Ivan Buzurovic - Academia.edu (original) (raw)

Papers by Ivan Buzurovic

2014 9th IEEE Conference on Industrial Electronics and Applications, 2014

Finite time instability for linear continuous timedelay systems was investigated in this paper. T... more Finite time instability for linear continuous timedelay systems was investigated in this paper. The novel Lyapunov-like functions were used in the analysis. The functions do not need to fulfill the following conditions: being positive definite on the whole state space domain and possessing negative derivatives along the system trajectories. These functions were previously used for the development of both the delay-dependent and delay-independent sufficient conditions for the investigation of the finite time stability of control systems. However, the reported conditions cannot be used for the precise calculation of the instant when the system trajectory leaves the prescribed boundaries. In this paper, a novel concept of finite time instability was introduced to solve this problem. Numerical examples were used to additionally clarify the procedure.

The article provides sufficient conditions for the practical and finite time stability of linear ... more The article provides sufficient conditions for the practical and finite time stability of linear singular continuous time delay systems fulfilling the following formulation: Ex(k+1)=A 0 x(k)+A 1 x(k-1). Analyzing the finite time stability concept, novel delay independent conditions have been presented. The conditions were derived using the linear matrix inequality (LMI) approach. The LMI method was based on the analysis of the Lyapunov-like functions and their properties within the subspace of consistent initial conditions. A novel sufficient delay-dependent criterion for the finite time stability based on the LMI approach has been established.

In this paper sufficient conditions for both practical and finite time stability of linear singul... more In this paper sufficient conditions for both practical and finite time stability of linear singular continuous time delay systems were introduced. The singular and singular time delay systems can be mathematically described as

International Journal of Radiation OncologyBiologyPhysics

2013 International Conference on System Science and Engineering (ICSSE), 2013

In this article novel sufficient conditions for the practical and finite time stability of linear... more In this article novel sufficient conditions for the practical and finite time stability of linear continuous system with time delay have been presented. A general mathematical description of the systems investigated was given as x(k+1)=A 0 x(k) + A 1 x(k-h). The proposed approach was based on the investigation of the Lyapunov-like functions which was used for derivation of the novel stability conditions, independent of time delay. The obtained results were applied to the investigation of systems' stability. The basic advantages of the presented conditions were the following: the functions used here did not have to be positive on the state space and there was no need for negative derivatives along the trajectory of systems.

2011 9th IEEE International Conference on Control and Automation (ICCA), 2011

ABSTRACT This paper gives sufficient conditions for the practical and finite time stability of a ... more ABSTRACT This paper gives sufficient conditions for the practical and finite time stability of a particular class of linear discrete time delay systems. Analyzing the finite time stability concept, these new delay-independent conditions are derived using an approach based on the Lyapunov-like functions. The practical stability and attractive practical stability for discrete time delay systems have been investigated. The above mentioned approach was supported by the classical Lyapunov technique to guarantee the attractivity properties of the system behavior.

2013 9th Asian Control Conference (ASCC), 2013

This paper provides sufficient conditions for the finite time stability of linear continuous time... more This paper provides sufficient conditions for the finite time stability of linear continuous time delay systems mathematically described as x , (t)=A 0 x(t) + A 1 x(t-τ). A novel method was used to derive new delay dependent conditions. The conditions obtained were applied in the system stability analysis. Consequently, the aggregation function does not have to be positive in the state space domain, and does not need to have the negative derivatives along the system trajectories. Finite time stability was analyzed using the novel conditions derived in the paper. The described approach was compared with some known methods. It was proved that the new results were in compliance with the previously reported results, but more convenient for numerical calculations. The numerical example was presented to support the results.

... dose are: (a) inter-and intra-observer Corresponding author: Tarun K. Podder,Thomas Jefferson... more ... dose are: (a) inter-and intra-observer Corresponding author: Tarun K. Podder,Thomas Jefferson Hospital, Philadelphia, PA 19107, email: tarun.podder@ jeffersonhospital.org. variations in Gross Tumor Volume (GTV) definition ...

