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Detection of SCC by Electrochemical Noise and In-Situ 3-D Microscopy
( Da-hai Xia ),( Yashar Behnamian ),( Jing-li Luo ),( Stan Klimas ) 한국부식방식학회(구 한국부식학회) 2017 Corrosion Science and Technology Vol.16 No.4
Stress-corrosion cracking (SCC) of alloy 600 and alloy 800 in 0.5 mol/L thiosulfate solution during constant strain was investigated using electrochemical noise (EN) combined with 3-D microscope techniques. The in-situ morphology observation and EN results indicate that the SCC process could be divided into three stages: (1) passive film stabilization and growth, (2) crack initiation, (3) and crack growth. Power Spectral Density (PSD) and the probability distribution obtained from EN were used as the “fingerprint” to distinguish the different processes. During passive film stabilization and growth, the current noise signals resembled “white noise”: when the crack initiated, many transient peaks could be seen in the current noise and the wavelet energy at low frequency as well as the noise resistance decreased. After crack propagation, the noise amplitudes increased, particularly the white noises at low and high frequencies (WL and WH) in the PSDs. Finally, the detection of metal structure corrosion in a simulated sea splash zone and pipeline corrosion in the atmosphere are established.
( Da Hai Yu ),( Ji Yu Yang ),( Fei Teng ),( Li Li Feng ),( Xue Xun Fang ),( He Jun Ren ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.7
The mature landfill leachate, which is characterized by a high concentration of ammonia nitrogen (NH3-N) and humic acid (HA), poses a challenge to biotreatment methods, due to the constituent toxicity and low biodegradable fraction of the organics. In this study, we applied bioaugmentation technology in landfill leachate degradation by introducing a domesticated NH3-N and HA resistant bacteria strain, which was identified as Bacillus cereus (abbreviated as B. cereus Jlu) and Enterococcus casseliflavus (abbreviated as E. casseliflavus Jlu), respectively. The isolated strains exhibited excellent tolerant ability for NH3-N and HA and they could also greatly improved the COD (chemical oxygen demand), NH3-N and HA removal rate, and efficiency of bioaugmentation degradation of landfill leachate. Only 3 days was required for the domesticated bacteria to remove about 70.0% COD, compared with 9 days`` degradation for the undomesticated (autochthonous) bacteria to obtain a similar removal rate. An orthogonal array was then used to further improve the COD and NH3-N removal rate. Under the optimum condition, the COD removal rate in leachate by using E. casseliflavus Jlu and B. cereus Jlu increased to 86.0% and 90.0%, respectively after, 2 days of degradation. The simultaneous removal of NH3-N and HA with more than 50% and 40% removal rate in leachate by employing the sole screened strain was first observed.
Applying Multifractal Spectrum Theory to Fingerprint Features Recognition
Hai Ming Ni,Da Wei Qi,Hongbo Mu 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.1
Fingerprint features recognition which can be used to distinguish between individuals is an intriguing study with many potential applications. In this paper, a new method for fingerprint recognition based on multifractal spectrum theory was proposed. The recognition process can be divided into the following main steps: (1) Extracting the core point in fingerprint; (2) Fragmenting the fingerprint image to get a subimage with fixed size; (3) Thinning the fingerprint image by using an improved OPTA algorithm; (4) Segmenting the curves in fingerprint image into digital straight segments with normalized straight length threshold; (5) Selecting the appropriate dividing scale to segment the processed fingerprint image; (6) Calculating and analyzing the multifractal spectrum curve - f (a) ; (7) Fitting curve equation and extracting the characteristic parameters of a - f(a); (8) Finally, the parameters matching and fingerprint feature recognition. A large number of experimental results show that our method is effective.
