bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid loss of hepatitis C virus genotype 1b from serum in patients receiving a triple treatment with telaprevir (MP‐424), pegylated interferon and ribavirin for 12 weeks
Authors: Suzuki Fumitaka , Akuta Norio , Suzuki Yoshiyuki , Sezaki Hitomi , Yatsuji Hiromi , Kawamura Yusuke , Hosaka Tetsuya , Kobayashi Masahiro , Arase Yasuji , Ikeda Kenji , Mineta Rie , Iwasaki Satomi , Watahiki Sachiyo , Kobayashi Mariko , Miyakawa Yuzo , Kumada Hiromitsu
Published: July 2009

Aim: To evaluate the efficacy and safety of the triple treatment with telaprevir (MP‐424), pegylated interferon (PEG‐IFN) and ribavirin during 12 weeks on‐treatment.

Methods: The triple treatment was given to 20 patients with chronic hepatitis C who had been infected with hepatitis C virus (HCV)‐1b in high viral load (median: 6.8 log IU/mL [range: 5.5–7.2]), with a median age of 54 years (range: 36–65 years). They were followed for early dynamics of HCV RNA in serum during 12 weeks and side‐effects.

Results: HCV RNA levels decreased by 4.8 logs by 7 days and 5.5 logs by 14 days. HCV RNA disappeared in 50% (10/20) at 2 weeks, 79% (15/19) at 4 weeks, 88% (14/16) at 6 weeks, 94% (15/16) at 8 weeks and 100% (13/13) at 12 weeks. HCV RNA disappeared equally frequently in 10 treatment‐naive patients, six non‐responders to IFN monotherapy and four non‐responders to PEG‐IFN and ribavirin. It was no different in the patients with and without amino acid substitutions reducing the response to IFN. The treatment was withdrawn in seven (35%) patients, mostly due to reduced hemoglobin of less than 8.5 g/dL, of whom six (86%) remained clear of HCV RNA at 12 weeks.

Conclusion: HCV RNA was lost from serum rapidly and universally in patients infected with HCV‐1b in high viral loads by the triple treatment. Because an early loss of HCV RNA correlates with high rates of sustained virological response (SVR), it would increase SVR substantially, and merit the patients who have not responded to previous therapies.
Efficacy and limitation of bone marrow transplantation in the treatment of acute and subacute liver failure in rats
Authors: Tokai Hirotaka , Kawashita Yujo , Ito Yuichiro , Yamanouchi Kosho , Takatsuki Mitsuhisa , Eguchi Susumu , Tajima Yoshitsugu , Kanematsu Takashi
Published: July 2009

Aim:  Recent reports have shown that bone marrow cells (BMC) retain the potential to differentiate into hepatocytes. Thus, the BMC have been recognized as an attractive source for liver regenerative medicine. However, it has not been clarified whether BMC transplantation can be used to treat liver damage in vivo. In the present study, we explored whether BMC possess therapeutic potential to treat acute and/or subacute liver failure.

Methods:  Fulminant hepatic failure (FHF) was induced by 70% hepatectomy with ligation of the right lobe pedicle (24% liver mass), followed by transplantation of BMC into the spleen. Dipeptidyl peptidase IV‐positive (DPPIV+) BMC were then transplanted into DPPIV‐negative (DPPIV‐) recipients following hepatic irradiation (HIR) in which 70% of the liver was resected and the remnant liver irradiated.

Results:  There was no benefit of BMC transplantation towards survival in the FHF model. DPPIV+ hepatocytes appeared in the liver tissues of the DPPIV‐ HIR model rats, but DPPIV+ hepatocytes replaced less than 13% of the recipient liver.

Conclusion:  BMC transplantation may have limitations in the treatment of fulminant or acute liver failure because they do not have sufficient time to develop into functional hepatocytes. Preparative HIR may be beneficial in help to convert the transplanted BMC into host hepatocytes, and provide a survival benefit. Although, However, the precise mechanism warrants further studies.
Matrine improves 17α‐ethinyl estradiol‐induced acute cholestasis in rats
Authors: Zhao Ying , Zhai Desheng , He Hui , Liu Junhua , Li Tingting , Chen Xijing , Ji Hui
Published: July 2009

Aim:  To explore the effects of matrine (MT) on acute intrahepatic cholestasis induced by 17α‐ethinyl estradiol (EE) in rats.

Methods:  Acute intrahepatic cholestasis in rats were induced by EE, and the effects of MT on acute intrahepatic cholestasis were explored and compared with ursodeoxycholic acid (UDCA) by serum biochemical determination and bile excretion experiments.

Results:  The serum biochemical and bile biochemical results indicated that MT and UDCA had notable hepatoprotective effects by counteracting cholestasis induced by EE. The bile flow and the bile excretion of glycocholic acid (GC, a substrate of bile salt export pump [Bsep]), ketoprofen glucuronide (KPG) and rhodamine 123 (Rh123, a substrate of multidrug resistance protein 1 [MDR1]) decreased by EE, were significantly improved after administration of MT.

