Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 46
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Aiming at the problem of DC voltage control deviation and instability caused by a large-scale renewable energy access VSC–MTDC system, this paper combines voltage margin control and droop control. A strategy for controlling collaborative optimization in a sparsely distributed communication network has been proposed. Firstly, the distributed modeling of the system is carried out by combining MAS technology with small signal modeling. Then, a distributed model predictive controller is designed for a single droop control converter station. On this basis, a distributed cooperative optimization control strategy is proposed. According to the DC voltage deviation, the system adopts different control methods to control the receiving converter station. Finally, based on PSCAD/EMTDC and MATLAB co-simulation platforms, a six-terminal flexible HVDC system is built to verify the effectiveness of the control strategy under different conditions such as input power fluctuation, any converter station out of operation and system communication failure.
Go to article

Authors and Affiliations

Jingye Li
1
Haiying Dong
2

  1. School of Automation and Electrical Engineering, Lanzhou Jiaotong University, China
  2. School of New Energy and Power Engineering, Lanzhou Jiaotong University, China
Download PDF Download RIS Download Bibtex

Abstract

In this paper, an experimental method was utilized to investigate acoustic emission (AE) characteristics and to identify emission sources of the nonlinear AE signal on the cylinder body of a large low-speed two-stroke marine diesel engine in real-working conditions on the sea in misfiring and normal firing modes. Measurements focused on the AE signal acquired in a transverse direction in low-frequency (20–80 kHz), medium-frequency (100–400 kHz) and high-frequency (400–900 kHz) ranges. The collected signals were analyzed on the crank angle and crank angle-frequency domains. The results showed that all potential sources of the nonlinear AE signal could be mapped in the low-frequency range. However, only the AE signal caused by the combustion process at around the top dead center could be well-observed in the medium-to-high-frequency range. The findings also revealed that in normal firing conditions, the AE energy radiated by friction in the down-stroke period was smaller than in the up-stroke process due to gas-sealing forces. Moreover, the AE energy in the misfiring condition was higher than in the normal firing state. These outcomes considerably contributed understandings to characteristics of friction and wear around the mid-stroke area of the cylinder on a two-stroke marine diesel engine.
Go to article

Authors and Affiliations

Xuan Thin Dong
1
Manh Hung Nguyen
1

  1. Vietnam Maritime University Hai Phong, Vietnam
Download PDF Download RIS Download Bibtex

Abstract

The structure and load characteristics of the roadway are simplified, and the experimental model of the roadway deformation and damage under compression-shear load is established. The experimental data acquisition system is built with a CCD camera. The digital speckle correlation method is used to calculate the image data of the experimental model. The correspondence between the evolution law of the deformation field, the interlayer displacement and deformation evolution are analysed, including the dynamic characteristic of the roadway surrounding the rock. Research results indicate: (1) The damage peak load of the weak layer structure shows a decreasing trend as the interlayer shear stress increases. As the initially applied shear stress increases, the value of interlayer sliding displacement increases, and the dynamic characteristics become more apparent. (2) In the sub-instability phase of the loading curve, when the surrounding rock slides along the layers under compression-shear load, the stress is re-distributed and transmitted to the deep part of the surrounding rock. Then the surrounding rock of the roadway forms the characteristic of alternating change, between tension to compression. (3) According to the state of dynamic and static mechanics, the deformation evolution of the roadway before the peak load belongs to the static process. Zonal fracturing is part of the transition phase from the static process to the slow dynamic process, and the rockburst damage is a high-speed dynamic process. (4) Under the compression-shear load, due to the weak layer structure of the coal and rock mass, the local fracture, damage, instability and sliding of the surrounding rock of the roadway are the mechanical causes of rockburst. (5) Even if the coal and rock mass does not have the condition of impact tendency, under stress load of the horizontal direction, distribution of large shear stress is formed between layers, and the dynamic damage of the rockburst may occur.
Go to article

Bibliography

[1] H. Lippman, The Mechanics of “Protruding” in Coal Mine: Discussion on The Violent Deformation on Both Sides of The Channel in Coal Seam [J], Advances in Mechanics 19 (2), 100-113+59 (1989). DOI: https://doi.org/10.6052/1000-0992-1989-1-j1989-011
[2] H.T. Li, J. Liu, S.K. Zhao, L.S. Cai, Q.X. Qi, L.H. Kong, Experimental Study on The Development Mechanism of Coal Bump Considering The Clamping Effect of Roof and Floor [J], Journal of China Coal Society 43 (11), 2951-2958 (2018). DOI: CNKI:SUN:MTXB.0.2018-11-001
[3] M.V. Kurlenya, V.N. Oparin, V.I. Vostrikov, Effect of Anomalously Low Friction in Block Media [J], Journal of Applied Mechanics & Technical Physics 40 (6), 1116-1120 (1999). DOI: https://doi.org/10.1007/BF02469182
[4] L .M. Dou, H. He, J. He, Z.Y. Wang, New Method of Rock Burst Risk Assessment Using Relative Stress Concentration Factor Superposition [J], Journal of China Coal Society 43 (2), 327-332 (2018). DOI: CNKI:SUN:MTXB.0.2018-02-004
[5] L .P. Li, W.J. Li, Y.S. Pan, Influence of Impact Disturbance on Anomalously Low Friction Rock Bursts [J], Chinese Journal of Rock Mechanics and Engineering, 38 (1), 111-120 (2019). DOI: https://doi.org/10.13722/j.cnki.jrme.2018.0922
[6] L .Y. Pan, H.Z. Yang, Dilatancy Theory for Identification of Premonitory Information of Rock Burst [J], Chinese Journal of Rock Mechanics and Engineering 23 (1), 4528-4530 (2004). DOI: https://doi.org/10.3321/j.issn:1000-6915.2004.z1.056
[7] Q.X. Qi, T.Q. Liu, Y.W. Shi, J.L. Lv, Mechanism of Friction Sliding Instability of Rock Burst [J], Ground Pressure and Strata Control 1, 174-177+200 (1995). DOI: CNKI:SUN:KSYL.0.1995-Z1-042
[8] Q.X. Qi, Y.W. Shi, T.Q. Liu, Mechanism of Instability Caused by Viscous Sliding in Rock Burst [J], Journal of China Coal Society 22 (2), 144-148 (1997). DOI: CNKI:SUN:MTXB.0.1997-02-006
[9] Q.X. Qi, Z.Z. Gao, S. Wang, The Theory of Rock Burst Led by Structure Damage of Bedded Coal-rock Mass [J], Coal Mining Technology (2), 14-17+64 (1998). DOI: CNKI:SUN:MKKC.0.1998-02-004
[10] E.I. Shemyakin, G.L. Fisenko, M.V. Kurlenya, V.N. Oparin, Y.S. Kuznetsov, Zonal Disintegration of Rocks around Underground Work, Part I:Data of In-situ Observations [J], Journal of Mining Science 22 (3), 157-168 (1986). DOI: https://doi.org/10.1007/BF02500863368
[11] E.I. Shemyakin, G.L. Fisenko, M.V. Kurlenya, V.N. Oparin, V.N. Reva, F.P. Glushikhin, M.A. Rozenbaum, E.A. Tropp, Y.S. Kuznetsov, Zonal Disintegration of Rocks around Underground Work, Part II: Rock Fracture Simulated in Equivalent Materials [J], Journal of Mining Science 22 (4), 223-232 (1986). DOI: https://doi.org/10.1007/BF02500845
[12] E.I. Shemyakin, G.L. Fisenko, M.V. Kurlenya, V.N. Oparin, Y.S. Kuznetsov, Zonal Disintegration of Rocks around Underground Workings, Part III: Theoretical Concepts [J], Journal of Mining Science 23 (1), 1-6 (1987). DOI: https://doi.org/10.1007/BF02534034
[13] E.I. Shemyakin, M.V. Kurlenya, V.N. Oparin, V.N. Reva, F.P. Glushikhin, E.A. Tropp, Zonal Disintegration of Rocks around Underground Workings, Part IV: Practical Applications [J], Journal of Mining Science 25 (4), 297- 302 (1989). DOI: https://doi.org/10.1007/BF02528546
[14] W.Q. Guo, S.P. Ma, Y.J. Kang, Q.W. Ma, Virtual Extensometer Based on Digital Speckle Correlation Method and Its Application to Deformation Field Evolution of Rock Specimen [J], Rock and Soil Mechanics 32 (10), 3196- 3200 (2011). DOI: https://doi.org/10.16285/j.rsm.2011.10.030
[15] X.T. Zhang, Q.Y. Zhang, W. Xiang, Q. Gao, S.B. Yuan, C. Wang, Model Test Study of Zonal Disintegration in Deep Layered Jointed Rock Mass [J], Rock and Soil Mechanics 35 (8), 2247-2254 (2014). DOI: CNKI:SUN:YTLX.0.2014-08-018
[16] Y. Xu, P. Yuan, Model Test of Zonal Disintegration in Deep Rock under Blasting Load [J], Chinese Journal of Rock Mechanics and Engineering 34 (S2), 3844-3851 (2015). DOI: CNKI:SUN:YSLX.0.2015-S2-027
[17] Y.M. Song, Z.X. Zhao, L.L. Deng, J.N. Wu, Deformation Field and Acoustic Emission Characteristics of Marble during Sub-instability Stage [J], Journal of Liaoning Technical University 37 (3), 541-546 (2018). DOI: CNKI:SUN:FXKY.0.2018-03-016
[18] Y.S. Pan, K.X. Wang, Pendulum-type Waves Theory on The Mechanism of Anomalously Low Friction between Rock Masses [J], Seismology and Geology 36 (3), 833-844 (2014). DOI: https://doi.org/10.3969/j.issn.0253-4967.2014.03.022
[19] Y.S. Pan, Y.H. Xiao, Z.H. Li, K.X. Wang, Study of Roadway Support Theory of Rock Burst in Coal Mine and Its Application [J], Journal of China Coal Society 39 (2), 222-228 (2014). DOI: https://doi.org/10.13225/j.cnki.jccs.2013.2015
[20] Z.L. Fang, Study on The Ground Pressure and Control Method for Openings in Soft and Broken Rocks in Jin Chuon Mine No. 2 [J]. Journal of Beijing Iron and Steel Institute (1), 1-20 (1984). DOI: CNKI:SUN:BJKD.0.1984-01-000
Go to article