고분자 폴리머 잉크를 이용한 고속 연속 전기 방사 프린팅
장대해(Da-Hai Zhang),권계시(Kye-Si Kwon) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.4
최근 전기방사를 이용한 프린팅이 미세 패터닝 분야에 응용이 되고 있다. 전기방사를 이용한 패터닝은 연속 프린팅 방식으로 기존의 요구적출형 방식에 비해 패터닝 속도가 빠르다는 장점이 있다. 안정적인 연속 프린팅을 위해서는 고분자의 폴리머를 프린팅하려고 하는 잉크에 혼합하는 것이 필요하다. 본 연구에서는 PEO 를 이러한 첨가 폴리머로 사용하였다. 이러한 폴리머의 첨가에 대한 잉크의 점도 및 Taylor cone 형성에 대해 미치는 영향을 조사하였다. 마지막으로 전기방사 프린팅의 예로서 실버 페이스트 잉크를 유리 기판 위에 패터닝하였다. Electrospinning has recently been used for micropatterning. The electrospinning method as a patterning tool has the advantage of a rapid patterning speed because it is based on a continuous printing mode rather than a drop-ondemand mode. To obtain stable continuous printing, a high molecular weight polymer must be mixed with functional materials for patterning. In this paper, polyethylene oxide (PEO) was used. The effect of polymer on viscosity and formation of a Taylor cone jet from the electrospinning nozzle was investigated. Finally, the electrospinning patterning results of a silver paste ink on a glass substrate were investigated.
Energy-saving optimization on active disturbance rejection decoupling multivariable control
Ding Da-Min,Yang Hai-Ma,Liu Jin,Zhang Da-Wei,Jiang Xiao-Hui 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.3
An industrial control process multiple-input multiple-output (MIMO) coupled system is analyzed in this study as an example of a Loss of Coolant Accident (LOCA) simulation system. Ordinary control algorithms can complete the steady state of the control system and even reduce the response time to some extent, but the entire system still consumes a large amount of energy after reaching the steady state. So a multivariable decoupled energy-saving control method is proposed, and a novel energy-saving function (economic function, Eco-Function) is specially designed based on the active disturbance rejection control algorithm. Simulations and LOCA simulation system tests show that the Eco-function algorithm can cope with the uncertainty of the multivariable system's internal parameters and external disturbances, and it can save up to 67% of energy consumption in maintaining the parameter steady state.
강다해솜(Kang, Da-Hai-Som),양진향(Yang, Jinhyang) 한국간호과학회 2016 Journal of Korean Academy of Nursing Vol.46 No.2
Purpose: This study was done to explore adaptation experience of living kidney donors after donation. Specific aims were to identify challenges donors face in the process of adaptation following surgery and how they interact with recipients and other people. Methods: Grounded theory methodology was utilized. Participants were 13 living kidney donors at six months or more after donation. Data were collected by in-depth interviews with individual participants. Data were analyzed using constants comparative method with theoretical saturation. Results: A core category emerged as ‘keeping the fences of my family in spite of vulnerability’. The adaptation process after donation was manifested in four phases: exploration, balance, maintenance, and acclimatization. Phenomenon was perception of vulnerability. Strategies to manage the vulnerability were assessing changes of body awareness, tailoring regimen to one’s own body condition, coping with health problems, keeping restoration of health, and ruminating on the meaning of one’s kidney donation. Consequences were reestablishing family well-being, realizing the values of one’s kidney donation, and living with uncertainty. Conclusion: Findings of the study indicate that there is a need for health professionals to understand the vulnerability of living kidney donors and help their family system maintain a healthy and productive life. The results of this study can be used to develop phase-specific, patient-centered, and tailored interventions for living kidney donors.
Applying Multifractal Formalism Combined with Wavelet Transform to Wood Defects Detection
Hai ming Ni,Da wei Qi,Hongbo Mu. 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.4
Nowadays, X-ray computed tomography (CT) wood nondestructive testing technology has been applied to detection of internal defects in log for the purpose of obtaining the optimal wood cutting plan. Multifractal spectrum and wavelet transform are usually used for analyzing, modeling, and extracting different complex features of signals and images. A novel CT image edge detection method which using multifractal spectrum theory combined with wavelet transform is applied in this paper. The new method can be divided into the following main steps: (1) Calculating the wavelet module values of wood defect image. (2) Combining wavelet transform module values with multifractal theory. (3) Calculating the multifractal spectrum from the wavelet transform. (4) Selecting the appropriate threshold to wood defects detection. A large number of experimental results show that the new method to recognize the wood defects is effective.