Conclusion:  MT exhibited potential protection against EE‐induced acute intrahepatic cholestasis.
Clinicopathological analysis of CD133+ and NCAM+ human hepatic stem/progenitor cells in damaged livers and hepatocellular carcinomas
Authors: Tsuchiya Atsunori , Kamimura Hiroteru , Takamura Masaaki , Yamagiwa Satoshi , Matsuda Yasunobu , Sato Yoshinobu , Nomoto Minoru , Ichida Takafumi , Aoyagi Yutaka
Published: July 2009

Aim:  Hepatic stem cells are capable of dramatically changing and differentiating to form mature hepatocytes in acute and chronically damaged livers; however, the clinicopathological characteristics of these heterogeneous cell populations have not been sufficiently analyzed.

Methods:  In this study, cells in tissue sections from 12 cases of acute damaged livers and 31 cases of hepatocellular carcinomas (HCC), and the surrounding chronically damaged liver tissues, were analyzed by immunohistochemistry using the previously reported hepatic stem/progenitor cell marker CD133 (AC133) and the neural cell adhesion molecule (NCAM) marker.

Results:  In both the acute and chronically damaged livers, CD133+ cells and NCAM+ cells were present in ductular reactions (DR), which include hepatic stem/progenitor cells, and became more apparent in proportion to the degree of fibrosis or histological damage. Analysis of their distribution and morphological similarities revealed that the NCAM+ cell population included cells that were closer to, and morphologically more similar to, hepatocytes than were CD133+ cells. Analysis of HCC using these markers revealed that 9.7% of HCC expressed NCAM (two cases had abundant NCAM+ cells), while CD133+ HCC were not detected.

Conclusion:  These results suggest that CD133 and NCAM can be employed to enrich for hepatic stem/progenitor cells and that DR can be distinguished in greater detail using these markers. NCAM+ HCC were detected, but their function remains unresolved. Expression of CD133, a potent stem cell marker, may be extremely rare in the common human HCC examined.
Guidelines for resident training in veterinary clinical pathology. III: cytopathology and surgical pathology
Authors: Kidney Beverly A. , Dial Sharon M. , Christopher Mary M.
Published: July 2009

The Education Committee of the American Society for Veterinary Clinical Pathology has identified a need for improved structure and guidance of training residents in clinical pathology. This article is the third in a series of articles that address this need. The goals of this article are to describe learning objectives and competencies in knowledge, abilities, and skills in cytopathology and surgical pathology (CSP); provide options and ideas for training activities; and identify resources in veterinary CSP for faculty, training program coordinators, and residents. Guidelines were developed in consultation with Education Committee members and peer experts and with evaluation of the literature. The primary objectives of training in CSP are: (1) to develop a thorough, extensive, and relevant knowledge base of biomedical and clinical sciences applicable to the practice of CSP in domestic animals, laboratory animals, and other nondomestic animal species; (2) to be able to reason, think critically, investigate, use scientific evidence, and communicate effectively when making diagnoses and consulting and to improve and advance the practice of pathology; and (3) to acquire selected technical skills used in CSP and pathology laboratory management. These guidelines define expected competencies that will help ensure proficiency, leadership, and the advancement of knowledge in veterinary CSP and will provide a useful framework for didactic and clinical activities in resident‐training programs.
Research on Two Key Technologies of Improving Dynamic Quality of Hydraulic System With High Flow
Authors: Wang Jing , Gong Guofang , Yang Huayong
Published: July 2009

The demand of hydraulic parallel motion system of space rendezvous and docking simulator to its hydraulic system is high flow and high performance. To achieve good motion simulation results and meet the requirements of precision control, a method of self-tuning parameters fuzzy PID control of proportional water valve opening has been employed to control oil temperature, a method of online vacuum degassing in a sealed system has been used to increase oil effective bulk modulus, and a device has been developed to measure oil bulk modulus online. Experimental research has been carried out on the hydraulic driving system of comprehensive test bed for docking mechanism. The experimental results show that precise control of oil temperature has been achieved and bulk modulus of oil has been increased obviously.
Modeling and Observability Analysis of DPF Regeneration
Authors: Brahma Avra
Published: July 2009

A Diesel Particulate Filter (DPF) is a necessary component on all modern Diesel vehicles in order to achieve the emission targets for particulate matter. A key problem in this context is the accurate real-time estimation of the soot in the DPF during or after a regeneration event. In this paper, a lumped parameter model for the regeneration regime of a Diesel Particulate Filter (DPF) is proposed which can be used as a starting point for the above purpose. Sensitivity of this model to various model parameters is discussed and significant parameters are identified. An observation problem is identified and a preliminary observability analysis is performed. Results of model performance and implications of the observability analysis are presented.
Performance Limitations in Mechatronic Systems With Friction
Authors: Mirnateghi Nasim , Paden Brad E.
Published: July 2009

In this paper we consider a simple model for systems with friction. The model includes differential equations with discontinuous right-hand side. We prove the existence and uniqueness of solution, and also discuss performance limitations caused by friction associated with tracking limitations.
Adaptive Control of Freeze-Form Extrusion Fabrication Processes
Authors: Zhao Xiyue , Landers Robert G. , Leu Ming C.
Published: July 2009