Authors and Affiliations

Yimin Song
1
He Ren
1
Hailiang Xu
1
Dong An
1

  1. North China University of Technology, School of Civil Engineering, China
Download PDF Download RIS Download Bibtex

Abstract

On the basis of induction heating, radiation heating and liquid nitrogen refrigeration, high-temperature, medium-temperature, normal-temperature and low-temperature heating/refrigeration furnaces were designed, respectively. An apparatus with a wide temperature range and high accuracy applied to test oxidation resistance of materials has been developed based on the thermogravimetric method and the heat transfer principle. The apparatus consists of four heating/cooling systems, a specimen fixture positioning unit, a laser positioning unit, vertical and horizontal moving guide rails, and a high-precision weighing balance. The apparatus, based on the thermogravimetric method, is able to test oxidation resistance of materials. In the test, the temperature range was −180∼3000◦C (the highest temperature is determined by material properties). The temperature control accuracy was ±5◦C. The accuracy of on-line weighing was ±0:1 mg. The measurement uncertainty was 0.2 mg. Compared with other relevant devices, this apparatus has its own advantages: simple operation, wide heating/cooling temperature range, sufficient specimen heating, high sensitivity and precision, and short heating/cooling time. The experimental results show that the developed apparatus presented in this study not only can be used for isothermal thermogravimetric tests, but also for thermal cycling tests and multi-step oxidation tests. With the effective integration of multiple heating apparatus and refrigeration apparatus, the apparatus breaks through the limitations of the heating/cooling temperature range of the existing devices, accomplishes the high-precision oxidation resistance test of materials in a wide temperature range, and will play a great role in improving the research of materials.

Go to article

Authors and Affiliations

Dong-Yang An
Jing-Min Dai
Peng Xiao
Download PDF Download RIS Download Bibtex

Abstract

In this study, the synthesis of lithium carbonate (Li2CO3) powder was conducted by a carbonation process using carbon dioxide gas (CO2) from waste acidic sludge based on sulfuric acid (H2SO4) containing around 2 wt.% lithium content. Lithium sulfate (Li2SO4) powder as a raw material was reacted with CO2 gas using a thermogravimetric apparatus to measure carbonation conditions such as temperature, time and CO2 content. It was noted that carbonation occurred at a temperature range of 800℃ to 900℃ within 2 hours. To prevent further oxidation during carbonation, calcium sulfate (CaO4S) was first introduced to mixing gases with CO2 and Ar and then led to meet in the chamber. The lithium carbonate obtained was examined by inductively coupled plasma–mass spectroscopy (ICP-MS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and it was found that of lithium carbonate with a purity above 99% was recovered.

Go to article

Authors and Affiliations

Dong Hyeon Choi
Jei Pil Wang
Download PDF Download RIS Download Bibtex

Abstract

In this paper, the recent ice regime variations in the Kara Sea have been described and quantified based on the high-resolution remote sensing database from 2003 to 2017. In general, the Kara Sea is fully covered with thicker sea ice in winter, but sea ice cover is continuously declining during the summer. The year 2003 was the year with the most severe ice conditions, while 2012 and 2016 were the least severe. The extensive sea ice begins to break up before May and becomes completely frozen at the end of December again. The duration of ice melting is approximately twice than that of the freezing. Since 2007, the minimum ice coverage has always been below 5%, resulting in wide open-waters in summer. Furthermore, the relevant local driving factors of external atmospheric forcing on ice conditions have been quantitatively calculated and analyzed. Winter accumulated surface air temperature has been playing a primary role on the ice concentration and thickness condition in winter and determining ice coverage index in the following melt-freeze stage. Correlation coefficients between winter accumulated temperature and ice thickness anomaly index, the ice coverage anomaly index, duration of melt-freeze stage can approach -0.72, -0.83 and 0.80, respectively. In summer, meridional winds contribute closely to summer ice coverage anomaly index, with correlation coefficient exceeding 0.80 since 2007 and 0.90 since 2010.

