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Sample records for optimal target placement

  1. Toward Optimal Target Placement for Neural Prosthetic Devices

    PubMed Central

    Cunningham, John P.; Yu, Byron M.; Gilja, Vikash; Ryu, Stephen I.; Shenoy, Krishna V.

    2008-01-01

    Neural prosthetic systems have been designed to estimate continuous reach trajectories (motor prostheses) and to predict discrete reach targets (communication prostheses). In the latter case, reach targets are typically decoded from neural spiking activity during an instructed delay period before the reach begins. Such systems use targets placed in radially symmetric geometries independent of the tuning properties of the neurons available. Here we seek to automate the target placement process and increase decode accuracy in communication prostheses by selecting target locations based on the neural population at hand. Motor prostheses that incorporate intended target information could also benefit from this consideration. We present an optimal target placement algorithm that approximately maximizes decode accuracy with respect to target locations. In simulated neural spiking data fit from two monkeys, the optimal target placement algorithm yielded statistically significant improvements up to 8 and 9% for two and sixteen targets, respectively. For four and eight targets, gains were more modest, as the target layouts found by the algorithm closely resembled the canonical layouts. We trained a monkey in this paradigm and tested the algorithm with experimental neural data to confirm some of the results found in simulation. In all, the algorithm can serve not only to create new target layouts that outperform canonical layouts, but it can also confirm or help select among multiple canonical layouts. The optimal target placement algorithm developed here is the first algorithm of its kind, and it should both improve decode accuracy and help automate target placement for neural prostheses. PMID:18829845

  2. Optimal Placement of Heterogeneous Sensors in Target Tracking

    DTIC Science & Technology

    2011-07-01

    PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10 . SPONSOR/MONITOR’S ACRONYM(S) 11. SPONSOR/MONITOR’S...it is easy to show that the linear least squares estimate of the target state is ( ))()(ˆ 0111010 xfzRHPHRHxx −++= −−−− TT ( 10 ) and the...given by M = M0+ HTR -1H. (12) Usually, the sensors are spatially disparate so that the measurement errors vi are statistically independent with

  3. Locating the optimal internal jugular target site for central venous line placement.

    PubMed

    Giordano, Chris R; Murtagh, Kevin R; Mills, Jaime; Deitte, Lori A; Rice, Mark J; Tighe, Patrick J

    2016-09-01

    Historically, the placement of internal jugular central venous lines has been accomplished by using external landmarks to help identify target-rich locations in order to steer clear of dangerous structures. This paradigm is largely being displaced, as ultrasound has become routine practice, raising new considerations regarding target locations and risk mitigation. Most human anatomy texts depict the internal jugular vein as a straight columnar structure that exits the cranial vault the same size that it enters the thoracic cavity. We dispute the notion that the internal jugulars are cylindrical columns that symmetrically descend into the thoracic cavity, and purport that they are asymmetric conical structures. The primary aim of this study was to evaluate 100 consecutive adult chest and neck computed tomography exams that were imaged at an inpatient hospital. We measured the internal jugular on the left and right sides at three different levels to look for differences in size as the internal jugular descends into the thoracic cavity. We revealed that as the internal jugular descends into the thorax, the area of the vessel increases and geometrically resembles a conical structure. We also reconfirmed that the left internal jugular is smaller than the right internal jugular. Understanding that the largest target area for central venous line placement is the lower portion of the right internal jugular vein will help to better target vascular access for central line placement. This is the first study the authors are aware of that depicts the internal jugular as a conical structure as opposed to the commonly depicted symmetrical columnar structure frequently illustrated in anatomy textbooks. This target area does come with additional risk, as the closer you get to the thoracic cavity, the greater the chances for lung injury. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Comparing the Selection and Placement of Best Management Practices in Improving Water Quality Using a Multiobjective Optimization and Targeting Method

    PubMed Central

    Chiang, Li-Chi; Chaubey, Indrajeet; Maringanti, Chetan; Huang, Tao

    2014-01-01

    Suites of Best Management Practices (BMPs) are usually selected to be economically and environmentally efficient in reducing nonpoint source (NPS) pollutants from agricultural areas in a watershed. The objective of this research was to compare the selection and placement of BMPs in a pasture-dominated watershed using multiobjective optimization and targeting methods. Two objective functions were used in the optimization process, which minimize pollutant losses and the BMP placement areas. The optimization tool was an integration of a multi-objective genetic algorithm (GA) and a watershed model (Soil and Water Assessment Tool—SWAT). For the targeting method, an optimum BMP option was implemented in critical areas in the watershed that contribute the greatest pollutant losses. A total of 171 BMP combinations, which consist of grazing management, vegetated filter strips (VFS), and poultry litter applications were considered. The results showed that the optimization is less effective when vegetated filter strips (VFS) are not considered, and it requires much longer computation times than the targeting method to search for optimum BMPs. Although the targeting method is effective in selecting and placing an optimum BMP, larger areas are needed for BMP implementation to achieve the same pollutant reductions as the optimization method. PMID:24619160

  5. Comparing the selection and placement of best management practices in improving water quality using a multiobjective optimization and targeting method.

    PubMed

    Chiang, Li-Chi; Chaubey, Indrajeet; Maringanti, Chetan; Huang, Tao

    2014-03-11

    Suites of Best Management Practices (BMPs) are usually selected to be economically and environmentally efficient in reducing nonpoint source (NPS) pollutants from agricultural areas in a watershed. The objective of this research was to compare the selection and placement of BMPs in a pasture-dominated watershed using multiobjective optimization and targeting methods. Two objective functions were used in the optimization process, which minimize pollutant losses and the BMP placement areas. The optimization tool was an integration of a multi-objective genetic algorithm (GA) and a watershed model (Soil and Water Assessment Tool-SWAT). For the targeting method, an optimum BMP option was implemented in critical areas in the watershed that contribute the greatest pollutant losses. A total of 171 BMP combinations, which consist of grazing management, vegetated filter strips (VFS), and poultry litter applications were considered. The results showed that the optimization is less effective when vegetated filter strips (VFS) are not considered, and it requires much longer computation times than the targeting method to search for optimum BMPs. Although the targeting method is effective in selecting and placing an optimum BMP, larger areas are needed for BMP implementation to achieve the same pollutant reductions as the optimization method.

  6. Targeted Pressure Management During CO2 Sequestration: Optimization of Well Placement and Brine Extraction

    DOE PAGES

    Cihan, Abdullah; Birkholzer, Jens; Bianchi, Marco

    2014-12-31

    Large-scale pressure increases resulting from carbon dioxide (CO2) injection in the subsurface can potentially impact caprock integrity, induce reactivation of critically stressed faults, and drive CO2 or brine through conductive features into shallow groundwater. Pressure management involving the extraction of native fluids from storage formations can be used to minimize pressure increases while maximizing CO2 storage. However, brine extraction requires pumping, transportation, possibly treatment, and disposal of substantial volumes of extracted brackish or saline water, all of which can be technically challenging and expensive. This paper describes a constrained differential evolution (CDE) algorithm for optimal well placement and injection/ extractionmore » control with the goal of minimizing brine extraction while achieving predefined pressure contraints. The CDE methodology was tested for a simple optimization problem whose solution can be partially obtained with a gradient-based optimization methodology. The CDE successfully estimated the true global optimum for both extraction well location and extraction rate, needed for the test problem. A more complex example application of the developed strategy was also presented for a hypothetical CO2 storage scenario in a heterogeneous reservoir consisting of a critically stressed fault nearby an injection zone. Through the CDE optimization algorithm coupled to a numerical vertically-averaged reservoir model, we successfully estimated optimal rates and locations for CO2 injection and brine extraction wells while simultaneously satisfying multiple pressure buildup constraints to avoid fault activation and caprock fracturing. The study shows that the CDE methodology is a very promising tool to solve also other optimization problems related to GCS, such as reducing ‘Area of Review’, monitoring design, reducing risk of leakage and increasing storage capacity and trapping.« less

  7. Sensor placement optimization in buildings

    NASA Astrophysics Data System (ADS)

    Bianco, Simone; Tisato, Francesco

    2012-01-01

    In this work we address the problem of optimal sensor placement for a given region and task. An important issue in designing sensor arrays is the appropriate placement of the sensors such that they achieve a predefined goal. There are many problems that could be considered in the placement of multiple sensors. In this work we focus on the four problems identified by Hörster and Lienhart. To solve these problems, we propose an algorithm based on Direct Search, which is able to approach the global optimal solution within reasonable time and memory consumption. The algorithm is experimentally evaluated and the results are presented on two real floorplans. The experimental results show that our DS algorithm is able to improve the results given by the most performing heuristic introduced in. The algorithm is then extended to work also on continuous solution spaces, and 3D problems.

  8. Optimal Jammer Placement in Wireless Localization Systems

    NASA Astrophysics Data System (ADS)

    Gezici, Sinan; Bayram, Suat; Kurt, Mehmet Necip; Gholami, Mohammad Reza

    2016-09-01

    In this study, the optimal jammer placement problem is proposed and analyzed for wireless localization systems. In particular, the optimal location of a jammer node is obtained by maximizing the minimum of the Cramer-Rao lower bounds (CRLBs) for a number of target nodes under location related constraints for the jammer node. For scenarios with more than two target nodes, theoretical results are derived to specify conditions under which the jammer node is located as close to a certain target node as possible, or the optimal location of the jammer node is determined by two of the target nodes. Also, explicit expressions are provided for the optimal location of the jammer node in the presence of two target nodes. In addition, in the absence of distance constraints for the jammer node, it is proved, for scenarios with more than two target nodes, that the optimal jammer location lies on the convex hull formed by the locations of the target nodes and is determined by two or three of the target nodes, which have equalized CRLBs. Numerical examples are presented to provide illustrations of the theoretical results in different scenarios.

  9. Targeted Pressure Management During CO2 Sequestration: Optimization of Well Placement and Brine Extraction

    SciTech Connect

    Cihan, Abdullah; Birkholzer, Jens; Bianchi, Marco

    2014-12-31

    Large-scale pressure increases resulting from carbon dioxide (CO2) injection in the subsurface can potentially impact caprock integrity, induce reactivation of critically stressed faults, and drive CO2 or brine through conductive features into shallow groundwater. Pressure management involving the extraction of native fluids from storage formations can be used to minimize pressure increases while maximizing CO2 storage. However, brine extraction requires pumping, transportation, possibly treatment, and disposal of substantial volumes of extracted brackish or saline water, all of which can be technically challenging and expensive. This paper describes a constrained differential evolution (CDE) algorithm for optimal well placement and injection/ extraction control with the goal of minimizing brine extraction while achieving predefined pressure contraints. The CDE methodology was tested for a simple optimization problem whose solution can be partially obtained with a gradient-based optimization methodology. The CDE successfully estimated the true global optimum for both extraction well location and extraction rate, needed for the test problem. A more complex example application of the developed strategy was also presented for a hypothetical CO2 storage scenario in a heterogeneous reservoir consisting of a critically stressed fault nearby an injection zone. Through the CDE optimization algorithm coupled to a numerical vertically-averaged reservoir model, we successfully estimated optimal rates and locations for CO2 injection and brine extraction wells while simultaneously satisfying multiple pressure buildup constraints to avoid fault activation and caprock fracturing. The study shows that the CDE methodology is a very promising tool to solve also other optimization problems related to GCS, such as reducing ‘Area of Review’, monitoring design, reducing risk of leakage and increasing storage capacity and trapping.

  10. Optimal Sensor Placement for Multiple Target Positioning with Range-Only Measurements in Two-Dimensional Scenarios

    PubMed Central

    Moreno-Salinas, David; Pascoal, Antonio M.; Aranda, Joaquin

    2013-01-01

    The problem of determining the optimal geometric configuration of a sensor network that will maximize the range-related information available for multiple target positioning is of key importance in a multitude of application scenarios. In this paper, a set of sensors that measures the distances between the targets and each of the receivers is considered, assuming that the range measurements are corrupted by white Gaussian noise, in order to search for the formation that maximizes the accuracy of the target estimates. Using tools from estimation theory and convex optimization, the problem is converted into that of maximizing, by proper choice of the sensor positions, a convex combination of the logarithms of the determinants of the Fisher Information Matrices corresponding to each of the targets in order to determine the sensor configuration that yields the minimum possible covariance of any unbiased target estimator. Analytical and numerical solutions are well defined and it is shown that the optimal configuration of the sensors depends explicitly on the constraints imposed on the sensor configuration, the target positions, and the probabilistic distributions that define the prior uncertainty in each of the target positions. Simulation examples illustrate the key results derived. PMID:23959235

  11. Two-dimensional optimal sensor placement

    SciTech Connect

    Zhang, H.

    1995-05-01

    A method for determining the optimal two-dimensional spatial placement of multiple sensors participating in a robot perception task is introduced in this paper. This work is motivated by the fact that sensor data fusion is an effective means of reducing uncertainties in sensor observations, and that the combined uncertainty varies with the relative placement of the sensors with respect to each other. The problem of optimal sensor placement is formulated and a solution is presented in the two dimensional space. The algebraic structure of the combined sensor uncertainty with respect to the placement of sensor is studied. A necessary condition for optimal placement is derived and this necessary condition is used to obtain an efficient closed-form solution for the global optimal placement. Numerical examples are provided to illustrate the effectiveness and efficiency of the solution. 11 refs.

  12. Optimization Strategies for Sensor and Actuator Placement

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Kincaid, Rex K.

    1999-01-01

    This paper provides a survey of actuator and sensor placement problems from a wide range of engineering disciplines and a variety of applications. Combinatorial optimization methods are recommended as a means for identifying sets of actuators and sensors that maximize performance. Several sample applications from NASA Langley Research Center, such as active structural acoustic control, are covered in detail. Laboratory and flight tests of these applications indicate that actuator and sensor placement methods are effective and important. Lessons learned in solving these optimization problems can guide future research.

  13. Wind Farm Turbine Type and Placement Optimization

    NASA Astrophysics Data System (ADS)

    Graf, Peter; Dykes, Katherine; Scott, George; Fields, Jason; Lunacek, Monte; Quick, Julian; Rethore, Pierre-Elouan

    2016-09-01

    The layout of turbines in a wind farm is already a challenging nonlinear, nonconvex, nonlinearly constrained continuous global optimization problem. Here we begin to address the next generation of wind farm optimization problems by adding the complexity that there is more than one turbine type to choose from. The optimization becomes a nonlinear constrained mixed integer problem, which is a very difficult class of problems to solve. This document briefly summarizes the algorithm and code we have developed, the code validation steps we have performed, and the initial results for multi-turbine type and placement optimization (TTP_OPT) we have run.

  14. Wind farm turbine type and placement optimization

    DOE PAGES

    Graf, Peter; Dykes, Katherine; Scott, George; ...

    2016-10-03

    The layout of turbines in a wind farm is already a challenging nonlinear, nonconvex, nonlinearly constrained continuous global optimization problem. Here we begin to address the next generation of wind farm optimization problems by adding the complexity that there is more than one turbine type to choose from. The optimization becomes a nonlinear constrained mixed integer problem, which is a very difficult class of problems to solve. Furthermore, this document briefly summarizes the algorithm and code we have developed, the code validation steps we have performed, and the initial results for multi-turbine type and placement optimization (TTP_OPT) we have run.

  15. Multi-Target Single Cycle Instrument Placement

    NASA Technical Reports Server (NTRS)

    Pedersen, Liam; Smith, David E.; Deans, Matthew; Sargent, Randy; Kunz, Clay; Lees, David; Rajagopalan, Srikanth; Bualat, Maria

    2005-01-01

    This presentation is about the robotic exploration of Mars using multiple targets command cycle, safe instrument placements, safe operation, and K9 Rover which has a 6 wheel steer rocket-bogey chassis (FIDO, MER), 70% MER size, 1.2 GHz Pentium M laptop running Linux OS, Odometry and compass/inclinometer, CLARAty architecture, 5 DOF manipulator w/CHAMP microscopic camera, SciCams, NavCams and HazCams.

  16. SPOT-A SENSOR PLACEMENT OPTIMIZATION TOOL FOR ...

    EPA Pesticide Factsheets

    journal article This paper presents SPOT, a Sensor Placement Optimization Tool. SPOT provides a toolkit that facilitates research in sensor placement optimization and enables the practical application of sensor placement solvers to real-world CWS design applications. This paper provides an overview of SPOT’s key features, and then illustrates how this tool can be flexibly applied to solve a variety of different types of sensor placement problems.

  17. SPOT-A SENSOR PLACEMENT OPTIMIZATION TOOL FOR ...

    EPA Pesticide Factsheets

    journal article This paper presents SPOT, a Sensor Placement Optimization Tool. SPOT provides a toolkit that facilitates research in sensor placement optimization and enables the practical application of sensor placement solvers to real-world CWS design applications. This paper provides an overview of SPOT’s key features, and then illustrates how this tool can be flexibly applied to solve a variety of different types of sensor placement problems.

  18. Optimizing Spacecraft Placement for Liaison Constellations

    NASA Technical Reports Server (NTRS)

    Chow, C. Channing; Villac, Benjamin F.; Lo, Martin W.

    2011-01-01

    A navigation and communications network is proposed to support an anticipated need for infrastructure in the Earth-Moon system. Periodic orbits will host the constellations while a novel, autonomous navigation strategy will guide the spacecraft along their path strictly based on satellite-to-satellite telemetry. In particular, this paper investigates the second stage of a larger constellation optimization scheme for multi-spacecraft systems. That is, following an initial orbit down-selection process, this analysis provides insights into the ancillary problem of spacecraft placement. Two case studies are presented that consider configurations of up to four spacecraft for a halo orbit and a cycler trajectory.

  19. Optimizing Spacecraft Placement for Liaison Constellations

    NASA Technical Reports Server (NTRS)

    Chow, C. Channing; Villac, Benjamin F.; Lo, Martin W.

    2011-01-01

    A navigation and communications network is proposed to support an anticipated need for infrastructure in the Earth-Moon system. Periodic orbits will host the constellations while a novel, autonomous navigation strategy will guide the spacecraft along their path strictly based on satellite-to-satellite telemetry. In particular, this paper investigates the second stage of a larger constellation optimization scheme for multi-spacecraft systems. That is, following an initial orbit down-selection process, this analysis provides insights into the ancillary problem of spacecraft placement. Two case studies are presented that consider configurations of up to four spacecraft for a halo orbit and a cycler trajectory.

  20. Efficient Method for Optimizing Placement of Sensors

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Vatan, Farrokh

    2009-01-01

    A computationally efficient method has been developed to enable optimization of the placement of sensors for the purpose of diagnosis of a complex engineering system (e.g., an aircraft or spacecraft). The method can be used both in (1) designing a sensor system in which the number and positions of sensors are initially not known and must be determined and (2) adding sensors to a pre-existing system to increase the diagnostic capability. The optimal-sensor-placement problem can be summarized as involving the following concepts, issues, and subproblems: a) Degree of Diagnosability - This is a concept for characterizing the set of faults that can be discriminated by use of a given set of sensors. b) Minimal Sensor Set - The idea is one of finding a minimal set of sensors that guarantees a specific degree of diagnosability. c) Minimal-Cost Sensors - In a case in which different sensors are assigned with different costs, it is desired to choose the least costly set of sensors that affords a specific degree of diagnosability.

  1. Target Tracking, Approach, and Camera Handoff for Automated Instrument Placement

    NASA Technical Reports Server (NTRS)

    Bajracharya, Max; Diaz-Calderon, Antonio; Robinson, Matthew; Powell, Mark

    2005-01-01

    This paper describes the target designation, tracking, approach, and camera handoff technologies required to achieve accurate, single-command autonomous instrument placement for a planetary rover. It focuses on robust tracking integrated with obstacle avoidance during the approach phase, and image-based camera handoff to allow vision-based instrument placement. It also provides initial results from a complete system combining these technologies with rover base placement to maximize arm manipulability and image-based instrument placement.

  2. Endoscopic Gold Fiducial Marker Placement into the Bladder Wall to Optimize Radiotherapy Targeting for Bladder-Preserving Management of Muscle-Invasive Bladder Cancer: Feasibility and Initial Outcomes

    PubMed Central

    Garcia, Maurice M.; Gottschalk, Alexander R.; Brajtbord, Jonathan; Konety, Badrinath R.; Meng, Maxwell V.; Roach, Mack; Carroll, Peter R.

    2014-01-01

    Background and Purpose Bladder radiotherapy is a management option for carefully selected patients with muscle-invasive bladder cancer. However, the inability to visualize the tumor site during treatment and normal bladder movement limits targeting accuracy and increases collateral radiation. A means to accurately and reliably target the bladder during radiotherapy is needed. Materials and Methods Eighteen consecutive patients with muscle-invasive bladder cancer (T1–T4) elected bladder-preserving treatment with maximal transurethral resection (TUR), radiation and concurrent chemotherapy. All underwent endoscopic placement of 24-K gold fiducial markers modified with micro-tines (70 [2.9×0.9 mm.]; 19 [2.1×0.7 mm.) into healthy submucosa 5-10 mm. from the resection margin, using custom-made coaxial needles. Marker migration was assessed for with intra-op bladder-filling cystogram and measurement of distance between markers. Set-up error and marker retention through completion of radiotherapy was confirmed by on-table portal imaging. Results Between 1/2007 and 7/2012, a total of 89 markers (3–5 per tumor site) were placed into 18 patients of mean age 73.6 years. Two patients elected cystectomy before starting treatment; 16/18 completed chemo-radiotherapy. All (100%) markers were visible with all on-table (portal, cone-beam CT), fluoroscopy, plain-film, and CT-scan imaging. In two patients, 1 of 4 markers placed at the tumor site fell-out (voided) during the second half of radiotherapy. All other markers (80/82, 98%) were present through the end of radio-therapy. No intraoperative (e.g. uncontrolled bleeding, collateral injury) or post-operative complications (e.g. stone formation, urinary tract infection, post-TUR hematuria >48 hours) occurred. Use of micro-tined fiducial tumor-site markers afforded a 2 to 6-fold reduction in bladder-area targeted with high-dose radiation. Discussion Placement of the micro-tined fiducial markers into the bladder was feasible and

  3. Both the middle and distal sections of the urethra may be regarded as optimal targets for 'outside-in' transobturator tape placement.

    PubMed

    Bogusiewicz, Michał; Monist, Marta; Gałczyński, Krzysztof; Woźniak, Magdalena; Wieczorek, Andrzej P; Rechberger, Tomasz

    2014-12-01

    To investigate whether the position of the tape under the urethra may influence 'outside-in' transobturator sling (TOT) outcome. The study comprised 141 women who underwent TOT for clinically and urodynamically proved stress urinary incontinence. The postoperative ultrasound examination with an endovaginal biplane probe was performed before discharging the patients from hospital. The measurements obtained described the position of the tape relative to the urethra and pubic symphysis, as well as anatomical relationships in the anterior compartment. Ninety-six (68.1 %) patients were cured, 27 (19.1 %) significantly improved, and in 18 cases (12.7 %), the surgery failed. The tape position under the midurethra (40-70th percentile of the urethral length) or distal urethra (>70th percentile) coincided with better results (cure rate 67.1 and 82.4 %, respectively) than the location in the proximity of the bladder neck (<40th percentile) (21.4 % cured, p = 0.0015 and p < 0.001, respectively). However, the risk of failure was the lowest when the tape was located under the distal urethra. Other ultrasonographic findings were not related to treatment results. The highest failure rate for 'outside-in' TOT is associated with the location of the tape under the proximal third of the urethra. Both the middle and distal sections of the urethra may be regarded as targets for transobturator tape placement.

  4. Optimal sensor placement in structural health monitoring using discrete optimization

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Büyüköztürk, Oral

    2015-12-01

    The objective of optimal sensor placement (OSP) is to obtain a sensor layout that gives as much information of the dynamic system as possible in structural health monitoring (SHM). The process of OSP can be formulated as a discrete minimization (or maximization) problem with the sensor locations as the design variables, conditional on the constraint of a given sensor number. In this paper, we propose a discrete optimization scheme based on the artificial bee colony algorithm to solve the OSP problem after first transforming it into an integer optimization problem. A modal assurance criterion-oriented objective function is investigated to measure the utility of a sensor configuration in the optimization process based on the modal characteristics of a reduced order model. The reduced order model is obtained using an iterated improved reduced system technique. The constraint is handled by a penalty term added to the objective function. Three examples, including a 27 bar truss bridge, a 21-storey building at the MIT campus and the 610 m high Canton Tower, are investigated to test the applicability of the proposed algorithm to OSP. In addition, the proposed OSP algorithm is experimentally validated on a physical laboratory structure which is a three-story two-bay steel frame instrumented with triaxial accelerometers. Results indicate that the proposed method is efficient and can be potentially used in OSP in practical SHM.

