Shiping Zhu

Chinese University of Hong Kong, Shenzhen

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Bo‐Geng Li

State Key Laboratory of Chemical Engineering

He Zhu

Chinese University of Hong Kong, Shenzhen

Qi Zhang

Chinese University of Hong Kong, Shenzhen

Wenjun Wang

Zhejiang University

Yiliang Wu

Wuyi University

A. E. Hamielec

McMaster University

Robert Pelton

McMaster University

Beng S. Ong

Hong Kong Baptist University

Zhibin Ye

Concordia University

Youqing Shen

Zhejiang University

Cooperative Institutions

McMaster University

121

Chinese Academy of Sciences

104

Zhejiang University

Sichuan University

University of Chinese Academy of Sciences

Chinese University of Hong Kong, Shenzhen

Wuhan University

Caerus Molecular Diagnostics (United States)

Concordia University

State Key Laboratory of Chemical Engineering

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ESR studies on oxidation state of titanocene and zirconocene catalysts

Journal of Polymer Science Part A Polymer Chemistry (1999)

Yun Huang Quanyong Yu Shiping Zhu Garry L. Rempel L. Li

An on-line electron spin resonance (ESR) technique was applied to investigate the oxidation states of the metallocene catalysts CpTiCl3, CpZrCl3, Cp2TiCl2, and Cp2ZrCl2. These metallocene catalysts were activated by modified methylaluminoxane (MMAO). It was found that the titanocene catalysts (CpTiCl3 and Cp2TiCl2) were readily reduced to the trivalent state while the zirconocene catalysts (CpZrCl3 and Cp2ZrCl2) were quite stable with respect to reduction. The concentrations of the trivalent species Ti(III) and Zr(III) showed linear relationships with the concentrations of metallocene catalyst precursors. However, their slopes were always smaller than unity indicating the existence of bimetallic interactions of the active sites. The ESR detectable Ti(III) and Zr(III) concentrations initially increased with the MAO/catalyst ratio and then leveled off after an 800–1000 Al/catalyst molar ratio. The deactivation processes were followed as a function of aging time over a range of temperature (25–100°C). The decay curves strongly depended on aging temperature with higher temperature giving faster decay rates. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1465–1472, 1999

Bimetallic strip

Methylaluminoxane

Post-metallocene catalyst

10.1002/(sici)1099-0518(19990515)37:10<1465::aid-pola9>3.0.co;2-q

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Citations (18)

Advanced DSP Control of Induction Motors Using Kalman Filter

Shiping Zhu

This research paper presents a novel method for the speed control of induction motors without using a speed sensor. The rotor speed can be accurately computed using an optimal control observer named the Kalman filter designed in this research paper. This replaces a speed sensor and eliminates the difficulty of the sensor installation in many applications. This research paper presents an advanced field oriented control of induction motors, based on a specific d-q coordinate model with the d-coordinate chosen to be in line with the rotor flux and the q-coordinate chosen to be 90⁰ lagging. The position of the rotor flux can be accurately computed using the Kalman filter. This eliminates the position sensors required accurately to monitor the flux. This research paper shows that as a result of this specific d-q transformation, the motor torque is proportional to the product of the rotor flux and the q-coordinate stator current. This significantly simplifies the induction motor control, such that the rotor flux is simply controlled by regulating the flux-related d-coordinates stator current and the motor torque is controlled just by regulating the q-coordinate stator current. This research paper presents a computational efficient recursive algorithm for Kalman filter which is specifically designed for the induction motor control. The Kalman filter provides the minimum variance state estimation and tolerates induction motor modelling and measurement errors. The Kalman filter can process all available measurements regardless of their precision (only two input current measurements required for the motor control), and provides a quick and optimal estimate of the variables of interest (the rotor speed and flux selected as outputs), as well as achieves a fast convergence. This research paper presents the digital signal processor (DSP) implementation of the field oriented control of induction motors using Kalman filter. The hardware requirements and all software modules are detailed. The experimental verification of the control method designed in this research paper is provided. Typical measurements are given to demonstrate the efficiency of the novel control presented in this research paper.

Alpha beta filter

10.32920/ryerson.14647683.v1

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Atom Transfer Radical Polymerization of Methyl Methacrylate Mediated by Copper Bromide−Tetraethyldiethylenetriamine Grafted on Soluble and Recoverable Poly(ethylene-b-ethylene glycol) Supports

Macromolecules (2001)

Youqing Shen Shiping Zhu

Polyethylene (PE) and polyethylene-block-poly(ethylene glycol) (PE-PEG) grafted with N,N,N',N'-tetraethyldiethylenetriamine (TEDETA) were used as soluble and recoverable supports for copper bromide mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). The PE chain length and poly(ethylene glycol) (PEG) spacer strongly affected the catalytic activity and control of the polymerization. With PE as a catalyst support, the catalytic activity and control of the polymerization were low and decreased as the PE support's chain length increased. The adverse effects of the PE support were minimized by using PEG as spacer to graft the catalyst onto the PE support. The PE25-PEG4-TEDETA-CuBr and PE16-PEG10-TEDETA-CuBr were found effectively mediated ATRP of MMA. The recycled PE-supported catalysts had low activity because of catalyst side reactions and/or catalyst loss, but the PE25-PEG4-TEDETA-CuBr retained 90% activity upon recycling and had good control over the polymerization.