Go to article

Authors and Affiliations

Chenglin Duan
Sheng Dong
Zhifeng Wang
Download PDF Download RIS Download Bibtex

Abstract

Rain gardens are one of the best measures for rainfall runoff and pollutant abatement in sponge city construction. The rain garden system was designed and developed for the problem of severely impeded urban water circulation. The rain gardens monitored the rainfall runoff abatement and pollutant removal capacity for 46 sessions from January 2018 to December 2019. Based on these data, the impact of rain gardens on runoff abatement rate and pollutant removal rate was studied. The results obtained indicated that the rain garden on the runoff abatement rate reached 82.5%, except with extreme rainfall, all fields of rainfall can be effectively abated. The removal rate of suspended solid particles was the highest, followed by total nitrogen and total phosphorus, the total removal rate in 66.35% above. The rain garden is still in the “youth stage”, and all aspects of the operation effect are good.
Go to article

Bibliography

  1. Boogaard, F. C. , Van, D. V. F. , Langeveld, J. G. , Kluck, J. & Van, D. G. N. (2015). Re-moval efficiency of storm water treatment techniques: standardized full scale laborato-ry testing. Urban Water Journal, 14(3-4):pp. 255-262. DOI:10.1080/1573062X.2015.1092562
  2. Chahal, M. K. , Shi, Z. & Flury, M. (2016). Nutrient leaching and copper speciation in compost-amended bioretention systems. Science of the Total Environment, 556, pp. 302-309. DOI:10.1016/j.scitotenv.2016.02.125
  3. Davis, A. P. , Traver, R. G. , Hunt, W. F. , Lee, R. , Brown, R. A. & Olszewski, J. M. (2012). Hydrologic Performance of Bioretention Storm-Water Control Measures. Journal of Hydrologic Engineering, 17(5), pp. 604-614. DOI:10.1061/(ASCE)HE .1943-5584.0000467
  4. Gao, Z. , Zhang, Q, H. , Xie, Y. D. , Wang, Q. , Dzakpasu, M. , Xiong, J. Q. & Wang, X. C.(2022). A novel multi-objective optimization framework for urban green-gray infrastructure implementation under impacts of climate change. Science of The Total Environment, 825: pp. 153954. DOI:10.1016/j.scitotenv.2022.153954
  5. Ghosh, S. P. & Maiti, S. K. (2018). Evaluation of heavy metal contamination in roadside deposited sediments and road surface runoff: a case study. Environmental Earth Sciences, 77(7):267. DOI:10.1007/s12665-018-7370-1
  6. Guo, C. , Li, J. , Li, H. , Zhang, B. , Ma, M. & Li, F.(2018). Seven-Year Running Effect Evaluation and Fate Analysis of Rain Gardens in Xi’an, Northwest China. Water, 10(7). DOI:10.3390/w10070944
  7. Guo, C. , Li, J. K. , Ma, Y. , Li, H, E. , Yuan, M. & Ji, G. Q.(2015). Operation life analysis and value estimation of rainwater garden. Journal of Environmental Science, 38(11), pp. 4391-4399(in Chinese).
  8. Gupta, A. , Thengane, S. K. & Mahajani, S. (2018). CO2 gasification of char from lignocellulosic garden waste: Experimental and kinetic study. Bioresource Technology, 263, pp. 180-191. DOI:10.1016/j.biortech.2018.04.097
  9. Hess, A. , Wadzuk, B. &Welker, A. (2021). Evapotranspiration estimation in rain gardens using soil moisture sensors. Vadose Zone Journal. DOI:10.1002/vzj2.20100
  10. Hong, J. , Geronimo, F. K. , Choi, H. &, Kim, L. H. (2018). Impacts of nonpoint source pollutants on microbial community in rain gardens. Chemosphere, 209, pp. 20-27. DOI:10.1016/j.chemosphere.2018.06.062
  11. Hsieh, C. & Davis, A. P. (2005). Evaluation and optimization of bioretention media for treatment of urban storm water runoff. Journal of Environmental Engineering, 131(11), pp. 1521-1531. DOI: 10.1061/(ASCE)0733-9372(2005)131:11(1521)
  12. Jeong, H., Choi, J.Y., Lee, J., Lim, J. & Ra, R. (2020). Heavy metal pollution by road-deposited sediments and its contribution to total suspended solids in rainfall runoff from intensive industrial areas. Environmental Pollution, 265:15028. DOI:10.1016/j.envpol.2020.115028
  13. Jiang, C. B., Li, J. K., Ma, Y., Li, H. E. & Ruan,T. S. (2012). The Regulating Effect of Rain Garden on Actual Rainfall Runoff. Journal of Soil and Water Conservation, 032(004), pp. 122-127(in Chinese).
  14. Kim, L. H. (2021). Stormwater runoff treatment using rain garden: performance monitoring and development of deep learning-based water quality prediction models. Water, 13(24), 3488. DOI:10.3390/w13243488
  15. Li, L. & Davis, A. P. (2014). Urban stormwater runoff nitrogen composition and fate in bioretention systems. Environmental Science & Technology, 2014, 48(6):3403. DOI: 10.1021/es4055302
  16. Ming-Han Li , Mark Swapp , Myung Hee Kim , Kung-Hui Chu , Chan Yong Sung (2014). Comparing bioretention designs with and without an internal water storage layer for treating highway runoff. Water Environment Research, 86(5), pp. 387-397. DOI: 10.2175/106143013X13789303501920
  17. Li, N. , Meng, Y. , Wang, J. ,Yu, Q. & Zhang, N. Q. (2008). Research on waterlogging reduction Effect of low-impact development measures -- A Case study of ji nan sponge test Area. Journal of Water Resources, 49(12), pp. 1489-1502(in Chinese).
  18. Luo, H. M., Che, W. , Li, J. Q. , Wang, H. L. , Meng, G. H. & He, J. P.(2008). Application of rainwater garden in flood control and utilization. China Water supply and Drainage, 24(06), pp. 48-52(in Chinese).
  19. Cheng, M. , Qin, H. P. , He, K. M. & Xu, H. L. (2018). Can floor-area-ratio incentive promote low impact development in a highly urbanized area? -A case study in Changzhou City, China. Frontiers of Environmental Science & Engineering, 12(2), pp. 1-8.
  20. Morales, V. L. , Gao, B. & Steenhuis, T. S. (2009). Grain Surface-Roughness Effects on Colloidal Retention in the Vadose Zone. Vadose Zone Journal, 8(1), pp. 11-20. DOI:10.2136/vzj2007.0171
  21. Palmer, E. T. , Poor, C. J. , Hinman, C. & Stark, J. D.(2013). Nitrate and Phosphate Removal through Enhanced Bioretention Media: Mesocosm Study. Water Environment Research, 85(9), pp. 823-832. DOI: 10.2175/106143013X13736496908997
  22. Sun, Y. , Wei, X. & Pomeroy, C. A. (2011). Research Status and Prospect of storm and flood resource regulation measures for low-impact Development. Progress in water science, 22(02), pp. 287-293(in Chinese).
  23. Tang, S. C. , Luo, W. , Jia, Z. H. , Li, S. , Wu, Y. & Zhou, M. (2015). Effect of rain garden on storm runoff reduction. Progress in water science, 26(06), pp. 787-794(in Chinese).
  24. Tang, S. C. , Luo, W. , Jia, Z. H. , Li, S. & Wu, Y. (2015). Effect of rain garden on the removal of nitrogen and phosphorus in different forms of occurrence and the effect of preferential flow in soil. Journal of water resources, 46(008), pp. 943-950(in Chinese).
  25. Tang, S. C. , Luo, W. , Jia, Z. H. & Yuan, H. C.(2012). Experimental Study on infiltration rainwater Runoff storage in Xi 'an Rainwater Garden. Journal of soil and water conservation, 26(06), pp. 75-79(in Chinese).
  26. Tang, S. C. , Luo, W. , Jia, Z. H. , Ma, X. Y. & Shao, Z. X. (2018). Influencing factors of rain garden operation effect based on drainable mod model. Progress in Water Science, 29(03), pp. 407-414(in Chinese).
  27. Trowsdale, S. A. & Simcock, R. (2011). Urban stormwater treatment using bioretention. Journal of Hydrology, 397(3-4), pp. 167-174. DOI: 10.1016/j.jhydrol.2010.11.023
  28. Wang, R. H. W. & Chiles, R. (2022). Ecosystem Benefits Provision of Green Stormwater Infrastructure in Chinese Sponge Cities. Environmental Management, 69(3), p. 558-575. DOI: 10.1007/s00267-021-01565-9
  29. Zhang, B. H., Deng, C. X. , Ma, Y. , Li, J, K , Jiang, C. B. & Ma, M. H. (2019). Retention and purification effect of rainwater garden on roof rainwater. China Water supply and Drainage, 21:29 (in Chinese).
  30. Zhang, J. Y. , Wang, Y. T. , Hu, Q. F. & He, R. M.(2016). Discussion on issues related to sponge city construction. Progress in water science, 27(06), pp. 793-799(in Chinese).
Go to article