Acta Polytechnica Hungarica

In this article, stability of the robotic manipulator with time delay in open kinematic chain con... more In this article, stability of the robotic manipulator with time delay in open kinematic chain configuration was analyzed. The dynamic equations of motions were derived for one five-degree-of-freedom (DOF) robotic system with system latency. The mathematical model includes the model of the actuators to define the parameters of the actuators that can stabilize such a system. Investigation of the system stability was performed using novel stability conditions. The system state responses and the system stability were analyzed for different time delays. The proposed control methodology was shown to be appropriate to maintain the stability of the robotic system during tracking tasks. To analyze the concept, we presented a numerical example together with an extensive system simulation. The stability analysis showed the full compliance of the system behavior with the desired system dynamics. The proposed method can be used for the stability analysis of any robotic system with state delays i...

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 2014

A new Monte Carlo (MC) source model (SM) has been developed for azimuthally symmetric photon beam... more A new Monte Carlo (MC) source model (SM) has been developed for azimuthally symmetric photon beams. The MC simulation tallied phase space file (PSF) is divided into two categories depending on the relationship of the particle track line to the beam central axis: multiple point source (MPS) and spatial mesh based surface source (SMBSS). To validate this SM, MCNPX2.6 was used to generate two PSFs for a 6 MV photon beam from a Varian 2100C/D linear accelerator. PDDs and profiles were calculated using the SM and original PSF for different field sizes from 5 × 5 to 40 × 40 cm2. Agreement was within 2% of the maximum dose at 100 cm SSD and 2.5% of the maximum dose at 200 cm SSD for beam profiles at depths of 3.5 cm and 15 cm with respect to the original PSF. Differences between the source model and the PSF in the out-of-field regions were less than 0.5% of the profile maximum value at 100 cm SSD. Differences between measured and calculated points were less than 2% of the maximum dose or 2...

Journal of applied clinical medical physics / American College of Medical Physics, 2013

In this article we describe commissioning and implementation procedures for the Dose Verification... more In this article we describe commissioning and implementation procedures for the Dose Verification System (DVS) with permanently implanted in vivo wireless, telemetric radiation dosimeters for absolute dose measurements. The dosimeter uses a semiconductor device called a metal-oxide semiconductor field-effect transistor (MOSFET) to measure radiation dose. A MOSFET is a transistor that is generally used for amplifying or switching electronic signals. The implantable dosimeter was implemented with the goal of verifying the dose delivered to radiation therapy patients. For the purpose of acceptance testing, commissioning, and clinical implementation and to evaluate characteristics of the dosimeter, the following tests were performed: 1) temperature dependence, 2) reproducibility,3) field size dependence, 4) postirradiation signal drift, 5) dependence on average dose rate, 6) linearity test, 7) angular dependence (different gantry angle position), 8) angular dependence (different DVS ang...

Brachytherapy, 2015

To increase intraprocedural efficiency in the use of clinical resources and to decrease planning ... more To increase intraprocedural efficiency in the use of clinical resources and to decrease planning time for cervical cancer brachytherapy treatments through redesign of the procedure's process map. A multidisciplinary team identified all tasks and associated resources involved in cervical cancer brachytherapy in our institution and arranged them in a process map. A redesign of the treatment planning component of the process map was conducted with the goal of minimizing planning time. Planning time was measured on 20 consecutive insertions, of which 10 were performed with standard procedures and 10 with the redesigned process map, and results were compared. Statistical significance (p < 0.05) was measured with a two-tailed t test. Twelve tasks involved in cervical cancer brachytherapy treatments were identified. The process map showed that in standard procedures, the treatment planning tasks were performed sequentially. The process map was redesigned to specify that contouring and some planning tasks are performed concomitantly. Some quality assurance tasks were reorganized to minimize adverse effects of a possible error on procedure time. Test dry runs followed by live implementation confirmed the applicability of the new process map to clinical conditions. A 29% reduction in planning time (p < 0.01) was observed with the introduction of the redesigned process map. A process map for cervical cancer brachytherapy was generated. The treatment planning component of the process map was redesigned, resulting in a 29% decrease in planning time and a streamlining of the quality assurance process.

