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Control of Cascaded H-Bridges STATCOM based on the Power Flow Management
Ping-Heng Wu,Chia-Tse Lee,Hsin-Chin Chen,Po-Tai Cheng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
As smart grid techniques are getting more positive perspective and expected to grow in the future, the STATic synchronous COMpensator (STATCOM) has become one of the most important roles to manage the power flow and regulate the grid voltage. The Modular Multilevel Cascaded Converter (MMCC) based on single star bridge cell (SSBC) is very suitable for STATCOM application at the medium-voltage level in the power system. The dc capacitors voltage balancing control is a critical issue to secure the stable operation of MMCCSSBC converter. Four different control methods based on power flow analysis have been considered. The performance of each controller is evaluated under steady state or even Low Voltage Ride Through (LVRT) operation. Each controller has its power flow management and its feature. Experimental test results are given to verify these control methods can well regulated the dc bus voltages under the unbalanced grid voltages.
Aslam, Muhammad,Yang, Peixian,Lee, Po-Heng,Kim, Jeonghwan Elsevier 2018 Journal of membrane science Vol.553 No.-
<P><B>Abstract</B></P> <P>Aluminum dioxide (Al<SUB>2</SUB>O<SUB>3</SUB>) flat-tubular ceramic membrane was applied in a novel staged anaerobic fluidized bed ceramic membrane bioreactor (SAF-CMBR) for low-strength wastewater treatment. Granular activated carbon (GAC) particles were fluidized by bulk recirculation through the membrane reactor to control membrane fouling without any biogas sparging. The SAF-CMBR was operated for 350 days at 25 °C with total hydraulic retention time (HRT) between 1.3 and 2.1 h. A net permeate flux of 22 L/m<SUP>2</SUP> h was achieved during the reactor operation combined with periodic maintenance cleaning using 25 mg/L of sodium hypochlorite solution under GAC fluidization. The overall chemical oxygen demand (COD) removal efficiency was 93%; with average SCOD was less than 30 mg/L in membrane permeate. Energy requirement to operate the SAF-CMBR was 0.024 kWh/m<SUP>3</SUP> and it was only 10% of the electrical energy converted from methane produced by the reactor. Biosolids production averaged 0.01 g volatile suspended solids per g COD removed. With SAF-CMBR, microbial classification revealed that anaerobic treatment was achieved mainly by microbial communities grown on the GAC particles fluidized in which propionate-degrading syntrophs, aceticlastic/DIET-dependent CO<SUB>2</SUB> reduction methanogens <I>Methanothrix</I> and exoelectrogenic <I>Geobacter</I> were dominated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Staged anaerobic fluidized bed ceramic membrane bioreactor was developed. </LI> <LI> Net flux of 22 LMH was achieved under GAC fluidization and maintenance cleaning. </LI> <LI> Overall COD removal of 93% was achieved with less than 30 mg/L COD in permeate. </LI> <LI> Only 10% of electrical energy produced by the reactor was required for system operation. </LI> <LI> <I>Methanothrix</I> and <I>Geobactor</I> were dominantly grown on GAC particles as fluidized media. </LI> </UL> </P>
Potential Methane Production on Anaerobic Co-digestion of Swine Manure and Food Waste
Shin, Joung-Du,Park, Sang-Won,Kim, Sang-Hyoun,Duangmanee, Jack,Lee, Po-Heng,Sung, Shi-Hwu,Lee, Bong-Hoon The Korean Society of Environmental Agriculture 2008 한국환경농학회지 Vol.27 No.2
Anaerobic co-digestion of swine manure and food waste for biogas production was performed in serum bottles at various volatile solids(VS) contents and mixing ratios of two substrates(swine manure:food waste=$100:0{\sim}0:100$). Through kinetic mode of surface methodology, the methane production was fitted to a Gompertz equation. The ultimate methane production potential of swine manure alone was lower than that of food waste regardless of VS contents. However, it was appeared that maximum methane production potentials in 80 : 20 of the mixing rate at VS 3% was enhanced at 144.7%, compared to its only swine manure. The potential increased up to 815.71 ml/g VS fed as VS concentration and food composition increased up to 3.0% and 20%, respectively. The ultimate amount of methane produced had significantly a positive relationship with that of methane yield rate. Overall, it would be strongly recommended that feeding stocks use 20% of mixing ratio of food waste based on VS 3% contents when operating the anaerobic reactor on site at $35^{\circ}C$ if not have treatment of its anaerobic waste water.