Authors and Affiliations

Weijia Liu
1
Qingbao Pei
2
Wenbiao Dong
2
Pengfan Chen
2

  1. East China University of Technology, Nanchang, China
  2. Nanchang Institute of Technology Poyang Lake Basin Water Engineering Safety and Efficient Utilization National and Local Joint Engineering Laboratory, Nanchang, China
Download PDF Download RIS Download Bibtex

Abstract

The possibility of a normal distribution indicates that few particles are in the same phase during a breath and their reflections can be observed on the chest wall, then a few explosive waves with relatively large power occurr occasionally. Therefore, the one-cycle sine wave which is simulated as a single burst of the explosive effect phenomenon penetrates through the chest wall and was analysed to explore the reason of the crackle sounds. The results explain the differences between the definitions of crackle proposed by Sovijärvi et al. (2000a). The crackles in the lungs were synthesised by a computer simulation. When the coarse crackles occur, the results indicate that higher burst frequency carriers (greater than 100 Hz) directly penetrate the bandpass filter to simulate the chest wall. The simulated coarse crackle sounds were low pitched, with a high amplitude and long duration. The total duration was greater than 10 ms. However, for a lower frequency carrier (approximately 50 Hz), the fundamental frequency component was filtered out. Therefore, the second harmonic component of the lower frequency carrier, i.e., the fine crackle, penetrated the chest wall. Consequently, it is very possible that the normal lung sounds may contain many crackle-shaped waves with very small amplitudes because of the filtering effects of the chest wall, environment noises, electric devices, stethoscopes, and human ears, the small crackles disappear in the auscultations. In addition, our study pointed out that some unknown crackles of the very low frequency under the bandwidth of the human ears cannot penetrate the airways and be detected by medical doctors. Therefore, it might be necessary to focus advanced electronic instrumentation on them in order to analyse their possible characteristics for diagnosis and treatment of the respiration system.
Go to article

Authors and Affiliations

Bing-Yuh Lu
1 2
Meng-Lun Hsueh
3
Huey-Dong Wu
4

  1. Faculty of Automation, Guangdong University of Petrochemical Technology, No. 139, Sec. 2, Guando Road, Maoming City, Guangdong 525000, China
  2. Department of Electronic Engineering, Tungnan University, No. 152, Sec. 3., BeiShen Rd., ShenKeng Dist., New Taipei City 22202, Taiwan (R.O.C.)
  3. Department of Electronic Engineering, Hwa Hsia University of Technology, No. 111, Gongzhuan Rd., Zhonghe Dist., New Taipei City 235, Taiwan (R.O.C.)
  4. Section of Respiration Therapy, Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, No. 7, Zhongshan S. Rd., Zhongzheng Dist., Taipei City 100, Taiwan (R.O.C.)
Download PDF Download RIS Download Bibtex

Abstract

In the hybrid multiple H-bridge topology of beam supply, the load change of a DC/DC full-bridge converter can greatly affect the output voltage during onsite operation. An improved sliding mode control (SMC) strategy is thus proposed in this paper, where the rate of switching control is added to the law of system equivalent control to create a law that can realize a complete sliding mode control. Considering the special operating conditions of the load can have an influence on the performance of the controller, the impact of uncertainty existing in onsite conditions is suppressed with the proposed strategy utilized. The validity of the proposed strategy, finally, is verified by simulation, which proves the outperformance of the system in both robustness and dynamics.

Go to article

Authors and Affiliations

Hao Zhang
Haiying Dong
Baoping Zhang
Tong Wu
Changwen Chen
Download PDF Download RIS Download Bibtex

Abstract

With the improvement of people’s living standards and rapid economic development, the incidence of diabetes mellitus (DM) is increasing in most parts of the world. DM presents an important potential threat to human health. In the present study, a model of diabetes in female mice was established, and fasting blood glucose was detected at week 4, after which the biochemical profiles were evaluated by histopathological analysis. The success rate of modeling in the normal control (NC) group and the low/ middle/high-dose streptozotocin (STZ) group were 0, 0, 25% and 60%, respectively. In the middle-dose and high-dose STZ groups, the liver index was increased significantly compared with the NC group (p<0.05). The blood biochemical indicators of total cholesterol and low density lipoprotein cholesterol in three STZ injection groups were as follows: alanine aminotransferase and aspartate transaminase in middle- and high-dose STZ groups, high-density lipoprotein cholesterol and serum creatinine in the high-dose STZ group, and blood urea nitrogen in the middle-dose STZ group were significantly increased (p<0.05). The level of total triglycerides was lower, obviously, in the high-dose STZ group than in the NC group (p<0.05). The mice showed marked steatosis, green-dyed fiber tissue coloring in varying degrees, and the contour of the hepatic lobules basically disappeared in STZ injection groups. The results suggest that to establish a diabetes model for female ICR mice, the optimum dose of STZ is 100 mg/kg.
Go to article

Authors and Affiliations

R. Guo
1 2
J. Dong
3
D.Q. Wang
3
Y.F. Gu
1 2

  1. State Key Laboratory for Diagnosis and Treatment of Infectious Disease, National Clinical Research Center for Infectious Disease, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
  2. Jinan Microecological Biomedicine Shandong Laboratory, No. 3716 Qingdao Road, Huaiyin District, Jinan City, Shandong Province, Solutia City Light West Building, 21F, Shandong Laboratory of Microecological Biomedicine, Jinan 250117, China
  3. Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
Download PDF Download RIS Download Bibtex

Abstract

The frictional resistance coefficient of ventilation of a roadway in a coal mine is a very important technical parameter in the design and renovation of mine ventilation. Calculations based on empirical formulae and field tests to calculate the resistance coefficient have limitations. An inversion method to calculate the mine ventilation resistance coefficient by using a few representative data of air flows and node pressures is proposed in this study. The mathematical model of the inversion method is developed based on the principle of least squares. The measured pressure and the calculated pressure deviation along with the measured flow and the calculated flow deviation are considered while defining the objective function, which also includes the node pressure, the air flow, and the ventilation resistance coefficient range constraints. The ventilation resistance coefficient inversion problem was converted to a nonlinear optimisation problem through the development of the model. A genetic algorithm (GA) was adopted to solve the ventilation resistance coefficient inversion problem. The GA was improved to enhance the global and the local search abilities of the algorithm for the ventilation resistance coefficient inversion problem.