Freeze–form Extrusion Fabrication (FEF) is an additive manufacturing process that extrudes high solids loading aqueous ceramic pastes in a layer–by–layer fashion below the paste freezing temperature for component fabrication. Due to effects such as the air bubble release, agglomerate breakdown, change in paste properties during extrusion as a result of liquid phase migration, etc., the extrusion force is difficult to control. In this paper, an adaptive controller is proposed to regulate the extrusion force. Recursive Least Squares is used to estimate extrusion force model parameters during fabrication and a low–order control scheme capable of tracking general reference trajectories is designed and implemented to regulate the extrusion process. Several parts were fabricated with the adaptive extrusion force controller. These results illustrate the need for extrusion force control and that variable reference extrusion force profiles are required to fabricate complex features.
Variable Powder Flow Rate Control in Laser Metal Deposition Processes
Authors: Tang Lie , Ruan Jianzhong , Landers Robert G. , Liou Frank
Published: July 2009

This paper proposes a novel method, called Variable Powder Flow Rate Control (VPFRC), for the regulation of powder flow rate in laser metal deposition processes. The idea of VPFRC is to adjust the powder flow rate to maintain a uniform powder deposition per unit length even when disturbances occur (e.g., the motion system accelerates and decelerates). Dynamic models of the powder delivery system motor and the powder transport system (i.e., five–meter pipe, powder dispenser, and cladding head) are constructed. A general tracking controller is then designed to track variable powder flow rate references. Since the powder flow rate at the nozzle exit cannot be directly measured, it is estimated using the powder transport system model. The input to this model is the DC motor rotation speed, which is estimated on–line using a Kalman filter. Experiments are conducted to examine the performance of the proposed control methodology. The experimental results demonstrate that the VPFRC method is successful in maintaining a uniform track morphology, even when the motion system accelerates and decelerates.
EKF-Based In-Vehicle Estimation of Relative CG Height
Authors: Huang Jihua , Lin William C.
Published: July 2009

The distance from the center of gravity (CG) of the sprung mass to the roll axis, referred to as the relative CG height, is a critical parameter in vehicle roll motion. Although the nominal value of the relative CG height can be measured, its actual value generally varies due to different vehicle loading conditions. To facilitate the control of vehicle roll motion, this paper presents a model-based in-vehicle estimation of the relative CG height. The parameter estimation utilizes information measured by common in-vehicle sensors and employs an approach for the parameter estimation in stochastic gray-boxes models. An Extended Kalman Filter (EKF) is developed based on a linear vehicle yaw/lateral/roll model and the best estimate was solved by minimizing the EKF prediction error. A simplified estimation algorithm for in-vehicle implementation is also presented; the simplified algorithm limits the parameter space to a finite number of candidate parameters and the candidate that yields the smallest EKF innovation is identified as the best estimate. The estimation results with vehicle experimental data are included to verify the effectiveness of the proposed design.
Model Reduction in Vehicle Dynamics Using Importance Analysis
Authors: Ersal Tulga , Kittirungsi Burit , Fathy Hosam K. , Stein Jeffrey L.
Published: July 2009

Previous work by the authors developed a novel model reduction method, namely, importance analysis, that offered a unique set of properties: concurrent dynamic and kinematic reduction, applicability to nonlinear systems, preservation of realization, and trajectory dependence. This paper investigates the utility of importance analysis as a model reduction tool within the context of vehicle dynamics. To this end, a high-fidelity model of a High Mobility Multipurpose Wheeled Vehicle (HMMWV) is considered, and this model is reduced for three different scenarios. Reduction is achieved in both dynamics and kinematics while preserving the original definition and interpretation of state variables and parameters. Furthermore, the resulting reduced models are very different in terms of complexity, containing only what is necessary for their respective scenarios, and providing important insight and computational savings. The conclusion is that importance analysis can be an invaluable reduction tool in vehicle dynamics, offering the aforementioned unique set of properties.
Large-Scale Parallel Multibody Dynamics With Frictional Contact on the GPU
Authors: Negrut Dan , Tasora Alessandro , Anitescu Mihai
Published: July 2009

In the context of simulating the frictional contact dynamics of large systems of rigid bodies, this paper reviews a novel method for solving large cone complementarity problems by means of a fixed-point iteration algorithm. The method is an extension of the Gauss-Seidel and Gauss-Jacobi methods with overrelaxation for symmetric convex linear complementarity problems. Convergent under fairly standard assumptions, the method is implemented in a parallel framework by using a single instruction multiple data (SIMD) computation paradigm promoted by the Compute Unified Device Architecture (CUDA) library for graphical processing unit (GPU) programming. The framework is anticipated to become a viable tool for investigating the dynamics of complex systems such as ground vehicles running on sand, powder composites, and granular material flow.
Lanekeeping at the Limits of Handling: Stability via Lyapunov Functions and a Comparison With Stability Control
Authors: Talvala Kirstin L. R. , Gerdes J. Christian
Published: July 2009