  5. Viewpoint placement optimization for binocular three-dimensional trajectory measurement of translating and rotating particle swarms

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Zhou, Yihao; Chen, Yan Qiu

    2011-12-01

    Three-dimensional (3-D) tracking and trajectory measurement of group translating and rotating particles may greatly help applications in collective behavior study, motion measurement, etc. Binocular stereo methods are commonly used to track and measure 3-D trajectories of drifting particles. Nevertheless, binocular methods usually suffer from severe stereo-matching ambiguity facing these situations even if motion constraint is adopted to disambiguate stereo matching. We try to help the disambiguating by optimizing viewpoint placement. We model the stereo-matching ambiguity and test different viewpoint placements upon our geometrical analysis to show the influence on the disambiguation that utilizes motion constraint. When the targets undergo group translation and rotation which are highly ambiguous, we find the optimal viewpoint placement such that stereo-matching ambiguity decreases as fast as possible over time. The optimal viewpoint placement can greatly improve the performance of existing methods.

  6. Particle swarm optimization for optimal sensor placement in ultrasonic SHM systems

    NASA Astrophysics Data System (ADS)

    Blanloeuil, Philippe; Nurhazli, Nur A. E.; Veidt, Martin

    2016-04-01

    A Particle Swarm Optimization (PSO) algorithm is used to improve sensors placement in an ultrasonic Structural Health Monitoring (SHM) system where the detection is performed through the beam-forming imaging algorithm. The imaging algorithm reconstructs the defect image and estimates its location based on analytically generated signals, considering circular through hole damage in an aluminum plate as the tested structure. Then, the PSO algorithm changes the position of sensors to improve the accuracy of the detection. Thus, the two algorithms are working together iteratively to optimize the system configuration, taking into account a complete modeling of the SHM system. It is shown that this approach can provide good sensors placements for detection of multiple defects in the target area, and for different numbers of sensors.

  7. Near-Optimal Antenna Placement Using Genetic Search

    DTIC Science & Technology

    2000-01-01

    H. L. Cheng‡ Optimal Synthesis Inc. Los Altos, CA Rich Burns§ Air Force Research Laboratory Kirtland Air Force Base, NM Shiang Liu** Aerospace...Optimal Synthesis Inc. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. optimal manner to minimize cost...Manual, Optimal Synthesis Inc., 1998-99. [10] Genetic Search Toolbox™ Application Notes, Optimal Synthesis Inc., 1998-99. Table 8. Comparison of placement

  8. Optimal placement of excitations and sensors by simulated annealing

    NASA Technical Reports Server (NTRS)

    Salama, Moktar; Bruno, R.; Chen, G.-S.; Garba, J.

    1989-01-01

    The optimal placement of discrete actuators and sensors is posed as a combinatorial optimization problem. Two examples for truss structures were used for illustration; the first dealt with the optimal placement of passive dampers along existing truss members, and the second dealt with the optimal placement of a combination of a set of actuators and a set of sensors. Except for the simplest problems, an exact solution by enumeration involves a very large number of function evaluations, and is therefore computationally intractable. By contrast, the simulated annealing heuristic involves far fewer evaluations and is best suited for the class of problems considered. As an optimization tool, the effectiveness of the algorithm is enhanced by introducing a number of rules that incorporate knowledge about the physical behavior of the problem. Some of the suggested rules are necessarily problem dependent.

  9. Kinematically optimal robot placement for minimum time coordinated motion

    SciTech Connect

    Feddema, J.T.

    1995-10-01

    This paper describes an algorithm for determining the optimal placement of a robotic manipulator within a workcell for minimum time coordinated motion. The algorithm uses a simple principle of coordinated motion to estimate the time of a joint interpolated motion. Specifically, the coordinated motion profile is limited by the slowest axis. Two and six degree of freedom (DOF) examples are presented. In experimental tests on a FANUC S-800 arm, the optimal placement of the robot can improve cycle time of a robotic operation by as much as 25%. In high volume processes where the robot motion is currently the limiting factor, this increased throughput can result in substantial cost savings.

  10. Kinematically optimal robot placement for minimum time coordinated motion

    NASA Astrophysics Data System (ADS)

    Feddema, John T.

    1995-11-01

    This paper describes an algorithm for determining the optimal placement of a robotic manipulator within a workcell for minimum time coordinated motion. The algorithm uses a simple principle of coordinated motion to estimate the time of a joint interpolated motion. Specifically, the coordinated motion profile is limited by the slowest axis. Two and six degrees of freedom examples are presented. In experimental tests on a FANUC S-800 arm, the optimal placement of the robot can improve the cycle time of a robotic operation by as much as 25%. In high volume processes where the robot motion is currently the limiting factor, this increased throughput can result in substantial cost savings.

  11. Optimization methods for passive damper placement and tuning

    NASA Technical Reports Server (NTRS)

    Milman, M. H.; Chu, C. C.

    1992-01-01

    The effectiveness of viscous elements in introducing damping in a structure is a function of several variables, including their number, their location in the structure, and their physical properties. In this paper several optimization problems are posed to optimize these variables. The paper investigates various metrics to define the optimization problem, and compares the damping profiles that are obtained. Both discrete and continuous optimization problems are formulated and solved, corresponding, respectively, to the problems of placement of damping elements and to the tuning of their parameters. The paper particularly emphasizes techniques to make feasible the large scale problems resulting from the optimization formulations. Numerical results involving a lightly damped tested structure are presented.

  12. Optimal Trajectories Generation in Robotic Fiber Placement Systems

    NASA Astrophysics Data System (ADS)

    Gao, Jiuchun; Pashkevich, Anatol; Caro, Stéphane

    2017-06-01

    The paper proposes a methodology for optimal trajectories generation in robotic fiber placement systems. A strategy to tune the parameters of the optimization algorithm at hand is also introduced. The presented technique transforms the original continuous problem into a discrete one where the time-optimal motions are generated by using dynamic programming. The developed strategy for the optimization algorithm tuning allows essentially reducing the computing time and obtaining trajectories satisfying industrial constraints. Feasibilities and advantages of the proposed methodology are confirmed by an application example.

  13. Optimal ignition placement using nonlinear adjoint looping

    NASA Astrophysics Data System (ADS)

    Qadri, Ubaid; Schmid, Peter; Magri, Luca; Ihme, Matthias

    2016-11-01

    Spark ignition of a turbulent mixture of fuel and oxidizer is a highly sensitive process. Traditionally, a large number of parametric studies are used to determine the effects of different factors on ignition and this can be quite tedious. In contrast, we treat ignition as an initial value problem and seek to find the initial condition that maximizes a given cost function. We use direct numerical simulation of the low Mach number equations with finite rate one-step chemistry, and of the corresponding adjoint equations, to study an axisymmetric jet diffusion flame. We find the L - 2 norm of the temperature field integrated over a short time to be a suitable cost function. We find that the adjoint fields localize around the flame front, identifying the most sensitive region of the flow. The adjoint fields provide gradient information that we use as part of an optimization loop to converge to a local optimal ignition location. We find that the optimal locations correspond with the stoichiometric surface downstream of the jet inlet plane. The methods and results of this study can be easily applied to more complex flow geometries.

  14. Optimizing robot placement for visit-point tasks

    SciTech Connect

    Hwang, Y.K.; Watterberg, P.A.

    1996-06-01

    We present a manipulator placement algorithm for minimizing the length of the manipulator motion performing a visit-point task such as spot welding. Given a set of points for the tool of a manipulator to visit, our algorithm finds the shortest robot motion required to visit the points from each possible base configuration. The base configurations resulting in the shortest motion is selected as the optimal robot placement. The shortest robot motion required for visiting multiple points from a given base configuration is computed using a variant of the traveling salesman algorithm in the robot joint space and a point-to-point path planner that plans collision free robot paths between two configurations. Our robot placement algorithm is expected to reduce the robot cycle time during visit- point tasks, as well as speeding up the robot set-up process when building a manufacturing line.

  15. Unsteady flow sensing and optimal sensor placement using machine learning

    NASA Astrophysics Data System (ADS)

    Semaan, Richard

    2016-11-01

    Machine learning is used to estimate the flow state and to determine the optimal sensor placement over a two-dimensional (2D) airfoil equipped with a Coanda actuator. The analysis is based on flow field data obtained from 2D unsteady Reynolds averaged Navier-Stokes (uRANS) simulations with different jet blowing intensities and actuation frequencies, characterizing different flow separation states. This study shows how the "random forests" algorithm is utilized beyond its typical usage in fluid mechanics estimating the flow state to determine the optimal sensor placement. The results are compared against the current de-facto standard of maximum modal amplitude location and against a brute force approach that scans all possible sensor combinations. The results show that it is possible to simultaneously infer the state of flow and to determine the optimal sensor location without the need to perform proper orthogonal decomposition. Collaborative Research Center (CRC) 880, DFG.

  16. Lumbar total disc arthroplasty: coronal midline definition and optimal TDA placement.

    PubMed

    Marshman, Laurence A G; Friesem, Tai; Rampersaud, Y Raja; Le Huec, Jean-Charles; Krishna, Manoj; Reddy, Guru R

    2008-01-01

    It is a general principle with arthroplasty insertion that precise implant centering is critical for long term function and outcome. Whilst some authors have proclaimed that lumbar total disc arthroplasty (TDA) may be different, and that off -centre placement may be functionally well tolerated, these claims are premature: significantly worse clinical results have already been reported with poorly placed TDA at 2 years. Accurate TDA placement requires a precise and consistent definition of the desired coronal midline target (which is currently lacking), as well as a procedural mechanism to optimize placement at that target. We summarize our experience, as well as others', in achieving these two requirements. Long-term outcomes after lumbar TDA insertion should only be compared with results from fusion where TDAs have been implanted accurately.

  17. Optimal accelerometer placement on a robot arm for pose estimation

    NASA Astrophysics Data System (ADS)

    Wijayasinghe, Indika B.; Sanford, Joseph D.; Abubakar, Shamsudeen; Saadatzi, Mohammad Nasser; Das, Sumit K.; Popa, Dan O.

    2017-05-01

    The performance of robots to carry out tasks depends in part on the sensor information they can utilize. Usually, robots are fitted with angle joint encoders that are used to estimate the position and orientation (or the pose) of its end-effector. However, there are numerous situations, such as in legged locomotion, mobile manipulation, or prosthetics, where such joint sensors may not be present at every, or any joint. In this paper we study the use of inertial sensors, in particular accelerometers, placed on the robot that can be used to estimate the robot pose. Studying accelerometer placement on a robot involves many parameters that affect the performance of the intended positioning task. Parameters such as the number of accelerometers, their size, geometric placement and Signal-to-Noise Ratio (SNR) are included in our study of their effects for robot pose estimation. Due to the ubiquitous availability of inexpensive accelerometers, we investigated pose estimation gains resulting from using increasingly large numbers of sensors. Monte-Carlo simulations are performed with a two-link robot arm to obtain the expected value of an estimation error metric for different accelerometer configurations, which are then compared for optimization. Results show that, with a fixed SNR model, the pose estimation error decreases with increasing number of accelerometers, whereas for a SNR model that scales inversely to the accelerometer footprint, the pose estimation error increases with the number of accelerometers. It is also shown that the optimal placement of the accelerometers depends on the method used for pose estimation. The findings suggest that an integration-based method favors placement of accelerometers at the extremities of the robot links, whereas a kinematic-constraints-based method favors a more uniformly distributed placement along the robot links.

  18. Robust optimization of contaminant sensor placement for community water systems.

    SciTech Connect

    Konjevod, Goran; Carr, Robert D.; Greenberg, Harvey J.; Hart, William Eugene; Morrison, Tod; Phillips, Cynthia Ann; Lin, Henry; Lauer, Erik

    2004-09-01

    We present a series of related robust optimization models for placing sensors in municipal water networks to detect contaminants that are maliciously or accidentally injected.We formulate sensor placement problems as mixed-integer programs, for which the objective coefficients are not known with certainty. We consider a restricted absolute robustness criteria that is motivated by natural restrictions on the uncertain data, and we define three robust optimization models that differ in how the coefficients in the objective vary. Under one set of assumptions there exists a sensor placement that is optimal for all admissible realizations of the coefficients. Under other assumptions, we can apply sorting to solve each worst-case realization efficiently, or we can apply duality to integrate the worst-case outcome and have one integer program. The most difficult case is where the objective parameters are bilinear, and we prove its complexity is NP-hard even under simplifying assumptions. We consider a relaxation that provides an approximation, giving an overall guarantee of nearoptimality when used with branch-and-bound search. We present preliminary computational experiments that illustrate the computational complexity of solving these robust formulations on sensor placement applications.

  19. Optimization of Geothermal Well Placement under Geological Uncertainty

    NASA Astrophysics Data System (ADS)

    Schulte, Daniel O.; Arnold, Dan; Demyanov, Vasily; Sass, Ingo; Geiger, Sebastian

    2017-04-01

    Well placement optimization is critical to commercial success of geothermal projects. However, uncertainties of geological parameters prohibit optimization based on a single scenario of the subsurface, particularly when few expensive wells are to be drilled. The optimization of borehole locations is usually based on numerical reservoir models to predict reservoir performance and entails the choice of objectives to optimize (total enthalpy, minimum enthalpy rate, production temperature) and the development options to adjust (well location, pump rate, difference in production and injection temperature). Optimization traditionally requires trying different development options on a single geological realization yet there are many possible different interpretations possible. Therefore, we aim to optimize across a range of representative geological models to account for geological uncertainty in geothermal optimization. We present an approach that uses a response surface methodology based on a large number of geological realizations selected by experimental design to optimize the placement of geothermal wells in a realistic field example. A large number of geological scenarios and design options were simulated and the response surfaces were constructed using polynomial proxy models, which consider both geological uncertainties and design parameters. The polynomial proxies were validated against additional simulation runs and shown to provide an adequate representation of the model response for the cases tested. The resulting proxy models allow for the identification of the optimal borehole locations given the mean response of the geological scenarios from the proxy (i.e. maximizing or minimizing the mean response). The approach is demonstrated on the realistic Watt field example by optimizing the borehole locations to maximize the mean heat extraction from the reservoir under geological uncertainty. The training simulations are based on a comprehensive semi

  20. Simultaneous optimization of cryoprobe placement and thermal protocol for cryosurgery

    NASA Astrophysics Data System (ADS)

    Baissalov, R.; Sandison, G. A.; Reynolds, D.; Muldrew, K.

    2001-07-01

    We demonstrate that it is possible to simultaneously optimize multiple cryoprobe placements and their thermal protocol for one freeze-thaw cycle. A numerical optimization algorithm is used and three different forms of objective function are examined in terms of algorithm convergence rate, minimum value of the chosen objective function, temperature-volume histograms and isotherm distributions. The optimization results depend on the initial values of the variables, the form of the objective function, optimization goals and the mathematical method adopted for gradient calculation. The proposed optimization model offers significant advantages over the previously reported semi-empirical approach to conformal cryotherapy, such as the ability to handle an unlimited number of variables and eliminating the need for the user input between iterations, thereby reducing, if not removing, the subjectivity of cryosurgery treatment planning.

  1. Optimal Resource Placement in a Distributed System. (Extended Abstract).

    DTIC Science & Technology

    1980-08-01

    edge in the desig- nated direction (towards or away from the root). Because we are looking only at trees, a necessary and sufficient condition for a...leaves. In fact, this is not strictly true unless t is a power of 2. The structure of optimal placement for non -power-of-two numbers of resources is...is an Integer, but there are cases where it Is demonstrably non - optimal . Nevertiless, it is always close to optimial, a tact that is crucial to the

  2. Optimal placement of active elements in control augmented structural synthesis

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Jin, I. M.; Schmit, L. A., Jr.

    1992-01-01

    A methodology for structural/control synthesis is presented in which the optimal location of active members is treated in terms of (0,1) variables. Structural member sizes, control gains and (0,1) placement variables are treated simultaneously as design variables. Optimization is carried out by generating and solving a sequence of explicit approximate problems using a branch and bound strategy. Intermediate design variable and intermediate response quantity concepts are used to enhance the quality of the approximate design problems. Numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.

  3. Discrete-Time ARMAv Model-Based Optimal Sensor Placement

    SciTech Connect

    Song Wei; Dyke, Shirley J.

    2008-07-08

    This paper concentrates on the optimal sensor placement problem in ambient vibration based structural health monitoring. More specifically, the paper examines the covariance of estimated parameters during system identification using auto-regressive and moving average vector (ARMAv) model. By utilizing the discrete-time steady state Kalman filter, this paper realizes the structure's finite element (FE) model under broad-band white noise excitations using an ARMAv model. Based on the asymptotic distribution of the parameter estimates of the ARMAv model, both a theoretical closed form and a numerical estimate form of the covariance of the estimates are obtained. Introducing the information entropy (differential entropy) measure, as well as various matrix norms, this paper attempts to find a reasonable measure to the uncertainties embedded in the ARMAv model estimates. Thus, it is possible to select the optimal sensor placement that would lead to the smallest uncertainties during the ARMAv identification process. Two numerical examples are provided to demonstrate the methodology and compare the sensor placement results upon various measures.

  4. Genetic evolutionary taboo search for optimal marker placement in infrared patient setup

    NASA Astrophysics Data System (ADS)

    Riboldi, M.; Baroni, G.; Spadea, M. F.; Tagaste, B.; Garibaldi, C.; Cambria, R.; Orecchia, R.; Pedotti, A.

    2007-09-01

    In infrared patient setup adequate selection of the external fiducial configuration is required for compensating inner target displacements (target registration error, TRE). Genetic algorithms (GA) and taboo search (TS) were applied in a newly designed approach to optimal marker placement: the genetic evolutionary taboo search (GETS) algorithm. In the GETS paradigm, multiple solutions are simultaneously tested in a stochastic evolutionary scheme, where taboo-based decision making and adaptive memory guide the optimization process. The GETS algorithm was tested on a group of ten prostate patients, to be compared to standard optimization and to randomly selected configurations. The changes in the optimal marker configuration, when TRE is minimized for OARs, were specifically examined. Optimal GETS configurations ensured a 26.5% mean decrease in the TRE value, versus 19.4% for conventional quasi-Newton optimization. Common features in GETS marker configurations were highlighted in the dataset of ten patients, even when multiple runs of the stochastic algorithm were performed. Including OARs in TRE minimization did not considerably affect the spatial distribution of GETS marker configurations. In conclusion, the GETS algorithm proved to be highly effective in solving the optimal marker placement problem. Further work is needed to embed site-specific deformation models in the optimization process.

  5. Genetic evolutionary taboo search for optimal marker placement in infrared patient setup.

    PubMed

    Riboldi, M; Baroni, G; Spadea, M F; Tagaste, B; Garibaldi, C; Cambria, R; Orecchia, R; Pedotti, A

    2007-10-07

    In infrared patient setup adequate selection of the external fiducial configuration is required for compensating inner target displacements (target registration error, TRE). Genetic algorithms (GA) and taboo search (TS) were applied in a newly designed approach to optimal marker placement: the genetic evolutionary taboo search (GETS) algorithm. In the GETS paradigm, multiple solutions are simultaneously tested in a stochastic evolutionary scheme, where taboo-based decision making and adaptive memory guide the optimization process. The GETS algorithm was tested on a group of ten prostate patients, to be compared to standard optimization and to randomly selected configurations. The changes in the optimal marker configuration, when TRE is minimized for OARs, were specifically examined. Optimal GETS configurations ensured a 26.5% mean decrease in the TRE value, versus 19.4% for conventional quasi-Newton optimization. Common features in GETS marker configurations were highlighted in the dataset of ten patients, even when multiple runs of the stochastic algorithm were performed. Including OARs in TRE minimization did not considerably affect the spatial distribution of GETS marker configurations. In conclusion, the GETS algorithm proved to be highly effective in solving the optimal marker placement problem. Further work is needed to embed site-specific deformation models in the optimization process.

  6. Efficient Sensor Placement Optimization Using Gradient Descent and Probabilistic Coverage

    PubMed Central

    Akbarzadeh, Vahab; Lévesque, Julien-Charles; Gagné, Christian; Parizeau, Marc

    2014-01-01

    We are proposing an adaptation of the gradient descent method to optimize the position and orientation of sensors for the sensor placement problem. The novelty of the proposed method lies in the combination of gradient descent optimization with a realistic model, which considers both the topography of the environment and a set of sensors with directional probabilistic sensing. The performance of this approach is compared with two other black box optimization methods over area coverage and processing time. Results show that our proposed method produces competitive results on smaller maps and superior results on larger maps, while requiring much less computation than the other optimization methods to which it has been compared. PMID:25196164

  7. Integrating event detection system operation characteristics into sensor placement optimization.

    SciTech Connect

    Hart, William Eugene; McKenna, Sean Andrew; Phillips, Cynthia Ann; Murray, Regan Elizabeth; Hart, David Blaine

    2010-05-01

    We consider the problem of placing sensors in a municipal water network when we can choose both the location of sensors and the sensitivity and specificity of the contamination warning system. Sensor stations in a municipal water distribution network continuously send sensor output information to a centralized computing facility, and event detection systems at the control center determine when to signal an anomaly worthy of response. Although most sensor placement research has assumed perfect anomaly detection, signal analysis software has parameters that control the tradeoff between false alarms and false negatives. We describe a nonlinear sensor placement formulation, which we heuristically optimize with a linear approximation that can be solved as a mixed-integer linear program. We report the results of initial experiments on a real network and discuss tradeoffs between early detection of contamination incidents, and control of false alarms.

  8. The optimal target hemoglobin.

    PubMed

    Ritz, E; Schwenger, V

    2000-07-01

    There is still controversy concerning the optimal target hemoglobin during treatment with recombinant human erythropoietin (rHuEPO). Some evidence suggests that hemoglobin concentrations higher than currently recommended lead to improvements in cognitive function, physical performance, and rehabilitation. At least in patients with advanced cardiac disease, however, one controlled trial failed to show a benefit from normalizing predialysis hemoglobin concentrations. In contrast, preliminary observations in three additional studies (albeit with limited statistical power) failed to show adverse cardiovascular effects from normalization of hemoglobin, but definite benefit with respect to quality of life, physical performance, and cardiac geometry. These observations are consistent with the notion that hemoglobin concentrations higher than those recommended by the National Kidney Foundation Dialysis Outcomes Quality Initiative Anemia Work Group are beneficial, at least in patients without advanced cardiac disease.

  9. Influence of model errors in optimal sensor placement

    NASA Astrophysics Data System (ADS)

    Vincenzi, Loris; Simonini, Laura

    2017-02-01

    The paper investigates the role of model errors and parametric uncertainties in optimal or near optimal sensor placements for structural health monitoring (SHM) and modal testing. The near optimal set of measurement locations is obtained by the Information Entropy theory; the results of placement process considerably depend on the so-called covariance matrix of prediction error as well as on the definition of the correlation function. A constant and an exponential correlation function depending on the distance between sensors are firstly assumed; then a proposal depending on both distance and modal vectors is presented. With reference to a simple case-study, the effect of model uncertainties on results is described and the reliability and the robustness of the proposed correlation function in the case of model errors are tested with reference to 2D and 3D benchmark case studies. A measure of the quality of the obtained sensor configuration is considered through the use of independent assessment criteria. In conclusion, the results obtained by applying the proposed procedure on a real 5-spans steel footbridge are described. The proposed method also allows to better estimate higher modes when the number of sensors is greater than the number of modes of interest. In addition, the results show a smaller variation in the sensor position when uncertainties occur.

  10. A quantitative method for optimized placement of continuous air monitors.

    PubMed

    Whicker, Jeffrey J; Rodgers, John C; Moxley, John S

    2003-11-01

    Alarming continuous air monitors (CAMs) are a critical component for worker protection in facilities that handle large amounts of hazardous materials. In nuclear facilities, continuous air monitors alarm when levels of airborne radioactive materials exceed alarm thresholds, thus prompting workers to exit the room to reduce inhalation exposures. To maintain a high level of worker protection, continuous air monitors are required to detect radioactive aerosol clouds quickly and with good sensitivity. This requires that there are sufficient numbers of continuous air monitors in a room and that they are well positioned. Yet there are no published methodologies to quantitatively determine the optimal number and placement of continuous air monitors in a room. The goal of this study was to develop and test an approach to quantitatively determine optimal number and placement of continuous air monitors in a room. The method we have developed uses tracer aerosol releases (to simulate accidental releases) and the measurement of the temporal and spatial aspects of the dispersion of the tracer aerosol through the room. The aerosol dispersion data is then analyzed to optimize continuous air monitor utilization based on simulated worker exposure. This method was tested in a room within a Department of Energy operated plutonium facility at the Savannah River Site in South Carolina, U.S. Results from this study show that the value of quantitative airflow and aerosol dispersion studies is significant and that worker protection can be significantly improved while balancing the costs associated with CAM programs.

  11. Optimal marker placement in hadrontherapy: intelligent optimization strategies with augmented Lagrangian pattern search.