Go to article

Authors and Affiliations

Ke Gao
Lijun Deng
Jian Liu
Liangxiu Wen
Dong Wong
Zeyi Liu
Download PDF Download RIS Download Bibtex

Abstract

Sub-bottom profiler (SBP) is an acoustic instrument commonly used to survey underwater shallow geological structure and embedded objects whose most important performance parameter is the actual vertical resolution. This paper presented a methodology to measure and evaluate the actual vertical resolution of SBP based on an experiment in an anechoic tank, which was divided into three components: building of artificial geological model, measurement of acoustic parameters, and determination of actual vertical resolution of the acoustic profiles. First, the wedge-shaped geological model, whose thickness could be accurately controlled, was designed and built in an anechoic tank to try to directly measure the vertical resolution of SBP. Then, the acoustic pulse width of SBP was measured to calculate the theoretical general vertical resolution and extreme vertical resolution. Finally, based on the acoustic profiles obtained in the experiment, the method which was used to evaluate the actual vertical resolution by measuring the duration of reflection event was put forward. Due to comparing measurement data of different parameter settings of the SBP, the study has revealed that the SBP had the lowest resolution in the 4 kHz–500 µs setting, which was 226.5 µs, or 36.2 cm, and the highest resolution in the 15 kHz–67 µs setting, which was 72.7 µs, or 11.6 cm. The vertical resolution decreased with the increase of the pulse width. The results also showed that the actual resolution was close to the theoretical general resolution and far from the extreme resolution.

Go to article

Authors and Affiliations

Fangqi Wang
Lifeng Dong
Jisheng Ding
Xinghua Zhou
Changfei Tao
Xubo Lin
Guanhui Liang
Download PDF Download RIS Download Bibtex

Abstract

A moving average (MA) is a commonly used noise reduction method in signal processing. Several studies on wheeze auscultation have used MA analysis for preprocessing. The present study compared the performance of MA analysis with that of differential operation (DO) by observing the produced spectrograms. These signal preprocessing methods are not only applicable to wheeze signals but also to signals produced by systems such as machines, cars, and flows. Accordingly, this comparison is relevant in various fields. The results revealed that DO increased the signal power intensity of episodes in the spectrograms by more than 10 dB in terms of the signal-to-noise ratio (SNR). A mathematical analysis of relevant equations demonstrated that DO could identify high-frequency episodes in an input signal. Compared with a two-dimensional Laplacian operation, the DO method is easier to implement and could be used in other studies on acoustic signal processing. DO achieved high performance not only in denoising but also in enhancing wheeze signal features. The spectrograms revealed episodes at the fourth or even fifth harmonics; thus, DO can identify high-frequency episodes. In conclusion, MA reduces noise and DO enhances episodes in the high-frequency range; combining these methods enables efficient signal preprocessing for spectrograms.
Go to article

Authors and Affiliations

Meng-Lun Hsueh
1
Jin-Peng Chen
2
Bing-Yuh Lu
2
Huey-Dong Wu
3
Pei-Yi Liu
2

  1. Graduate Institute of Intelligent Robotics, Hwa Hsia University of Technology, New Taipei City, Taiwan
  2. Faculty of Automation, Guangdong University of Petrochemical Technology, Guangdong, China
  3. Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
Download PDF Download RIS Download Bibtex

Abstract

Starting from the consideration that sustainability of landscape heritage is logically coupled with today’s sustainable development needs, the research explores the general ideas, methods and strategies of ancient Chinese urban water management. Based on the traditional Chinese water management experience from the ancient city of Ganzhou, the paper — analyses the current water landscape heritage in Jiangxi Province, China.
Based on the historic experience and knowledge introduced and analyzed in the case study of Ganzhou, it is possible to define rainwater management principles and sustainable development strategies for modern urban landscape that could be the basis of a new research perspective in facing today’s climate anomalies.
Go to article

Bibliography

Albert, Karin, „Mountains and Water in Chinese Art’, Bonsai Clubs International, September/October 1988, Volume XXVII, No. 5.
Carter, R.C., Tyrrel, S.F. & Howsam, P. ‘The impact and sustainability of community water supply and sanita- tion programmes in developing countries’, Water and Environment Journal, 13(4)/1999, pp. 292–296.
Crouch, D.P. (1990), ‘Planning water management for an ancient Greek city. In Hydrological processes and water management in urban areas’, Lectures and papers, UNE- SCO/IHP symposium, Duisburg, Lelystad, Amsterdam, and Rotterdam, 1988
Cun, C. et al. ‘Review of urban drainage and stormwater ma- nagement in ancient China’, [in:] Landscape and Urban Planning, Vol. 190, p. 103600, Elsevier B.V, https://doi. org/10.1016/j.landurbplan.2019.103600.
Fekete, A., Dong Ge, Ning (2019), ‘Sustainable Water Ma- nagement Model as Landscape Heritage in Shang Gan Tang Village, China’, IOSR Journal of Engineering (IO- SRJEN), www.iosrjen.org ISSN (e): 2250–3021, ISSN (p): 2278-8719, Vol. 10, Issue 5, May 2020, Series –II, PP 01–13.
Ganzhou Government (2021). https://www.ganzhou.gov.cn/gzszf/c100206/shuju3.shtml, (accessed: 7.09.2021).
Guanzi: political, economic, and philosophical essays fromearly China (2021), Princeton Library of Asian Translations Vol. 159, Princeton University Press.
Shaofeng Jia, Yuanyuan Li, Aifeng Lü, Wenhua Liu, Wenbin Zhu, Jiabao Yan, Yuan Liang, Xiaozhi Xiang & Zilong Guan (2019) 'City storm-flood events in China, 1984–2015', International Journal of Water Resources Development, 35:4, 605-618, DOI: https://doi.org/10.1080/07900627.
Haidari, R. & Fekete, A. (2015), The compositional role of water in Persian gardens, Transsylvania, Nostra, 9(2).
He, J. et al. ‘Provenance versus weathering control on sedi- ment composition in tropical monsoonal climate (South China)’ — 1. ‘Geochemistry and clay mineralogy’, Chemical Geology, 558, 119860, https://doi.org/10.1016/j.chemgeo.2020.119860.
http://data.cma.cn/search/uSearch.html?keywords=%E8%B5%A3%E5%B7%9E, (accessed: 7.09.2021).
Kundzewicz, Z.W. et al. (2020), ‘Climate variability and floods in China — A review’, Earth-Science Reviews, Vol. 211, p. 103434, Elsevier B.V, https://doi.org/10.1016/j.earscirev.2020.103434.
Li, L., Uyttenhove, P. & Vaneetvelde, V. ‘Planning green infrastructure to mitigate urban surface water flooding risk — A methodology to identify priority areas applied in the city of Ghent’, Landscape and Urban Planning, 194(October 2019), 103703, https://doi.org/10.1016/j.landurbplan.2019.103703.
Jian-bin Liu, Zhong-jian Zhang, Biao Li, Microscopic & macroscopic characterizations of Beijing marble as a building material for UNESCO heritage sites: New insights into physico-mechanical property estimation and weathering resistance, Construction and Building Materials, Volume 225, 2019, Pages 510-525, ISSN 0950-0618, https://doi.org/10.1016/j.conbuildmat.2019.07.094.
National Meteorological Center of CMA (2021).
Pahl-Wostl, C. ‘Transitions towards adaptive management of water facing climate and global change’, Water Resources Management, 21(1)/2007, pp. 49–62, https://doi.org/10.1007/s11269-006-9040-4.
Stead, D. ‘Urban planning, water management and climate change strategies: Adaptation, mitigation and resilience narratives in the Netherlands’, International Journal of Sustainable Development and World Ecology, 21(1)/2014, pp. 15–27, https://doi.org/10.1080/13504509.2013.824928.
Sun, Y. et al. ‘Integration of green and gray infrastructures for sponge city’: Water and energy nexus, 3/202, pp. 29–40, https://doi.org/10.1016/j.wen.2020.03.003.
Tillie, N. & van der Heijden, R. ‘Advancing urban eco- system governance in Rotterdam: From experimenting and evidence gathering to new ways for integrated planning’, Environmental Science and Policy, 62/2016, pp. 139–145, https://doi.org/10.1016/j.envsci.2016.04.016.
Xu, Y. S., Shen, S. L., Lai, Y., & Zhou, A. N. (2018), 'Design of sponge city: Lessons learnt from an ancient drainage system in Ganzhou, China', Journal of Hydrology (Vol. 563, pp. 900–908). Elsevier B.V. https://doi.org/10.1016/j.jhydrol.2018.06.075
Go to article