( Cheng-maw Ho ),( Shu-li Ho ),( Chia-tung Shun ),( Po-huang Lee ),( Ya-hui Chen ),( Chin-sung Chien ),( Hui-ling Chen ),( Rey-heng Hu ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1
Aims: Primary liver progenitor cell cancer is a rare disease entity without definite evidence and characterization. Current nomenclature of primary liver cancer with prominent progenitor features is not comprehensive. This study was aimed to investigate the existence of this kind of primary liver cancer and characterize it immunohistopathologically based on the emerging understanding of cancer stem cell pathobiology. Methods: Surgical specimens from primary liver cancer which posed diagnostic difficulty fitting within current WHO classification of combined hepatocellular-cholangiocellular carcinoma with stem-cell features according to the growth morphology and its suggested immunohistochemical features, were stained with antibodies against well-defined markers of progenitor cells, stemness, and differentiation toward hepatocytes or cholangiocytes. Comparative interpretation of images was processed considering the histological morphology and characteristic markers. Results: The primary liver cancer consisted of CD24+ cancer progenitor cells and CD90+ mesenchymal stromal cells, which were intimately mixed. CD24+ cancer cells demonstrated bi-directional trends of differentiation: bile ductule transformation (cytokeratin 19+, epithelial cell adhesion molecule [EpCAM]+, neural cell adhesion molecule [NCAM]+, CD133+, and delta-like 1 homolog [DLK1]+); and trabecular or nested cell clusters toward hepatic lineage (hepatocyte nuclear factor-4 alpha [HNF-4α]+, Hep Par1+ and negative for CK19, EpCAM, CD133, and DLK1). Moderate lymphocyte (mostly CD4+ and CD8+ T cells) infiltrated in the CD90+ cancer- associated stroma. Conclusions: We provided the corroboration that liver progenitor cells can form primary liver cancer, not just presented as few side population of cancer stem cells. Its existence might pose significance for future stem cell therapeutic intervention targeting liver diseases, albeit the disease is rare.
( Cheng-maw Ho ),( Go Wakabayashi ),( Chi-chuan Yeh ),( Rey- Heng Hu ),( Takanori Sakaguchi ),( Takeshi Takahara ),( Po- Huang Lee ) 대한간학회 2018 춘·추계 학술대회 (KASL) Vol.2018 No.1
Aims: Liver resection is a complex procedure for trainee surgeons. Cognitive task analysis facilitates understanding and decomposing tasks that require a great proportion of mental activity from experts. Methods: Using cognitive task analysis and video-based coaching to compare liver resection by open and laparoscopic approaches, we decomposed the task of liver resection into exposure (visual field building), adequate tension made at the working plane (which may change three-dimensionally during the resection process), and target processing (intervention strategy) that can bridge the gap from the basic surgical principle. Results: The key steps of highly-specialized techniques, including hanging maneuvers and looping of extra-hepatic hepatic veins, will be shown on video by open and laparoscopic approaches. Conclusions: Familiarization with laparoscopic anatomical orientation may help surgeons already skilled at open liver resection transit to perform laparoscopic liver resection smoothly. Facilities at hand (such as patient tolerability, advanced instruments, and trained teams of personnel) can influence surgical decision making. Application of the rationale and realizing the interplay between the surgical principles and the other paramedical factors may help surgeons in training to understand the mental abstractions of experienced surgeons, to choose the most appropriate surgical strategy effectively at will, and to minimize the gap.
Hepatocyte and mesenchymal stem cell co-transplantation in rats with acute liver failure
Cheng-Maw Ho,Ya-Hui Chen,Chin-Sung Chien,Shu-Li Ho,Hui-Ling Chen,Rey-Heng Hu,Po-Huang Lee 대한이식학회 2020 Korean Journal of Transplantation Vol.34 No.2
Background: Cell therapy is considered a potential alternative to liver transplantation in acute liver failure (ALF). We aimed to evaluate the add-on therapeutic benefit of hepatocyte and mesenchymal stem cell (MSC) cotransplantation over hepatocyte-only transplantations in a rat model of ALF. Methods: ALF was induced by D-galactosamine in Sprague-Dawley rats. Freshly isolated donor hepatocytes were derived from Tg (UBC-emGFP) rats and MSCs were collected from the bone marrow cells of DsRed rats. Donor hepatocytes (1×107/mL) were intraportally transplanted 24 hours after treatment with D-galactosamine over a 70-second interval, and donor MSCs (0.5, 1, or 2×106/0.5 mL) were intraportally transplanted 1 hour after the hepatocyte transplantation was complete. Animals were sacrificed after 7 and 14 days and subjected to donor cell identification, liver histology, serologic testing, and immunohistopathological examination. Results: MSCs were observed in the periportal area, 1 and 2 weeks after transplantation. Transplanted hepatocytes did not actively proliferate when compared to hepatocyte-only transplantation. Morphologically, transplanted MSCs did not appear to differentiate into hepatocytes even 2 weeks after transplantation. Cotransplantation of MSCs was associated with lower macrophage infiltration, and reduced type I collagen, hepatocyte growth factor, tumor necrosis factor-α, and interleukin 10 expression, with similar gene expression profiles for epidermal growth factor and interleukin 6, when compared to hepatocyte-only transplantation. Conclusions: Hepatocyte and MSC cotransplantation is feasible and safe in rat models of ALF. MSCs were found to survive the process and could be located within the periportal niches 2 weeks after treatment, without enhancing transplanted hepatocyte proliferation or differentiating into hepatocytes, while ameliorating the inflammatory response.