Background Although traditional surgical procedures for glaucoma(such as trabeculectomy and tube-shunt implantation)can significantly reduce intraocular pressure(IOP),they are associated with numerous complications,so...Background Although traditional surgical procedures for glaucoma(such as trabeculectomy and tube-shunt implantation)can significantly reduce intraocular pressure(IOP),they are associated with numerous complications,some of which are vision-threatening,or involve prolonged recovery or a highly intensive postoperative course.Micro-invasive glaucoma surgery(MIGS)procedures have shown better safety but reduced efficacy in achieving target IOP.Combinations of these methods have led to the development of subconjunctival micro-invasive procedures with safety comparable to traditional surgery and greater efficacy than minimally invasive methods.This review describes the use of one of these devices,the poly(styrene-block-isobutylene-block-styrene)(SIBS)-based PreserFlo MicroShunt(Santen,Emeryville,CA),in the surgical treatment of patients with glaucoma.Main text The MicroShunt is an 8.5-mm tube made of an inert polymer with no endplate,an internal diameter of 70μm,and fins intended to prevent peritubular flow and anchor the device within the sclera to prevent proximal migration into the eye.Following ab externo implantation,the tube provides a conduit for flow of aqueous humor from the anterior chamber into the subconjunctival/sub-Tenon space.Clinical trials to date have shown that,when paired with mitomycin C(MMC)treatment,MicroShunt implantation significantly reduced both IOP and the number of glaucoma medications.These IOP-lowering results were found both when surgery was performed alone and with phacoemulsification.The MicroShunt also showed a safety profile comparable to that of traditional filtering surgery.Conclusions The MicroShunt and other novel subconjunctival procedures have shown substantial IOP reductions while mitigating hypotony-related complications.MMC,which modulates fibrosis and scarring postoperatively,is essential to surgical success.Randomized,long-term clinical trials will further clarify the role of controlled micro-incisional device-assisted ab externo glaucoma filtering surgery in long-term glaucoma management.展开更多
This paper investigates a Luenberger flux observer with speed adaptation for a direct field oriented control of an induction motor. An improved method of speed estimation that operates on the principle of speed adapti...This paper investigates a Luenberger flux observer with speed adaptation for a direct field oriented control of an induction motor. An improved method of speed estimation that operates on the principle of speed adaptive flux and current observer has been proposed. An observer is basically an estimator that uses a plant model and a feedback loop with measured stator voltage and current. Simulation results show that the proposed direct field oriented control with the proposed observer provides good performance dynamic characteristics. The induction motor is fed by an indirect power electronics converter. This indirect converter is controlled by a sliding mode technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. The robustness of the overall system is studied using simulation for different operating modes and varied parameters.展开更多
In this paper, a new sensorless interior permanent magnet synchronous motor （IPMSM） drives method with extended Kalman filter （EKF） for speed, rotor position and load torque estimation is proposed. The direct torq...In this paper, a new sensorless interior permanent magnet synchronous motor （IPMSM） drives method with extended Kalman filter （EKF） for speed, rotor position and load torque estimation is proposed. The direct torque control （DTC） technique for permanem magnet synchronous motor （PMSM） is receiving increasing attention due to the important advantages of the low dependence on motor parameters when compared with other motor control techniques. The Kalman filter is an observer for linear and non-linear systems and is based on the stochastic intromission, in others words, noise. The PMSM is fed by an indirect power electronic converter which is controlled by a sliding mode technique. The simulation tests performed for different operating condi- tions have confirmed the robustness of the overall system; and it is shown that the sliding mode technique has successfully minimized the different harmonics introduced by the line converter.展开更多
With the advent of microinvasive glaucoma surgery(MIGS),the spectrum of modalities available to manage patients with this chronic and heterogeneous condition has broadened.Despite its novelty however,there has been a ...With the advent of microinvasive glaucoma surgery(MIGS),the spectrum of modalities available to manage patients with this chronic and heterogeneous condition has broadened.Despite its novelty however,there has been a rapid evolution in the development of a multitude of devices,each targeting a structure along the aqueous drainage pathway.A growing body of evidence has demonstrated IOP and medication burden reduction,and a more favorable safety profile with MIGS procedures in contrast to traditional incisional surgeries.Among the array of MIGS,the Hydrus®Microstent(Ivantis,Inc.,Irvine,CA)is a recent FDA approved device,designed to bypass the trabecular meshwork and provide a scaffold for Schlemm’s canal.The objective of this article is to review the Hydrus from conception to clinical use,and present data on its efficacy and safety to date.The available literature has shown promise,however inherent to all novel devices,only longterm monitoring will ensure sustained IOP control and an acceptable safety profile.Surgical advancements in glaucoma have revolutionized the field,and continued research and development will establish these approaches in clinical treatment algorithms.展开更多
