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Search Results: 1 - 10 of 15116 matches for " Zhongqi Ren "
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Null exact controllability of the parabolic equations with equivalued surface boundary condition
Zhongqi Yin
International Journal of Stochastic Analysis , 2006, DOI: 10.1155/jamsa/2006/62694
Abstract: This paper is devoted to showing the null exact controllability for a class of parabolic equations with equivalued surface boundary condition. Our method is based on the duality argument and global Carleman-type estimate for a parabolic operator.
Null exact controllability of the parabolic equations with equivalued surface boundary condition
Zhongqi Yin
International Journal of Stochastic Analysis , 2006,
Abstract: This paper is devoted to showing the null exact controllability for a class of parabolic equations with equivalued surface boundary condition. Our method is based on the duality argument and global Carleman-type estimate for a parabolic operator.
The New Trend of Trade Protectionism in the Post-Financial Crisis Era and Countermeasures of China  [PDF]
Zhongqi Hua
Open Journal of Social Sciences (JSS) , 2019, DOI: 10.4236/jss.2019.78005
Abstract: Based on database of trade protection measures of GTA (Global Trade Alert), this paper attends to analyze the new trend of trade protectionism in the post-financial crisis era as well as the protection measures that China faced with. The analyzing results appeal that the number of trade protection measures increase rapidly with several new features, which reflects a new trend of global trade protectionism. China is the biggest victim in face of it. In respond to New Trade Protectionism, the paper proposes countermeasures in five respects.
A Signal Based Triangular Structuring Element for Mathematical Morphological Analysis and Its Application in Rolling Element Bearing Fault Diagnosis
Zhaowen Chen,Ning Gao,Wei Sun,Qiong Chen,Fengying Yan,Xinyu Zhang,Maria Iftikhar,Shiwei Liu,Zhongqi Ren
Shock and Vibration , 2014, DOI: 10.1155/2014/590875
Abstract: Mathematical morphology (MM) is an efficient nonlinear signal processing tool. It can be adopted to extract fault information from bearing signal according to a structuring element (SE). Since the bearing signal features differ for every unique cause of failure, the SEs should be well tailored to extract the fault feature from a particular signal. In the following, a signal based triangular SE according to the statistics of the magnitude of a vibration signal is proposed, together with associated methodology, which processes the bearing signal by MM analysis based on proposed SE to get the morphology spectrum of a signal. A correlation analysis on morphology spectrum is then employed to obtain the final classification of bearing faults. The classification performance of the proposed method is evaluated by a set of bearing vibration signals with inner race, ball, and outer race faults, respectively. Results show that all faults can be detected clearly and correctly. Compared with a commonly used flat SE, the correlation analysis on morphology spectrum with proposed SE gives better performance at fault diagnosis of bearing, especially the identification of the location of outer race fault and the level of fault severity. 1. Introduction Rolling element bearings are one of the most important and common components in rotating machinery. Their carrying capacity and reliability are essential for the overall machine performance. Therefore the fault diagnosis of rolling element bearing has been studied intensively for the security of mechanical systems [1]. When a fault in one surface of a bearing strikes another surface, a force impulse is generated which excites some vibration response in the bearing and machine system. The vibration response can be obtained and converted into vibration signal. As most information concerning the fault feature is contained in vibration signal, the vibration-based bearing fault diagnosis method has attracted extensive interests from both academia and industry [2, 3]. The vibration signals, usually indirect and nonlinear, are additionally masked by noise. Therefore an accurate signal processing and final diagnosis largely depend on the extraction of feature information from vibration signals. A number of studies have been conducted on vibration signal processing [4]. The most accepted approach for the demodulation and feature extraction of vibration signal, the envelope analysis (EA) technique [5, 6], has been widely used in the detection of mechanical failures since 1980s. However, a prior knowledge of the filtering band is
Unique Continuation for Stochastic Heat Equations
Qi Lu,Zhongqi Yin
Mathematics , 2013,
Abstract: We establish a unique continuation property for stochastic heat equations evolving in a bounded domain $G$. Our result shows that the value of the solution can be determined uniquely by means of its value on an arbitrary open subdomain of $G$ at any given positive time constant. Further, when $G$ is convex and bounded, we also give a quantitative version of the unique continuation property. As applications, we get an observability estimate for stochastic heat equations, an approximate result and a null controllability result for a backward stochastic heat equation.