Authors and Affiliations

Ning Dong Ge
1
Yang Yang
1
ORCID: ORCID
Albert Fekete
2
ORCID: ORCID

  1. Institute of Landscape Architecture, Urban Planning and Garden Art, Hungarian University of Agriculture and Life Sciences
  2. Department of Garden Art and Design, Institute of Landscape Architecture, Urban Planning and Garden Art, Hungarian University of Agriculture and Life Sciences
Download PDF Download RIS Download Bibtex

Abstract

Current networks are designed for peak loads leading to low utilization of power resources. In order to solve this problem, a heuristic energy-saving virtual network embedding algorithm based on the Katz centrality (Katz-VNE) is proposed. For solving an energy-saving virtual network embedding problem, we introduce the Katz centrality to represent the node influence. In order to minimize the energy consumption of the substrate network, the energy-saving virtual network embedding problem is formulated as an integer linear program, and the Katz-VNE is used to solve this problem. The Katz-VNE tries to embed the virtual nodes onto the substrate nodes with high Katz centrality, which is effective, and uses the shortest paths offering the best factor of bandwidths to avoid the hot nodes. The simulation results demonstrate that the long-term average energy consumption of the substrate network is reduced significantly, and the long-term revenue/cost ratio, the acceptance rate of virtual network requests, and the hibernation rate of substrate nodes as well as links are improved significantly.

Go to article

Authors and Affiliations

Qiang Zhu
Qing-Jun Wang
Mu-Jun Zang
Zhen-Dong Wang
Chang Xiao
Download PDF Download RIS Download Bibtex

Abstract

Commutation reactance is an important component in the voltage-source converter- based high-voltage direct current (VSC–HVDC) transmission system. Due to its connection to the converter, when there is a fault occurring on the valve-side bushing of a converter transformer, the nonlinearity operation of the converter complicates the characteristics of current flowing through commutation reactance, which may lead to maloperation of its overcurrent protection. It is of great significance to study the performance of commutation reactance overcurrent protection under this fault condition and propose corresponding improvement measures to ensure the safe and stable operation of AC and DC systems. In the VSC–HVDC system with the pseudo-bipolar structure of a three-phase two-level voltage source converter, the valve has six working periods in a power frequency cycle, and each period is divided into five working states. According to the difference between the fault phase and non-fault phase of the conductive bridge arms at the time of fault occurrence, these five working states are merged into two categories. On this basis, various faults of the valve-side bushing of a converter transformer are analyzed, and the conclusion is drawn that the asymmetric fault of valve-side bushing can lead to the maloperation of the commutation reactance overcurrent protection. Based on the characteristics that the current flowing through the commutation reactance after the asymmetric fault of the valve-side bushing contains decaying aperiodic components in addition to the fundamental frequency wave, a scheme to prevent the maloperation of commutation reactance overcurrent protection is proposed, which uses the unequal of two half cycle integral values with different starting points to realize the blocking of commutation reactance overcurrent protection, and it makes up the deficiency of existing protection in this aspect. Finally, this paper builds a VSC–HVDC system simulation model in the PSCAD/EMTDC platform to verify the effectiveness of the scheme.
Go to article

Authors and Affiliations

Yanxia Zhang
1
Guanghao Dong
1
ORCID: ORCID
Le Wei
1
Jinting Ma
1
Shanshan Du
1

  1. School of Electrical and Information Engineering, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin, China
Download PDF Download RIS Download Bibtex

Abstract

Wind power integration through the voltage source converter-based high-voltage direct current (VSC-HVDC) system will be a potential solution for delivering large-scale wind power to the “Three-North Regions” of China. However, the interaction between the doubly-fed induction generator (DFIG) and VSC-HVDC system may cause the risk of subsynchronous oscillation (SSO). This paper establishes a small-signal model of the VSC based multi-terminal direct current (VSC-MTDC) system with new energy access for the problem, and the influencing factors causing SSO are analyzed based on the eigenvalue analysis method. The theoretical analysis results show that the SSO in the system is related to the wind farm operating conditions, the rotor-side controller (RSC) of the DFIG and the interaction of the controller in the VSC-MTDC system. Then, the phase lag characteristic is obtained based on the signal test method, and a multi-channel variable-parameter subsynchronous damping controller (SSDC) is designed via selecting reasonable parameters. Finally, the correctness of the theoretical analysis and the effectiveness of the multi-channel variable-parameter SSDC are verified based on time-domain simulation.
Go to article