    PubMed

    Altomare, Cristina; Guglielmann, Raffaella; Riboldi, Marco; Bellazzi, Riccardo; Baroni, Guido

    2015-02-01

    In high precision photon radiotherapy and in hadrontherapy, it is crucial to minimize the occurrence of geometrical deviations with respect to the treatment plan in each treatment session. To this end, point-based infrared (IR) optical tracking for patient set-up quality assessment is performed. Such tracking depends on external fiducial points placement. The main purpose of our work is to propose a new algorithm based on simulated annealing and augmented Lagrangian pattern search (SAPS), which is able to take into account prior knowledge, such as spatial constraints, during the optimization process. The SAPS algorithm was tested on data related to head and neck and pelvic cancer patients, and that were fitted with external surface markers for IR optical tracking applied for patient set-up preliminary correction. The integrated algorithm was tested considering optimality measures obtained with Computed Tomography (CT) images (i.e. the ratio between the so-called target registration error and fiducial registration error, TRE/FRE) and assessing the marker spatial distribution. Comparison has been performed with randomly selected marker configuration and with the GETS algorithm (Genetic Evolutionary Taboo Search), also taking into account the presence of organs at risk. The results obtained with SAPS highlight improvements with respect to the other approaches: (i) TRE/FRE ratio decreases; (ii) marker distribution satisfies both marker visibility and spatial constraints. We have also investigated how the TRE/FRE ratio is influenced by the number of markers, obtaining significant TRE/FRE reduction with respect to the random configurations, when a high number of markers is used. The SAPS algorithm is a valuable strategy for fiducial configuration optimization in IR optical tracking applied for patient set-up error detection and correction in radiation therapy, showing that taking into account prior knowledge is valuable in this optimization process. Further work will be

  12. WAMA: a method of optimizing reticle/die placement to increase litho cell productivity

    NASA Astrophysics Data System (ADS)

    Dor, Amos; Schwarz, Yoram

    2005-05-01

    This paper focuses on reticle/field placement methodology issues, the disadvantages of typical methods used in the industry, and the innovative way that the WAMA software solution achieves optimized placement. Typical wafer placement methodologies used in the semiconductor industry considers a very limited number of parameters, like placing the maximum amount of die on the wafer circle and manually modifying die placement to minimize edge yield degradation. This paper describes how WAMA software takes into account process characteristics, manufacturing constraints and business objectives to optimize placement for maximum stepper productivity and maximum good die (yield) on the wafer.

  13. Optimal sensor placement for modal testing on wind turbines

    NASA Astrophysics Data System (ADS)

    Schulze, Andreas; Zierath, János; Rosenow, Sven-Erik; Bockhahn, Reik; Rachholz, Roman; Woernle, Christoph

    2016-09-01

    The mechanical design of wind turbines requires a profound understanding of the dynamic behaviour. Even though highly detailed simulation models are already in use to support wind turbine design, modal testing on a real prototype is irreplaceable to identify site-specific conditions such as the stiffness of the tower foundation. Correct identification of the mode shapes of a complex mechanical structure much depends on the placement of the sensors. For operational modal analysis of a 3 MW wind turbine with a 120 m rotor on a 100 m tower developed by W2E Wind to Energy, algorithms for optimal placement of acceleration sensors are applied. The mode shapes used for the optimisation are calculated by means of a detailed flexible multibody model of the wind turbine. Among the three algorithms in this study, the genetic algorithm with weighted off-diagonal criterion yields the sensor configuration with the highest quality. The ongoing measurements on the prototype will be the basis for the development of optimised wind turbine designs.

  14. Optimal Placement of Accelerometers for the Detection of Everyday Activities

    PubMed Central

    Cleland, Ian; Kikhia, Basel; Nugent, Chris; Boytsov, Andrey; Hallberg, Josef; Synnes, Kåre; McClean, Sally; Finlay, Dewar

    2013-01-01

    This article describes an investigation to determine the optimal placement of accelerometers for the purpose of detecting a range of everyday activities. The paper investigates the effect of combining data from accelerometers placed at various bodily locations on the accuracy of activity detection. Eight healthy males participated within the study. Data were collected from six wireless tri-axial accelerometers placed at the chest, wrist, lower back, hip, thigh and foot. Activities included walking, running on a motorized treadmill, sitting, lying, standing and walking up and down stairs. The Support Vector Machine provided the most accurate detection of activities of all the machine learning algorithms investigated. Although data from all locations provided similar levels of accuracy, the hip was the best single location to record data for activity detection using a Support Vector Machine, providing small but significantly better accuracy than the other investigated locations. Increasing the number of sensing locations from one to two or more statistically increased the accuracy of classification. There was no significant difference in accuracy when using two or more sensors. It was noted, however, that the difference in activity detection using single or multiple accelerometers may be more pronounced when trying to detect finer grain activities. Future work shall therefore investigate the effects of accelerometer placement on a larger range of these activities. PMID:23867744

  15. Optimal sensor placement using FRFs-based clustering method

    NASA Astrophysics Data System (ADS)

    Li, Shiqi; Zhang, Heng; Liu, Shiping; Zhang, Zhe

    2016-12-01

    The purpose of this work is to develop an optimal sensor placement method by selecting the most relevant degrees of freedom as actual measure position. Based on observation matrix of a structure's frequency response, two optimal criteria are used to avoid the information redundancy of the candidate degrees of freedom. By using principal component analysis, the frequency response matrix can be decomposed into principal directions and their corresponding singular. A relatively small number of principal directions will maintain a system's dominant response information. According to the dynamic similarity of each degree of freedom, the k-means clustering algorithm is designed to classify the degrees of freedom, and effective independence method deletes the sensors which are redundant of each cluster. Finally, two numerical examples and a modal test are included to demonstrate the efficient of the derived method. It is shown that the proposed method provides a way to extract sub-optimal sets and the selected sensors are well distributed on the whole structure.

  16. Optimal sensor placement for parameter estimation of bridges

    NASA Astrophysics Data System (ADS)

    Eskew, Edward; Jang, Shinae

    2017-04-01

    Gathering measurements from a structure can be extremely valuable for tasks such as verifying a numerical model, or structural health monitoring (SHM) to identify changes in the natural frequencies and mode shapes which can be attributed to changes in the system. In most monitoring applications, the number of potential degrees-of-freedom (DOF) for monitoring greatly outnumbers the available sensors. Optimal sensor placement (OSP) is a field of research into different methods for locating the available sensors to gather the optimal measurements. Three common methods of OSP are the effective independence (EI), effective independence driving point residue (EI-DPR), and modal kinetic energy (MKE) methods. However, comparisons of the different OSP methods for SHM applications are limited. In this paper, a comparison of the performance of the three described OSP methods for parameter estimation is performed. Parameter estimation is implemented using modified parameter localization with direct model updating, and added mass quantification utilizing a genetic algorithm (GA). The quantification of the mass addition, using simulated measurements from the sensor networks developed by each OSP method, is compared to provide an evaluation of each OSP methods capability for parameter estimation applications.

  17. Optimal Sparse Upstream Sensor Placement for Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Robert; Strom, Benjamin; Ross, Hannah; Hill, Craig; Polagye, Brian

    2016-11-01

    Accurate measurement of the flow field incident upon a hydrokinetic turbine is critical for performance evaluation during testing and setting boundary conditions in simulation. Additionally, turbine controllers may leverage real-time flow measurements. Particle image velocimetry (PIV) is capable of rendering a flow field over a wide spatial domain in a controlled, laboratory environment. However, PIV's lack of suitability for natural marine environments, high cost, and intensive post-processing diminish its potential for control applications. Conversely, sensors such as acoustic Doppler velocimeters (ADVs), are designed for field deployment and real-time measurement, but over a small spatial domain. Sparsity-promoting regression analysis such as LASSO is utilized to improve the efficacy of point measurements for real-time applications by determining optimal spatial placement for a small number of ADVs using a training set of PIV velocity fields and turbine data. The study is conducted in a flume (0.8 m2 cross-sectional area, 1 m/s flow) with laboratory-scale axial and cross-flow turbines. Predicted turbine performance utilizing the optimal sparse sensor network and associated regression model is compared to actual performance with corresponding PIV measurements.

  18. Optimization of Source and Receiver Placement in Multistatic Sonar Environments

    DTIC Science & Technology

    2015-06-01

    the new preprocessing algorithm LOC -GEN-II to determine possible locations for sources given a set of targets and receivers. The high efficiency of this...problem was solved with the simplification of setting receivers randomly and placing only sources optimally. We develop LOC -GEN-II further into a two-step

  19. Optimizing sensor placement using predictive geospatial analytics, the physical environment, and surveillance constraints

    NASA Astrophysics Data System (ADS)

    Schmidt, Greg; Witham, Brandon; Valore, Jason; Holland, Ben; Dalton, Jason

    2012-06-01

    Military, police, and industrial surveillance operations could benefit from having sensors deployed in configurations that maximize collection capability. We describe a surveillance planning approach that optimizes sensor placements to collect information about targets of interest by using information from predictive geospatial analytics, the physical environment, and surveillance constraints. We designed a tool that accounts for multiple sensor aspects-collection footprints, groupings, and characteristics; multiple optimization objectives-surveillance requirements and predicted threats; and multiple constraints-sensing, physical environment (including terrain), and geographic surveillance constraints. The tool uses a discrete grid model to keep track of geographic sensing objectives and constraints, and from these, estimate probabilities for collection containment and detection. We devised an evolutionary algorithm and polynomial time approximation schemes (PTAS) to optimize the tool variables above to generate the positions and aspect for a network of sensors. We also designed algorithms to coordinate a mixture of sensors with different competing objectives, competing constraints, couplings, and proximity constraints.

  20. Optimal marker placement in photogrammetry patient positioning system.

    PubMed

    Liu, Haisong; Yu, Yan; Schell, M C; O'Dell, Walter G; Ruo, Russell; Okunieff, Paul

    2003-02-01

    A photogrammetry-based patient positioning system has been used instead of the conventional laser alignment technique for patient set-up in external beam radiotherapy. It tracks skin affixed reflective markers with multiple infrared cameras. The three-dimensional (3D) positions of the markers provide reference information to determine the treatment plan isocenter location and hence provide the ability to position the lesion at the isocenter of the treatment linear accelerator. However, in current clinical practice for lung or liver lesion treatments, fiducial markers are usually randomly affixed onto the patients' chest and abdomen, so that the actual target registration error (TRE) of the internal lesions inside the body may be large, depending on the fiducial registration error (FRE). There exists an optimal marker configuration that can minimize the TRE. In this paper, we developed methods to design the patient-specific optimal configurations of the surface makers to minimize the TRE, given the patient's surface contour, the lesion position and the FRE. Floating genetic algorithm (GA) optimization was used to optimize the positions of the skin markers. The surface curve of the patient body was determined by an automatic segmentation algorithm from the planning CT. The method was evaluated using a body phantom implanted with a metal ball (a simulated target). By registering two CT scans using the surface markers and measuring the displacement of the target, the TRE was measured. The TRE was also measured by taking two orthogonal portal films after positioning the phantom using the photogrammetry based patient positioning system. A 50% reduction in TRE has been achieved by using the optimal configuration compared to the random configuration. This result demonstrates that the optimization of a fiducial configuration can result in improved tumor targeting ability.

  1. Optimal PMU placement using topology transformation method in power systems.

    PubMed

    Rahman, Nadia H A; Zobaa, Ahmed F

    2016-09-01

    Optimal phasor measurement units (PMUs) placement involves the process of minimizing the number of PMUs needed while ensuring the entire power system completely observable. A power system is identified observable when the voltages of all buses in the power system are known. This paper proposes selection rules for topology transformation method that involves a merging process of zero-injection bus with one of its neighbors. The result from the merging process is influenced by the selection of bus selected to merge with the zero-injection bus. The proposed method will determine the best candidate bus to merge with zero-injection bus according to the three rules created in order to determine the minimum number of PMUs required for full observability of the power system. In addition, this paper also considered the case of power flow measurements. The problem is formulated as integer linear programming (ILP). The simulation for the proposed method is tested by using MATLAB for different IEEE bus systems. The explanation of the proposed method is demonstrated by using IEEE 14-bus system. The results obtained in this paper proved the effectiveness of the proposed method since the number of PMUs obtained is comparable with other available techniques.

  2. Optimal markers' placement on the thorax for clinical gait analysis.

    PubMed

    Armand, Stéphane; Sangeux, Morgan; Baker, Richard

    2014-01-01

    Although, several thorax models have been proposed for clinical gait analysis, none has received widespread acceptance nor been subject to any extensive validation work, especially for the marker set to use. The aim of this study was thus to determine the optimal and minimal makers' placement on the thorax for clinical gait analysis. Ten healthy subjects have performed a series of movements (arm, head, trunk) with large amplitude during walking. Reflective markers were taped on the thorax (C7, T2, T4, T6, T8, T10, T12, sternum, clavicles and ribs) and their 3D positions were captured with an opto-electronic system. Each combination of 3 markers has been tested. The global error of each model was computed with the estimated position of the markers considering the thorax segment as a solid segment. Two families of marker sets were identified with the lowest error. The first family was composed by two anterior and one posterior marker on the thorax (incisura jugularis (IJ), xiphoid process, and T8). The second family was composed by two posterior and one anterior maker (IJ, T2 and T8 or T10). Even, if these two families of marker sets presented a similar error for marker position, the angles obtained from these marker sets showed large differences especially for the axial rotation movement of the trunk (up to 40.1°). The optimal and minimal maker set identified with a variety of large movements of the trunk, head and arms was IJ, T2 and T8 or T10.

  3. A Framework for Optimizing the Placement of Tidal Turbines

    NASA Astrophysics Data System (ADS)

    Nelson, K. S.; Roberts, J.; Jones, C.; James, S. C.

    2013-12-01

    Power generation with marine hydrokinetic (MHK) current energy converters (CECs), often in the form of underwater turbines, is receiving growing global interest. Because of reasonable investment, maintenance, reliability, and environmental friendliness, this technology can contribute to national (and global) energy markets and is worthy of research investment. Furthermore, in remote areas, small-scale MHK energy from river, tidal, or ocean currents can provide a local power supply. However, little is known about the potential environmental effects of CEC operation in coastal embayments, estuaries, or rivers, or of the cumulative impacts of these devices on aquatic ecosystems over years or decades of operation. There is an urgent need for practical, accessible tools and peer-reviewed publications to help industry and regulators evaluate environmental impacts and mitigation measures, while establishing best sitting and design practices. Sandia National Laboratories (SNL) and Sea Engineering, Inc. (SEI) have investigated the potential environmental impacts and performance of individual tidal energy converters (TECs) in Cobscook Bay, ME; TECs are a subset of CECs that are specifically deployed in tidal channels. Cobscook Bay is the first deployment location of Ocean Renewable Power Company's (ORPC) TidGenTM unit. One unit is currently in place with four more to follow. Together, SNL and SEI built a coarse-grid, regional-scale model that included Cobscook Bay and all other landward embayments using the modeling platform SNL-EFDC. Within SNL-EFDC tidal turbines are represented using a unique set of momentum extraction, turbulence generation, and turbulence dissipation equations at TEC locations. The global model was then coupled to a local-scale model that was centered on the proposed TEC deployment locations. An optimization frame work was developed that used the refined model to determine optimal device placement locations that maximized array performance. Within the

  4. Optimized, Budget-constrained Monitoring Well Placement Using DREAM

    DOE PAGES

    Yonkofski, Catherine M. R.; Davidson, Casie L.; Rodriguez, Luke R.; ...

    2017-08-18

    Defining the ideal suite of monitoring technologies to be deployed at a carbon capture and storage (CCS) site presents a challenge to project developers, financers, insurers, regulators and other stakeholders. The monitoring, verification, and accounting (MVA) toolkit offers a suite of technologies to monitor an extensive range of parameters across a wide span of spatial and temporal resolutions, each with their own degree of sensitivity to changes in the parameter being monitored. Understanding how best to optimize MVA budgets to minimize the time to leak detection could help to address issues around project risks, and in turn help support broadmore » CCS deployment. This paper presents a case study demonstrating an application of the Designs for Risk Evaluation and Management (DREAM) tool using an ensemble of CO2 leakage scenarios taken from a previous study on leakage impacts to groundwater. Impacts were assessed and monitored as a function of pH, total dissolved solids (TDS), and trace metal concentrations of arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb). Using output from the previous study, DREAM was used to optimize monitoring system designs based on variable sampling locations and parameters. The algorithm requires the user to define a finite budget to limit the number of monitoring wells and technologies deployed, and then iterates well placement and sensor type and location until it converges on the configuration with the lowest time to first detection of the leak averaged across all scenarios. To facilitate an understanding of the optimal number of sampling wells, DREAM was used to assess the marginal utility of additional sampling locations. Based on assumptions about monitoring costs and replacement costs of degraded water, the incremental cost of each additional sampling well can be compared against its marginal value in terms of avoided aquifer degradation. Applying this method, DREAM identified the most cost-effective ensemble with 14

  5. The Homogeneity of Optimal Sensor Placement Across Multiple Winged Insect Species

    NASA Astrophysics Data System (ADS)

    Jenkins, Abigail L.

    Taking inspiration from biology, control algorithms can be implemented to imitate the naturally occurring control systems present in nature. This research is primarily concerned with insect flight and optimal wing sensor placement. Many winged insects with halteres are equipped with mechanoreceptors termed campaniform sensilla. Although the exact information these receptors provide to the insect's nervous system is unknown, it is thought to have the capability of measuring inertial rotation forces. During flight, when the wing bends, the information measured by the campaniform sensilla is received by the central nervous system, and provides the insect necessary data to control flight. This research compares three insect species - the hawkmoth Manduca sexta, the honeybee Apis mellifera, and the fruit fly Drosophila melanogaster. Using an observability-based sensor placement algorithm, the optimal sensor placement for these three species is determined. Simulations resolve if this optimal sensor placement corresponds to the insect's campaniform sensilla, as well as if placement is homogeneous across species.

  6. Optimizing electrode placement using finite-element models in radiofrequency ablation treatment planning.

    PubMed

    Chen, Chun-Cheng R; Miga, Michael I; Galloway, Robert L

    2009-02-01

    Conventional radiofrequency ablation (RFA) planning methods for identifying suitable electrode placements typically use geometric shapes to model ablation outcomes. A method is presented for searching electrode placements that couples finite-element models (FEMs) of RFA together with a novel optimization strategy. The method was designed to reduce the need for model solutions per local search step. The optimization strategy was tested against scenarios requiring single and multiple ablations. In particular, for a scenario requiring multiple ablations, a domain decomposition strategy was described to minimize the complexity of simultaneously searching multiple electrode placements. The effects of nearby vasculature on optimal electrode placement were also studied. Compared with geometric planning approaches, FEMs could potentially deliver electrode placement plans that provide more physically meaningful predictions of therapeutic outcomes.

  7. Optimized passive sonar placement to allow improved interdiction

    NASA Astrophysics Data System (ADS)

    Johnson, Bruce A.; Matthews, Cameron

    2016-05-01

    The Art Gallery Problem (AGP) is the name given to a constrained optimization problem meant to determine the maximum amount of sensor coverage while utilizing the minimum number of resources. The AGP is significant because a common issue among surveillance and interdiction systems is obtaining an understanding of the optimal position of sensors and weapons in advance of enemy combatant maneuvers. The implication that an optimal position for a sensor to observe an event or for a weapon to engage a target autonomously is usually very clear after the target has passed, but for autonomous systems the solution must at least be conjectured in advance for deployment purposes. This abstract applies the AGP as a means to solve where best to place underwater sensor nodes such that the amount of information acquired about a covered area is maximized while the number of resources used to gain that information is minimized. By phrasing the ISR/interdiction problem this way, the issue is addressed as an instance of the AGP. The AGP is a member of a set of computational problems designated as nondeterministic polynomial-time (NP)-hard. As a member of this set, the AGP shares its members' defining feature, namely that no one has proven that there exists a deterministic algorithm providing a computationally-tractable solution to the AGP within a finite amount of time. At best an algorithm meant to solve the AGP can asymptotically approach perfect coverage with minimal resource usage but providing perfect coverage would either break the minimal resource usage constraint or require an exponentially-growing amount of time. No perfectly-optimal solution yet exists to the AGP, however, approximately optimal solutions to the AGP can approach complete area or barrier coverage while simultaneously minimizing the number of sensors and weapons utilized. A minimal number of underwater sensor nodes deployed can greatly increase the Mean Time Between Operational Failure (MTBOF) and logistical

  8. Evaluating a Targeted Social Program When Placement Is Decentralized. Policy Research Working Papers No. 1945.

    ERIC Educational Resources Information Center

    Ravallion, Martin; Wodon, Quentin

    Assessment of welfare gains from a targeted social program can be seriously biased unless the endogeneity of program participation is addressed. Bias comes from two sources of placement endogeneity: the purposive targeting of geographic areas, and the targeting of individual recipients within selected areas. Partial decentralization of program…

  9. Simultaneous optimization of loading pattern and burnable poison placement for PWRs

    SciTech Connect

    Alim, F.; Ivanov, K.; Yilmaz, S.

    2006-07-01

    To solve in-core fuel management optimization problem, GARCO-PSU (Genetic Algorithm Reactor Core Optimization - Pennsylvania State Univ.) is developed. This code is applicable for all types and geometry of PWR core structures with unlimited number of fuel assembly (FA) types in the inventory. For this reason an innovative genetic algorithm is developed with modifying the classical representation of the genotype. In-core fuel management heuristic rules are introduced into GARCO. The core re-load design optimization has two parts, loading pattern (LP) optimization and burnable poison (BP) placement optimization. These parts depend on each other, but it is difficult to solve the combined problem due to its large size. Separating the problem into two parts provides a practical way to solve the problem. However, the result of this method does not reflect the real optimal solution. GARCO-PSU achieves to solve LP optimization and BP placement optimization simultaneously in an efficient manner. (authors)

  10. A new placement optimization method for viscoelastic dampers: Energy dissipation method

    NASA Astrophysics Data System (ADS)

    Qu, Ji-Ting

    2012-09-01

    A new mathematic model of location optimization for viscoelastic dampers is established through energy analysis based on force analogy method. Three working conditions (three lower limits of the new location index) as well as four ground motions are considered in this study, using MATLAB and SAP2000 in programming and verifying. This paper deals with the optimal placement of viscoelastic dampers and step-by-step time history analyses are carried out. Numerical analysis is illustrated to verify the effectiveness and feasibility of the new mathematic model for structural control. In addition, not only the optimal placement method using force analogy method can confirm dampers' locations all at once and be accurate to each span, but also it is without circular calculating. At last, a few helpful conclusions on viscoelastic dampers' optimal placement are made.

  11. Optimal placement of tuning masses on truss structures by genetic algorithms

    NASA Technical Reports Server (NTRS)

    Ponslet, Eric; Haftka, Raphael T.; Cudney, Harley H.

    1993-01-01

    Optimal placement of tuning masses, actuators and other peripherals on large space structures is a combinatorial optimization problem. This paper surveys several techniques for solving this problem. The genetic algorithm approach to the solution of the placement problem is described in detail. An example of minimizing the difference between the two lowest frequencies of a laboratory truss by adding tuning masses is used for demonstrating some of the advantages of genetic algorithms. The relative efficiencies of different codings are compared using the results of a large number of optimization runs.

  12. Optimization of absorption placement using geometrical acoustic models and least squares.

    PubMed

    Saksela, Kai; Botts, Jonathan; Savioja, Lauri

    2015-04-01

    Given a geometrical model of a space, the problem of optimally placing absorption in a space to match a desired impulse response is in general nonlinear. This has led some to use costly optimization procedures. This letter reformulates absorption assignment as a constrained linear least-squares problem. Regularized solutions result in direct distribution of absorption in the room and can accommodate multiple frequency bands, multiple sources and receivers, and constraints on geometrical placement of absorption. The method is demonstrated using a beam tracing model, resulting in the optimal absorption placement on the walls and ceiling of a classroom.

  13. Robust optimal sensor placement for operational modal analysis based on maximum expected utility

    NASA Astrophysics Data System (ADS)

    Li, Binbin; Der Kiureghian, Armen

    2016-06-01

    Optimal sensor placement is essentially a decision problem under uncertainty. The maximum expected utility theory and a Bayesian linear model are used in this paper for robust sensor placement aimed at operational modal identification. To avoid nonlinear relations between modal parameters and measured responses, we choose to optimize the sensor locations relative to identifying modal responses. Since the modal responses contain all the information necessary to identify the modal parameters, the optimal sensor locations for modal response estimation provide at least a suboptimal solution for identification of modal parameters. First, a probabilistic model for sensor placement considering model uncertainty, load uncertainty and measurement error is proposed. The maximum expected utility theory is then applied with this model by considering utility functions based on three principles: quadratic loss, Shannon information, and K-L divergence. In addition, the prior covariance of modal responses under band-limited white-noise excitation is derived and the nearest Kronecker product approximation is employed to accelerate evaluation of the utility function. As demonstration and validation examples, sensor placements in a 16-degrees-of-freedom shear-type building and in Guangzhou TV Tower under ground motion and wind load are considered. Placements of individual displacement meter, velocimeter, accelerometer and placement of mixed sensors are illustrated.

  14. Sampling design and optimal sensor placement strategies for basin-scale SWE estimation

    NASA Astrophysics Data System (ADS)

    Kerkez, B.; Welch, S. C.; Bales, R. C.; Glaser, S. D.; Rittger, K. E.; Rice, R.