Atom-transfer radical-polymerization

Chain transfer

10.1021/ma010996d

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Citations (67)

Chain-length-dependent termination for free radical polymerization

Macromolecules (1989)

Shiping Zhu A. E. Hamielec

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChain-length-dependent termination for free radical polymerizationS. Zhu and A. E. HamielecCite this: Macromolecules 1989, 22, 7, 3093–3098Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://pubs.acs.org/doi/10.1021/ma00197a033https://doi.org/10.1021/ma00197a033research-articleACS PublicationsRequest reuse permissionsArticle Views468Altmetric-Citations73LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

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10.1021/ma00197a033

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Citations (76)

Atom‐transfer radical grafting polymerization of 2‐methacryloyloxyethyl phosphorylcholine from silicon wafer surfaces

Journal of Polymer Science Part A Polymer Chemistry (2004)

Wei Feng John L. Brash Shiping Zhu

Abstract 2‐Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was grafted from silicon wafer surfaces at room temperature by combining self‐assembly of initiator and surface‐initiated atom transfer radical polymerization. Two methods were used to control the grafting process. One was to add free initiator to the reaction system; the other was to add excess deactivator. The grafting densities up to 0.3 chains/nm 2 were obtained. The surface thickness increased linearly with MPC conversion. The thickness depended on catalyst and monomer concentrations, as well as activator/deactivator ratio. Poly(MPC) layers of >100 nm thick were obtained by optimizing the polymerization conditions. A second block of either poly(MPC) or poly[2‐(dimethylamino)ethyl methacrylate] was also grown from the grafted poly(MPC), demonstrating the system livingness. X‐ray photoelectron spectroscopy was used to examine the surface chemical compositions showed good agreement with the theoretical values. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2931–2942, 2004

Atom-transfer radical-polymerization

10.1002/pola.20095

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Citations (153)

Synthesis of low molecular weight polyethylenes and polyethylene mimics with controlled chain structures

Progress in Polymer Science (2013)

L. So Santiago Faucher Shiping Zhu

Chain (unit)

10.1016/j.progpolymsci.2013.08.002

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Citations (15)

110th Anniversary: Model-Guided Preparation of Copolymer Sequence Distributions through Programmed Semibatch RAFT Mini-Emulsion Styrene/Butyl Acrylate Copolymerization

Industrial & Engineering Chemistry Research (2019)

Jie Jiang Wenjun Wang Bo‐Geng Li Shiping Zhu

The tactics of targeting copolymer composition (CC) and molecular weight (MW) via semibatch controlled radical polymerization (CRP) have been extensively studied. However, little effort is made to target copolymer sequence length (CSL) and its triad sequence, which are among the key microstructures determining material properties of the copolymers. This work presents a method to design and synthesize targeted CSL and copolymer triads in a reversible addition–fragmentation chain transfer radical mini-emulsion copolymerization system (RAFT) through a semibatch chain and sequence model coupled with Alfrey Mayo model. The kinetic model was first derived and correlated with experimental results of the batch St/BA copolymerizations. The semibatch RAFT model was then employed to calculate the feed-rate to target CSL and their triads. St/BA copolymers with different uniform CSLs and their triads are synthesized through the programmed semibatch RAFT mini-emulsion copolymerization processes.

Raft

Chain transfer

Emulsion polymerization

Triad (sociology)

Sequence (biology)

Butyl acrylate

10.1021/acs.iecr.9b03414

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Citations (7)

Branched-PE/i-PP Reactor Blends Prepared through Ethylene Gas-Phase Polymerization Catalyzed by α-Diimine Nickel Supported on iPP Particles

Studies in surface science and catalysis (2006)

Chunwen Guo Hong Fan Bo‐Geng Li Shiping Zhu

Diimine

10.1016/s0167-2991(06)80467-2

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Citations (3)

Surface modification of active metals through atom transfer radical polymerization grafting of acrylics

Applied Surface Science (2008)

Rachel Gong Shane Maclaughlin Shiping Zhu

Atom-transfer radical-polymerization

Chain transfer

Surface Modification

10.1016/j.apsusc.2008.04.101

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Citations (39)

ESR Study and Radical Observation in Transition Metal-Mediated Polymerization: Unified View of Atom Transfer Radical Polymerization Mechanism

ACS symposium series (2003)

Aileen R. Wang Shiping Zhu Krzysztof Matyjaszewski

Using an on-line electron spin resonance (ESR) technique, we studied the electron paramagnetic species of oxidized metal centers and carbon radicals in three representative catalyst/ligand systems of transition metal-mediated polymerization of methyl methacrylate. These systems were: (1) CuBr/Bpy, (2) RuCl2(PPh3)/Al(OiPr)3, and (3) CuBr/N-pentyl-2-pyridylmethanimine. Ethylene glycol dimethacrylate was used as crosslinker to trigger the diffusion-controlled radical deactivation so that the radical population was accumulated to an ESR detectable level. Methacrylate radicals were observed in all the systems. Their signal hyperfine structures were typical of nine line and were identical to those observed in conventional free radical polymerization processes. There were also peculiar signals observed at low dimethacrylate levels in (2) and (3). These paramagnetic species were present without the monomer addition. The nature of the propagating center type was analyzed. This work provided a unified view for the radical mechanisms of atom transfer radical polymerization.

Atom-transfer radical-polymerization

Ethylene glycol dimethacrylate

10.1021/bk-2003-0854.ch012

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Citations (1)