Bibliography

[1] Tang G.F., HVDC based on voltage source converter, China Electric Power Press (2010).
[2] Li C.S., Li Y.K., Guo J., He P., Research on emergency DC power support coordinated control for hybrid multi-infeed HVDC system, Archives of Electrical Engineering, vol. 61, no. 1, pp. 5–21(2020).
[3] Liu T.Q., Tao Y., Li B.H., Critical problems of wind farm integration via MMC-MTDC system, Power System Technology, vol. 41, no. 10, pp. 3251–3260 (2017).
[4] Wu J.H., Ai Q., Research on multi-terminal VSC-HVDC system for wind-farms, Power System Technology, vol. 33, no. 4, pp. 22–27 (2009).
[5] Chen C., Du W.J., Wang H.F., Review on mechanism of sub-synchronous oscillations caused by gridconnected wind farms in power systems, Southern Power System Technology, vol. 12, no. 1, pp. 84–93 (2018).
[6] Amin M., Molinas M., Understanding the origin of oscillatory phenomena observed between wind farms and HVDC systems, IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 5, no. 1, pp. 378–392 (2017).
[7] Wang W.S., Zhang C., He G.Q., Li G.H., Zhang J.Y., Wang H.J., Overview of research on subsynchronous oscillations in large-scale wind farm integrated system, Power System Technology, vol. 41, no. 4, pp. 1050–1060 (2017).
[8] Jiang Q.R., Wang L., Xie X.R., Study on oscillations of power-electronized power system and their mitigation schemes, High Voltage Engineering, vol. 43, no. 4, pp. 1057–1066 (2017).
[9] Xie X.R., Liu H.K., He J.B., Liu H., Liu W., On new oscillation issues of power system, Proceedings of the CSEE, vol. 38, no. 10, pp. 2821–2828+3133 (2018).
[10] Wang L., Yang Z.H., Lu X.Y., Prokhorow A.V., Stability analysis of a hybrid multi-infeed HVDC system connected between two offshore wind farms and two power grids, IEEE Transactions on Industry Applications, vol. 53, no. 3, pp. 1824–1833 (2017).
[11] Kunjumuhammed L.P., Pal B.C., Oates C., Dyke K.J., Electrical oscillations in wind farm systems: analysis and insight based on detailed modeling, IEEE Transactions on Sustainable Energy, vol. 7, no. 1, pp. 51–61 (2016).
[12] Sun K., Yao W., Wen J.Y., Mechanism and characteristics analysis of subsynchronous oscillation caused by DFIG-based wind farm integrated into grid through VSC-HVDC system, Proceedings of the CSEE, vol. 38, no. 22, pp. 6520–6533 (2018).
[13] Song S.H., Zhao S.Q., Analysis of sub-synchronous oscillation of DFIG-based Wind Farm integrated to grid through VSC-HVDC system based on torque method, Power System Technology, vol. 44, no. 2, pp. 630–636 (2020).
[14] Bian X.Y., Ding Y., Mai K., Zhou Q., Zhao Y., Tang L., Sub-Synchronous oscillation caused by grid-connection of offshore wind farm through VSC-HVDC and its mitigation, Automation of Electric Power Systems, vol. 42, no. 17, pp. 25–39 (2018).
[15] Lyu J., Dong P., Shi G., Cai X., Li X.L., Subsynchronous oscillation and its mitigation of MMC-based HVDC with large doubly-fed induction generator-based wind farm integration, Proceedings of the CSEE, vol. 35, no. 19, pp. 4852–4860 (2015).
[16] Lyu J., Cai X., Amin M., Molinas M., Sub-synchronous oscillation mechanism and its suppression in MMC-based HVDC connected wind farms, IET Generation, Transmission and Distribution, vol. 12, no. 4, pp. 1021–1029 (2018).
[17] Shao B.B., Zhao S.Q., Pei J.K., Li R., Subsynchronous oscillation characteristics analysis of gridconnected direct-drive wind farms via VSC-HVDC system, Power System Technology, vol. 43, no. 9, pp. 3344–3355 (2019).
[18] Chen B.P., Study on characteristics and suppression of sub/super-synchronous oscillation caused by power system with D-PMSG and VSC-HVDC, Wuhan University (2018).
[19] Guo X.S., Li Y.F., Xie X.T., Hou Y.L., Zhang D., Sub-synchronous oscillation characteristics caused by PMSG-based wind plant farm integrated via flexible HVDC system, Proceedings of the CSEE, vol. 40, no. 4, pp. 1149–1160+1407 (2020).
[20] Sun K., Mechanism and characteristics analysis of subsynchronous oscillation caused by DFIG-based wind farm integrated into grid through VSC-HVDC system, Huazhong University of Science and Technology (2018).
[21] He J., Li Q., Qin S.Y., Wang R.M., DFIG wind turbine modeling and validation for LVRT behavior, IEEE PES Innovative Smart Grid Technologies, Tianjin, pp. 1–5 (2012).
[22] Lu X.J., Lin W.X., Wen J.Y., Li Y.F., Wu Y.L., An T., Modularized small signal modeling method for DC grid, Proceedings of the CSEE, vol. 36, no. 11, pp. 2880–2889 (2016).
[23] Kalcon G.O., Adam G.P., Anaya-Lara O., Lo S., Uhlen K., Small-signal stability analysis of multiterminal VSC-based DC transmission systems, IEEE Transactions on Power Systems, vol. 27, no. 4, pp. 1818–1830 (2012).
[24] Zhou G.L., Shi X.C., Fu Ch.,Wei X.G., Zhu X.R., VSC-HVDC discrete model and its control strategy under unbalanced input voltage, Transactions of China Electrotechnical Society, vol. 23, no. 12, pp. 137–143+159 (2008).
[25] Gao B.F., Zhao C.Y., Xiao X.N., Yin W.Y., Guo C.L., Li Y.N., Design and implementation of SSDC for HVDC, High Voltage Engineering, vol. 36, no. 2, pp. 501–506 (2010).
[26] Jiang P., Hu T., Wu X., VSC-HVDC multi-channel additional damping control suppresses subsynchronous oscillation, Electric Power Automation Equipment, vol. 31, no. 9, pp. 27–31 (2011).
Go to article

Authors and Affiliations

Miaohong Su
1
ORCID: ORCID
Haiying Dong
1 2
Kaiqi Liu
1
Weiwei Zou
1

  1. School of Automatic and Electrical Engineering, Lanzhou Jiaotong University, China
  2. School of New Energy and Power Engineering, Lanzhou Jiaotong University, China
Download PDF Download RIS Download Bibtex

Abstract

Dissimilar Al/Ti alloy sheets were lap welded with ultrasonic assistance in this work. The influence of ultrasonic vibration on formation, intermetallic compounds (IMCs) and tensile failure load of the obtained joints was discussed. The results showed that voids formed at the lap interface without ultrasonic assistance. No voids can be observed on the joint welded with ultrasonic because the vibration during welding improved the material flow. No obvious IMC formed at the Al/Ti bonding interface of the joint welded without ultrasonic assistance. An IMC layer formed at the bonding interface of Al/Ti with ultrasonic assistance and its thickness increased with decreasing the welding speed. The failure load of the joint welded with ultrasonic assistance was higher than the joint without ultrasonic because the void was eliminated and the thin IMC layer formed at the bonding interface was beneficial to joint strength. All joints presented shear failure mode during the tensile shear tests.
Go to article

Authors and Affiliations

Zhibo Dong
1
Ziao Zhang
2
Wei Hu
2
Peng Gong
2
ORCID: ORCID
Zan Lv
2

  1. Harbin Institute of Technology, State Key Laboratory of Advanced Welding and Joining, Harbin 150001, China
  2. Shenyang Aerospace University, School of Aerospace Engineering, Shenyang 110136, China
Download PDF Download RIS Download Bibtex