    2012-12-01

    We present a quantitative framework by which to assess the number of required samples (sensors), as well as their respective locations, to most optimally estimate spatial SWE patterns using sensor networks across the 5000 sq. km American River basin of California. To inform the selection of future sensor locations, 11 years of reconstructed, spatially dense (500 x 500 m resolution) SWE data were used to develop metrics of historical SWE distributions. The historical data were split into eight years of training and three years of validation data, clustering the data set to derive spatial regions which share similar SWE characteristics. Rank-based clustering was compared to geographically-based clustering (sub-basin delineation) to determine the existence of stationary covariance structures within the overall SWE dataset. Within each cluster, a quantitative sensor-placement algorithm, based on maximizing the metric of Mutual Information, was implemented and compared to a randomized placement approach. Gaussian process models were then trained to evaluate the efficacy of each placement approach. Rank based clusters remained stable inter-annually, suggesting that rankings of pixel-by-pixel SWE exhibit stationary features that can be exploited by a sensor-placement algorithm. Rank-based clustering yielded 200 mm average root mean square error (RMSE) for twenty randomly selected sensing locations, outperforming geographic and basin-wide placement approaches, which generated 460 mm and 290 mm RMSE, respectively. Mutual Information-based sampling provided the best placement strategy, improving RMSE between 0 and 100 mm compared to random placements. Increasing the number of rank-based clusters consistently lowered average RMSE from 400 mm for one cluster to 175 mm for eight clusters, for twenty total sensors placed. To optimize sensor placement, or to inform future sampling or surveying strategies, we recommend a strategy that couples rank-based clustering with Mutual

  15. Optimal placement of actuators and sensors in control augmented structural optimization

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Schmit, L. A., Jr.

    1990-01-01

    A control-augmented structural synthesis methodology is presented in which actuator and sensor placement is treated in terms of (0,1) variables. Structural member sizes and control variables are treated simultaneously as design variables. A multiobjective utopian approach is used to obtain a compromise solution for inherently conflicting objective functions such as strucutal mass control effort and number of actuators. Constraints are imposed on transient displacements, natural frequencies, actuator forces and dynamic stability as well as controllability and observability of the system. The combinatorial aspects of the mixed - (0,1) continuous variable design optimization problem are made tractable by combining approximation concepts with branch and bound techniques. Some numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.

  16. Optimal placement of actuators and sensors in control augmented structural optimization

    NASA Technical Reports Server (NTRS)

    Sepulveda, A. E.; Schmit, L. A., Jr.

    1990-01-01

    A control-augmented structural synthesis methodology is presented in which actuator and sensor placement is treated in terms of (0,1) variables. Structural member sizes and control variables are treated simultaneously as design variables. A multiobjective utopian approach is used to obtain a compromise solution for inherently conflicting objective functions such as strucutal mass control effort and number of actuators. Constraints are imposed on transient displacements, natural frequencies, actuator forces and dynamic stability as well as controllability and observability of the system. The combinatorial aspects of the mixed - (0,1) continuous variable design optimization problem are made tractable by combining approximation concepts with branch and bound techniques. Some numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.

  17. Improved indexes for targeting placement of buffers of Hortonian runoff

    Treesearch

    M.G. Dosskey; Z. Qiu; M.J. Helmers; D.E. Eisenhauer

    2011-01-01

    Targeting specific locations within agricultural watersheds for installing vegetative buffers has been advocated as a way to enhance the impact of buffers and buffer programs on stream water quality. Existing models for targeting buffers of Hortonian, or infiltration-excess, runoff are not well developed. The objective was to improve on an existing soil survey–based...

  18. Optimized baffle and aperture placement in neutral beamlines

    SciTech Connect

    Stone, R.; Duffy, T.; Vetrovec, J.

    1983-11-23

    Most neutral beamlines contain an iron-core ion-bending magnet that requires shielding between the end of the neutralizer and this magnet. This shielding allows the gas pressure to drop prior to the beam entering the magnet and therefore reduces beam losses in this drift region. We have found that the beam losses can be reduced even further by eliminating the iron-core magnet and the magnetic shielding altogether. The required bending field can be supplied by current coils without the iron poles. In addition, placement of the baffles and apertures can affect the cold gas entering the plasma region and the losses in the neutral beam due to re-ionization. In our study we varied the placement of the baffles, which determine the amount of pumping in each chamber, and the apertures, which determine the beam loss. Our results indicate that a baffle/aperture configuration can be set for either minimum cold gas into the plasma region or minimum beam losses, but not both.

  19. Optimal sensor placement for spatial lattice structure based on genetic algorithms

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Gao, Wei-cheng; Sun, Yi; Xu, Min-jian

    2008-10-01

    Optimal sensor placement technique plays a key role in structural health monitoring of spatial lattice structures. This paper considers the problem of locating sensors on a spatial lattice structure with the aim of maximizing the data information so that structural dynamic behavior can be fully characterized. Based on the criterion of optimal sensor placement for modal test, an improved genetic algorithm is introduced to find the optimal placement of sensors. The modal strain energy (MSE) and the modal assurance criterion (MAC) have been taken as the fitness function, respectively, so that three placement designs were produced. The decimal two-dimension array coding method instead of binary coding method is proposed to code the solution. Forced mutation operator is introduced when the identical genes appear via the crossover procedure. A computational simulation of a 12-bay plain truss model has been implemented to demonstrate the feasibility of the three optimal algorithms above. The obtained optimal sensor placements using the improved genetic algorithm are compared with those gained by exiting genetic algorithm using the binary coding method. Further the comparison criterion based on the mean square error between the finite element method (FEM) mode shapes and the Guyan expansion mode shapes identified by data-driven stochastic subspace identification (SSI-DATA) method are employed to demonstrate the advantage of the different fitness function. The results showed that some innovations in genetic algorithm proposed in this paper can enlarge the genes storage and improve the convergence of the algorithm. More importantly, the three optimal sensor placement methods can all provide the reliable results and identify the vibration characteristics of the 12-bay plain truss model accurately.

  20. The problem of optimal placement of sub-resolution assist features (SRAF)

    NASA Astrophysics Data System (ADS)

    Mukherjee, Maharaj; Mansfield, Scott; Liebmann, Lars; Lvov, Alexey; Papadapoulou, Evanthia; Lavin, Mark; Zhao, Zengqin

    2005-05-01

    In this paper, we present a formulation of the Sub-Resolution Assist Feature (SRAF) placement problem as a geometric optimization problem. We present three independent geometric methodologies that use the above formulation to optimize SRAF placements under mask and lithographic process constraints. Traditional rules-based methodology, are mainly one dimensional in nature. These methods, though apparently very simple, has proven to be inadequate for complex two-dimensional layouts. The methodologies presented in this paper, on the other hand, are inherently two-dimensional and attempt to maximize SRAF coverage on real and complex designs, and minimizes mask rule and lithographic violations.

  1. Influence of multi-valued diagnostic signals on optimal sensor placement

    NASA Astrophysics Data System (ADS)

    Rostek, Kornel

    2017-01-01

    In this paper the comparison of results of optimal sensor placement with the use of binary and multi-valued diagnostic signals is given. The exoneration assumption was introduced and its effects were discussed. The influence of multi-valued diagnostic signals on several fault isolability metrics were discussed. The optimal sensor placement problem under budgetary constraints is formulated. A branch-and-bound algorithm solving this problem is described. It is used in context of three tanks system with 25 possible diagnostic signals.

  2. Optimal placement of magnets in Indus-2 storage ring

    NASA Astrophysics Data System (ADS)

    Riyasat, Husain; A, D. Ghodke; Singh, Gurnam

    2015-03-01

    In Indus-2, by optimizing the position of the magnetic elements, using the simulated annealing algorithm, at different locations in the ring with their field errors, the effects on beam parameters have been minimized. Closed orbit distortion and beta beat are considerably reduced by optimizing the dipole and quadrupole magnets positions in the ring. For the Indus-2 storage ring, sextupole optimization gives insignificant improvement in dynamic aperture with chromaticity-correcting sextupoles. The magnets have been placed in the ring with the optimized sequence and storage of the beam has been achieved at injection energy without energizing any corrector magnets. Magnet sorting has led to the easy beam current accumulation and the measurement of parameters such as closed orbit distortion, beta function, dispersion, dynamic aperture etc.

  3. Targeted Placement of Gold Nanoparticles on SWCNT Transistors Using Electrodeposition

    NASA Astrophysics Data System (ADS)

    Liu, Yian; Barbara, Paola; Paranjape, Makarand

    2013-03-01

    We present a simple in-situ electrochemical method to target the deposition of gold and other metallic nanoparticles along a single-walled carbon nanotube (SWCNT) field effect transistor (CNTFET). The transistors, fabricated on SiO2/Si substrates, are passivated by a thin layer of poly(methyl-methacrylate), or PMMA. Areas of the PMMA along the carbon nanotube are exposed using electron-beam lithography to target the locations where Au nanoparticles need to be placed. An appropriate potential difference is applied between an in-situ sacrificial gold electrode and the SWCNT, all immersed under a droplet of electrolyte solution. By adjusting the applied voltage and time of deposition, the size of the Au nanoparticle can be controlled from 10 nm to over 100 nm. This method provides better control and is much easier to carry out compared to other site-specific deposition techniques. Such decorated Au nanoparticle/CNTFET heterostructures will allow for a better understanding of single-electron transport behavior, as well as finding application in site-specific biomolecule anchoring for the development of highly sensitive and selective biosensors.

  4. OPTIMIZING BMP PLACEMENT AT WATERSHED-SCALE USING SUSTAIN

    EPA Science Inventory

    Watershed and stormwater managers need modeling tools to evaluate alternative plans for environmental quality restoration and protection needs in urban and developing areas. A watershed-scale decision-support system, based on cost optimization, provides an essential tool to suppo...

  5. OPTIMIZING BMP PLACEMENT AT WATERSHED-SCALE USING SUSTAIN

    EPA Science Inventory

    Watershed and stormwater managers need modeling tools to evaluate alternative plans for environmental quality restoration and protection needs in urban and developing areas. A watershed-scale decision-support system, based on cost optimization, provides an essential tool to suppo...

  6. Anterior Segment Optical Coherence Tomography for Targeted Transconjunctival Suture Placement in Overfiltering Trabeculectomy Blebs.

    PubMed

    Heisler, Morgan; Quong, Whitney L; Lee, Sieun; Han, Sherry; Beg, Mirza F; Sarunic, Marinko V; Mackenzie, Paul J

    2017-05-01

    To demonstrate the utility of swept-source anterior segment optical coherence tomography (SS-AS-OCT) in guiding placement of transconjunctival sutures in hypotonous patients after a trabeculectomy. This is a longitudinal case series of 10 eyes from 10 patients who required transconjunctival sutures after a trabeculectomy. SS-AS-OCT was used to aid in the placement of the sutures to improve the function of the overfiltering bleb. SS-AS-OCT reliably identified localized areas of overfiltering, allowing for targeted suture placement in 8 eyes. The 2 eyes in which localized areas of overfiltering were not found required further surgical intervention. SS-AS-OCT enhances transconjunctival suturing for overfiltering blebs when focal fluid accumulation is visualized.

  7. Exploration of Objective Functions for Optimal Placement of Weather Stations

    NASA Astrophysics Data System (ADS)

    Snyder, A.; Dietterich, T.; Selker, J. S.

    2016-12-01

    Many regions of Earth lack ground-based sensing of weather variables. For example, most countries in Sub-Saharan Africa do not have reliable weather station networks. This absence of sensor data has many consequences ranging from public safety (poor prediction and detection of severe weather events), to agriculture (lack of crop insurance), to science (reduced quality of world-wide weather forecasts, climate change measurement, etc.). The Trans-African Hydro-Meteorological Observatory (TAHMO.org) project seeks to address these problems by deploying and operating a large network of weather stations throughout Sub-Saharan Africa. To design the TAHMO network, we must determine where to locate each weather station. We can formulate this as the following optimization problem: Determine a set of N sites that jointly optimize the value of an objective function. The purpose of this poster is to propose and assess several objective functions. In addition to standard objectives (e.g., minimizing the summed squared error of interpolated values over the entire region), we consider objectives that minimize the maximum error over the region and objectives that optimize the detection of extreme events. An additional issue is that each station measures more than 10 variables—how should we balance the accuracy of our interpolated maps for each variable? Weather sensors inevitably drift out of calibration or fail altogether. How can we incorporate robustness to failed sensors into our network design? Another important requirement is that the network should make it possible to detect failed sensors by comparing their readings with those of other stations. How can this requirement be met? Finally, we provide an initial assessment of the computational cost of optimizing these various objective functions. We invite everyone to join the discussion at our poster by proposing additional objectives, identifying additional issues to consider, and expanding our bibliography of relevant

  8. Optimal placement of fast cut back units based on the theory of cellular automata and agent

    NASA Astrophysics Data System (ADS)

    Yan, Jun; Yan, Feng

    2017-06-01

    The thermal power generation units with the function of fast cut back could serve power for auxiliary system and keep island operation after a major blackout, so they are excellent substitute for the traditional black-start power sources. Different placement schemes for FCB units have different influence on the subsequent restoration process. Considering the locality of the emergency dispatching rules, the unpredictability of specific dispatching instructions and unexpected situations like failure of transmission line energization, a novel deduction model for network reconfiguration based on the theory of cellular automata and agent is established. Several indexes are then defined for evaluating the placement schemes for FCB units. The attribute weights determination method based on subjective and objective integration and grey relational analysis are combinatorically used to determine the optimal placement scheme for FCB unit. The effectiveness of the proposed method is validated by the test results on the New England 10-unit 39-bus power system.

  9. The performance improvement of SRAF placement rules using GA optimization

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Zhang, Bidan; Wang, Changan; Wilkinson, William; Bolton, John

    2016-10-01

    In this paper, genetic algorithm (GA) method is applied to both positive and negative Sub Resolution Assist Features (SRAF) insertion rules. Simulation results and wafer data demonstrated that the optimized SRAF rules helped resolve the SRAF printing issues while dramatically improving the process window of the working layer. To find out the best practice to place the SRAF, model-based SRAF (MBSRAF), rule-based SRAF (RBSRAF) with pixelated OPC simulation and RBSRAF with GA method are thoroughly compared. The result shows the apparent advantage of RBSRAF with GA method.

  10. Optimal placement and sizing of wind / solar based DG sources in distribution system

    NASA Astrophysics Data System (ADS)

    Guan, Wanlin; Guo, Niao; Yu, Chunlai; Chen, Xiaoguang; Yu, Haiyang; Liu, Zhipeng; Cui, Jiapeng

    2017-06-01

    Proper placement and sizing of Distributed Generation (DG) in distribution system can obtain maximum potential benefits. This paper proposes quantum particle swarm algorithm (QPSO) based wind turbine generation unit (WTGU) and photovoltaic (PV) array placement and sizing approach for real power loss reduction and voltage stability improvement of distribution system. Performance modeling of wind and solar generation system are described and classified into PQ\\PQ (V)\\PI type models in power flow. Considering the WTGU and PV based DGs in distribution system is geographical restrictive, the optimal area and DG capacity limits of each bus in the setting area need to be set before optimization, the area optimization method is proposed . The method has been tested on IEEE 33-bus radial distribution systems to demonstrate the performance and effectiveness of the proposed method.

  11. A technique for optimizing electrode placement for electromyographic control of prostheses.

    PubMed

    Walbran, Scott H; Calius, Emilio P; Dunlop, G; Anderson, Iain A

    2009-01-01

    We present a technique that enables optimization of Electromyographic (EMG) electrode placement for grasp recognition. Previous works have shown that sophisticated control techniques for prosthetic devices are becoming available; however the issue of electrode placement has yet to be addressed. By processing a rich field of data, it is possible to determine which of the data sets will allow for greatest accuracy in prosthetic control. Data has been collected and processed from 128 sites on a human forearm while two different grasps were performed. Using two different feature extraction techniques - integral of absolute value and differential absolute value - the difference in means between performing each grasp type has been analyzed. This resulted in several regions around the wrist and the elbow that would be optimal for this particular setup. While the optimization process has been used here for discrimination between two particular grasps, it has the potential to extend to any desired actuation pattern.

  12. Optimizing Tuberculosis Case Detection through a Novel Diagnostic Device Placement Model: The Case of Uganda

    PubMed Central

    Pho, Mai T.; Deo, Sarang; Palamountain, Kara M.; Joloba, Moses Lutaakome; Bajunirwe, Francis; Katamba, Achilles

    2015-01-01

    Background Xpert MTB/RIF (Xpert) is being widely adopted in high TB burden countries. Analysis is needed to guide the placement of devices within health systems to optimize the tuberculosis (TB) case detection rate (CDR). Methods We used epidemiological and operational data from Uganda (139 sites serving 87,600 individuals tested for TB) to perform a model-based comparison of the following placement strategies for Xpert devices: 1) Health center level (sites ranked by size from national referral hospitals to health care level III centers), 2) Smear volume (sites ranked from highest to lowest volume of smear microscopy testing), 3) Antiretroviral therapy (ART) volume (sites ranked from greatest to least patients on ART), 4) External equality assessment (EQA) performance (sites ranked from worst to best smear microscopy performance) and 5) TB prevalence (sites ranked from highest to lowest). We compared two clinical algorithms, one where Xpert was used only for smear microscopy negative samples versus another replacing smear microscopy. The primary outcome was TB CDR; secondary outcomes were detection of multi-drug resistant TB, number of sites requiring device placement to achieve specified rollout coverage, and cost. Results Placement strategies that prioritized sites with higher TB prevalence maximized CDR, with an incremental rate of 6.2–12.6% compared to status quo (microscopy alone). Diagnosis of MDR-TB was greatest in the TB Prevalence strategy when Xpert was used in place of smear microscopy. While initial implementation costs were lowest in the Smear Volume strategy, cost per additional TB case detected was lowest in the TB prevalence strategy. Conclusion In Uganda, placement of Xpert devices in sites with high TB prevalence yielded the highest TB CDR at the lowest cost per additional case diagnosed. These results represent novel use of program level data to inform the optimal placement of new technology in resource-constrained settings. PMID:25830297

  13. Optimal Colostomy Placement in Spinal Cord Injury Patients.

    PubMed

    Xu, Jiashou; Dharmarajan, Sekhar; Johnson, Frank E

    2016-03-01

    Barring unusual circumstances, sigmoid colostomy is the optimal technique for management of defecation in spinal cord injury (SCI) patients. We sought to provide evidence that a sigmoid colostomy is not difficult to perform in SCI patients and has better long-term results. The St. Louis Department of Veterans Affairs has a Commission on Accreditation of Rehabilitation Facilities (CARF)-approved SCI Unit. We reviewed the operative notes on all SCI patients who received a colostomy for fecal management by three ASCRS-certified colorectal surgeons at the St. Louis Department of Veterans Affairs from January 1, 2007 to November 26, 2012. There were 27 operations for which the recorded indication for surgery suggested that the primary disorder was SCI. Fourteen had traumatic SCI of the thoracic and/or lumbar spine and were evaluable. Of these 14 patients, 12 had laparoscopic sigmoid colostomy and two had open sigmoid colostomy. We encountered one evaluable patient with a remarkably large amount of retroperitoneal bony debris who successfully underwent laparoscopic sigmoid colostomy. In conclusion, sigmoid colostomy is the consensus optimal procedure for fecal management in SCI patients. Laparoscopic procedures are preferred. Care providers should specify sigmoid colostomy when contacting a surgeon.

  14. Layer aware source mask target optimization

    NASA Astrophysics Data System (ADS)

    Chen, Ao; Foong, Yee Mei; Schramm, Jessy; Ji, Liang; Hsu, Stephen; Guerrero, James; Li, Xiaoyang; Shaw, Joe; Wang, Joe

    2016-03-01

    In this paper, we present the approach and results of layer-aware source mask target optimization. In this approach, the design target is co-optimized during source mask optimization (SMO) by considering inter-layer constraints. We tested the method on a 2x nm node metal layer by using both standard and customized cost functions for source optimization. Variable targets were defined for two process window limiting critical pattern cells, with contact-to-metal and metal-tovia coverage rules taken into consideration. The results indicate that layer-aware source mask target optimization gives consistent process window improvement over conventional SMO. The optimized targets prove to be a good balance between lithography process window and post-etch inter-layer coverage margin.

  15. Optimal placement of active material actuators using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Johnson, Terrence; Frecker, Mary I.

    2004-07-01

    Actuators based on smart materials generally exhibit a tradeoff between force and stroke. Researchers have surrounded piezoelectric materials (PZT"s) with complaint structures to magnify either their geometric or mechanical advantage. Most of these designs are literally built around a particular piezoelectric device, so the design space consists of only the compliant mechanism. Materials scientists researchers have demonstrated the ability to pole a PZT in an arbitrary direction, and some engineers have taken advantage of this to build "shear mode" actuators. The goal of this work is to determine if the performance of compliant mechanisms improves by the inclusion of the piezoelectric polarization as a design variable. The polarization vector is varied via transformation matrixes, and the compliant actuator is modeled using the SIMP (Solid Isotropic Material with Penalization) or "power-law method." The concept of mutual potential energy is used to form an objective function to measure the piezoelectric actuator"s performance. The optimal topology of the compliant mechanism and orientation of the polarization method are determined using a sequential linear programming algorithm. This paper presents a demonstration problem that shows small changes in the polarization vector have a marginal effect on the optimum topology of the mechanism, but improves actuation.

  16. Optimal sensor placement for leak location in water distribution networks using genetic algorithms.

    PubMed

    Casillas, Myrna V; Puig, Vicenç; Garza-Castañón, Luis E; Rosich, Albert

    2013-11-04

    This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach.

  17. Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms

    PubMed Central

    Casillas, Myrna V.; Puig, Vicenç; Garza-Castañón, Luis E.; Rosich, Albert

    2013-01-01

    This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. PMID:24193099

  18. Optimization of strut placement in flow diverter stents for four different aneurysm configurations.

    PubMed

    Anzai, Hitomi; Falcone, Jean-Luc; Chopard, Bastien; Hayase, Toshiyuki; Ohta, Makoto

    2014-06-01

    A modern technique for the treatment of cerebral aneurysms involves insertion of a flow diverter stent. Flow stagnation, produced by the fine mesh structure of the diverter, is thought to promote blood clotting in an aneurysm. However, apart from its effect on flow reduction, the insertion of the metal device poses the risk of occlusion of a parent artery. One strategy for avoiding the risk of arterial occlusion is the use of a device with a higher porosity. To aid the development of optimal stents in the view point of flow reduction maintaining a high porosity, we used lattice Boltzmann flow simulations and simulated annealing optimization to investigate the optimal placement of stent struts. We constructed four idealized aneurysm geometries that resulted in four different inflow characteristics and employed a stent model with 36 unconnected struts corresponding to the porosity of 80%. Assuming intracranial flow, steady flow simulation with Reynolds number of 200 was applied for each aneurysm. Optimization of strut position was performed to minimize the average velocity in an aneurysm while maintaining the porosity. As the results of optimization, we obtained nonuniformed structure as optimized stent for each aneurysm geometry. And all optimized stents were characterized by denser struts in the inflow area. The variety of inflow patterns that resulted from differing aneurysm geometries led to unique strut placements for each aneurysm type.

  19. The effect of prediction error correlation on optimal sensor placement in structural dynamics

    NASA Astrophysics Data System (ADS)

    Papadimitriou, Costas; Lombaert, Geert

    2012-04-01

    The problem of estimating the optimal sensor locations for parameter estimation in structural dynamics is re-visited. The effect of spatially correlated prediction errors on the optimal sensor placement is investigated. The information entropy is used as a performance measure of the sensor configuration. The optimal sensor location is formulated as an optimization problem involving discrete-valued variables, which is solved using computationally efficient sequential sensor placement algorithms. Asymptotic estimates for the information entropy are used to develop useful properties that provide insight into the dependence of the information entropy on the number and location of sensors. A theoretical analysis shows that the spatial correlation length of the prediction errors controls the minimum distance between the sensors and should be taken into account when designing optimal sensor locations with potential sensor distances up to the order of the characteristic length of the dynamic problem considered. Implementation issues for modal identification and structural-related model parameter estimation are addressed. Theoretical and computational developments are illustrated by designing the optimal sensor configurations for a continuous beam model, a discrete chain-like stiffness-mass model and a finite element model of a footbridge in Wetteren (Belgium). Results point out the crucial effect the spatial correlation of the prediction errors have on the design of optimal sensor locations for structural dynamics applications, revealing simultaneously potential inadequacies of spatially uncorrelated prediction errors models.

  20. Newtonian Imperialist Competitve Approach to Optimizing Observation of Multiple Target Points in Multisensor Surveillance Systems

    NASA Astrophysics Data System (ADS)

    Afghan-Toloee, A.; Heidari, A. A.; Joibari, Y.

    2013-09-01

    The problem of specifying the minimum number of sensors to deploy in a certain area to face multiple targets has been generally studied in the literatures. In this paper, we are arguing the multi-sensors deployment problem (MDP). The Multi-sensor placement problem can be clarified as minimizing the cost required to cover the multi target points in the area. We propose a more feasible method for the multi-sensor placement problem. Our method makes provision the high coverage of grid based placements while minimizing the cost as discovered in perimeter placement techniques. The NICA algorithm as improved ICA (Imperialist Competitive Algorithm) is used to decrease the performance time to explore an enough solution compared to other meta-heuristic schemes such as GA, PSO and ICA. A three dimensional area is used for clarify the multiple target and placement points, making provision x, y, and z computations in the observation algorithm. A structure of model for the multi-sensor placement problem is proposed: The problem is constructed as an optimization problem with the objective to minimize the cost while covering all multiple target points upon a given probability of observation tolerance.