2012 IEEE 10th Jubilee International Symposium on Intelligent Systems and Informatics, 2012

This paper provides sufficient conditions for the asymptotic practical and finite time stability ... more This paper provides sufficient conditions for the asymptotic practical and finite time stability of linear continuous time delay systems mathematically described as

2014 9th IEEE Conference on Industrial Electronics and Applications, 2014

Finite time instability for linear continuous timedelay systems was investigated in this paper. T... more Finite time instability for linear continuous timedelay systems was investigated in this paper. The novel Lyapunov-like functions were used in the analysis. The functions do not need to fulfill the following conditions: being positive definite on the whole state space domain and possessing negative derivatives along the system trajectories. These functions were previously used for the development of both the delay-dependent and delay-independent sufficient conditions for the investigation of the finite time stability of control systems. However, the reported conditions cannot be used for the precise calculation of the instant when the system trajectory leaves the prescribed boundaries. In this paper, a novel concept of finite time instability was introduced to solve this problem. Numerical examples were used to additionally clarify the procedure.

The article provides sufficient conditions for the practical and finite time stability of linear ... more The article provides sufficient conditions for the practical and finite time stability of linear singular continuous time delay systems fulfilling the following formulation: Ex(k+1)=A 0 x(k)+A 1 x(k-1). Analyzing the finite time stability concept, novel delay independent conditions have been presented. The conditions were derived using the linear matrix inequality (LMI) approach. The LMI method was based on the analysis of the Lyapunov-like functions and their properties within the subspace of consistent initial conditions. A novel sufficient delay-dependent criterion for the finite time stability based on the LMI approach has been established.

In this paper sufficient conditions for both practical and finite time stability of linear singul... more In this paper sufficient conditions for both practical and finite time stability of linear singular continuous time delay systems were introduced. The singular and singular time delay systems can be mathematically described as

International Journal of Radiation OncologyBiologyPhysics

2013 International Conference on System Science and Engineering (ICSSE), 2013

In this article novel sufficient conditions for the practical and finite time stability of linear... more In this article novel sufficient conditions for the practical and finite time stability of linear continuous system with time delay have been presented. A general mathematical description of the systems investigated was given as x(k+1)=A 0 x(k) + A 1 x(k-h). The proposed approach was based on the investigation of the Lyapunov-like functions which was used for derivation of the novel stability conditions, independent of time delay. The obtained results were applied to the investigation of systems' stability. The basic advantages of the presented conditions were the following: the functions used here did not have to be positive on the state space and there was no need for negative derivatives along the trajectory of systems.

2011 9th IEEE International Conference on Control and Automation (ICCA), 2011

ABSTRACT This paper gives sufficient conditions for the practical and finite time stability of a ... more ABSTRACT This paper gives sufficient conditions for the practical and finite time stability of a particular class of linear discrete time delay systems. Analyzing the finite time stability concept, these new delay-independent conditions are derived using an approach based on the Lyapunov-like functions. The practical stability and attractive practical stability for discrete time delay systems have been investigated. The above mentioned approach was supported by the classical Lyapunov technique to guarantee the attractivity properties of the system behavior.

2013 9th Asian Control Conference (ASCC), 2013

This paper provides sufficient conditions for the finite time stability of linear continuous time... more This paper provides sufficient conditions for the finite time stability of linear continuous time delay systems mathematically described as x , (t)=A 0 x(t) + A 1 x(t-τ). A novel method was used to derive new delay dependent conditions. The conditions obtained were applied in the system stability analysis. Consequently, the aggregation function does not have to be positive in the state space domain, and does not need to have the negative derivatives along the system trajectories. Finite time stability was analyzed using the novel conditions derived in the paper. The described approach was compared with some known methods. It was proved that the new results were in compliance with the previously reported results, but more convenient for numerical calculations. The numerical example was presented to support the results.

... dose are: (a) inter-and intra-observer Corresponding author: Tarun K. Podder,Thomas Jefferson... more ... dose are: (a) inter-and intra-observer Corresponding author: Tarun K. Podder,Thomas Jefferson Hospital, Philadelphia, PA 19107, email: tarun.podder@ jeffersonhospital.org. variations in Gross Tumor Volume (GTV) definition ...

