested that engineered strain pdc5ΔpILV2 pARO10 generated lower ethanol titers and higher acetate acid titers than the control strain, while the growth rate and glucose consumption rate of engineered strain pdc5ΔpILV2 pARO10 were slightly lower than that of the control strain. Meanwhile, the biomass concentration of pdc5ΔpILV2 pARO10 decreased dramatically than that of the control strain.

Protective effect of cilostazol on vascular injury in rats with acute ischemic stroke complicated with chronic renal failure

Sun Ru,Gu Qun,Zhang Xufeng,Zeng Ruiqi,Chen Dan,Yao Jingjing,Min Jingjing 한국독성학회 2024 Toxicological Research Vol.40 No.2

Chronic renal failure (CRF) resulting in vascular calcification, which does damage to blood vessels and endothelium, is an independent risk factor for stroke. It has been reported that cilostazol has a protective effect on the focal cerebral ischemic infarct. However, its impact on vascular injury in CRF combined stroke and its molecular protection mechanism have not been investigated. In this study, we carried out the effect of cilostazol on CRF combined stroke rats, and the results confirmed that it improved the neurobehavior, renal function as well as pathologic changes in both the kidney and brain. In addition, the inflammation and oxidative stress factors in the kidney and brain were suppressed. Moreover, the rates of brain edema and infarction were decreased. The injured brain-blood barrier (BBB) was recovered with less Evans blue extravasation and more expressions of zonula occludens-1(ZO-1) and occludin. More cerebral blood flow (CBF) in the ipsilateral hemisphere and more expression of CD31 and vascular endothelial growth factor (VEGF) in brain and kidney were found in the cilostazol group. Furthermore, cell apoptosis and cell autophagy became less, on the contrary, proteins of vascular endothelial growth factor receptor 2 (VEGFR2) after the cilostazol treatment were increased. More importantly, this protective effect is related to the pathway of Janus Kinase (JAK)/signal transducer and activator of transcription 3 (STAT3), mammalian target of rapamycin (mTOR), and the hypoxia inducible factor-1α (HIF-1α). In conclusion, our results confirmed that cilostazol exerted a protective effect on the brain and kidney function, specifically in vascular injury, oxidative stress, cell apoptosis, cell autophagy, and inflammation response in CRF combined with stroke rats which were related to the upregulation of JAK/STAT3/mTOR signal pathway.

COVID-19 vaccine immunogenicity among chronic liver disease patients and liver transplant recipients: A meta-analysis

Ka Shing Cheung,Chiu Hang Mok,Xianhua Mao,Ruiqi Zhang,Ivan FN Hung,Wai Kay Seto,Man Fung Yuen 대한간학회 2022 Clinical and Molecular Hepatology(대한간학회지) Vol.28 No.4

Background/Aims: Data of coronavirus disease 2019 (COVID-19) vaccine immunogenicity among chronic liver disease (CLD) and liver transplant (LT) patients are conflicting. We performed meta-analysis to examine vaccine immunogenicity regarding etiology, cirrhosis status, vaccine platform and type of antibody. Methods: We collected data via three databases from inception to February 16, 2022, and reported pooled seroconversion rate, T cell response and safety data after two vaccine doses. Results: Twenty-eight (CLD only: 5; LT only: 18; both: 2; LT with third dose: 3) observational studies of 3,945 patients were included. For CLD patients, seroconversion rate ranged between 84% (95% confidence interval [CI], 76–90%) and 91% (95% CI, 83–95%), based predominantly on neutralizing antibody and anti-spike antibody, respectively. Seroconversion rate was 81% (95% CI, 76–86%) in chronic hepatitis B, 96% (95% CI, 93–97%) in non-alcoholic fatty liver disease, 85% (95% CI, 75–91%) in cirrhosis and 85% (95% CI, 78–90%) in non-cirrhosis, 86% (95% CI, 78–92%) for inactivated vaccine and 89% (95% CI, 71–96%) for mRNA vaccine. The pooled seroconversion rate of anti-spike antibody was 66% (95% CI, 55– 75%) after two doses of mRNA vaccines and 88% (95% CI, 58–98%) after third dose among LT recipients. T cell response rate was 65% (95% CI, 30–89%). Prevalence of adverse events was 27% (95% CI, 18–38%) and 63% (95% CI, 39–82%) among CLD and LT groups, respectively. Conclusions: CLD patients had good humoral response to COVID-19 vaccine, while LT recipients had lower response.