  1. A Bayesian approach to optimal sensor placement for structural health monitoring with application to active sensing

    NASA Astrophysics Data System (ADS)

    Flynn, Eric B.; Todd, Michael D.

    2010-05-01

    This paper introduces a novel approach for optimal sensor and/or actuator placement for structural health monitoring (SHM) applications. Starting from a general formulation of Bayes risk, we derive a global optimality criterion within a detection theory framework. The optimal configuration is then established as the one that minimizes the expected total presence of either type I or type II error during the damage detection process. While the approach is suitable for many sensing/actuation SHM processes, we focus on the example of active sensing using guided ultrasonic waves by implementing an appropriate statistical model of the wave propagation and feature extraction process. This example implements both pulse-echo and pitch-catch actuation schemes and takes into account line-of-site visibility and non-uniform damage probabilities over the monitored structure. The optimization space is searched using a genetic algorithm with a time-varying mutation rate. We provide three actuator/sensor placement test problems and discuss the optimal solutions generated by the algorithm.

  2. A multi-objective optimization tool for the selection and placement of BMPs for pesticide control

    NASA Astrophysics Data System (ADS)

    Maringanti, C.; Chaubey, I.; Arabi, M.; Engel, B.

    2008-07-01

    Pesticides (particularly atrazine used in corn fields) are the foremost source of water contamination in many of the water bodies in Midwestern corn belt, exceeding the 3 ppb MCL established by the U.S. EPA for drinking water. Best management practices (BMPs), such as buffer strips and land management practices, have been proven to effectively reduce the pesticide pollution loads from agricultural areas. However, selection and placement of BMPs in watersheds to achieve an ecologically effective and economically feasible solution is a daunting task. BMP placement decisions under such complex conditions require a multi-objective optimization algorithm that would search for the best possible solution that satisfies the given watershed management objectives. Genetic algorithms (GA) have been the most popular optimization algorithms for the BMP selection and placement problem. Most optimization models also had a dynamic linkage with the water quality model, which increased the computation time considerably thus restricting them to apply models on field scale or relatively smaller (11 or 14 digit HUC) watersheds. However, most previous works have considered the two objectives individually during the optimization process by introducing a constraint on the other objective, therefore decreasing the degree of freedom to find the solution. In this study, the optimization for atrazine reduction is performed by considering the two objectives simultaneously using a multi-objective genetic algorithm (NSGA-II). The limitation with the dynamic linkage with a distributed parameter watershed model was overcome through the utilization of a BMP tool, a database that stores the pollution reduction and cost information of different BMPs under consideration. The model was used for the selection and placement of BMPs in Wildcat Creek Watershed (located in Indiana, for atrazine reduction. The most ecologically effective solution from the model had an annual atrazine concentration reduction

  3. Ultrasonic Sensor Placement Optimization in Structural Health Monitoring Using Evolutionary Strategy

    NASA Astrophysics Data System (ADS)

    Gao, H.; Rose, J. L.

    2006-03-01

    In structural health monitoring (SHM), sensor network scale and sensor distribution decisions are critical since sensor network performance and system cost are greatly affected. A quantitative sensor placement optimization method with covariance matrix adaptation evolutionary strategy (CMAES) is presented in this paper. A damage detection probability model is developed for ultrasonic guided wave sensor networks. Two sample problems are presented in this paper. One is for structure with irregular damage distribution probability, and the other is for an E2 aircraft wing section. The reliability of this genetic and evolutionary optimization method is proved in this study. Sensor network configurations with minimum missed-detection probability are obtained from the results of evolutionary optimization. The tradeoff relationship between optimized sensor network performance and the number of sensors is also presented in this paper.

  4. Optimal placement of piezoelectric actuators on plate structures for active vibration control using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Vashist, Suresh K.; Chhabra, Deepak

    2014-03-01

    The present work considers the optimal placement of piezoelectric actuators on a thin plate using integer coded genetic algorithm. The fitness function reflects on the controllability index which is the singular values decomposition of a control matrix. The index measures the input energy required to achieve the desired structural control using piezoelectric actuators. The LQR (Linear Quadratic Regulator) optimal control scheme has been applied to study the control effectiveness. It is observed that the frequency responses of cantilever obtained from finite element code hold good in agreement with the experimental results. Numerical simulations revealed that optimal locations obtained by integer coded GA based on controllability index with LQR controller offers effective control as compared non-optimal locations.

  5. Optimized electrode placement along the channel of a Hall thruster for ion focusing

    NASA Astrophysics Data System (ADS)

    Qing, Shaowei; E, Peng; Xia, Guangqing; Tang, Ming-Chun; Duan, Ping

    2014-01-01

    An optimal placement of the segmented electrode for increasing the lifetime of the Aton-type Hall thruster, i.e., reducing the plume divergence, is demonstrated using a 2D3V fully kinetic Particle-in-Cell method. Segmented electrodes, embedded near the ionization region of non-segmented case and biased above anode potential, lead to an increased separation between the ionization and acceleration regions and the formation of an efficient acceleration electric field configuration as potential lens. Due to this electrode placement, the sheath near the ceramic walls of the acceleration region is collapsed and an excellent ion beam focusing is demonstrated. The potential contour pockets around the electrodes and the sheath collapse phenomenon are also discussed.

  6. Optimized electrode placement along the channel of a Hall thruster for ion focusing

    SciTech Connect

    Qing, Shaowei; E, Peng; Xia, Guangqing; Tang, Ming-Chun; Duan, Ping

    2014-01-21

    An optimal placement of the segmented electrode for increasing the lifetime of the Aton-type Hall thruster, i.e., reducing the plume divergence, is demonstrated using a 2D3V fully kinetic Particle-in-Cell method. Segmented electrodes, embedded near the ionization region of non-segmented case and biased above anode potential, lead to an increased separation between the ionization and acceleration regions and the formation of an efficient acceleration electric field configuration as potential lens. Due to this electrode placement, the sheath near the ceramic walls of the acceleration region is collapsed and an excellent ion beam focusing is demonstrated. The potential contour pockets around the electrodes and the sheath collapse phenomenon are also discussed.

  7. Optimal radar waveform design for moving target

    NASA Astrophysics Data System (ADS)

    Zhu, Binqi; Gao, Yesheng; Wang, Kaizhi; Liu, Xingzhao

    2016-07-01

    An optimal radar waveform-design method is proposed to detect moving targets in the presence of clutter and noise. The clutter is split into moving and static parts. Radar-moving target/clutter models are introduced and combined with Neyman-Pearson criteria to design optimal waveforms. Results show that optimal waveform for a moving target is different with that for a static target. The combination of simple-frequency signals could produce maximum detectability based on different noise-power spectrum density situations. Simulations show that our algorithm greatly improves signal-to-clutter plus noise ratio of radar system. Therefore, this algorithm may be preferable for moving target detection when prior information on clutter and noise is available.

  8. Optimal placement of water-lubricated rubber bearings for vibration reduction of flexible multistage rotor systems

    NASA Astrophysics Data System (ADS)

    Liu, Shibing; Yang, Bingen

    2017-10-01

    Flexible multistage rotor systems with water-lubricated rubber bearings (WLRBs) have a variety of engineering applications. Filling a technical gap in the literature, this effort proposes a method of optimal bearing placement that minimizes the vibration amplitude of a WLRB-supported flexible rotor system with a minimum number of bearings. In the development, a new model of WLRBs and a distributed transfer function formulation are used to define a mixed continuous-and-discrete optimization problem. To deal with the case of uncertain number of WLRBs in rotor design, a virtual bearing method is devised. Solution of the optimization problem by a real-coded genetic algorithm yields the locations and lengths of water-lubricated rubber bearings, by which the prescribed operational requirements for the rotor system are satisfied. The proposed method is applicable either to preliminary design of a new rotor system with the number of bearings unforeknown or to redesign of an existing rotor system with a given number of bearings. Numerical examples show that the proposed optimal bearing placement is efficient, accurate and versatile in different design cases.

  9. Articulatory Placement for /t/, /d/, /k/ and /g/ Targets in School Age Children with Speech Disorders Associated with Cleft Palate

    ERIC Educational Resources Information Center

    Gibbon, Fiona; Ellis, Lucy; Crampin, Lisa

    2004-01-01

    This study used electropalatography (EPG) to identify place of articulation for lingual plosive targets /t/, /d/, /k/ and /g/ in the speech of 15 school age children with repaired cleft palate. Perceptual judgements indicated that all children had correct velar placement for /k/, /g/ targets, but /t/, /d/ targets were produced as errors involving…

  10. Targeting treatment for optimal outcome.

    PubMed

    Husted, S E

    2000-01-01

    Rapid assessment of patients presenting with acute chest pain is essential, in order to distinguish between those who have a life-threatening condition, such as myocardial infarction or unstable angina, and the substantial proportion who do not have an acute coronary syndrome. It is thus of vital importance that reliable techniques are available to facilitate rapid risk stratification, as an aid to both clinical diagnosis and management strategy decisions. Assessments based on clinical findings, electrocardiographic monitoring, symptom-limited exercise testing, and biochemical marker measurements, used either singly or in various combinations, can fulfill this role. The present paper reviews some of the recent data that demonstrate the value of these techniques. Very few studies allow conclusions to be drawn about optimal treatment strategies in relation to groups stratified according to prognostic markers, and the question of whether intense medical treatment or early invasive intervention is most beneficial is one that clinical trials have yet to address adequately. In the recently completed Fragmin and Fast Revascularization during InStability in Coronary artery disease (FRISC II) study, comparisons were made of clinical outcomes achieved with early invasive versus noninvasive (i.e., medical) management strategies, and with short-term versus prolonged anticoagulation with dalteparin sodium (Fragmin), in patients with unstable coronary artery disease. All study participants underwent symptom-limited exercise testing and provided blood sample for measurements of biochemical markers; continuous electrocardiography monitoring and echocardiography were also performed in a high proportion of patients. Data from the FRISC II trial thus shed further light on the issue of risk stratification and its use to determine optimal treatment strategies.

  11. Enhanced nonlinearity interval mapping scheme for high-performance simulation-optimization of watershed-scale BMP placement

    NASA Astrophysics Data System (ADS)

    Zou, Rui; Riverson, John; Liu, Yong; Murphy, Ryan; Sim, Youn

    2015-03-01

    Integrated continuous simulation-optimization models can be effective predictors of a process-based responses for cost-benefit optimization of best management practices (BMPs) selection and placement. However, practical application of simulation-optimization model is computationally prohibitive for large-scale systems. This study proposes an enhanced Nonlinearity Interval Mapping Scheme (NIMS) to solve large-scale watershed simulation-optimization problems several orders of magnitude faster than other commonly used algorithms. An efficient interval response coefficient (IRC) derivation method was incorporated into the NIMS framework to overcome a computational bottleneck. The proposed algorithm was evaluated using a case study watershed in the Los Angeles County Flood Control District. Using a continuous simulation watershed/stream-transport model, Loading Simulation Program in C++ (LSPC), three nested in-stream compliance points (CP)—each with multiple Total Maximum Daily Loads (TMDL) targets—were selected to derive optimal treatment levels for each of the 28 subwatersheds, so that the TMDL targets at all the CP were met with the lowest possible BMP implementation cost. Genetic Algorithm (GA) and NIMS were both applied and compared. The results showed that the NIMS took 11 iterations (about 11 min) to complete with the resulting optimal solution having a total cost of 67.2 million, while each of the multiple GA executions took 21-38 days to reach near optimal solutions. The best solution obtained among all the GA executions compared had a minimized cost of 67.7 million—marginally higher, but approximately equal to that of the NIMS solution. The results highlight the utility for decision making in large-scale watershed simulation-optimization formulations.

  12. Near-optimal sensor placement for health monitoring of civil structures

    NASA Astrophysics Data System (ADS)

    van der Linden, Gwendolyn W.; Emami-Naeini, Abbas; Kosut, Robert L.; Sederat, Hassan; Lynch, Jerome P.

    2010-04-01

    In this paper we focus on the optimal placement of sensors for state estimation-based continuous health monitoring of structures using three approaches. The first aims to minimize the static estimation error of the structure deflections, using the linear stiffness matrix derived from a finite element model. The second approach aims to maximize the observability of the derived linear state space model. The third approach aims to minimize the dynamic estimation error of the deflections using a Linear Quadratic Estimator. Both nonlinear mixed-integer and relaxed convex optimization formulations are presented. A simple search-based optimization implementation for each of the three approaches is demonstrated on a model of the long-span New Carquinez Bridge in California.

  13. Optimal sensor placement for maximum area coverage (MAC) for damage localization in composite structures

    NASA Astrophysics Data System (ADS)

    Thiene, M.; Sharif Khodaei, Z.; Aliabadi, M. H.

    2016-09-01

    In this paper an optimal sensor placement algorithm for attaining the maximum area coverage (MAC) within a sensor network is presented. The proposed novel approach takes into account physical properties of Lamb wave propagation (attenuation profile, direction dependant group velocity due to material anisotropy) and geometrical complexities (boundary reflections, presence of openings) of the structure. A feature of the proposed optimization approach lies in the fact that it is independent of characteristics of the damage detection algorithm (e.g. probability of detection) making it readily up-scalable to large complex composite structures such as aircraft stiffened composite panel. The proposed fitness function (MAC) is independent of damage parameters (type, severity, location). Statistical analysis carried out shows that the proposed optimum sensor network with MAC results in high probability of damage localization. Genetic algorithm is coupled with the fitness function to provide an efficient optimization strategy.

  14. SSD-Optimized Workload Placement with Adaptive Learning and Classification in HPC Environments

    SciTech Connect

    Wan, Lipeng; Lu, Zheng; Cao, Qing; Wang, Feiyi; Oral, H Sarp; Settlemyer, Bradley W

    2014-01-01

    In recent years, non-volatile memory devices such as SSD drives have emerged as a viable storage solution due to their increasing capacity and decreasing cost. Due to the unique capability and capacity requirements in large scale HPC (High Performance Computing) storage environment, a hybrid config- uration (SSD and HDD) may represent one of the most available and balanced solutions considering the cost and performance. Under this setting, effective data placement as well as movement with controlled overhead become a pressing challenge. In this paper, we propose an integrated object placement and movement framework and adaptive learning algorithms to address these issues. Specifically, we present a method that shuffle data objects across storage tiers to optimize the data access performance. The method also integrates an adaptive learning algorithm where real- time classification is employed to predict the popularity of data object accesses, so that they can be placed on, or migrate between SSD or HDD drives in the most efficient manner. We discuss preliminary results based on this approach using a simulator we developed to show that the proposed methods can dynamically adapt storage placements and access pattern as workloads evolve to achieve the best system level performance such as throughput.

  15. A triaxial accelerometer monkey algorithm for optimal sensor placement in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Jia, Jingqing; Feng, Shuo; Liu, Wei

    2015-06-01

    Optimal sensor placement (OSP) technique is a vital part of the field of structural health monitoring (SHM). Triaxial accelerometers have been widely used in the SHM of large-scale structures in recent years. Triaxial accelerometers must be placed in such a way that all of the important dynamic information is obtained. At the same time, the sensor configuration must be optimal, so that the test resources are conserved. The recommended practice is to select proper degrees of freedom (DOF) based upon several criteria and the triaxial accelerometers are placed at the nodes corresponding to these DOFs. This results in non-optimal placement of many accelerometers. A ‘triaxial accelerometer monkey algorithm’ (TAMA) is presented in this paper to solve OSP problems of triaxial accelerometers. The EFI3 measurement theory is modified and involved in the objective function to make it more adaptable in the OSP technique of triaxial accelerometers. A method of calculating the threshold value based on probability theory is proposed to improve the healthy rate of monkeys in a troop generation process. Meanwhile, the processes of harmony ladder climb and scanning watch jump are proposed and given in detail. Finally, Xinghai NO.1 Bridge in Dalian is implemented to demonstrate the effectiveness of TAMA. The final results obtained by TAMA are compared with those of the original monkey algorithm and EFI3 measurement, which show that TAMA can improve computational efficiency and get a better sensor configuration.

  16. Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results

    NASA Astrophysics Data System (ADS)

    Botta, F.; Marx, N.; Gentili, S.; Schwingshackl, C. W.; Di Mare, L.; Cerri, G.; Dini, D.

    2012-04-01

    It is well known that the gas turbine blade vibrations can give rise to catastrophic failures and a reduction of the blades life because of fatigue related phenomena[1]-[3] . In last two decades, the adoption of piezoelectric elements, has received considerable attention by many researcher for its potential applicability to different areas of mechanical, aerospace, aeronautical and civil engineering. Recently, a number of studies of blades vibration control via piezoelectric plates and patches have been reported[4]-[6] . It was reported that the use of piezoelectric elements can be very effective in actively controlling vibrations. In one of their previous contributions[7] , the authors of the present manuscript studied a model to control the blade vibrations by piezoelectric elements and validated their results using a multi-physics finite elements package (COMSOL) and results from the literature. An optimal placement method of piezoelectric plate has been developed and applied to different loading scenarios for realistic configurations encountered in gas turbine blades. It has been demonstrated that the optimal placement depends on the spectrum of the load, so that segmented piezoelectric patches have been considered and, for different loads, an optimal combination of sequential and/or parallel actuation and control of the segments has been studied. In this paper, an experimental investigation carried out by the authors using a simplified beam configuration is reported and discussed. The test results obtained by the investigators are then compared with the numerical predictions [7] .

  17. New Approach to Optimize the Apfs Placement Based on Instantaneous Reactive Power Theory by Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Hashemi-Dezaki, Hamed; Mohammadalizadeh-Shabestary, Masoud; Askarian-Abyaneh, Hossein; Rezaei-Jegarluei, Mohammad

    2014-01-01

    In electrical distribution systems, a great amount of power are wasting across the lines, also nowadays power factors, voltage profiles and total harmonic distortions (THDs) of most loads are not as would be desired. So these important parameters of a system play highly important role in wasting money and energy, and besides both consumers and sources are suffering from a high rate of distortions and even instabilities. Active power filters (APFs) are innovative ideas for solving of this adversity which have recently used instantaneous reactive power theory. In this paper, a novel method is proposed to optimize the allocation of APFs. The introduced method is based on the instantaneous reactive power theory in vectorial representation. By use of this representation, it is possible to asses different compensation strategies. Also, APFs proper placement in the system plays a crucial role in either reducing the losses costs and power quality improvement. To optimize the APFs placement, a new objective function has been defined on the basis of five terms: total losses, power factor, voltage profile, THD and cost. Genetic algorithm has been used to solve the optimization problem. The results of applying this method to a distribution network illustrate the method advantages.

  18. Optimal placement of active braces by using PSO algorithm in near- and far-field earthquakes

    NASA Astrophysics Data System (ADS)

    Mastali, M.; Kheyroddin, A.; Samali, B.; Vahdani, R.

    2016-03-01

    One of the most important issues in tall buildings is lateral resistance of the load-bearing systems against applied loads such as earthquake, wind and blast. Dual systems comprising core wall systems (single or multi-cell core) and moment-resisting frames are used as resistance systems in tall buildings. In addition to adequate stiffness provided by the dual system, most tall buildings may have to rely on various control systems to reduce the level of unwanted motions stemming from severe dynamic loads. One of the main challenges to effectively control the motion of a structure is limitation in distributing the required control along the structure height optimally. In this paper, concrete shear walls are used as secondary resistance system at three different heights as well as actuators installed in the braces. The optimal actuator positions are found by using optimized PSO algorithm as well as arbitrarily. The control performance of buildings that are equipped and controlled using the PSO algorithm method placement is assessed and compared with arbitrary placement of controllers using both near- and far-field ground motions of Kobe and Chi-Chi earthquakes.

  19. Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets

    NASA Technical Reports Server (NTRS)

    Felder, Michael; Nesnas, Issa A.; Pivtoraiko, Mihail; Kelly, Alonzo; Volpe, Richard

    2011-01-01

    Exploring planetary surfaces typically involves traversing challenging and unknown terrain and acquiring in-situ measurements at designated locations using arm-mounted instruments. We present field results for a new implementation of an autonomous capability that enables a rover to traverse and precisely place an arm-mounted instrument on remote targets. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover's mast cameras. The rover then autonomously traverse the rocky terrain for a distance of 10 - 15 m, tracks the target(s) of interest during the traverse, positions itself for approaching the target, and then precisely places an arm-mounted instrument within 2-3 cm from the originally designated target. The rover proceeds to acquire science measurements with the instrument. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight thread-the-needle maneuvers. We integrated these algorithms on the newly refurbished Athena Mars research rover and fielded them in the JPL Mars Yard. We conducted 43 runs with targets at distances ranging from 5 m to 15 m and achieved a success rate of 93% for placement of the instrument within 2-3 cm.

  20. Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets

    NASA Technical Reports Server (NTRS)

    Felder, Michael; Nesnas, Issa A.; Pivtoraiko, Mihail; Kelly, Alonzo; Volpe, Richard

    2011-01-01

    Exploring planetary surfaces typically involves traversing challenging and unknown terrain and acquiring in-situ measurements at designated locations using arm-mounted instruments. We present field results for a new implementation of an autonomous capability that enables a rover to traverse and precisely place an arm-mounted instrument on remote targets. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover's mast cameras. The rover then autonomously traverse the rocky terrain for a distance of 10 - 15 m, tracks the target(s) of interest during the traverse, positions itself for approaching the target, and then precisely places an arm-mounted instrument within 2-3 cm from the originally designated target. The rover proceeds to acquire science measurements with the instrument. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight thread-the-needle maneuvers. We integrated these algorithms on the newly refurbished Athena Mars research rover and fielded them in the JPL Mars Yard. We conducted 43 runs with targets at distances ranging from 5 m to 15 m and achieved a success rate of 93% for placement of the instrument within 2-3 cm.

  1. [Method for optimal sensor placement in water distribution systems with nodal demand uncertainties].

    PubMed

    Liu, Shu-Ming; Wu, Xue; Ouyang, Le-Yan

    2013-08-01

    The notion of identification fitness was proposed for optimizing sensor placement in water distribution systems. Nondominated Sorting Genetic Algorithm II was used to find the Pareto front between minimum overlap of possible detection times of two events and the best probability of detection, taking nodal demand uncertainties into account. This methodology was applied to an example network. The solutions show that the probability of detection and the number of possible locations are not remarkably affected by nodal demand uncertainties, but the sources identification accuracy declines with nodal demand uncertainties.

  2. Optimization of COS/FUV Spectrum Placement at Lifetime Position 4

    NASA Astrophysics Data System (ADS)

    De Rosa, Gisella

    2017-08-01

    We give a summary of the rationale, structure and preliminary analysis of the Lifetime Position 4 (LP4) special calibration program 14841, aimed at determining the optimal placement of the spectra at LP4. The program obtained deep (S/N = 60 per resel) exposures of the standard star WD0308-565 with G130M/1291 and G130M/1222 settings at -2.52" below LP3 in the cross dispersion direction. These particular settings were chosen because they have the widest footprints on the detectors. Science spectra were successfully extracted at this position without any contamination due to gain-sag at LP3.

  3. Optimal placement of off-stream water sources for ephemeral stream recovery

    USGS Publications Warehouse

    Rigge, Matthew B.; Smart, Alexander; Wylie, Bruce

    2013-01-01

    Uneven and/or inefficient livestock distribution is often a product of an inadequate number and distribution of watering points. Placement of off-stream water practices (OSWP) in pastures is a key consideration in rangeland management plans and is critical to achieving riparian recovery by improving grazing evenness, while improving livestock performance. Effective OSWP placement also minimizes the impacts of livestock use radiating from OSWP, known as the “piosphere.” The objective of this study was to provide land managers with recommendations for the optimum placement of OSWP. Specifically, we aimed to provide minimum offset distances of OSWP to streams and assess the effective range of OSWP using Normalized Difference Vegetation Index (NDVI) values, an indicator of live standing crop. NDVI values were determined from a time-series of Satellite Pour l'Observation de la Terre (SPOT) 20-m images of western South Dakota mixed-grass prairie. The NDVI values in ephemeral stream channels (in-channel) and uplands were extracted from pre- and post-OSWP images taken in 1989 and 2010, respectively. NDVI values were normalized to a reference imagine and subsequently by ecological site to produce nNDVI. Our results demonstrate a significant (P 2 = 0.49, P = 0.05) and increased with average distance to OSWP in a pasture (R2 = 0.43, P = 0.07). Piospheric reduction in nNDVI was observed within 200 m of OSWP, occasionally overlapping in-channel areas. The findings of this study suggest placement of OSWP 200 to 1 250 m from streams to achieve optimal results. These results can be used to increase grazing efficiency by effectively placing OSWP and insure that piospheres do not overlap ecologically important in-channel areas.