Acta Polytechnica Hungarica

In this article, stability of the robotic manipulator with time delay in open kinematic chain con... more In this article, stability of the robotic manipulator with time delay in open kinematic chain configuration was analyzed. The dynamic equations of motions were derived for one five-degree-of-freedom (DOF) robotic system with system latency. The mathematical model includes the model of the actuators to define the parameters of the actuators that can stabilize such a system. Investigation of the system stability was performed using novel stability conditions. The system state responses and the system stability were analyzed for different time delays. The proposed control methodology was shown to be appropriate to maintain the stability of the robotic system during tracking tasks. To analyze the concept, we presented a numerical example together with an extensive system simulation. The stability analysis showed the full compliance of the system behavior with the desired system dynamics. The proposed method can be used for the stability analysis of any robotic system with state delays i...

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 2014

A new Monte Carlo (MC) source model (SM) has been developed for azimuthally symmetric photon beam... more A new Monte Carlo (MC) source model (SM) has been developed for azimuthally symmetric photon beams. The MC simulation tallied phase space file (PSF) is divided into two categories depending on the relationship of the particle track line to the beam central axis: multiple point source (MPS) and spatial mesh based surface source (SMBSS). To validate this SM, MCNPX2.6 was used to generate two PSFs for a 6 MV photon beam from a Varian 2100C/D linear accelerator. PDDs and profiles were calculated using the SM and original PSF for different field sizes from 5 × 5 to 40 × 40 cm2. Agreement was within 2% of the maximum dose at 100 cm SSD and 2.5% of the maximum dose at 200 cm SSD for beam profiles at depths of 3.5 cm and 15 cm with respect to the original PSF. Differences between the source model and the PSF in the out-of-field regions were less than 0.5% of the profile maximum value at 100 cm SSD. Differences between measured and calculated points were less than 2% of the maximum dose or 2...

Journal of applied clinical medical physics / American College of Medical Physics, 2013

In this article we describe commissioning and implementation procedures for the Dose Verification... more In this article we describe commissioning and implementation procedures for the Dose Verification System (DVS) with permanently implanted in vivo wireless, telemetric radiation dosimeters for absolute dose measurements. The dosimeter uses a semiconductor device called a metal-oxide semiconductor field-effect transistor (MOSFET) to measure radiation dose. A MOSFET is a transistor that is generally used for amplifying or switching electronic signals. The implantable dosimeter was implemented with the goal of verifying the dose delivered to radiation therapy patients. For the purpose of acceptance testing, commissioning, and clinical implementation and to evaluate characteristics of the dosimeter, the following tests were performed: 1) temperature dependence, 2) reproducibility,3) field size dependence, 4) postirradiation signal drift, 5) dependence on average dose rate, 6) linearity test, 7) angular dependence (different gantry angle position), 8) angular dependence (different DVS ang...

Brachytherapy, 2015

To increase intraprocedural efficiency in the use of clinical resources and to decrease planning ... more To increase intraprocedural efficiency in the use of clinical resources and to decrease planning time for cervical cancer brachytherapy treatments through redesign of the procedure's process map. A multidisciplinary team identified all tasks and associated resources involved in cervical cancer brachytherapy in our institution and arranged them in a process map. A redesign of the treatment planning component of the process map was conducted with the goal of minimizing planning time. Planning time was measured on 20 consecutive insertions, of which 10 were performed with standard procedures and 10 with the redesigned process map, and results were compared. Statistical significance (p < 0.05) was measured with a two-tailed t test. Twelve tasks involved in cervical cancer brachytherapy treatments were identified. The process map showed that in standard procedures, the treatment planning tasks were performed sequentially. The process map was redesigned to specify that contouring and some planning tasks are performed concomitantly. Some quality assurance tasks were reorganized to minimize adverse effects of a possible error on procedure time. Test dry runs followed by live implementation confirmed the applicability of the new process map to clinical conditions. A 29% reduction in planning time (p < 0.01) was observed with the introduction of the redesigned process map. A process map for cervical cancer brachytherapy was generated. The treatment planning component of the process map was redesigned, resulting in a 29% decrease in planning time and a streamlining of the quality assurance process.

2012 IEEE 10th Jubilee International Symposium on Intelligent Systems and Informatics, 2012

This paper provides sufficient conditions for the asymptotic practical and finite time stability ... more This paper provides sufficient conditions for the asymptotic practical and finite time stability of linear continuous time delay systems mathematically described as