Effect of moderate-to-severe hepatic steatosis on neutralising antibody response among BNT162b2 and CoronaVac recipients

Ka Shing Cheung,Lok Ka Lam,Rex Wan Hin Hui,Xianhua Mao,Ruiqi R Zhang,Kwok Hung Chan,Ivan FN Hung,Wai Kay Seto,Man-Fung Yuen 대한간학회 2022 Clinical and Molecular Hepatology(대한간학회지) Vol.28 No.3

Background/Aims: Studies of hepatic steatosis (HS) effect on COVID-19 vaccine immunogenicity are lacking. We aimed to compare immunogenicity of BNT162b2 and CoronaVac among moderate/severe HS and control subjects. Methods: Two hundred ninety-five subjects who received BNT162b2 or CoronaVac vaccines from five vaccination centers were categorized into moderate/severe HS (controlled attenuation parameter ≥268 dB/m on transient elastography) (n=74) or control (n=221) groups. Primary outcomes were seroconversion rates of neutralising antibody by live virus Microneutralization (vMN) assay (titer ≥10) at day21 (BNT162b2) or day28 (CoronaVac) and day56 (both). Secondary outcome was highest-tier titer response (top 25% of vMN titer; cutoff: 160 [BNT162b2] and 20 [CoronaVac]) at day 56. Results: For BNT162b2 (n=228, 77.3%), there was no statistical differences in seroconversion rates (day21: 71.7% vs. 76.6%; day56: 100% vs. 100%) or vMN geometric mean titer (GMT) (day21: 13.2 vs. 13.3; day56: 91.9 vs. 101.4) among moderate/severe HS and control groups respectively. However, lower proportion of moderate/severe HS patients had highest-tier response (day56: 5.0% vs. 15.5%; P=0.037). For CoronaVac (n=67, 22.7%), there was no statistical differences in seroconversion rates (day21: 7.1% vs. 15.1%; day56: 64.3% vs. 83.0%) or vMN GMT (5.3 vs. 5.8,) at day28. However, moderate/severe HS patients had lower vMN GMT (9.1 vs. 14.8, P=0.021) at day 56 with lower proportion having highesttier response (21.4% vs. 52.8%, P=0.036). Conclusions: While there was no difference in seroconversion rate between moderate/severe HS and control groups after two doses of vaccine, a lower proportion of moderate/severe HS patients achieved highest-tier response for either BNT162b2 or CoronaVac.

Structural health monitoring of high-speed railway tracks using diffuse ultrasonic wave-based condition contrast: theory and validation

Kai Wang,Wuxiong Cao,Zhongqing Su,Pengxiang Wang,Xiongjie Zhang,Lijun Chen,Ruiqi Guan,Ye Lu 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.2

Despite proven effectiveness and accuracy in laboratories, the existing damage assessment based on guided ultrasonic waves (GUWs) or acoustic emission (AE) confronts challenges when extended to real-world structural health monitoring (SHM) for railway tracks. Central to the concerns are the extremely complex signal appearance due to highly dispersive and multimodal wave features, restriction on transducer installations, and severe contaminations of ambient noise. It remains a critical yet unsolved problem along with recent attempts to implement SHM in bourgeoning high-speed railway (HSR). By leveraging authors' continued endeavours, an SHM framework, based on actively generated diffuse ultrasonic waves (DUWs) and a benchmark-free condition contrast algorithm, has been developed and deployed via an all-in-one SHM system. Miniaturized lead zirconate titanate (PZT) wafers are utilized to generate and acquire DUWs in long-range railway tracks. Fatigue cracks in the tracks show unique contact behaviours under different conditions of external loads and further disturb DUW propagation. By contrast DUW propagation traits, fatigue cracks in railway tracks can be characterised quantitatively and the holistic health status of the tracks can be evaluated in a real-time manner. Compared with GUW- or AE-based methods, the DUW-driven inspection philosophy exhibits immunity to ambient noise and measurement uncertainty, less dependence on baseline signals, use of significantly reduced number of transducers, and high robustness in atrocious engineering conditions. Conformance tests are performed on HSR tracks, in which the evolution of fatigue damage is monitored continuously and quantitatively, demonstrating effectiveness, adaptability, reliability and robustness of DUW-driven SHM towards HSR applications.

Block Sparse Signals Recovery via Block Backtracking- Based Matching Pursuit Method

( Rui Qi ),( Yujie Zhang ),( Hongwei Li ) 한국정보처리학회 2017 Journal of information processing systems Vol.13 No.2

In this paper, a new iterative algorithm for reconstructing block sparse signals, called block backtrackingbased adaptive orthogonal matching pursuit (BBAOMP) method, is proposed. Compared with existing methods, the BBAOMP method can bring some flexibility between computational complexity and reconstruction property by using the backtracking step. Another outstanding advantage of BBAOMP algorithm is that it can be done without another information of signal sparsity. Several experiments illustrate that the BBAOMP algorithm occupies certain superiority in terms of probability of exact reconstruction and running time.