  4. Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets

    NASA Technical Reports Server (NTRS)

    Nesnas, Issa A.; Pivtoraiko, Mihail N.; Kelly, Alonzo; Fleder, Michael

    2012-01-01

    This software controls a rover platform to traverse rocky terrain autonomously, plan paths, and avoid obstacles using its stereo hazard and navigation cameras. It does so while continuously tracking a target of interest selected from 10 20 m away. The rover drives and tracks the target until it reaches the vicinity of the target. The rover then positions itself to approach the target, deploys its robotic arm, and places the end effector instrument on the designated target to within 2-3-cm accuracy of the originally selected target. This software features continuous navigation in a fairly rocky field in an outdoor environment and the ability to enable the rover to avoid large rocks and traverse over smaller ones. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover s mast cameras. The navigation software uses stereo imaging, traversability analysis, path planning, trajectory generation, and trajectory execution. It also includes visual target tracking of a designated target selected from 10 m away while continuously navigating the rocky terrain. Improvements in this design include steering while driving, which uses continuous curvature paths. There are also several improvements to the traversability analyzer, including improved data fusion of traversability maps that result from pose estimation uncertainties, dealing with boundary effects to enable tighter maneuvers, and handling a wider range of obstacles. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight, thread-the-needle maneuvers. These algorithms were integrated on the newly refurbished Athena Mars research rover, and were fielded in the JPL Mars Yard. Forty-three runs were conducted with targets at distances ranging from 5 to 15 m, and a success rate of 93% was achieved for placement of the instrument within

  5. On the Design of Smart Parking Networks in the Smart Cities: An Optimal Sensor Placement Model.

    PubMed

    Bagula, Antoine; Castelli, Lorenzo; Zennaro, Marco

    2015-06-30

    Smart parking is a typical IoT application that can benefit from advances in sensor, actuator and RFID technologies to provide many services to its users and parking owners of a smart city. This paper considers a smart parking infrastructure where sensors are laid down on the parking spots to detect car presence and RFID readers are embedded into parking gates to identify cars and help in the billing of the smart parking. Both types of devices are endowed with wired and wireless communication capabilities for reporting to a gateway where the situation recognition is performed. The sensor devices are tasked to play one of the three roles: (1) slave sensor nodes located on the parking spot to detect car presence/absence; (2) master nodes located at one of the edges of a parking lot to detect presence and collect the sensor readings from the slave nodes; and (3) repeater sensor nodes, also called "anchor" nodes, located strategically at specific locations in the parking lot to increase the coverage and connectivity of the wireless sensor network. While slave and master nodes are placed based on geographic constraints, the optimal placement of the relay/anchor sensor nodes in smart parking is an important parameter upon which the cost and efficiency of the parking system depends. We formulate the optimal placement of sensors in smart parking as an integer linear programming multi-objective problem optimizing the sensor network engineering efficiency in terms of coverage and lifetime maximization, as well as its economic gain in terms of the number of sensors deployed for a specific coverage and lifetime. We propose an exact solution to the node placement problem using single-step and two-step solutions implemented in the Mosel language based on the Xpress-MPsuite of libraries. Experimental results reveal the relative efficiency of the single-step compared to the two-step model on different performance parameters. These results are consolidated by simulation results

  6. On the Design of Smart Parking Networks in the Smart Cities: An Optimal Sensor Placement Model

    PubMed Central

    Bagula, Antoine; Castelli, Lorenzo; Zennaro, Marco

    2015-01-01

    Smart parking is a typical IoT application that can benefit from advances in sensor, actuator and RFID technologies to provide many services to its users and parking owners of a smart city. This paper considers a smart parking infrastructure where sensors are laid down on the parking spots to detect car presence and RFID readers are embedded into parking gates to identify cars and help in the billing of the smart parking. Both types of devices are endowed with wired and wireless communication capabilities for reporting to a gateway where the situation recognition is performed. The sensor devices are tasked to play one of the three roles: (1) slave sensor nodes located on the parking spot to detect car presence/absence; (2) master nodes located at one of the edges of a parking lot to detect presence and collect the sensor readings from the slave nodes; and (3) repeater sensor nodes, also called “anchor” nodes, located strategically at specific locations in the parking lot to increase the coverage and connectivity of the wireless sensor network. While slave and master nodes are placed based on geographic constraints, the optimal placement of the relay/anchor sensor nodes in smart parking is an important parameter upon which the cost and efficiency of the parking system depends. We formulate the optimal placement of sensors in smart parking as an integer linear programming multi-objective problem optimizing the sensor network engineering efficiency in terms of coverage and lifetime maximization, as well as its economic gain in terms of the number of sensors deployed for a specific coverage and lifetime. We propose an exact solution to the node placement problem using single-step and two-step solutions implemented in the Mosel language based on the Xpress-MPsuite of libraries. Experimental results reveal the relative efficiency of the single-step compared to the two-step model on different performance parameters. These results are consolidated by simulation results

  7. Mirror placement optimization for the multi-segmented James Webb Space Telescope primary mirror

    NASA Astrophysics Data System (ADS)

    Porpora, D.; Wachs, J.; Barto, A.; Knight, J. S.

    2014-08-01

    The Primary Mirror (PM) of NASA's James Webb Space Telescope (JWST) consists of 18 segment assemblies that are aligned on-orbit using hexapod actuators to function as a single monolithic optic. The individual segment assemblies are polished into one of three different prescriptions. Each segment of a given prescription may be placed in one of six different locations for that prescription, resulting in tens of millions of possible placement combinations of the 18 segments on the backplane of the telescope. A method is proposed to optimize the placement based on minimizing the known alignment offsets of as-built mirrors in combination with the predicted shifts of each attachment point on the telescope backplane due to material creep, cool down shifts, launch shifts, and gravity release. The optimization routine can be configured to allow for minimization of errors in any of the six rigid-body degrees of freedom and can further reduce selection options based on defined hardware constraints. Such a routine can be utilized to minimize initial misalignments of the PM on-orbit, reducing the need to exercise mirror actuators to achieve an aligned state. The end result is reduced commissioning time and increased probability of success of the mission.

  8. Optimal placement and active vibration control for piezoelectric smart flexible cantilever plate

    NASA Astrophysics Data System (ADS)

    Qiu, Zhi-cheng; Zhang, Xian-min; Wu, Hong-xin; Zhang, Hong-hua

    2007-04-01

    Some flexible appendages of spacecraft are cantilever plate structures, such as sun plate and satellite antenna. Thus, vibration problem will be caused by parameter uncertainties and environmental disturbances. In this paper, piezoelectric ceramics patches are used as sensors and actuators to suppress the vibration of the smart flexible clamped plate. Firstly, modal equations and piezoelectric control equations of cantilever plate are derived. Secondly, an optimal placement method for the locations of piezoelectric actuators and sensors is developed based on the degree of observability and controllability indices for cantilever plate. The bending and torsional modes are decoupled by the proposed method using bandwidth Butterworth filter. Thirdly, an efficient control method by combining positive position feedback and proportional-derivative control is proposed for vibration reduction. The analytical results for modal frequencies, transient responses and control responses are carried out. Finally, an experimental setup of piezoelectric smart plate is designed and built up. The modal frequencies and damping ratios of the plate setup are obtained by identification method. Also, the experimental studies on vibration control of the cantilever plate including bending modes and torsional modes are conducted. The analytical and experimental results demonstrate that the presented control method is feasible, and the optimal placement method is effective.

  9. Optimal Sequential Diagnostic Strategy Generation Considering Test Placement Cost for Multimode Systems

    PubMed Central

    Zhang, Shigang; Song, Lijun; Zhang, Wei; Hu, Zheng; Yang, Yongmin

    2015-01-01

    Sequential fault diagnosis is an approach that realizes fault isolation by executing the optimal test step by step. The strategy used, i.e., the sequential diagnostic strategy, has great influence on diagnostic accuracy and cost. Optimal sequential diagnostic strategy generation is an important step in the process of diagnosis system construction, which has been studied extensively in the literature. However, previous algorithms either are designed for single mode systems or do not consider test placement cost. They are not suitable to solve the sequential diagnostic strategy generation problem considering test placement cost for multimode systems. Therefore, this problem is studied in this paper. A formulation is presented. Two algorithms are proposed, one of which is realized by system transformation and the other is newly designed. Extensive simulations are carried out to test the effectiveness of the algorithms. A real-world system is also presented. All the results show that both of them have the ability to solve the diagnostic strategy generation problem, and they have different characteristics. PMID:26457709

  10. Spatial and temporal optimization in habitat placement for a threatened plant: the case of the western prairie fringed orchid

    Treesearch

    John Hof; Carolyn Hull Sieg; Michael Bevers

    1999-01-01

    This paper investigates an optimization approach to determining the placement and timing of habitat protection for the western prairie fringed orchid. This plant’s population dynamics are complex, creating a challenging optimization problem. The sensitivity of the orchid to random climate conditions is handled probabilistically. The plant’s seed, protocorm and above-...

  11. A heuristic for deriving the optimal number and placement of reconnaissance sensors

    NASA Astrophysics Data System (ADS)

    Nanda, S.; Weeks, J.; Archer, M.

    2008-04-01

    A key to mastering asymmetric warfare is the acquisition of accurate intelligence on adversaries and their assets in urban and open battlefields. To achieve this, one needs adequate numbers of tactical sensors placed in locations to optimize coverage, where optimality is realized by covering a given area of interest with the least number of sensors, or covering the largest possible subsection of an area of interest with a fixed set of sensors. Unfortunately, neither problem admits a polynomial time algorithm as a solution, and therefore, the placement of such sensors must utilize intelligent heuristics instead. In this paper, we present a scheme implemented on parallel SIMD processing architectures to yield significantly faster results, and that is highly scalable with respect to dynamic changes in the area of interest. Furthermore, the solution to the first problem immediately translates to serve as a solution to the latter if and when any sensors are rendered inoperable.

  12. Optimal Capacitor Placement in Radial Distribution Feeders Using Fuzzy-Differential Evolution for Dynamic Load Condition

    NASA Astrophysics Data System (ADS)

    Kannan, S. M.; Renuga, P.; Kalyani, S.; Muthukumaran, E.

    2015-12-01

    This paper proposes new methods to select the optimal values of fixed and switched shunt capacitors in Radial distribution feeders for varying load conditions so as to maximize the annual savings and minimizes the energy loss by taking the capacitor cost into account. The identification of the weak buses, where the capacitors should be placed is decided by a set of rules given by the fuzzy expert system. Then the sizing of the fixed and switched capacitors is modeled using differential evolution (DE) and particle swarm optimization (PSO). A case study with an existing 15 bus rural distribution feeder is presented to illustrate the applicability of the algorithm. Simulation results show the better saving in cost over previous capacitor placement algorithm.

  13. Rise and Shock: Optimal Defibrillator Placement in a High-rise Building.

    PubMed

    Chan, Timothy C Y

    2017-01-01

    Out-of-hospital cardiac arrests (OHCA) in high-rise buildings experience lower survival and longer delays until paramedic arrival. Use of publicly accessible automated external defibrillators (AED) can improve survival, but "vertical" placement has not been studied. We aim to determine whether elevator-based or lobby-based AED placement results in shorter vertical distance travelled ("response distance") to OHCAs in a high-rise building. We developed a model of a single-elevator, n-floor high-rise building. We calculated and compared the average distance from AED to floor of arrest for the two AED locations. We modeled OHCA occurrences using floor-specific Poisson processes, the risk of OHCA on the ground floor (λ1) and the risk on any above-ground floor (λ). The elevator was modeled with an override function enabling direct travel to the target floor. The elevator location upon override was modeled as a discrete uniform random variable. Calculations used the laws of probability. Elevator-based AED placement had shorter average response distance if the number of floors (n) in the building exceeded three quarters of the ratio of ground-floor OHCA risk to above-ground floor risk (λ1/λ) plus one half (n ≥ 3λ1/4λ + 0.5). Otherwise, a lobby-based AED had shorter average response distance. If OHCA risk on each floor was equal, an elevator-based AED had shorter average response distance. Elevator-based AEDs travel less vertical distance to OHCAs in tall buildings or those with uniform vertical risk, while lobby-based AEDs travel less vertical distance in buildings with substantial lobby, underground, and nearby street-level traffic and OHCA risk.

  14. Field-Based Optimal Placement of Antennas for Body-Worn Wireless Sensors.

    PubMed

    Januszkiewicz, Łukasz; Di Barba, Paolo; Hausman, Sławomir

    2016-05-17

    We investigate a case of automated energy-budget-aware optimization of the physical position of nodes (sensors) in a Wireless Body Area Network (WBAN). This problem has not been presented in the literature yet, as opposed to antenna and routing optimization, which are relatively well-addressed. In our research, which was inspired by a safety-critical application for firefighters, the sensor network consists of three nodes located on the human body. The nodes communicate over a radio link operating in the 2.4 GHz or 5.8 GHz ISM frequency band. Two sensors have a fixed location: one on the head (earlobe pulse oximetry) and one on the arm (with accelerometers, temperature and humidity sensors, and a GPS receiver), while the position of the third sensor can be adjusted within a predefined region on the wearer's chest. The path loss between each node pair strongly depends on the location of the nodes and is difficult to predict without performing a full-wave electromagnetic simulation. Our optimization scheme employs evolutionary computing. The novelty of our approach lies not only in the formulation of the problem but also in linking a fully automated optimization procedure with an electromagnetic simulator and a simplified human body model. This combination turns out to be a computationally effective solution, which, depending on the initial placement, has a potential to improve performance of our example sensor network setup by up to about 20 dB with respect to the path loss between selected nodes.

  15. Multi-projector auto-calibration and placement optimization for non-planar surfaces

    NASA Astrophysics Data System (ADS)

    Li, Dong; Xie, Jinghui; Zhao, Lu; Zhou, Lijing; Weng, Dongdong

    2015-10-01

    Non-planar projection has been widely applied in virtual reality and digital entertainment and exhibitions because of its flexible layout and immersive display effects. Compared with planar projection, a non-planar projection is more difficult to achieve because projector calibration and image distortion correction are difficult processes. This paper uses a cylindrical screen as an example to present a new method for automatically calibrating a multi-projector system in a non-planar environment without using 3D reconstruction. This method corrects the geometric calibration error caused by the screen's manufactured imperfections, such as an undulating surface or a slant in the vertical plane. In addition, based on actual projection demand, this paper presents the overall performance evaluation criteria for the multi-projector system. According to these criteria, we determined the optimal placement for the projectors. This method also extends to surfaces that can be parameterized, such as spheres, ellipsoids, and paraboloids, and demonstrates a broad applicability.

  16. Branch target buffer design and optimization

    NASA Technical Reports Server (NTRS)

    Perleberg, Chris H.; Smith, Alan J.

    1993-01-01

    Consideration is given to two major issues in the design of branch target buffers (BTBs), with the goal of achieving maximum performance for a given number of bits allocated to the BTB design. The first issue is BTB management; the second is what information to keep in the BTB. A number of solutions to these problems are reviewed, and various optimizations in the design of BTBs are discussed. Design target miss ratios for BTBs are developed, making it possible to estimate the performance of BTBs for real workloads.

  17. Branch target buffer design and optimization

    NASA Technical Reports Server (NTRS)

    Perleberg, Chris H.; Smith, Alan J.

    1993-01-01

    Consideration is given to two major issues in the design of branch target buffers (BTBs), with the goal of achieving maximum performance for a given number of bits allocated to the BTB design. The first issue is BTB management; the second is what information to keep in the BTB. A number of solutions to these problems are reviewed, and various optimizations in the design of BTBs are discussed. Design target miss ratios for BTBs are developed, making it possible to estimate the performance of BTBs for real workloads.

  18. Optimal actuator placement and active structure design for control of helicopter airframe vibrations

    NASA Astrophysics Data System (ADS)

    Heverly, David Ellsworth, II

    A comprehensive research program on active control of rotorcraft airframe vibration is detailed in this thesis. A systematic design methodology, to realize an active vibration control system, is proposed and studied. The methodology is a four-part design cycle and relies heavily on numerical computation, modeling, and analysis. The various analytical tools, models, and processes required to execute the methodology are described. Two dynamic models of the helicopter airframe and an optimization procedure for actuator placement are utilized within the methodology. The optimization procedure simultaneously determines the type of actuation, the locations to apply actuation, and the corresponding active control actions. A feasibility study is conducted to examine the effectiveness of helicopter vibration control by distributing actuators at optimal locations within the airframe, rather than confining actuation to a centralized region. Results indicate that distributed actuation is capable of greater vibration suppression and requires less control effort than a centralized actuation configuration. An analytical and experimental investigation is conducted on a scaled model of a helicopter tailboom. The scaled tailboom model is used to study the actuation design and realization issues associated with integrating dual-point actuation into a semi-monocoque airframe structure. A piezoelectric stack actuator configuration is designed and installed within the tailboom model. Experimental tests indicate the stack actuator configuration is able to produce a bending moment within the structure to suppress vibration without causing excessive localized stress in the structure.

  19. The effects of initial conditions and control time on optimal actuator placement via a max-min Genetic Algorithm

    SciTech Connect

    Redmond, J.; Parker, G.

    1993-07-01

    This paper examines the role of the control objective and the control time in determining fuel-optimal actuator placement for structural vibration suppression. A general theory is developed that can be easily extended to include alternative performance metrics such as energy and time-optimal control. The performance metric defines a convex admissible control set which leads to a max-min optimization problem expressing optimal location as a function of initial conditions and control time. A solution procedure based on a nested Genetic Algorithm is presented and applied to an example problem. Results indicate that the optimal locations vary widely as a function of control time and initial conditions.

  20. Optimizing Trial Designs for Targeted Therapies

    PubMed Central

    Beckman, Robert A.; Burman, Carl-Fredrik; König, Franz; Stallard, Nigel; Posch, Martin

    2016-01-01

    An important objective in the development of targeted therapies is to identify the populations where the treatment under consideration has positive benefit risk balance. We consider pivotal clinical trials, where the efficacy of a treatment is tested in an overall population and/or in a pre-specified subpopulation. Based on a decision theoretic framework we derive optimized trial designs by maximizing utility functions. Features to be optimized include the sample size and the population in which the trial is performed (the full population or the targeted subgroup only) as well as the underlying multiple test procedure. The approach accounts for prior knowledge of the efficacy of the drug in the considered populations using a two dimensional prior distribution. The considered utility functions account for the costs of the clinical trial as well as the expected benefit when demonstrating efficacy in the different subpopulations. We model utility functions from a sponsor’s as well as from a public health perspective, reflecting actual civil interests. Examples of optimized trial designs obtained by numerical optimization are presented for both perspectives. PMID:27684573

  1. Optimal sensor placement for multi-setup modal analysis of structures

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Maes, Kristof; De Roeck, Guido; Reynders, Edwin; Papadimitriou, Costas; Lombaert, Geert

    2017-08-01

    Modal tests on large structures are often performed in multiple setups for practical reasons. Several sensors are kept fixed as reference sensors over all setups, while the other, so called roving sensors, are moved from one setup to another. This paper develops an optimal sensor placement strategy for multi-setup modal identification, which simultaneously optimizes the locations of the reference sensors and roving sensors. As an optimality criterion, the Information Entropy is adopted, which is a scalar measure of uncertainty in the Bayesian framework. The focus in the application goes to repetitive structures where modes typically occur in clusters, with closely spaced natural frequencies and similar wavelengths. The proposed strategy is illustrated for selecting optimal positions of uni-axial sensors for a repetitive frame structure. The influence of the number of reference sensors and two strategies for positioning roving sensors, i.e. a cluster and a uniform distribution of roving sensors, are investigated. The number of reference sensors is found to be preferably equal to or larger than the number of modes to be identified. In this case, the information content, as quantified by the Information Entropy, is not very sensitive to the roving sensor strategy. If less reference sensors are used, it is highly preferred to distribute the roving sensors uniformly over the structure instead of clustering them. The proposed strategy has been validated by an experimental modal test on a floor of an office building of KU Leuven, which has a nearly repetitive structural layout. The results show how optimally locating sensors allows extracting more information from the data. Though the focus is on applications involving repetitive structures, the proposed strategy can be applied to multi-setup modal identification of any large structure.

  2. Virtual sensors for active noise control in acoustic-structural coupled enclosures using structural sensing: part II--Optimization of structural sensor placement.

    PubMed

    Halim, Dunant; Cheng, Li; Su, Zhongqing

    2011-04-01

    The work proposed an optimization approach for structural sensor placement to improve the performance of vibro-acoustic virtual sensor for active noise control applications. The vibro-acoustic virtual sensor was designed to estimate the interior sound pressure of an acoustic-structural coupled enclosure using structural sensors. A spectral-spatial performance metric was proposed, which was used to quantify the averaged structural sensor output energy of a vibro-acoustic system excited by a spatially varying point source. It was shown that (i) the overall virtual sensing error energy was contributed additively by the modal virtual sensing error and the measurement noise energy; (ii) each of the modal virtual sensing error system was contributed by both the modal observability levels for the structural sensing and the target acoustic virtual sensing; and further (iii) the strength of each modal observability level was influenced by the modal coupling and resonance frequencies of the associated uncoupled structural/cavity modes. An optimal design of structural sensor placement was proposed to achieve sufficiently high modal observability levels for certain important panel- and cavity-controlled modes. Numerical analysis on a panel-cavity system demonstrated the importance of structural sensor placement on virtual sensing and active noise control performance, particularly for cavity-controlled modes.

  3. Improved targeting device and computer navigation for accurate placement of brachytherapy needles

    SciTech Connect

    Pappas, Ion P.I.; Ryan, Paul; Cossmann, Peter; Kowal, Jens; Borgeson, Blake; Caversaccio, Marco

    2005-06-15

    Successful treatment of skull base tumors with interstitial brachytherapy requires high targeting accuracy for the brachytherapy needles to avoid harming vital anatomical structures. To enable safe placement of the needles in this area, we developed an image-based planning and navigation system for brachytherapy, which includes a custom-made mechanical positioning arm that allows rough and fine adjustment of the needle position. The fine-adjustment mechanism consists of an XYZ microstage at the base of the arm and a needle holder with two fine-adjustable inclinations. The rotation axes of the inclinations cross at the tip of the needle so that the inclinational adjustments do not interfere with the translational adjustments. A vacuum cushion and a noninvasive fixation frame are used for the head immobilization. To avoid mechanical bending of the needles due to the weight of attached tracking markers, which would be detrimental for targeting accuracy, only a single LED marker on the tail of the needle is used. An experimental phantom-based targeting study with this setup demonstrated that a positioning accuracy of 1.4 mm (rms) can be achieved. The study showed that the proposed setup allows brachytherapy needles to be easily aligned and inserted with high targeting accuracy according to a preliminary plan. The achievable accuracy is higher than if the needles are inserted manually. The proposed system can be linked to a standard afterloader and standard dosimetry planning module. The associated additional effort is reasonable for the clinical practice and therefore the proposed procedure provides a promising tool for the safe treatment of tumors in the skull base area.

  4. Target and collection optimization for muon colliders

    SciTech Connect

    Mokhov, N.V.; Noble, R.J.; Van Ginneken, A.

    1996-01-10

    To achieve adequate luminosity in a muon collider it is necessary to produce and collect large numbers of muons. The basic method used in this paper follows closely a proposed scheme which starts with a proton beam impinging on a thick target ({approximately} one interaction length) followed by a long solenoid which collects muons resulting mainly from pion decay. Production and collection of pions and their decay muons must be optimized while keeping in mind limitations of target integrity and of the technology of magnets and cavities. Results of extensive simulations for 8 GeV protons on various targets and with various collection schemes are reported. Besides muon yields results include-energy deposition in target and solenoid to address cooling requirements for these systems. Target composition, diameter, and length are varied in this study as well as the configuration and field strengths of the solenoid channel. A curved solenoid field is introduced to separate positive and negative pions within a few meters of the target. This permits each to be placed in separate RF buckets for acceleration which effectively doubles the number of muons per bunch available for collisions and increases the luminosity fourfold.

  5. A Simultaneous Biogeography based Optimal Placement of DG Units and Capacitor Banks in Distribution Systems with Nonlinear Loads

    NASA Astrophysics Data System (ADS)

    Sadeghi, Hassan; Ghaffarzadeh, Navid

    2016-09-01

    This paper uses a new algorithm namely biogeography based optimization (BBO) intended for the simultaneous placement of the distributed generation (DG) units and the capacitor banks in the distribution network. The procedure of optimization has been conducted in the presence of nonlinear loads (a cause of harmonic injection). The purpose of simultaneous optimal placement of the DG and the capacitor is the reduction of active and reactive losses. The difference in the values of loss reduction at different levels of the load have been included in the objective function and the considered objective function includes the constraints of voltage, size and the number of DG units and capacitor banks and the allowable range of the total harmonic distortion (THD) of the total voltage in accordance with the IEEE 519 standards. In this paper the placement has been performed on two load types ie constant and mixed power, moreover the effects of load models on the results and the effects of optimal placement on reduction of the THD levels have also been analyzed. The mentioned cases have been studied on a 33 bus radial distribution system.

