Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat ... more Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat swabs of the patients with Severe Acute Respiratory Syndrome (SARS) and the causative association with SARS was determined. To reveal further the characteristics of the virus and to provide insight about the molecular mechanism of SARS etiology, a proteomic strategy was utilized to identify the structural proteins of SARS coronavirus (SARS-CoV) isolated from Vero E6 cells infected with the BJ-01 strain of the virus. At first, Western blotting with the convalescent sera from SARS patients demonstrated that there were various structural proteins of SARS-CoV in the cultured supernatant of virus infected-Vero E6 cells and that nucleocaspid (N) protein had a prominent immunogenicity to the convalescent sera from the patients with SARS, while the immune response of spike (S) protein probably binding with membrane (M) glycoprotein was much weaker. Then, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to separate the complex protein constituents, and the strategy of continuous slicing from loading well to the bottom of the gels was utilized to search thoroughly the structural proteins of the virus. The proteins in sliced slots were trypsinized in-gel and identified by mass spectrometry. Three structural proteins named S, N and M proteins of SARS-CoV were uncovered with the sequence coverage of 38.9, 93.1 and 28.1% respectively. Glycosylation modification in S protein was also analyzed and four glycosylation sites were discovered by comparing the mass spectra before and after deglycosylation of the peptides with PNGase F digestion. Matrix-assisted laser desorption/ionization-mass spectrometry determination showed that relative molecular weight of intact N protein is 45 929 Da, which is very close to its theoretically calculated molecular weight 45 935 Da based on the amino acid sequence deduced from the genome with the first amino acid methionine at the N-terminus depleted and second, serine, acetylated, indicating that phosphorylation does not happen at all in the predicted phosphorylation sites within infected cells nor in virus particles. Intriguingly, a series of shorter isoforms of N protein was observed by SDS-PAGE and identified by mass spectrometry characterization. For further confirmation of this phenomenon and its related mechanism, recombinant N protein of SARS-CoV was cleaved in vitro by caspase-3 and -6 respectively. The results demonstrated that these shorter isoforms could be the products from cleavage of caspase-3 rather than that of caspase-6. Further, the relationship between the caspase cleavage and the viral infection to the host cell is discussed.
A crucial component of a grid-connected converter system is the phase-locked loop (PLL) that sync... more A crucial component of a grid-connected converter system is the phase-locked loop (PLL) that synchronizes the control to the grid voltage. Accurate, fast responding PLLs are required to provide phase angle and frequency measurements of the grid voltage for control and protection purposes. This paper proposes novel feedback mechanisms using the estimated frequency and phase in single-phase PLLs (in the stationary and rotating reference frames) which enhances performance. The estimated frequency ripple is eliminated without using low-pass filters (LPFs), and feedback terms are shown to improve the synchronization speed, by as much as 80% in some cases. Mathematical analyses, simulation, and hardware results are presented to verify the methods.
... most commonly unidirec-tional two-stage converter featuring the step-up (boost) dc-dc convert... more ... most commonly unidirec-tional two-stage converter featuring the step-up (boost) dc-dc converter stage and ... and 400 V to allow for power sharing and voltage regulation using the droop control. ... Starting with the bidirectional grid interface converter, its VI curve is shown at the top ...
This paper presents the structure and capabilities of a small, grid-interactive distributed energ... more This paper presents the structure and capabilities of a small, grid-interactive distributed energy resource system comprised of a photovoltaic source, plug-in hybrid electric vehicle, and various local loads. Implemented at the residential level, this system, with a plug-in hybrid electrical vehicle, has the ability to isolate a house from the utility grid (intentionally due to a fault or other abnormal grid conditions), work in the standalone mode, synchronize and reconnect to the utility grid, without load power interruptions. Plug-in hybrid electrical vehicles, with a built-in bidirectional power converter, present the opportunity for demand-response operation in the grid connected mode, whereas in the islanded mode, it can perform frequency and voltage regulation of the power bus. In this paper, system structure and modes of operation are described, and measured results are presented for two main modes of operation and mode transitions.
Batch processes are very important to the chemical and manufacturing industries. Techniques for m... more Batch processes are very important to the chemical and manufacturing industries. Techniques for monitoring these batch processes to ensure their safe operation and to produce consistently high-quality products are needed. Nomikos and MacGregor (1994) presented a multiway principal component analysis (MPCA) approach for monitoring batch processes, and test results show that the method is simple, powerful, and effective. MPCA, however, is a linear method, and most batch processes are nonlinear. Although data treatment techniques can remove some nonlinearity from the data, nonlinearity is still a problem when using MPCA for monitoring. In this article a nonlinear principal component analysis (NLPCA) method (Dong and McAvoy, 1993) is used for batch process monitoring. Results show that this method is excellent for this problem. Another interesting extension of this approach involves multistage batch process monitoring, which is illustrated through a detailed simulation study.
Batch processes are very important to the chemical and manufacturing industries. Techniques for m... more Batch processes are very important to the chemical and manufacturing industries. Techniques for monitoring these batch processes to ensure their safe operation and to produce consistently high-quality products are needed. Nomikos and MacGregor (1994) presented a multiway principal component analysis (MPCA) approach for monitoring batch processes, and test results show that the method is simple, powerful, and effective. MPCA, however, is a linear method, and most batch processes are nonlinear. Although data treatment techniques can remove some nonlinearity from the data, nonlinearity is still a problem when using MPCA for monitoring. In this article a nonlinear principal component analysis (NLPCA) method (Dong and McAvoy, 1993) is used for batch process monitoring. Results show that this method is excellent for this problem. Another interesting extension of this approach involves multistage batch process monitoring, which is illustrated through a detailed simulation study.
Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat ... more Recently, a new coronavirus was isolated from the lung tissue of autopsy sample and nasal/throat swabs of the patients with Severe Acute Respiratory Syndrome (SARS) and the causative association with SARS was determined. To reveal further the characteristics of the virus and to provide insight about the molecular mechanism of SARS etiology, a proteomic strategy was utilized to identify the structural proteins of SARS coronavirus (SARS-CoV) isolated from Vero E6 cells infected with the BJ-01 strain of the virus. At first, Western blotting with the convalescent sera from SARS patients demonstrated that there were various structural proteins of SARS-CoV in the cultured supernatant of virus infected-Vero E6 cells and that nucleocaspid (N) protein had a prominent immunogenicity to the convalescent sera from the patients with SARS, while the immune response of spike (S) protein probably binding with membrane (M) glycoprotein was much weaker. Then, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to separate the complex protein constituents, and the strategy of continuous slicing from loading well to the bottom of the gels was utilized to search thoroughly the structural proteins of the virus. The proteins in sliced slots were trypsinized in-gel and identified by mass spectrometry. Three structural proteins named S, N and M proteins of SARS-CoV were uncovered with the sequence coverage of 38.9, 93.1 and 28.1% respectively. Glycosylation modification in S protein was also analyzed and four glycosylation sites were discovered by comparing the mass spectra before and after deglycosylation of the peptides with PNGase F digestion. Matrix-assisted laser desorption/ionization-mass spectrometry determination showed that relative molecular weight of intact N protein is 45 929 Da, which is very close to its theoretically calculated molecular weight 45 935 Da based on the amino acid sequence deduced from the genome with the first amino acid methionine at the N-terminus depleted and second, serine, acetylated, indicating that phosphorylation does not happen at all in the predicted phosphorylation sites within infected cells nor in virus particles. Intriguingly, a series of shorter isoforms of N protein was observed by SDS-PAGE and identified by mass spectrometry characterization. For further confirmation of this phenomenon and its related mechanism, recombinant N protein of SARS-CoV was cleaved in vitro by caspase-3 and -6 respectively. The results demonstrated that these shorter isoforms could be the products from cleavage of caspase-3 rather than that of caspase-6. Further, the relationship between the caspase cleavage and the viral infection to the host cell is discussed.
A crucial component of a grid-connected converter system is the phase-locked loop (PLL) that sync... more A crucial component of a grid-connected converter system is the phase-locked loop (PLL) that synchronizes the control to the grid voltage. Accurate, fast responding PLLs are required to provide phase angle and frequency measurements of the grid voltage for control and protection purposes. This paper proposes novel feedback mechanisms using the estimated frequency and phase in single-phase PLLs (in the stationary and rotating reference frames) which enhances performance. The estimated frequency ripple is eliminated without using low-pass filters (LPFs), and feedback terms are shown to improve the synchronization speed, by as much as 80% in some cases. Mathematical analyses, simulation, and hardware results are presented to verify the methods.
... most commonly unidirec-tional two-stage converter featuring the step-up (boost) dc-dc convert... more ... most commonly unidirec-tional two-stage converter featuring the step-up (boost) dc-dc converter stage and ... and 400 V to allow for power sharing and voltage regulation using the droop control. ... Starting with the bidirectional grid interface converter, its VI curve is shown at the top ...
This paper presents the structure and capabilities of a small, grid-interactive distributed energ... more This paper presents the structure and capabilities of a small, grid-interactive distributed energy resource system comprised of a photovoltaic source, plug-in hybrid electric vehicle, and various local loads. Implemented at the residential level, this system, with a plug-in hybrid electrical vehicle, has the ability to isolate a house from the utility grid (intentionally due to a fault or other abnormal grid conditions), work in the standalone mode, synchronize and reconnect to the utility grid, without load power interruptions. Plug-in hybrid electrical vehicles, with a built-in bidirectional power converter, present the opportunity for demand-response operation in the grid connected mode, whereas in the islanded mode, it can perform frequency and voltage regulation of the power bus. In this paper, system structure and modes of operation are described, and measured results are presented for two main modes of operation and mode transitions.
Batch processes are very important to the chemical and manufacturing industries. Techniques for m... more Batch processes are very important to the chemical and manufacturing industries. Techniques for monitoring these batch processes to ensure their safe operation and to produce consistently high-quality products are needed. Nomikos and MacGregor (1994) presented a multiway principal component analysis (MPCA) approach for monitoring batch processes, and test results show that the method is simple, powerful, and effective. MPCA, however, is a linear method, and most batch processes are nonlinear. Although data treatment techniques can remove some nonlinearity from the data, nonlinearity is still a problem when using MPCA for monitoring. In this article a nonlinear principal component analysis (NLPCA) method (Dong and McAvoy, 1993) is used for batch process monitoring. Results show that this method is excellent for this problem. Another interesting extension of this approach involves multistage batch process monitoring, which is illustrated through a detailed simulation study.
Batch processes are very important to the chemical and manufacturing industries. Techniques for m... more Batch processes are very important to the chemical and manufacturing industries. Techniques for monitoring these batch processes to ensure their safe operation and to produce consistently high-quality products are needed. Nomikos and MacGregor (1994) presented a multiway principal component analysis (MPCA) approach for monitoring batch processes, and test results show that the method is simple, powerful, and effective. MPCA, however, is a linear method, and most batch processes are nonlinear. Although data treatment techniques can remove some nonlinearity from the data, nonlinearity is still a problem when using MPCA for monitoring. In this article a nonlinear principal component analysis (NLPCA) method (Dong and McAvoy, 1993) is used for batch process monitoring. Results show that this method is excellent for this problem. Another interesting extension of this approach involves multistage batch process monitoring, which is illustrated through a detailed simulation study.
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