Lanekeeping assistance systems and stability control systems both seek to control the yaw behavior of the vehicle. However, lanekeeping systems are typically thought of as linear systems, while stability control systems are explicitly designed to work at the limits of handling. In order to bring these two systems together, there is a need to investigate lanekeeping up to and beyond the limits of handling. This paper presents a nonlinear tire model suitable for analyzing the behavior of a lanekeeping system at all points along the tire curve and a method for finding common quadratic Lyapunov functions to prove stability. The results show that the lanekeeping system is stable well into the nonlinear tire region. This stability holds even under changes in the lanekeeping gain and the understeering/oversteering characteristics of the vehicle. The results suggest that future safety systems could benefit from incorporating integrated lanekeeping and stability control functionality.
Effect of Interaction Modeling in AFM-Based Nanomanipulation
Authors: Landolsi Fakhreddine , Ghorbel Fathi H. , Dabney James B.
Published: July 2009

AFM-based nanomanipulation is very challenging because of the complex mechanics in tip-sample interactions and the limitations in AFM visual sensing capabilities. In the present paper, we investigate the modeling of AFM-based nanomanipulation emphasizing the effects of the relevant interactions at the nanoscale. The major contribution of the present work is the use of a combined DMT-JKR interaction model in order to describe the complete collision process between the AFM tip and the sample. The coupling between the interactions and the friction at the nanoscale is emphasized. The efficacy of the proposed model to reproduce experimental data is demonstrated via numerical simulations.
Hybrid System Modeling for UAV Adversarial Operations
Authors: Faied Mariam , Girard Anouck
Published: July 2009

We address a dynamic configuration strategy for teams of Unmanned Air Vehicles (UAVs). A team is a collection of UAVs which may evolve through different organizations, called configurations. The team configuration may change with time to adapt to changes in the environment. To each configuration there corresponds a set of different properties for the UAVs in the team. The design for the configuration control problem involves a distributed hierarchical control architecture where the properties of the system can be formally analyzed. We do this in the framework of dynamic networks of hybrid automata. We present results from simulation to demonstrate these ideas.
Transmission Clutch Fill Control Using a Customized Dynamic Programming Method
Authors: Song Xingyong , Mohd Zulkefli Mohd Azrin , Sun Zongxuan , Miao Hsu-Chiang
Published: July 2009

Clutch fill control is critical for automotive transmission performance and fuel economy, including both automatic and hybrid transmissions. The traditional approach, by which the clutch fill pressure command is manually calibrated, has a couple of limitations. First, the pressure profile is not optimized to reduce the peak clutch fill flow demand. Moreover, it is not systematically designed to account for uncertainties in the system, such as variations of solenoid valve time delay and parameters of the clutch assembly. In this paper, we present a systematic approach to evaluate the clutch fill dynamics and synthesize the optimal pressure profile. First, a clutch fill dynamic model is constructed and analyzed. Second, the applicability of the conventional numerical Dynamic Programming (DP) algorithm to the clutch fill control problem is explored and shown to be ineffective. Thus we developed a new customized DP method to obtain the optimal and robust pressure profile subject to specified constraints. After a series of simulations and case studies, the new customized DP approach is demonstrated to be effective, efficient, and robust for solving the clutch fill optimal control problem.
The Basin of Entrainment of Human Gait Under Mechanical Perturbation
Authors: Ahn Jooeun , Hogan Neville
Published: July 2009

Using Anklebot, a therapeutic robot module, we perturbed human gait by applying external torque to the human ankle at various frequencies. We observed that with a properly designed perturbation, 8 subjects out of 10 exhibited entrained gaits: their gait frequencies were adapted to the frequency of mechanical perturbation, and they synchronized their ankle actuation with the external torque supplied by the robot. This preliminary result suggests that a limit-cycle oscillator, a plausible element of the coupled system of central nervous system and musculo-skeletal periphery, plays a significant role in the neuro-motor execution of human locomotion. The entrainment of human gait by periodic torque from a robotic aid may provide a novel approach to walking therapy that is uniquely supportive of normal biological function.
Design Criteria for Serial Chains Based on Kinetic Energy Partition Values
Authors: Rios Oziel , Tesar Delbert
Published: July 2009

In this article, a description of the kinetic energy partition values (or energy ratios) of serial chain mechanisms, as well as their rates of change, are presented. These energy ratios are indicators of the kinetic energy distribution within the system and they exploit the structure of the effective inertia matrix. The rates of change of the kinetic energy partition values with respect to the input parameters of the system indicate the sensitivity of change of the kinetic energy, meaning that a high value for the partition value rate of change together with a high operational state implies that the amount of kinetic energy flowing in the system is large further implying a loss of precision in the system due to large inertial torques applied about the joint axes. Two design criteria, one based on the kinetic energy partition values and another based on their rates of change, are presented. A two degree-of-freedom (DOF) mechanism is used to illustrate the solution of a multi-criteria design optimization problem where three design criteria are considered: a kinetic energy partition value criterion, a force capability criterion and an effective mass criterion. The design variables for the optimization problem are the transmission reduction ratios of the actuators. It is shown that the reduction ratios significantly influence the kinetic energy distribution within the system due to the high levels of kinetic energy in the rotary mass of the prime movers.
Piston Secondary Motions and Hydrodynamic Lubrication Regime in a Single Cylinder Internal Combustion Engine
Authors: Chalhoub N. G. , Edelby W.
Published: July 2009