  6. Field-Based Optimal Placement of Antennas for Body-Worn Wireless Sensors

    PubMed Central

    Januszkiewicz, Łukasz; Di Barba, Paolo; Hausman, Sławomir

    2016-01-01

    We investigate a case of automated energy-budget-aware optimization of the physical position of nodes (sensors) in a Wireless Body Area Network (WBAN). This problem has not been presented in the literature yet, as opposed to antenna and routing optimization, which are relatively well-addressed. In our research, which was inspired by a safety-critical application for firefighters, the sensor network consists of three nodes located on the human body. The nodes communicate over a radio link operating in the 2.4 GHz or 5.8 GHz ISM frequency band. Two sensors have a fixed location: one on the head (earlobe pulse oximetry) and one on the arm (with accelerometers, temperature and humidity sensors, and a GPS receiver), while the position of the third sensor can be adjusted within a predefined region on the wearer’s chest. The path loss between each node pair strongly depends on the location of the nodes and is difficult to predict without performing a full-wave electromagnetic simulation. Our optimization scheme employs evolutionary computing. The novelty of our approach lies not only in the formulation of the problem but also in linking a fully automated optimization procedure with an electromagnetic simulator and a simplified human body model. This combination turns out to be a computationally effective solution, which, depending on the initial placement, has a potential to improve performance of our example sensor network setup by up to about 20 dB with respect to the path loss between selected nodes. PMID:27196911

  7. Simultaneous optimization of force and placement of friction dampers under seismic loading

    NASA Astrophysics Data System (ADS)

    Fleck Fadel Miguel, Letícia; Fleck Fadel Miguel, Leandro; Holdorf Lopez, Rafael

    2016-04-01

    It is known that the use of passive energy-dissipation devices, such as friction dampers, reduces considerably the dynamic response of a structure subjected to earthquake ground motions. Nevertheless, the parameters of each damper and the best placement of these devices remain difficult to determine. Some articles on optimum design of tuned mass dampers and viscous dampers have been published; however, there is a lack of studies on optimization of friction dampers. The main contribution of this article is to propose a methodology to simultaneously optimize the location of friction dampers and their friction forces in structures subjected to seismic loading, to achieve a desired level of reduction in the response. For this purpose, the recently developed backtracking search optimization algorithm (BSA) is employed, which can deal with optimization problems involving mixed discrete and continuous variables. For illustration purposes, two different structures are presented. The first is a six-storey shear building and the second is a transmission line tower. In both cases, the forces and positions of friction dampers are the design variables, while the objective functions are to minimize the interstorey drift for the first case and to minimize the maximum displacement at the top of the tower for the second example. The results show that the proposed method was able to reduce the interstorey drift of the shear building by more than 65% and the maximum displacement at the top of the tower by approximately 55%, with only three friction dampers. The proposed methodology is quite general and it could be recommended as an effective tool for optimum design of friction dampers for structural response control. Thus, this article shows that friction dampers can be designed in a safe and economic way.

  8. Impact of Brine Extraction and Well Placement Optimization on Geologic Carbon Storage Capacity Estimation

    NASA Astrophysics Data System (ADS)

    Ganjdanesh, R.; Hosseini, S. A.

    2015-12-01

    Capacity of carbon dioxide storage aquifers depends on a variety of factors including geologic properties and operational designs. The injection well numbers, well spacing and location, open versus closed boundary conditions, and injection with or without extraction of brine are of the parameters that impact the capacity of a storage site. Brine extraction from storage formations has been introduced as an effective strategy for enhancing the storage capacity and mitigating the risk of rapid pressure buildup. It is proposed that extracted brine can be disposed within an overlying formation or will be desalinated at surface facilities. Optimal well placement and rate of CO2 injection/brine extraction control achieving a predefined pressure constraint at the end of a specific period of storage operation. Reservoir simulation study is required to solve the two-phase flow of gas/brine and pressure buildup in the aquifer. Numerical simulation of geological storage using multiple injectors and extractors is costly and time consuming. Instead, analytical simulation can provide the results with a very good accuracy in a fraction of time compared to the numerical simulation. In this study, an analytical solution was implemented for pressure buildup calculation. The analytical model includes the effects of two-phase relative permeability, CO2 dissolution into reservoir brine and formation of a dry-out zone around the wellbore. Through the optimization algorithm coupled with analytical model, the optimal rates and locations of CO2 injectors and brine extractors were estimated, while simultaneously satisfying the pressure constraint to avoid fracture pressure in all injectors. The optimized results of analytical model was verified with a numerical simulator for several reservoir conditions, well configurations and operating constraints. The comparison of the results shows that the analytical model is a reliable tool for preliminary capacity estimation of saline aquifers and

  9. Multi-Scale Low-Entropy Method for Optimizing the Processing Parameters during Automated Fiber Placement.

    PubMed

    Han, Zhenyu; Sun, Shouzheng; Fu, Hongya; Fu, Yunzhong

    2017-09-03

    Automated fiber placement (AFP) process includes a variety of energy forms and multi-scale effects. This contribution proposes a novel multi-scale low-entropy method aiming at optimizing processing parameters in an AFP process, where multi-scale effect, energy consumption, energy utilization efficiency and mechanical properties of micro-system could be taken into account synthetically. Taking a carbon fiber/epoxy prepreg as an example, mechanical properties of macro-meso-scale are obtained by Finite Element Method (FEM). A multi-scale energy transfer model is then established to input the macroscopic results into the microscopic system as its boundary condition, which can communicate with different scales. Furthermore, microscopic characteristics, mainly micro-scale adsorption energy, diffusion coefficient entropy-enthalpy values, are calculated under different processing parameters based on molecular dynamics method. Low-entropy region is then obtained in terms of the interrelation among entropy-enthalpy values, microscopic mechanical properties (interface adsorbability and matrix fluidity) and processing parameters to guarantee better fluidity, stronger adsorption, lower energy consumption and higher energy quality collaboratively. Finally, nine groups of experiments are carried out to verify the validity of the simulation results. The results show that the low-entropy optimization method can reduce void content effectively, and further improve the mechanical properties of laminates.

  10. Optimizing ventriculoperitoneal shunt placement in the treatment of idiopathic intracranial hypertension: an analysis of neuroendoscopy, frameless stereotaxy, and intraoperative CT.

    PubMed

    Yim, Benjamin; Reid Gooch, M; Dalfino, John C; Adamo, Matthew A; Kenning, Tyler J

    2016-03-01

    Cerebrospinal fluid shunting can effectively lower intracranial pressure and improve the symptoms of idiopathic intracranial hypertension (IIH). Placement of ventriculoperitoneal (VP) shunts in this patient population can often be difficult due to the small size of the ventricular system. Intraoperative adjuvant techniques can be used to improve the accuracy and safety of VP shunts for these patients. The purpose of this study was to analyze the efficacy of some of these techniques, including the use of intraoperative CT (iCT) and frameless stereotaxy, in optimizing postoperative ventricular catheter placement. The authors conducted a retrospective review of 49 patients undergoing initial ventriculoperitoneal shunt placement for the treatment of IIH. The use of the NeuroPEN Neuroendoscope, intraoperative neuronavigation, and iCT was examined. To analyze ventricular catheter placement on postoperative CT imaging, the authors developed a new grading system: Grade 1, catheter tip terminates optimally in the ipsilateral frontal horn or third ventricle; Grade 2, catheter tip terminates in the contralateral frontal horn; Grade 3, catheter terminates in a nontarget CSF space; and Grade 4, catheter tip terminates in brain parenchyma. All shunts had spontaneous CSF flow upon completion of the procedure. The average body mass index among all patients was 37.6 ± 10.9 kg/m2. The NeuroPEN Neuroendoscope was used in 44 of 49 patients. Intraoperative CT scans were obtained in 24 patients, and neuronavigation was used in 32 patients. Grade 1 or 2 final postoperative shunt placement was achieved in 90% of patients (44 of 49). In terms of achieving optimal postoperative ventricular catheter placement, the use of iCT was as effective as neuronavigation. Two patients had their ventricular catheter placement modified based on an iCT study. The use of neuronavigation significantly increased time in the operating room (223.4 ± 46.5 vs. 190.8 ± 31.7 minutes, p = 0.01). There were no

  11. MaNGA: Target selection and Optimization

    NASA Astrophysics Data System (ADS)

    Wake, David

    2016-01-01

    The 6-year SDSS-IV MaNGA survey will measure spatially resolved spectroscopy for 10,000 nearby galaxies using the Sloan 2.5m telescope and the BOSS spectrographs with a new fiber arrangement consisting of 17 individually deployable IFUs. We present the simultaneous design of the target selection and IFU size distribution to optimally meet our targeting requirements. The requirements for the main samples were to use simple cuts in redshift and magnitude to produce an approximately flat number density of targets as a function of stellar mass, ranging from 1x109 to 1x1011 M⊙, and radial coverage to either 1.5 (Primary sample) or 2.5 (Secondary sample) effective radii, while maximizing S/N and spatial resolution. In addition we constructed a "Color-Enhanced" sample where we required 25% of the targets to have an approximately flat number density in the color and mass plane. We show how these requirements are met using simple absolute magnitude (and color) dependent redshift cuts applied to an extended version of the NASA Sloan Atlas (NSA), how this determines the distribution of IFU sizes and the resulting properties of the MaNGA sample.

  12. MaNGA: Target selection and Optimization

    NASA Astrophysics Data System (ADS)

    Wake, David

    2015-01-01

    The 6-year SDSS-IV MaNGA survey will measure spatially resolved spectroscopy for 10,000 nearby galaxies using the Sloan 2.5m telescope and the BOSS spectrographs with a new fiber arrangement consisting of 17 individually deployable IFUs. We present the simultaneous design of the target selection and IFU size distribution to optimally meet our targeting requirements. The requirements for the main samples were to use simple cuts in redshift and magnitude to produce an approximately flat number density of targets as a function of stellar mass, ranging from 1x109 to 1x1011 M⊙, and radial coverage to either 1.5 (Primary sample) or 2.5 (Secondary sample) effective radii, while maximizing S/N and spatial resolution. In addition we constructed a 'Color-Enhanced' sample where we required 25% of the targets to have an approximately flat number density in the color and mass plane. We show how these requirements are met using simple absolute magnitude (and color) dependent redshift cuts applied to an extended version of the NASA Sloan Atlas (NSA), how this determines the distribution of IFU sizes and the resulting properties of the MaNGA sample.

  13. Optimal training for emergency needle thoracostomy placement by prehospital personnel: didactic teaching versus a cadaver-based training program.

    PubMed

    Grabo, Daniel; Inaba, Kenji; Hammer, Peter; Karamanos, Efstathios; Skiada, Dimitra; Martin, Matthew; Sullivan, Maura; Demetriades, Demetrios

    2014-09-01

    Tension pneumothorax can rapidly progress to cardiac arrest and death if not promptly recognized and appropriately treated. We sought to evaluate the effectiveness of traditional didactic slide-based lectures (SBLs) as compared with fresh tissue cadaver-based training (CBT) for placement of needle thoracostomy (NT). Forty randomly selected US Navy corpsmen were recruited to participate from incoming classes of the Navy Trauma Training Center at the LAC + USC Medical Center and were then randomized to one of two NT teaching methods. The following outcomes were compared between the two study arms: (1) time required to perform the procedure, (2) correct placement of the needle, and (3) magnitude of deviation from the correct position. During the study period, a total of 40 corpsmen were enrolled, 20 randomized to SBL and 20 to CBT arms. When outcomes were analyzed, time required to NT placement was not different between the two arms. Examination of the location of needle placement revealed marked differences between the two study groups. Only a minority of the SBL group (35%) placed the NT correctly in the second intercostal space. In comparison, the majority of corpsmen assigned to the CBT group demonstrated accurate placement in the second intercostal space (75%). In a CBT module, US Navy corpsmen were better trained to place NT accurately than their traditional didactic SBL counterparts. Further studies are indicated to identify the optimal components of effective simulation training for NT and other emergent interventions.

  14. Optimal sensor placement for time-domain identification using a wavelet-based genetic algorithm

    NASA Astrophysics Data System (ADS)

    Mahdavi, Seyed Hossein; Razak, Hashim Abdul

    2016-06-01

    This paper presents a wavelet-based genetic algorithm strategy for optimal sensor placement (OSP) effective for time-domain structural identification. Initially, the GA-based fitness evaluation is significantly improved by using adaptive wavelet functions. Later, a multi-species decimal GA coding system is modified to be suitable for an efficient search around the local optima. In this regard, a local operation of mutation is introduced in addition with regeneration and reintroduction operators. It is concluded that different characteristics of applied force influence the features of structural responses, and therefore the accuracy of time-domain structural identification is directly affected. Thus, the reliable OSP strategy prior to the time-domain identification will be achieved by those methods dealing with minimizing the distance of simulated responses for the entire system and condensed system considering the force effects. The numerical and experimental verification on the effectiveness of the proposed strategy demonstrates the considerably high computational performance of the proposed OSP strategy, in terms of computational cost and the accuracy of identification. It is deduced that the robustness of the proposed OSP algorithm lies in the precise and fast fitness evaluation at larger sampling rates which result in the optimum evaluation of the GA-based exploration and exploitation phases towards the global optimum solution.

  15. A Dynamic Programming Algorithm for Finding the Optimal Placement of a Secondary Structure Topology in Cryo-EM Data.

    PubMed

    Biswas, Abhishek; Ranjan, Desh; Zubair, Mohammad; He, Jing

    2015-09-01

    The determination of secondary structure topology is a critical step in deriving the atomic structures from the protein density maps obtained from electron cryomicroscopy technique. This step often relies on matching the secondary structure traces detected from the protein density map to the secondary structure sequence segments predicted from the amino acid sequence. Due to inaccuracies in both sources of information, a pool of possible secondary structure positions needs to be sampled. One way to approach the problem is to first derive a small number of possible topologies using existing matching algorithms, and then find the optimal placement for each possible topology. We present a dynamic programming method of Θ(Nq(2)h) to find the optimal placement for a secondary structure topology. We show that our algorithm requires significantly less computational time than the brute force method that is in the order of Θ(q(N) h).

  16. The BLAIRR Irradiation Facility Hybrid Spallation Target Optimization

    SciTech Connect

    Simos N.; Hanson A.; Brown, D.; Elbakhshawn, M.

    2016-04-11

    BLAIRR STUDY STATUS OVERVIEW Beamline Complex Evaluation/Assessment and Adaptation to the Goals Facility Radiological Constraints ? Large scale analyses of conventional facility and integrated shield (concrete, soil)Target Optimization and Design: Beam-target interaction optimization Hadronic interaction and energy deposition limitations Single phase and Hybrid target concepts Irradiation Damage Thermo-mechanical considerations Spallation neutron fluence optimization for (a) fast neutron irradiation damage (b) moderator/reflector studies, (c) NTOF potential and optimization (d) mono-energetic neutron beam

  17. Method for Vibration Response Simulation and Sensor Placement Optimization of a Machine Tool Spindle System with a Bearing Defect

    PubMed Central

    Cao, Hongrui; Niu, Linkai; He, Zhengjia

    2012-01-01

    Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response. PMID:23012514

  18. PI controller design of a wind turbine: evaluation of the pole-placement method and tuning using constrained optimization

    NASA Astrophysics Data System (ADS)

    Mirzaei, Mahmood; Tibaldi, Carlo; Hansen, Morten H.

    2016-09-01

    PI/PID controllers are the most common wind turbine controllers. Normally a first tuning is obtained using methods such as pole-placement or Ziegler-Nichols and then extensive aeroelastic simulations are used to obtain the best tuning in terms of regulation of the outputs and reduction of the loads. In the traditional tuning approaches, the properties of different open loop and closed loop transfer functions of the system are not normally considered. In this paper, an assessment of the pole-placement tuning method is presented based on robustness measures. Then a constrained optimization setup is suggested to automatically tune the wind turbine controller subject to robustness constraints. The properties of the system such as the maximum sensitivity and complementary sensitivity functions (Ms and Mt ), along with some of the responses of the system, are used to investigate the controller performance and formulate the optimization problem. The cost function is the integral absolute error (IAE) of the rotational speed from a disturbance modeled as a step in wind speed. Linearized model of the DTU 10-MW reference wind turbine is obtained using HAWCStab2. Thereafter, the model is reduced with model order reduction. The trade-off curves are given to assess the tunings of the poles- placement method and a constrained optimization problem is solved to find the best tuning.

  19. Method for vibration response simulation and sensor placement optimization of a machine tool spindle system with a bearing defect.

    PubMed

    Cao, Hongrui; Niu, Linkai; He, Zhengjia

    2012-01-01

    Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response.

  20. Dose-shaping using targeted sparse optimization

    SciTech Connect

    Sayre, George A.; Ruan, Dan

    2013-07-15

    }{sup sparse} improves tradeoff between planning goals by 'sacrificing' voxels that have already been violated to improve PTV coverage, PTV homogeneity, and/or OAR-sparing. In doing so, overall plan quality is increased since these large violations only arise if a net reduction in E{sub tot}{sup sparse} occurs as a result. For example, large violations to dose prescription in the PTV in E{sub tot}{sup sparse}-optimized plans will naturally localize to voxels in and around PTV-OAR overlaps where OAR-sparing may be increased without compromising target coverage. The authors compared the results of our method and the corresponding clinical plans using analyses of DVH plots, dose maps, and two quantitative metrics that quantify PTV homogeneity and overdose. These metrics do not penalize underdose since E{sub tot}{sup sparse}-optimized plans were planned such that their target coverage was similar or better than that of the clinical plans. Finally, plan deliverability was assessed with the 2D modulation index.Results: The proposed method was implemented using IBM's CPLEX optimization package (ILOG CPLEX, Sunnyvale, CA) and required 1-4 min to solve with a 12-core Intel i7 processor. In the testing procedure, the authors optimized for several points on the Pareto surface of four 7-field 6MV prostate cases that were optimized for different levels of PTV homogeneity and OAR-sparing. The generated results were compared against each other and the clinical plan by analyzing their DVH plots and dose maps. After developing intuition by planning the four prostate cases, which had relatively few tradeoffs, the authors applied our method to a 7-field 6 MV pancreas case and a 9-field 6MV head-and-neck case to test the potential impact of our method on more challenging cases. The authors found that our formulation: (1) provided excellent flexibility for balancing OAR-sparing with PTV homogeneity; and (2) permitted the dose planner more control over the evolution of the PTV's spatial dose

  1. Dose-shaping using targeted sparse optimization.

    PubMed

    Sayre, George A; Ruan, Dan

    2013-07-01

    planning goals by "sacrificing" voxels that have already been violated to improve PTV coverage, PTV homogeneity, and/or OAR-sparing. In doing so, overall plan quality is increased since these large violations only arise if a net reduction in E tot (sparse) occurs as a result. For example, large violations to dose prescription in the PTV in E tot (sparse)-optimized plans will naturally localize to voxels in and around PTV-OAR overlaps where OAR-sparing may be increased without compromising target coverage. The authors compared the results of our method and the corresponding clinical plans using analyses of DVH plots, dose maps, and two quantitative metrics that quantify PTV homogeneity and overdose. These metrics do not penalize underdose since Etot (sparse)-optimized plans were planned such that their target coverage was similar or better than that of the clinical plans. Finally, plan deliverability was assessed with the 2D modulation index. The proposed method was implemented using IBM's CPLEX optimization package (ILOG CPLEX, Sunnyvale, CA) and required 1-4 min to solve with a 12-core Intel i7 processor. In the testing procedure, the authors optimized for several points on the Pareto surface of four 7-field 6MV prostate cases that were optimized for different levels of PTV homogeneity and OAR-sparing. The generated results were compared against each other and the clinical plan by analyzing their DVH plots and dose maps. After developing intuition by planning the four prostate cases, which had relatively few tradeoffs, the authors applied our method to a 7-field 6 MV pancreas case and a 9-field 6MV head-and-neck case to test the potential impact of our method on more challenging cases. The authors found that our formulation: (1) provided excellent flexibility for balancing OAR-sparing with PTV homogeneity; and (2) permitted the dose planner more control over the evolution of the PTV's spatial dose distribution than conventional objective functions. In particular, Etot

  2. SUSTAIN -AN EVALUATION AND COST-OPTIMIZATION TOOL FOR PLACEMENT OF BMPS

    EPA Science Inventory

    Since 2003, the U.S. Environmental Protection Agency (USEPA) has been developing a decision support system for placement of best management practices (BMPs) to assist stormwater management professionals in planning for BMPs implementation at strategic locations in urban watershed...

  3. SUSTAIN -AN EVALUATION AND COST-OPTIMIZATION TOOL FOR PLACEMENT OF BMPS

    EPA Science Inventory

    Since 2003, the U.S. Environmental Protection Agency (USEPA) has been developing a decision support system for placement of best management practices (BMPs) to assist stormwater management professionals in planning for BMPs implementation at strategic locations in urban watershed...

  4. Data on four criteria for targeting the placement of conservation buffers in agricultural landscapes

    PubMed Central

    Qiu, Zeyuan; Dosskey, Michael G.; Kang, Yang

    2016-01-01

    Four criteria are generally used to prioritize agricultural lands for placing conservation buffers. The criteria include soil erodibility, hydrological sensitivity, wildlife habitat, and impervious surface rate that capture conservation buffers’ benefits in reducing soil erosion, controlling runoff generation, enhancing wildlife habitat, and mitigating stormwater impacts, respectively. This article describes the data used to derive the values of those attributes and a scheme to classify the values in multi-criteria analysis of conservation buffer placement in “Choosing between alternative placement strategies for conservation buffers using borda count” [1]. PMID:27222843

  5. Laparoscopic-assisted catheter insertion for continuous ambulatory peritoneal dialysis: A case report of simple technique for optimal placement

    PubMed Central

    Hori, Tomohide; Nakauchi, Masaya; Nagao, Kazuhiro; Oike, Fumitaka; Tanaka, Takahiro; Gunji, Daigo; Okada, Noriyuki

    2013-01-01

    A 40-year-old male underwent tube placement surgery for continuous ambulatory peritoneal dialysis (CAPD). A 2-cm skin incision was made, and the peritoneum was reflected enough to perform secure fixation. A swan-necked, double-felted silicone CAPD catheter was inserted, and the felt cuff was sutured to the peritoneum to avoid postoperative leakage. An adequate gradient for tube fixation to the abdominal wall was confirmed. The CAPD tube was passed through a subcutaneous tunnel. Aeroperitoneum was induced to confirm that there was no air leakage from the sites of CAPD insertion. Two trocars were placed, and we confirmed that the CAPD tube led to the rectovesical pouch. Tip position was reliably observed laparoscopically. Optimal patency of the CAPD tube was confirmed during surgery. Placement of CAPD catheters by laparoscopic-assisted surgery has clear advantages in simplicity, safety, flexibility, and certainty. Laparoscopic technique should be considered the first choice for CAPD tube insertion. PMID:24179625

  6. The tool positioning tutor: a target-pose tracking and display system for learning correct placement of a medical device.

    PubMed

    Nelson, Douglas A; Samosky, Joseph T

    2011-01-01

    Safe and successful performance of medical procedures often requires the correct manual positioning of a tool. For example, during endotracheal intubation a laryngoscope is used to open a passage in the airway through which a breathing tube is inserted. During training it can be challenging for an experienced practitioner to effectively communicate to a novice the correct placement and orientation of a tool. We have implemented a real-time tracking and position display system to enhance learning correct laryngoscope placement. The system displays a 3D model of the laryngoscope. A clinical teacher can correctly position the laryngoscope to open the airway of a full-body simulator, then set this tool pose as the target position. The system displays to the learner the fixed, target pose and a real-time display of the current, "live" laryngoscope position. Positional error metrics are displayed as color-coded visual cues to guide the user toward successful targeting of the reference position. This technique provides quantitative assessment of the degree to which a learner has matched a specified "expert" position with a tool, and is potentially applicable to a wide variety of tools and procedures.

  7. Automated Zebrafish Chorion Removal and Single Embryo Placement: Optimizing Throughput of Zebrafish Developmental Toxicity Screens

    PubMed Central

    Mandrell, David; Truong, Lisa; Jephson, Caleb; Sarker, Mushfiqur R.; Moore, Aaron; Lang, Christopher; Simonich, Michael T.; Tanguay, Robert L.

    2012-01-01

    The potential of the developing zebrafish model for toxicology and drug discovery is limited by inefficient approaches to manipulating and chemically exposing zebrafish embryos—namely, manual placement of embryos into 96- or 384-well plates and exposure of embryos while still in the chorion, a barrier of poorly characterized permeability enclosing the developing embryo. We report the automated dechorionation of 1600 embryos at once at 4 h postfertilization (hpf) and placement of the dechorionated embryos into 96-well plates for exposure by 6 hpf. The process removed ≥95% of the embryos from their chorions with 2% embryo mortality by 24 hpf, and 2% of the embryos malformed at 120 hpf. The robotic embryo placement allocated 6-hpf embryos to 94.7% ± 4.2% of the wells in multiple 96-well trials. The rate of embryo mortality was 2.8% (43 of 1536) from robotic handling, the rate of missed wells was 1.2% (18 of 1536), and the frequency of multipicks was <0.1%. Embryo malformations observed at 24 hpf occurred nearly twice as frequently from robotic handling (16 of 864; 1.9%) as from manual pipetting (9 of 864; 1%). There was no statistical difference between the success of performing the embryo placement robotically or manually. PMID:22357610

  8. AN EVALUATION AND COST-OPTIMIZATION TOOL FOR PLACEMENT OF BMPS

    EPA Science Inventory

    To assist stormwater management professionals in planning for best management practices (BMPs) implementation, the U.S. Environmental Protection Agency (USEPA) is developing a decision-support system for placement of BMPs at strategic locations in urban watersheds. This tool wil...