Phosphatase Hydrolysis of Organic Phosphorus Compounds  [PDF]
Irenus A. Tazisong, Zachary N. Senwo, Zhongqi He
Advances in Enzyme Research (AER) , 2015, DOI: 10.4236/aer.2015.32005
Abstract: Phosphatases are diverse groups of enzymes that deserve special attention because of their significant roles in organic phosphorus (OP) mineralization to inorganic available forms (Pi). This work 1) compared the catalytic potentials of commercially acid phosphatase from wheat germ, sweet potato, and potato, and alkaline phosphatase from E. coli; 2) demonstrated that the rate of hydrolysis, catalytic efficiency, thermal stability, and optimal pH of these enzymes depended on enzyme sources and the stereochemical or stereoisomeric structures of the substrates; 3) revealed that both acid and alkaline phosphatases exhibited broad range of substrate hydrolysis with high affinity for p-nitrophenyl phosphate bis (cyclohexylammonium) than the widely used p-nitrophenyl phosphate disodium hexahydrate for phosphatase assay. Sweet potato had relatively higher reaction kinetics (Vmax, Km, Kcat, Kcat/Km) values with most substrates tested. The order of catalytic activity was in the order: sweet potato > wheat germ > potato, while the order of substrate hydrolyzed was: PNPBC > PNP > PNP2A2E > DG6P2Na > DG6PNa > Bis-PNP > phytate. The optimum pH for the acid phosphatase was observed to be 5.0. Generally, the activity of alkaline phosphatase was similar to that of acid phosphatase with optimal pH between 10 and 13, depending on the substrates. Knowledge derived from this work would be helpful in enzyme catalysis in soils and water environments.
Speciation and Mobility of Phosphate in the Eutrophic Ponds at Prospect Park, Brooklyn, New York, USA  [PDF]
Ying Liu, Zhongqi Cheng, Brett F. Branco, John F. Marra
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.56004
Abstract:
The water system at the Prospect Park ponds of Brooklyn, NY has been receiving chronic loads of orthophosphate from the municipal water since the mid ’90s. The ponds are currently eutrophic with degraded water quality and high levels of P in the sediment. In this study, the distribution and speciation of P within the water column was examined. The dominant form of P in the water was found as soluble reactive phosphate (SRP) and the temporal change of SRP indicated significant internal loading from the sediment during late summer in the ponds downstream. Lake sediment was investigated for P fractionation and phosphate bound to Fe-hydroxides was the dominant form of P in the sediment. Both external and internal P pools are important and should be taken into consideration when planning for restoration.
PHASE DIAGRAM AND PROPERTIES OF TERNARY Al-Mg-Ce ALLOYS
CUI Zhongqi,WU Rengeng,
金属学报 , 1984,
Abstract:
Differences in Modified Morgan Phosphorus Levels Determined by Colorimetric and Inductively Coupled Plasma Methods  [PDF]
Zhongqi He, Hailin Zhang, O. Modesto Olanya, Jonathan M. Frantz, Robert P. Larkin
Open Journal of Soil Science (OJSS) , 2012, DOI: 10.4236/ojss.2012.23030
Abstract: Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P < 0.001). In average, the ICP-based MMP level of the 192 samples was 23.3 mg P kg–1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.
Economic Potential of Compost Amendment as an Alternative to Irrigation in Maine Potato Production Systems  [PDF]
John M. Halloran, Robert P. Larkin, Sherri L. DeFauw, O. Modesto Olanya, Zhongqi He
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.42031
Abstract: Potato productivity in the northeastern US has been relatively constant for over 50 years, raising questions about what factors are limiting productivity. Research was initiated in 2004 to identify key constraints to potato productivity by evaluating Status Quo (SQ), Soil Conserving (SC), and Soil Improving (SI) cropping systems under both rainfed and irrigated management, and it was found that addition of compost or irrigation substantially increased yield. In this study, we employed partial budgeting to determine cost differences and their impact on net revenue for these cropping systems. Differences in systems were primarily associated with rotation length, tillage operations, compost and application expenses, and water management practices. When compost (as composted dairy manure) was annually applied at 19 Mg haf-1 and evaluated over the entire 3-year crop rotation cycle, the compost-amended rainfed SI system was more expensive to maintain than the irrigated SC system if compost cost exceeded $3.63 Mg-1. Average marketable yields were used to calculate gross and net revenue for each system. Because average potato yield for the irrigated SQ system (28.4 Mg·ha-1) equaled that in the rainfed SI system (28.3 Mg·ha-1), we were able to compare cost of irrigation versus compost for achieving comparable yield. The compost-amended SI system under rainfed management generated more net revenue from the potato crop than the irrigated SQ system when compost costs were less than $7.42 Mg-1. When compared to the commonly used rainfed SQ system, rainfed SI achieved higher net revenue as long as compost cost was less than $22.95 Mg-1. The rainfed SI system achieved higher net revenue than the irrigated SC system when compost cost was $9.43 Mg-1or less, but generated greater net revenue than the rainfed SC system regardless of compost costs, due to substantially higher yields associated with compost amendment. This investigation demonstrates that compost is a potentially viable substitute to irrigation for potato in the northeastern US; however, such potential is highly dependent on suitable compost sources and application costs.
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