A major portion of the frictional losses in internal combustion engines has been attributed to the piston-assembly. The current work examines the piston secondary motions and the relationships with which they interact with the lubricating oil film. This is done by developing a model that accounts for the rigid and flexible motions of the crank-slider mechanism of a single cylinder engine. The model considers the secondary motions of the piston and has a variable structure, which allows for the number of degrees of freedom of the system to vary depending on the nature of contact between the piston and the liner. The 3-D Reynolds’ equation is used to determine the instantaneous oil pressure, which is needed for the computation of the normal and the hydrodynamic friction forces exerted on the piston-assembly. The simulation results demonstrate the capability of the model in predicting the hydrodynamic friction force, the piston secondary motions, and the instantaneous oil film thickness.
Exploiting Time Scale Separation for Efficient Real-Time Optimization of Integrated Shipboard Power Systems
Authors: Seenumani Gayathri , Sun Jing , Peng Huei
Published: July 2009

Ship-board integrated power systems (IPS) play a crucial role in the all-electric ships (AES) initiative, where the power generation, conversion and distribution are done on a common electric platform. Along with many advantages of the IPS, its inter-connectivity presents a major opportunity as well a challenge for reconfiguration control. To ensure overall optimal performance while sustaining the critical ship service loads, the reconfiguration problem can be formulated as a trajectory optimization problem with the inputs to power sources as optimization variables. The high dimensional and nonlinear nature, along with the extended time horizon involved, makes many grid and gradient based methodologies infeasible for this application, especially when real-time requirements are considered. This paper, motivated by the IPS reconfiguration control, proposes strategies for improving the real-time computational efficiency of the IPS optimization by leveraging the time scale separation of its dynamics. The trade-offs between the computational efficiency and optimization accuracy are analyzed and a numerical example is provided to illustrate the effectiveness of the proposed algorithm.
Vehicle Dynamics in Response to the Maneuver of Precision Immobilization Technique
Authors: Zhou Jing , Lu Jianbo , Peng Huei
Published: July 2009

The Precision Immobilization Technique (PIT) is a maneuver frequently used by the law enforcement to terminate a hazardous vehicle pursuit situation. The maneuver is performed by intentionally nudging the pursued vehicle sideways to create large yaw motion which renders the pursued vehicle out of control. This work investigates the behavior of vehicles involved in this maneuver, develops dynamics models for the pre-impact, impact, and post-impact stages. Simulation results provide guidelines for the effective execution of the maneuver. In addition, the case for the vehicle equipped with an active yaw control system, such as the Electronic Stability Control, in response to the PIT maneuver is also addressed.
Frequency Sweeping With Concurrent Parametric Amplification
Authors: Miller Nicholas J. , Shaw Steven W.
Published: July 2009

In this paper we explore parametric amplification of multidegree of freedom mechanical systems. We consider frequency conditions for modal interactions and determine stability conditions for three important cases. We develop conditions under which it is possible to sweep with direct and parametric excitation to produce a sweep response with amplified effective quality factor of resonances encountered during the sweep. With this technique it is possible to improve the measurement of resonance locations in swept devices, such as those that operate on resonance shifting. A numerical example motivated by a MEMS mass sensor is given in support of the analysis.
Output-Only Modal Analysis of Randomly Excited Systems Using Smooth Orthogonal Decomposition
Authors: Farooq Umar , Feeny Brian F.
Published: July 2009

Modal parameter estimation in terms of natural frequencies and mode shapes is studied using smooth orthogonal decomposition (SOD) for randomly excited vibration systems. This work shows that under certain conditions, the SOD eigenvalue problem formulated from white noise induced response data can be tied to the unforced structural eigenvalue problem, and thus can be used for modal parameter estimation. Using output response ensembles only, the generalized eigenvalue problem is formed to estimate modal frequencies and modal vectors for a sixteen-degree-of-freedom lightly damped vibratory system. The estimated frequencies are compared against system frequencies obtained from the structural eigenvalue problem and estimated modal vectors are checked using the modal assurance criterion. Simulations show that for light damping, satisfactory results are obtained for estimating both system frequencies and modal vectors even in presence of sensor noise.
Color Registration Error Reduction in Document Scanner Using Iterative Velocity Command Synthesis
Authors: Mukhtar Moeed , Yi Jonghyon , Chiu George T.-C.
Published: July 2009