Abstract

The aluminum alloy performance gradient plate was prepared by friction stir joining. Analysis results of the macro morphology, microstructure, and hardness of the aluminum alloy performance gradient plate prepared under various parameters show that when the feed speed of the stirring tool is 250 mm/min, the downward pressure of the stirring tool is 6.6 mm, and the rotation speed of the stirring tool changes from 200 rpm to 800 rpm. The macroscopic morphology of the aluminum alloy gradient plates prepared by the method first changed from burr to smooth, and vice versa. There is a different cross-section morphology of the prepared aluminum alloy gradient plates, however, the aluminum alloy plates are stirred and involved with each other, and the grains of the prepared plates are refined. The hardness of the upper and lower surfaces of the aluminum alloy gradient sheet decreases, whereas that of the upper surface of the side increases, and that of the middle and bottom sides also decreases. However, the hardness of the middle side of the sheet prepared with the rotation speed of the stirring tool at 800 rpm increases, but that of the bottom side still decreases. Obtained through analysis that the performance of the aluminum alloy gradient sheet prepared at the stirring tool rotation speed of 500 rpm increases in equal proportion to achieve a good performance gradient change.
Go to article

Authors and Affiliations

Song Weiwei
1 2 3
Pu Jiafei
1 2 3
Jiang Di
1 2 3
Ge Xiaole
1 2 3
Dong Qi
1 2 3
Wang Hongfeng
1 2 3

  1. Huangshan University, School of Mechanical and Electrical Engineering, Huangshan 245041, P.R. China
  2. Anhui Simulation Design and Modern Engineering Research Center, Huangshan 245041, P.R. China
  3. Anhui Province Tea Chrysanthemum Intelligent Processing Equipment Engineering Research Center, Huangshan 245041, P.R. China
Download PDF Download RIS Download Bibtex

Abstract

The study was aimed to develop an indirect enzyme-linked immunosorbent assay (ELISA), which can detect specifically Feline herpesvirus type 1 (FHV-1). The primers were designed based on the conserved sequence of FHV-1 glycoprotein B gene. The recombinant protein with reactogenicity was purified as coating antigen of the assay. The indirect ELISA, characterized by high sensitivity showed no cross-reaction with two types of feline virus, had detection limit at 1:2000 dilution. The positive rate of the assay, according to the determined cutoff value (0.25), was basically consistent with Feline Herpes Virus Antibody ELISA kit. In conclusion, the indirect ELISA with high repeatability and reproducibility can be used for detecting FHV-1, and can provide necessary support to related research.

Go to article

Authors and Affiliations

Y. Tan
G. Dong
J. Niu
Y. Guo
S. Yi
M. Sun
K. Wang
G. Hu
Download PDF Download RIS Download Bibtex

Abstract

The underframe passive inerter-based suspended device, based on the inerter-spring-damper vibration attenuation structure, could improve the dynamic performance of the train body, but its parameters are fixed and cannot meet the dynamic performance requirements under different operating conditions. Therefore, a semi-active inerter-based suspended device based on the linear quadratic regulator (LQR) control strategy is proposed to further enhance the dynamic performance. The rigid-flexible coupling vertical dynamic model of the train body and an underframe semi-active inerter-based suspended device are established. The structural parameters of the semi-active inerter-based suspended device are adjusted using LQR control strategy. Dynamic response of the system is obtained using the virtual excitation method. The dynamic characteristic of the system is evaluated using the Sperling index and compared with those of the passive and semi-active traditional suspended devices as well as the passive inerter-based suspended devices. The vertical vibration acceleration of the train body and Sperling index using the semi-active inerter-based suspended device is the smallest among the four suspended devices, which denotes the advantages of using the inerter and LQR control strategy. The semi-active inerter-based suspended device could decrease the vertical vibration acceleration of the train body and further suppress its elastic vibration in the lower frequency band, more effectively than the other three suspended devices. Overall, the semi-active inerter-based suspended device could significantly reduce elastic vibration of the train body and improve its dynamical performance.
Go to article

Authors and Affiliations

Yong Wang
1 2
ORCID: ORCID
Hao-Xuan Li
2
Hao-Dong Meng
3
Yang Wang
1

  1. State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130022, China
  2. Automotive Engineering Research Institute, Jiangsu University, Zhenjiang 212013, China
  3. School of Automotive Engineering, Changzhou Institute of Technology, Changzhou 213002, China
Download PDF Download RIS Download Bibtex

Abstract

Section steels produced by welding are essential parts for shipbuilding and offshore plant production. T-type and H-type section steels are produced by handwork for secondary processing, which is a generally difficult and tedious activity. Therefore, automatic welding, with sound welding properties and a high-speed process, is necessary to meet the production demands. Welding conditions can be optimized by controlling various parameters to obtain suitable and highly reliable microstructural properties. In this study, the heat affected zone and weld defects of fillet-welded Angle and T-bar parts were investigated in terms of their microstructural, macrostructural, and mechanical properties to ensure the soundness of AH36 section steel parts joined by continuous welds.

Go to article

Authors and Affiliations

Jihoon Jang
Changsuk Yoon
Sangik Lee
Dong-Geun Lee
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

Fe-based PM alloy powder of Fe-2.5Ni-0.5Mo-2Cu-0.4C was pressed by high velocity compaction combined with die wall lubrication, and the effect of die wall lubrication on high velocity compaction behavior and sintering properties of the Fe-based PM alloy were studied. The results indicate that the impact force, green density, sintered density of samples increase with the augment of the impact velocity and die wall lubrication. Compared with that without die wall lubrication, the green density and sintered density of the sample with die wall lubrication are about 0.07-0.12 g/cm3 and 0.08~0.11 g/cm3 higher at the same impact velocity, respectively, while the ejection force of the die wall lubricated sample is much smaller, and reduced about 26%~36%. The green compact with die wall lubrication has much fewer porosity than that without die wall lubrication, and more mechanical bonding and cold welding regions are observed. The sintered samples mainly consists of gray pearlite and white ferrite, and more pearlite is observed in the sintered sample with die wall lubrication.

Go to article

Authors and Affiliations

Zili Liu
Dong Li
Xiqin Liu
Haohao Li
Xin Huang
Zhihao Tang
Yuwen Zou
Download PDF Download RIS Download Bibtex

Abstract

The microstructure and macroscopic properties of WC-50Ni+stellite 1(Co-Cr-W, ST1) coating layer fabricated by HVOF spray have been investigated. WC-50Ni powder and ST1 powders were mixed in the ratio of 1:0 and 5:5 wt.%, respectively. Argon heat treatment (Ar) and high-frequency heat treatment (H.F.) were conducted on the coating materials. WC was decomposed in the Ar heat treatment specimen, but decomposition of WC was not observed in the H.F. heat treatment specimen. Hardness was measured for as-sprayed WC-50Ni (821.5Hv) and as-sprayed WC-50Ni+ST1 (668.1 Hv). Hardness of Ar heat treatment specimen was reduced by about 14~18% than that of the as-sprayed coating layers. However, when the H.F. heat treatment was performed, the hardness inversely increased by about 6~10% than the as-sprayed coating layer. Based on these results, the method to improve the mechanical property of HVOF sprayed WC-50Ni+ST1 coating layer has also been also discussed.

Go to article

Authors and Affiliations

Gi-Su Ham
Dong-Yeol Wi
Sun-Hong Park
Kee-Ahn Lee
ORCID: ORCID

This page uses 'cookies'. Learn more