文摘Background Although traditional surgical procedures for glaucoma(such as trabeculectomy and tube-shunt implantation)can significantly reduce intraocular pressure(IOP),they are associated with numerous complications,some of which are vision-threatening,or involve prolonged recovery or a highly intensive postoperative course.Micro-invasive glaucoma surgery(MIGS)procedures have shown better safety but reduced efficacy in achieving target IOP.Combinations of these methods have led to the development of subconjunctival micro-invasive procedures with safety comparable to traditional surgery and greater efficacy than minimally invasive methods.This review describes the use of one of these devices,the poly(styrene-block-isobutylene-block-styrene)(SIBS)-based PreserFlo MicroShunt(Santen,Emeryville,CA),in the surgical treatment of patients with glaucoma.Main text The MicroShunt is an 8.5-mm tube made of an inert polymer with no endplate,an internal diameter of 70μm,and fins intended to prevent peritubular flow and anchor the device within the sclera to prevent proximal migration into the eye.Following ab externo implantation,the tube provides a conduit for flow of aqueous humor from the anterior chamber into the subconjunctival/sub-Tenon space.Clinical trials to date have shown that,when paired with mitomycin C(MMC)treatment,MicroShunt implantation significantly reduced both IOP and the number of glaucoma medications.These IOP-lowering results were found both when surgery was performed alone and with phacoemulsification.The MicroShunt also showed a safety profile comparable to that of traditional filtering surgery.Conclusions The MicroShunt and other novel subconjunctival procedures have shown substantial IOP reductions while mitigating hypotony-related complications.MMC,which modulates fibrosis and scarring postoperatively,is essential to surgical success.Randomized,long-term clinical trials will further clarify the role of controlled micro-incisional device-assisted ab externo glaucoma filtering surgery in long-term glaucoma management.
文摘This paper investigates a Luenberger flux observer with speed adaptation for a direct field oriented control of an induction motor. An improved method of speed estimation that operates on the principle of speed adaptive flux and current observer has been proposed. An observer is basically an estimator that uses a plant model and a feedback loop with measured stator voltage and current. Simulation results show that the proposed direct field oriented control with the proposed observer provides good performance dynamic characteristics. The induction motor is fed by an indirect power electronics converter. This indirect converter is controlled by a sliding mode technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. The robustness of the overall system is studied using simulation for different operating modes and varied parameters.
文摘In this paper, a new sensorless interior permanent magnet synchronous motor （IPMSM） drives method with extended Kalman filter （EKF） for speed, rotor position and load torque estimation is proposed. The direct torque control （DTC） technique for permanem magnet synchronous motor （PMSM） is receiving increasing attention due to the important advantages of the low dependence on motor parameters when compared with other motor control techniques. The Kalman filter is an observer for linear and non-linear systems and is based on the stochastic intromission, in others words, noise. The PMSM is fed by an indirect power electronic converter which is controlled by a sliding mode technique. The simulation tests performed for different operating condi- tions have confirmed the robustness of the overall system; and it is shown that the sliding mode technique has successfully minimized the different harmonics introduced by the line converter.
基金support for the research,authorship,and/or publication of this article:this study was supported by Ivantis,Inc.,(Irvine,CA).
文摘With the advent of microinvasive glaucoma surgery(MIGS),the spectrum of modalities available to manage patients with this chronic and heterogeneous condition has broadened.Despite its novelty however,there has been a rapid evolution in the development of a multitude of devices,each targeting a structure along the aqueous drainage pathway.A growing body of evidence has demonstrated IOP and medication burden reduction,and a more favorable safety profile with MIGS procedures in contrast to traditional incisional surgeries.Among the array of MIGS,the Hydrus®Microstent(Ivantis,Inc.,Irvine,CA)is a recent FDA approved device,designed to bypass the trabecular meshwork and provide a scaffold for Schlemm’s canal.The objective of this article is to review the Hydrus from conception to clinical use,and present data on its efficacy and safety to date.The available literature has shown promise,however inherent to all novel devices,only longterm monitoring will ensure sustained IOP control and an acceptable safety profile.Surgical advancements in glaucoma have revolutionized the field,and continued research and development will establish these approaches in clinical treatment algorithms.