Document scanners enjoy widespread use for converting hardcopy documents into digital images. Improving image quality is a key issue for scanner manufacturers. This paper proposes an ILC based step timing synthesis technique for reducing color registration error in stepper motor driven document scanners with no real-time feedback. To quantify color registration error, a line pattern image based technique is devised. Based on the measured color registration error signal, a single iteration convergent iterative learning control scheme is proposed to synthesize a stepper motor step timing command for the scan region. Reduction in color registration error is achieved by compensating for velocity fluctuations in the constant speed portion of the motion. Experimental results demonstrate the effectiveness of the proposed approach in reducing color registration error in scanned image.
Differential Flatness-Based Robust Control of a Two-Wheeled Mobile Robot in the Presence of Slip
Authors: Ryu Ji-Chul , Agrawal Sunil K.
Published: July 2009

In this paper, we present two robust trajectory-tracking controllers for a differentially driven two-wheeled mobile robot using its kinematic and dynamic model in the presence of slip. The structure of the differential flatness-based controller, which is an integrated framework for planning and control, is extended in this paper to account for slip disturbances by adding a corrective control term. Simulation results for both kinematic and dynamic controllers are presented to demonstrate the effectiveness of the robust controllers. Experiments with the kinematic controller were conducted to validate the performance of the robust controller. The simulation and experimental results show that the robust controllers are very effective in the presence of slip.
Hierarchical Diagnosis and Prognosis Strategy for Electrical Power Generation and Storage System
Authors: Bologna Linda , Guerini Ivo , Onori Simona , Rizzoni Giorgio , Salman Mutasim A. , Zhang Frank
Published: July 2009

This paper presents a hierarchical approach to fault detection and isolation (FDI) of an automotive electrical power generation and storage (EPGS) system. In particular, this work focuses on a fault diagnosis strategy for the alternator and belt of the EPGS system. The proposed approach is able to detect and isolate the faults of the following components: the voltage regulator, the diodes and the belt. Preliminary evaluation results using an EPGS system test bench have shown the effectiveness of the algorithm.
Theoretical Basis for Short Maneuver Optimal Pulse-Width Control
Authors: Buffinton Keith W. , Hoffman Katie L. , Berg Martin C.
Published: July 2009

Two problems encountered in precision manufacturing are friction and flexibility. With regard to friction, Pulse-Width Control (PWC) has been shown to be exceptionally effective for rigid systems. When used to control flexible systems, however, residual vibrations often result, limiting speed and precision. In a previous related paper, an optimal pulse-width controller was developed that uses two pulses such that the second pulse cancels vibration induced by the first Based on a numerical process minimizing vibration attenuation time, optimal zero vibration (ZV) solutions for the first pulse width, the second pulse width, and the time between pulses were found. Trends in these numerical solutions were also identified that approached limiting values for short maneuvers. In the present paper, a theoretical foundation for these limiting values is derived. This derivation shows that for short maneuvers analytical expressions for pulse widths and timings are easily obtained. These analytical expressions are then used as the basis of an optimal pulse-width controller that is shown to function effectively in both simulation and experiment.
An Adaptive Robust Scheme for Multiple Actuator Fault Accommodation
Authors: Gayaka Shreekant , Yao Bin
Published: July 2009

In this paper, we solve the problem of output tracking for linear systems in presence of unknown actuator failures using discontinuous projection based output feedback adaptive robust control (ARC) scheme. The faulty actuators are characterized as unknown inputs stuck within certain bounds at unknown instants of time. This problem is of prime importance for safety critical missions like flight control system. Many existing techniques to solve this problem use model reference adaptive control (MRAC), which is not well suited for handling various disturbances and modeling errors inherent to any realistic system model. In comparison, the backstepping based output feedback ARC approach used here can effectively deal with such uncertainties. Simulation studies are carried out on a linearized Boeing 747 model, which shows the effectiveness of the proposed scheme. Furthermore, we compare our simulation results with that of MRAC in presence of disturbances, which clearly illustrates the superior performance of the proposed ARC based actuator fault compensation scheme.
Model-Based Fault Diagnosis for NiMH Battery
Authors: Suozzo Chris , Onori Simona , Rizzoni Giorgio
Published: July 2009

The objective of this paper is to present a fault diagnosis methodology for hybrid electric vehicle battery systems. The faults that have been considered include: temperature sensor fault, current sensor fault, and voltage sensor. Many of these faults, if left undetected, will result in decreased battery performance and could eventually lead to pack failure.
Image Method With Distributed Multipole Models for Analyzing Permanent-Magnet-Based Electromagnetic Actuators
Authors: Lee Kok-Meng , Son Hungsun , Bai Kun
Published: July 2009

Many high-torque electromagnetic problems involve solving three dimensional (3D) magnetic fields of the permanent magnets (PMs) and/or electromagnet magnets (EMs) in the presence of magnetically conducting surfaces. This paper extends the distributed multi-pole (DMP) method, which offers a means to present the three-dimensional magnetic field solution in closed form, to account for the effects of the magnetic conducting boundary using an image method. We validate the DMP/image method by comparing the torques calculated using the Lorentz force equation and Maxwell stress tensor against numerical results computed using a finite element method (FEM). While two methods agree to within 5% in maximum torque, the DMP/image method takes less than 1% of the FEM computation time. With the numerically validated torque computation, we demonstrate how the DMP/image method can be used to analyze designs of a spherical wheel motor as illustrative practical applications.
Kinematic Control of Nonholonomic Wheeled Mobile Manipulator: A Differential Flatness Approach
Authors: Tang Chin Pei , Miller Patrick T. , Krovi Venkat N. , Ryu Ji-Chul , Agrawal Sunil K.
Published: July 2009

This paper presents an integrated motion planning and control framework for a nonholonomic wheeled mobile manipulator (WMM) system taking advantage of the (differential) flatness property. We first develop the kinematic model of the system and analyze its flatness properties. Subsequently, a statically feedback linearizable system description is developed by appropriately choosing the flat outputs. Motion-planning can now be achieved by polynomial curve fitting to satisfying the terminal conditions in the flat output space while control design reduces to a pole-placement problem for a linear system. A case study of point-to-point motion is considered to study the effectiveness of pose stabilization in the WMM. The simulation and experimental results highlight the ease-of-implementation of proposed method for online real-time integrated motion-planning/control within a hardware-in-the-loop (HIL) electro-mechanical testing.
Coldstart Control Analysis Using Dynamic Programming
Authors: Jurado Jose´ Carlos Zavala , Sanketi Pannag , Hedrick Karl
Published: July 2009

The need to reduce the negative effects of automotive hydrocarbon emissions on human health has drawn attention to the coldstart period of a combustion engine. The coldstart phase consists of the first few minutes of operation of the engine and generates a large percentage of the total cumulative hydrocarbon emissions. The focus of this study is on developing strategies to reduce emissions without adding extra hardware components to the engine. The control strategy was based on Dynamic Programming. The problem of minimizing hydrocarbon emissions was set up in such a way that optimality could be analyzed for different time horizons. The results explain the tradeoffs involved in the coldstart problem. The resulting optimal control strategy can be used to define tracking profiles in a Dynamic Surface Controller developed previously.
Optimal Dispensing Strategy for a Two Component Xerographic Development Process
Authors: Liu Feng , Chiu George T.-C. , Hamby Eric S. , Eun Yongsoon
Published: July 2009

Inconsistent color reproduction is a major performance and quality issue for high volume digital press. Literature has shown that loss of developability of the toner particles in the development stage of xerography is a main contributing factor for inconsistent color reproduction. Previous works have shown that a second order system model is able to predict and characterize the inevitable loss of developability. In this paper, a nonlinear constrained optimal control problem is formulated to find the optimal dispensing strategy that maximizes the time for which acceptable developability is maintained. An analytical solution to the constrained optimal control problem is derived based on the Maximum Principle without explicitly solving for the costate dynamics. Results show that the state feedback based optimal dispensing strategy starts with the minimal allowable dispensing rate while increasing the development voltage to maintain the desired development quality until the maximal development voltage is reached. Then, the optimal dispense rate switches to maintain the developability at maximal development voltage. Numerical examples support the analytical solution.
Investigation of Control Design of Vehicle Active Steering
Authors: Eskandarian Azim , Bauer Mathias , Soudbakhsh Damoon
Published: July 2009

The design of a controller for active steering systems in evasive maneuvers of vehicles is investigated. Dynamics of a vehicle using the bicycle model along with a steering model is developed in state space representation. Parameters of a sports utility vehicle are used. The developed model is validated with simulation results from a commercial vehicle dynamics simulation software. The effects of a PID controller to control the host vehicle in obstacle avoidance maneuvers are investigated. The desired trajectory path is used as an input, and influence of the different gain parameters are studied. Controller can handle disturbances (such as driver’s input) supporting or opposing the maneuver up to a limit. It handles reduced headway distances up to about 60% of the distance to obstacles, but is only capable of keeping the system stable in a small range of velocities.
Reconfiguration for Modular Robots Using Kinodynamic Motion Planning
Authors: S¸ucan Ioan A. , Kruse Jonathan F. , Yim Mark , Kavraki Lydia E.
Published: July 2009

This paper presents computational and experimental evidence that it is possible to plan and execute dynamic motions that involve chain reconfiguration for modular reconfigurable robots in the presence of obstacles. At the heart of the approach is the use of a sampling-based motion planner that is tightly integrated with a physics-based dynamic simulator. To evaluate the method, the planner is used to compute motions for a chain robot constructed from CKbot modules to perform a reconfiguration, attaching more modules and continuing a dynamic motion while avoiding obstacles. These motions are then executed on hardware and compared with the ones predicted by the planner.
In-Line Inspection of Engine Valve Seats Using a Non-Contact Range Sensor
Authors: Srivatsan Vijay , Powałka Bartosz , Katz Reuven , Agapiou John
Published: July 2009

This paper presents a methodology for the inspection of geometric features on an internal combustion engine valve seat. Inspection of valve seat geometry using a high-precision non-contact range sensor is investigated. A method that can extract the cone angle, the valve seat length and the roundness of the cone surface has been presented. In-line implementation requires a methodology to analyze data from a minimum number of parallel cross sectional profiles of the valve seat. An in-line valve seat inspection prototype machine with two axes of motion that utilizes the method presented in this paper is presented. Validation of the method on several valve seat samples shows a high degree of repeatability, and the results are comparable to coordinate measurement machine measurements of the same samples.
Extended Geometric Filter for Reconstruction as a Basis for Computational Inspection
Authors: Miropolsky Alexander , Fischer Anath
Published: July 2009

Inspection of machined objects is one of the most important quality control tasks in the manufacturing industry. Contemporary scanning technologies have provided the impetus for the development of computational inspection methods, where the computer model of the manufactured object is reconstructed from the scan data, and then verified against its design computer model. Scan data, however, is typically very large scale (i.e. many points), unorganized, noisy and incomplete. Therefore, reconstruction is problematic. To overcome the above problems the reconstruction methods may exploit diverse feature data, that is, diverse information about the properties of the scanned object. Based on this concept, the paper proposes a new method for de-noising and reduction of scan data by Extended Geometric Filter (EGF). The proposed method is applied directly on the scanned points and is automatic, fast and straightforward to implement. The paper demonstrates the integration of the proposed method into the framework of the computational inspection process.
Optimal Model Selection Using MP Criterion for Uncertain Multivariable 2×2 Systems Based on IMC
Authors: Shani Inbal , Brauner Neima , Brosilow Coleman B.
Published: July 2009

IMC controller design for a process is based on choosing a mathematical model that describes the real process. The mathematical model describing such process is often not unique because the real variables of the process can vary within an interval. In such cases the performance of the control system varies, possibly substantially, as process parameters change. To limit such performance variations, we have developed an algorithm for choosing the model gains and the filter time constants of the IMC controller, to minimize the amount of interaction between outputs due to set point changes and disturbances for multivariable decoupled control systems. Some examples illustrate the algorithm.
Molten Metal Flow Visualization Using Dynamical Magnetic Induction Tomography
Authors: Soleimani Manuchehr
Published: July 2009

Magnetic induction tomography (MIT) is a contactless electromagnetic imaging. In our previous study we have demonstrated that the MIT is able to image metal flow in continous casting. In this paper we demonstrate application of a Kalman filter for the image reconstruction problem of MIT using real data from a continous casting unit. The proposed method is using data from each excitation to reconstruct the conductivity distribution. We discuss the advantage of the dynamical method compared to traditional static image reconstruction technique.
The Influence of Valve Seats Machining Process on Roundness Error
Authors: Powałka Bartosz , Katz Reuven
Published: July 2009

This paper presents a methodology of valve seat machining force model development. A cutting force model coefficients are calibrated without the need of performing separate cutting tests for the blades of the valve seat tool. The developed cutting force model is validated using results of valve seat machining when the misalignement of the tool and workpiece axes was introduced. Also the model for the prediction of the roundess error that employs machine tool dynamics represented by frequency response function and cutting force model is proposed. Prediction quality of the roundness error model is compared to the CMM profile measurements.
Close-Up of Mushroom-Shaped Fibrillar Adhesive Microstructure: Contact Element Behavior
Authors: Varenberg M. , Gorb S.
Published: July 2009

To analyze the performance of a mushroom-shaped fibrillar adhesive microstructure, its behavior was studied during different stages of attachment-loading-detachment cycle. Visualizing the evolutions of real contact area of single microfibers, it is shown that the mushroom-shaped geometry of contact elements promotes fast and simple generation of reliable adhesion. Mushroom-shaped geometry seems to transform fibrillar contact elements into passive suction devices and makes them tolerant to overload, thus enhancing their robustness and stability. These findings may also be extrapolated to biological fibrillar attachment devices sharing the same geometry.
Large Angle Parametrically Excited Tilting Micro Actuator
Authors: Ya’akobovitz Assaf , Krylov Slava
Published: July 2009

We present novel operational principle of a tilting MEMS device based on parametric excitation and linear to angular motion transformation. The device is fabricated using a single layer of silicon on insulator (SOI) wafer and combines simple fabrication process with several beneficial features including large tilting angles, wide bandwidth, low sensitivity to deviation in geometrical and operational parameters and low actuation voltage. A theoretical feasibility and performance study was carried out using a lumped model of the device and verified by a coupled three-dimensional simulation. Parametric excitation of the tilting motion was demonstrated experimentally using and external piezoelectric transducer and tilting angles of 39° were registered. The suggested operational approach could be efficiently implemented in many MEMS based applications incorporating tilting elements including micromirrors, bio medical devices and inertial sensors.
The Effect of Misalignment on Power Loss in Ball Bearings
Authors: Damian Ioan , Oancea Ion , Cretu Spiridon
Published: July 2009

A vectorial method has been developed to solve the quasi-static equilibrium in angular contact ball bearings. In the quai-static model the effects induced by the centrifugal forces, gyroscopic moments and misalignments between bearing’s rings were considered. The lubricant parameters, traction forces and fluid drag action on balls and raceways were further included in a quasi-dynamic model. An experimental study has been further carried out to validate the quasi-dynamic model when a certain degree of misalignment exists between the inner and outer rings of the bearing. Both numerical simulation and experimental measurements emphasized the major contribution of the rings misalignment upon the bearing power loss.