  9. AN EVALUATION AND COST-OPTIMIZATION TOOL FOR PLACEMENT OF BMPS

    EPA Science Inventory

    To assist stormwater management professionals in planning for best management practices (BMPs) implementation, the U.S. Environmental Protection Agency (USEPA) is developing a decision-support system for placement of BMPs at strategic locations in urban watersheds. This tool wil...

  10. Optimal placement of sensors for structural system identification and health monitoring using a hybrid swarm intelligence technique

    NASA Astrophysics Data System (ADS)

    Rama Mohan Rao, A.; Anandakumar, Ganesh

    2007-12-01

    Setting up a health monitoring system for large-scale civil engineering structures requires a large number of sensors and the placement of these sensors is of great significance for such spatially separated large structures. In this paper, we present an optimal sensor placement (OSP) algorithm by treating OSP as a combinatorial optimization problem which is solved using a swarm intelligence technique called particle swarm optimization (PSO). We propose a new hybrid PSO algorithm by combining a self-configurable PSO with the Nelder-Mead algorithm to solve this rather difficult combinatorial problem of OSP. The proposed algorithm aims precisely to achieve the best identification of modal frequencies and mode shapes. Numerical experiments have been carried out by considering civil engineering structures to evaluate the performance of the proposed swarm-intelligence-based OSP algorithm. Numerical studies indicate that the proposed hybrid PSO algorithm generates sensor configurations superior to the conventional iterative information-based approaches which have been popularly used for large structures. Further, the proposed hybrid PSO algorithm exhibits superior convergence characteristics when compared to other PSO counterparts.

  11. Altered Passive Eruption Complicating Optimal Orthodontic Bracket Placement: A Case Report and Review of Literature

    PubMed Central

    Chitra, Prasad

    2015-01-01

    An unusual case of altered passive eruption with gingival hyperpigmentation and a Class I malocclusion in a 12-year-old girl having no previous history of medication is presented. The patient reported with spacing in the upper arch, moderate crowding in the lower arch, anterior crossbite and excessive gingival tissue on the labial surfaces of teeth in both the arches. The inadequate crown lengths made placement of the orthodontic brackets difficult. Preadjusted orthodontic brackets have a very precise placement protocol which can affect tooth movement in all 3 planes of space if violated. The periodontal condition was diagnosed as altered passive eruption Type IA. Interdisciplinary treatment protocols including periodontal surgical and orthodontic procedures were used. The periodontal surgical procedures were carried out prior to orthodontic therapy and the results obtained were satisfactory. It is suggested that orthodontists should be aware of conditions like altered passive eruption and modalities of management. In most instances, orthodontic therapy is not hindered. PMID:26672498

  12. Optimal base station placement for wireless sensor networks with successive interference cancellation.

    PubMed

    Shi, Lei; Zhang, Jianjun; Shi, Yi; Ding, Xu; Wei, Zhenchun

    2015-01-14

    We consider the base station placement problem for wireless sensor networks with successive interference cancellation (SIC) to improve throughput. We build a mathematical model for SIC. Although this model cannot be solved directly, it enables us to identify a necessary condition for SIC on distances from sensor nodes to the base station. Based on this relationship, we propose to divide the feasible region of the base station into small pieces and choose a point within each piece for base station placement. The point with the largest throughput is identified as the solution. The complexity of this algorithm is polynomial. Simulation results show that this algorithm can achieve about 25% improvement compared with the case that the base station is placed at the center of the network coverage area when using SIC.

  13. Optimal Base Station Placement for Wireless Sensor Networks with Successive Interference Cancellation

    PubMed Central

    Shi, Lei; Zhang, Jianjun; Shi, Yi; Ding, Xu; Wei, Zhenchun

    2015-01-01

    We consider the base station placement problem for wireless sensor networks with successive interference cancellation (SIC) to improve throughput. We build a mathematical model for SIC. Although this model cannot be solved directly, it enables us to identify a necessary condition for SIC on distances from sensor nodes to the base station. Based on this relationship, we propose to divide the feasible region of the base station into small pieces and choose a point within each piece for base station placement. The point with the largest throughput is identified as the solution. The complexity of this algorithm is polynomial. Simulation results show that this algorithm can achieve about 25% improvement compared with the case that the base station is placed at the center of the network coverage area when using SIC. PMID:25594600

  14. Optimal sensor placement for detecting organophosphate intrusions into water distribution systems.

    PubMed

    Ohar, Ziv; Lahav, Ori; Ostfeld, Avi

    2015-04-15

    Placement of water quality sensors in a water distribution system is a common approach for minimizing contamination intrusion risks. This study incorporates detailed chemistry of organophosphate contaminations into the problem of sensor placement and links quantitative measures of the affected population as a result of such intrusions. The suggested methodology utilizes the stoichiometry and kinetics of the reactions between organophosphate contaminants and free chlorine for predicting the number of affected consumers. This is accomplished through linking a multi-species water quality model and a statistical dose-response model. Three organophosphates (chlorpyrifos, malathion, and parathion) are tested as possible contaminants. Their corresponding by-products were modeled and accounted for in the affected consumers impact calculations. The methodology incorporates a series of randomly generated intrusion events linked to a genetic algorithm for minimizing the contaminants impact through a sensors system. Three example applications are explored for demonstrating the model capabilities through base runs and sensitivity analyses.

  15. Optical network unit placement in Fiber-Wireless (FiWi) access network by Moth-Flame optimization algorithm

    NASA Astrophysics Data System (ADS)

    Singh, Puja; Prakash, Shashi

    2017-07-01

    Hybrid wireless-optical broadband access network (WOBAN) or Fiber-Wireless (FiWi) is the integration of wireless access network and optical network. This hybrid multi-domain network adopts the advantages of wireless and optical domains and serves the demand of technology savvy users. FiWi exhibits the properties of cost effectiveness, robustness, flexibility, high capacity, reliability and is self organized. Optical Network Unit (ONU) placement problem in FiWi contributes in simplifying the network design and enhances the performance in terms of cost efficiency and increased throughput. Several individual-based algorithms, such as Simulated Annealing (SA), Tabu Search, etc. have been suggested for ONU placement, but these algorithms suffer from premature convergence (trapping in a local optima). The present research work undertakes the deployment of FiWi and proposes a novel nature-inspired heuristic paradigm called Moth-Flame optimization (MFO) algorithm for multiple optical network units' placement. MFO is a population based algorithm. Population-based algorithms are better in handling local optima avoidance. The simulation results are compared with the existing Greedy and Simulated Annealing algorithms to optimize the position of ONUs. To the best of our knowledge, MFO algorithm has been used for the first time in this domain, moreover it has been able to provide very promising and competitive results. The performance of MFO algorithm has been analyzed by varying the 'b' parameter. MFO algorithm results in faster convergence than the existing strategies of Greedy and SA and returns a lower value of overall cost function. The results exhibit the dependence of the objective function on the distribution of wireless users also.

  16. Multilevel optimization for the placement of piezo-actuators on plate structures for active vibration control using modified heuristic genetic algorithm

    NASA Astrophysics Data System (ADS)

    Chhabra, Deepak; Bhushan, Gian; Chandna, Pankaj

    2014-03-01

    The present work considers with the optimal placement of piezoelectric actuators on a thin plate via modified control matrix and singular value decomposition (MCSVD) approach using Modified Heuristic Genetic Algorithm (MHGA). Optimal placement of piezoelectric actuators is investigated to suppress the first six modes on cantilever plate. Vibration suppression has been studied for cantilever plate with piezoelectric patches in optimal positions using LQR (Linear Quadratic regulator) scheme. It is observed that developed present approach has given the greater closed loop damping ratio and lesser computational requirements.

  17. Targeted Gene Therapies: Tools, Applications, Optimization

    PubMed Central

    Humbert, Olivier; Davis, Luther; Maizels, Nancy

    2012-01-01

    Many devastating human diseases are caused by mutations in a single gene that prevent a somatic cell from carrying out its essential functions, or by genetic changes acquired as a result of infectious disease or in the course of cell transformation. Targeted gene therapies have emerged as potential strategies for treatment of such diseases. These therapies depend upon rare-cutting endonucleases to cleave at specific sites in or near disease genes. Targeted gene correction provides a template for homology-directed repair, enabling the cell's own repair pathways to erase the mutation and replace it with the correct sequence. Targeted gene disruption ablates the disease gene, disabling its function. Gene targeting can also promote other kinds of genome engineering, including mutation, insertion, or gene deletion. Targeted gene therapies present significant advantages compared to approaches to gene therapy that depend upon delivery of stably expressing transgenes. Recent progress has been fueled by advances in nuclease discovery and design, and by new strategies that maximize efficiency of targeting and minimize off-target damage. Future progress will build on deeper mechanistic understanding of critical factors and pathways. PMID:22530743

  18. Placement of Base Stations in Broadband Power Line Communications Access Networks by Means of Multi-criteria Optimization

    NASA Astrophysics Data System (ADS)

    Haidine, Abdelfatteh; Lehnert, Ralf

    Broadband Power Line Communications (B-PLC) technology is an alternative for broadband access networks, allowing bit rates up to currently 200Mbps. This technique uses the wiring of the low-voltage grid in order to offer to the users the telecommunications services, such as Internet, VoIP, VoD, etc. The B-PLC design process is sub-divided into two parts: the Generalized Base Station Placement (GBSP) problem and the PLC Channel Allocation Problem (P-CAP). This paper focuses on GBSP that is modeled as multi-criteria combinatorial optimization problem. Based on our published mathematical modeling, this paper supplies more numerical experiments for the evaluation of Multi-Objective Evolutionary Algorithms (MOEAs) in solving GBSP. Their performance is compared with the single-objective optimization.

  19. Accuracy of targeted wire guided tube thoracostomy in comparison to classical surgical chest tube placement - A clinical study.

    PubMed

    Protic, Alen; Barkovic, Igor; Ivancic, Aldo; Kricka, Ozren; Zuvic-Butorac, Marta; Sustic, Alan

    2015-11-01

    Chest tube malfunction, after the tube thoracostomy, is often the result of an inappropriate chest tube tip position. The aim of this study was to analyse the precision of chest tube placement using the targeted wire guide technique (TWG technique) with curve dilator and to compare it to the classical surgical technique (CS technique). In this clinical study 80 patients with an indication for thoracic drainage, due to pneumothorax or pleural effusion were included. Experimental group contained 39 patients whose chest tube was placed using the TWG technique. The control group contained 41 patients whose chest tube was placed using the CS technique. The comparison of the outcomes of the two techniques applied suggests that the TWG technique was significantly more successful in achieving adequate (precise) chest tube placement, irrespective of patient diagnosis (TWG vs. CS in all patients, 78.4% vs. 36.6%, p<0.001). In the pleural effusion group, TWG and CS had success rates of 78.2% and 37.5% (p=0.005), respectively, while in pneumothorax group, TWG and CS had success rates of 78.6% and 35.3% (p=0.029), respectively. Using a curved dilator and the TWG technique for the thoracic drainage procedure we found statistically significant advantage to the TWG technique in comparison to the CS technique (78% vs. 37%) regarding precise chest tube placement within the pleural cavity. Introducing the materials and technique used in this clinical trial into clinical practice may improve the quality of thoracic drainage, including residual volume of air and/or fluid, poor functioning of the chest tube, and, as a consequence of both, prolonged hospitalisation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Deterministic optimal maneuver strategy for multi-target missions

    NASA Technical Reports Server (NTRS)

    Dwivedi, N. P.

    1975-01-01

    This paper presents an optimal strategy for making impulsive correction to a multi-target trajectory by a single maneuver. The concept of an optimal maneuver time is introduced. The choice of suitable weighting functions is explored to enable one to properly translate the subjective desire of mission success into an objective cost function whose minimization yields the optimal strategy. It is shown that a number of strategies previously formulated are derivable from one general expression. A number of other interesting properties of the optimal strategy are described. Numerical results are presented for a typical two-target mission. It is shown that the strategy formulated is optimal. For some perturbations, there exists an optimal maneuver time different from the time of initiation of the perturbation. That is, the physical properties of the trajectory can be exploited to select the optimal time of making a corrective maneuver.

  1. Targeted Optimization of Quasi-Symmetric Stellarators

    SciTech Connect

    Hegna, Chris C.; Anderson, D. T.; Talmadge, J. N.

    2016-10-06

    The proposed research focuses on targeted areas of plasma physics dedicated to improving the stellarator concept. Research was pursued in the technical areas of edge/divertor physics in 3D configurations, magnetic island physics in stellarators, the role of 3D shaping on microinstabilities and turbulent transport and energetic ion confinement in stellarators.

  2. Optimization of the Target for Muon Colliders.

    NASA Astrophysics Data System (ADS)

    Takahashi, H.; An, Y.; Chen, X.; Nomura, M.

    1997-05-01

    To obtain high luminosity in a muon collider it is necessary to produce and collect a large number of muons. To evaluate the various nuclear cascade codes, we calculated the rate of particle production and energy deposition of a 1 cm radius target with a radiation length of 1.5, of carbon or copper, placed in a 28 Tesla solenoid field, into which 8 or 30 GeV protons were injected using the LAHET and GEANT codes. We compared the results with those calculated with MARS, DPMJET and ARC. The positive pion yields from the LAHET are almost the same as tose from the MARS calculation, however, the negative pion yield for the high energy proton injection is higher than the yield of positive pions. The yield of positive and negative pions by GEANT code are, respectively, 1.5 and 2.0 times greater than the MARS calculation. The energy deposition calculated by the GEANT code is very close to the one calculated by MARS: 143 and 153 kW/cc for carbon target at 8 and 30 GeV proton injected, and for copper target they are, respectively, 376 and 744 kW/cc. The deposition energy in the copper target calculated by the LAHET codes is smaller than those obtained by GEANT code.

  3. Optimal Geometrical Set for Automated Marker Placement to Virtualized Real-Time Facial Emotions.

    PubMed

    Maruthapillai, Vasanthan; Murugappan, Murugappan

    2016-01-01

    In recent years, real-time face recognition has been a major topic of interest in developing intelligent human-machine interaction systems. Over the past several decades, researchers have proposed different algorithms for facial expression recognition, but there has been little focus on detection in real-time scenarios. The present work proposes a new algorithmic method of automated marker placement used to classify six facial expressions: happiness, sadness, anger, fear, disgust, and surprise. Emotional facial expressions were captured using a webcam, while the proposed algorithm placed a set of eight virtual markers on each subject's face. Facial feature extraction methods, including marker distance (distance between each marker to the center of the face) and change in marker distance (change in distance between the original and new marker positions), were used to extract three statistical features (mean, variance, and root mean square) from the real-time video sequence. The initial position of each marker was subjected to the optical flow algorithm for marker tracking with each emotional facial expression. Finally, the extracted statistical features were mapped into corresponding emotional facial expressions using two simple non-linear classifiers, K-nearest neighbor and probabilistic neural network. The results indicate that the proposed automated marker placement algorithm effectively placed eight virtual markers on each subject's face and gave a maximum mean emotion classification rate of 96.94% using the probabilistic neural network.

  4. Optimal Geometrical Set for Automated Marker Placement to Virtualized Real-Time Facial Emotions

    PubMed Central

    Maruthapillai, Vasanthan; Murugappan, Murugappan

    2016-01-01

    In recent years, real-time face recognition has been a major topic of interest in developing intelligent human-machine interaction systems. Over the past several decades, researchers have proposed different algorithms for facial expression recognition, but there has been little focus on detection in real-time scenarios. The present work proposes a new algorithmic method of automated marker placement used to classify six facial expressions: happiness, sadness, anger, fear, disgust, and surprise. Emotional facial expressions were captured using a webcam, while the proposed algorithm placed a set of eight virtual markers on each subject’s face. Facial feature extraction methods, including marker distance (distance between each marker to the center of the face) and change in marker distance (change in distance between the original and new marker positions), were used to extract three statistical features (mean, variance, and root mean square) from the real-time video sequence. The initial position of each marker was subjected to the optical flow algorithm for marker tracking with each emotional facial expression. Finally, the extracted statistical features were mapped into corresponding emotional facial expressions using two simple non-linear classifiers, K-nearest neighbor and probabilistic neural network. The results indicate that the proposed automated marker placement algorithm effectively placed eight virtual markers on each subject’s face and gave a maximum mean emotion classification rate of 96.94% using the probabilistic neural network. PMID:26859884

  5. Swarm intelligence algorithms for integrated optimization of piezoelectric actuator and sensor placement and feedback gains

    NASA Astrophysics Data System (ADS)

    Dutta, Rajdeep; Ganguli, Ranjan; Mani, V.

    2011-10-01

    Swarm intelligence algorithms are applied for optimal control of flexible smart structures bonded with piezoelectric actuators and sensors. The optimal locations of actuators/sensors and feedback gain are obtained by maximizing the energy dissipated by the feedback control system. We provide a mathematical proof that this system is uncontrollable if the actuators and sensors are placed at the nodal points of the mode shapes. The optimal locations of actuators/sensors and feedback gain represent a constrained non-linear optimization problem. This problem is converted to an unconstrained optimization problem by using penalty functions. Two swarm intelligence algorithms, namely, Artificial bee colony (ABC) and glowworm swarm optimization (GSO) algorithms, are considered to obtain the optimal solution. In earlier published research, a cantilever beam with one and two collocated actuator(s)/sensor(s) was considered and the numerical results were obtained by using genetic algorithm and gradient based optimization methods. We consider the same problem and present the results obtained by using the swarm intelligence algorithms ABC and GSO. An extension of this cantilever beam problem with five collocated actuators/sensors is considered and the numerical results obtained by using the ABC and GSO algorithms are presented. The effect of increasing the number of design variables (locations of actuators and sensors and gain) on the optimization process is investigated. It is shown that the ABC and GSO algorithms are robust and are good choices for the optimization of smart structures.

  6. Dexterity optimization by port placement in robot-assisted minimally invasive surgery

    NASA Astrophysics Data System (ADS)

    Selha, Shaun; Dupont, Pierre; Howe, Robert D.; Torchiana, David F.

    2002-02-01

    A computer-based algorithm has been developed which uses preoperative images to provide a surgeon with a list of feasible port triplets ranked according to tool dexterity and endoscopic view quality at each surgical site involved in a procedure. A computer simulation allows the surgeon to select from among the proposed port locations. The procedure selected for the development of the system consists of a coronary artery bypass graft (CABG). In this procedure, the interior mammary artery (IMA) is mobilized from the interior chest wall, and one end is attached to the coronary arteries to provide a new blood supply for the heart. Approximately 10-20 cm is dissected free, using blunt dissection and a harmonic scalpel or electrocautery. At present, the port placement system is being evaluated in clinical trials.

  7. A novel radiographic targeting guide for percutaneous placement of transfacet screws in the cervical spine with limited fluoroscopy: A cadaveric feasibility study

    PubMed Central

    Jackson, David M.; Karp, Jacqueline E.; O'Brien, Joseph R.; Anderson, D. Greg; Gelb, Daniel E.; Ludwig, Steven C.

    2012-01-01

    Background We describe a technique for percutaneous transfacet screw placement in the cervical spine without the need for lateral-view fluoroscopy. Methods Previously established articular pillar morphometry was used to define the ideal trajectory for transfacet screw placement in the subaxial cervical spine. A unique targeting guide was developed to allow placement of Kirschner wires across the facet joint at 90° without the guidance of lateral-view fluoroscopy. Kirschner wires and cannulated screws were placed percutaneously in 7 cadaveric specimens. Placement of instrumentation was performed entirely under modified anteroposterior-view fluoroscopy. All specimens were assessed for acceptable screw placement by 2 fellowship-trained orthopaedic spine surgeons using computed tomography. Open dissection was used to confirm radiographic interpretation. Acceptable placement was defined as a screw crossing the facet joint, achieving purchase in the inferior and superior articular processes, and not violating critical structures. Malposition was defined as a violation of the transverse foramen, spinal canal, or nerve root or inadequate fixation. Results A total of 48 screws were placed. Placement of 45 screws was acceptable. The 3 instances of screw malposition included a facet fracture, a facet distraction, and a C6-7 screw contacting the C7 nerve root in a specimen with a small C7 superior articular process. Conclusions Our data show that with the appropriate radiographic technique and a targeting guide, percutaneous transfacet screws can be safely placed at C3-7 without the need for lateral-view fluoroscopy during the targeting phase. Because of the variable morphometry of the C7 lateral mass, however, care must be taken when placing a transfacet screw at C6-7. Clinical Relevance This study describes a technique that has the potential to provide a less invasive strategy for posterior instrumentation of the cervical spine. Further investigation is needed before this

  8. Targeting the subthalamic nucleus for deep brain stimulation: technical approach and fusion of pre- and postoperative MR images to define accuracy of lead placement.

    PubMed

    Hamid, N A; Mitchell, R D; Mocroft, P; Westby, G W M; Milner, J; Pall, H

    2005-03-01

    To define the role of magnetic resonance imaging (MRI) and intraoperative electrophysiological recording in targeting the subthalamic nucleus (STN) in Parkinson's disease and to determine accuracy of electrode placement. We implanted 54 electrodes into the STN in 27 patients. Target planning was done by coordinate guidelines and visualising the STN on MRI and defined in relation to the mid-point of the AC-PC line. Intraoperative microelectrode recording was used. We adjusted electrode positions for placement in the centre of the STN electrical activity and verified this on postoperative MRI in 16 cases, which were fused to the preoperative images to measure actual error in electrode placement in the three axes. Based on coordinate calculation and MRI localisation, the mean of the target was 11.5 mm lateral, 2.5 mm posterior and 4.1 mm inferior to the mid-point of the AC-PC line. Fifty good electrophysiological recordings of the STN (average length 4.65 mm) were achieved and target point adjusted in 90% of lead placements. The mean of the final target after electrophysiological correction was 11.7 mm lateral, 2.1 mm posterior, and 3.8 mm inferior to the mid-point. The distance from the centre of the electrode artefact to the final target used after electrophysiological recording on the fused images was 0.48 mm, 0.69 mm, and 2.9 mm in the x, y, and z axes, respectively. No postoperative MRI related complication was observed. Both direct visualisation of the STN on MRI and intraoperative electrophysiological recording are important in defining the best target. Individual variations exist in the location of the STN target. Fewer tracks were required to define STN activity on the side operated first. Our current stereotactic method of electrode placement is relatively accurate.

  9. Single-Command Approach and Instrument Placement by a Robot on a Target

    NASA Technical Reports Server (NTRS)

    Huntsberger, Terrance; Cheng, Yang

    2005-01-01

    AUTOAPPROACH is a computer program that enables a mobile robot to approach a target autonomously, starting from a distance of as much as 10 m, in response to a single command. AUTOAPPROACH is used in conjunction with (1) software that analyzes images acquired by stereoscopic cameras aboard the robot and (2) navigation and path-planning software that utilizes odometer readings along with the output of the image-analysis software. Intended originally for application to an instrumented, wheeled robot (rover) in scientific exploration of Mars, AUTOAPPROACH could be adapted to terrestrial applications, notably including the robotic removal of land mines and other unexploded ordnance. A human operator generates the approach command by selecting the target in images acquired by the robot cameras. The approach path consists of multiple legs. Feature points are derived from images that contain the target and are thereafter tracked to correct odometric errors and iteratively refine estimates of the position and orientation of the robot relative to the target on successive legs. The approach is terminated when the robot attains the position and orientation required for placing a scientific instrument at the target. The workspace of the robot arm is then autonomously checked for self/terrain collisions prior to the deployment of the scientific instrument onto the target.

  10. Optimal placement of actuators for active vibration control of seismic excited tall buildings using a multiple start guided neighbourhood search (MSGNS) algorithm

    NASA Astrophysics Data System (ADS)

    Rama Mohan Rao, A.; Sivasubramanian, K.

    2008-03-01

    Active control devices can be implemented on seismically excited high rise buildings using appropriate active control theory, to reduce structural responses to a desired level. Certain locations of the structure are advantageous for placement of actuators in the sense that these locations effectively reduce the structural responses. Hence, optimal placement of actuators at discrete locations is an important problem that will have significant impact on control of civil structures like high rise buildings, bridges, etc. This optimal placement problem leads to a combinatorial optimisation and is difficult to solve. This paper presents a multi-start meta-heuristic algorithm called multiple start guided neighbourhood search (MSGNS) algorithm, which makes use of the good features of guided local searches like simulated annealing (SA) and tabu search (TS). Four distinct design criteria which influence the active control design are considered in this paper to study the optimal actuator placement problem. The sensitivities of the four optimisation criteria with respect to different earthquake records are explored. Further, in this paper, we deviate from the usual practice of using shear building models (or simple lumped mass model) in active control research for finding optimal actuator locations. Instead, we use detailed finite element models and demonstrate through numerical examples their effectiveness in arriving at the optimal actuator locations. Finally, the superior performance of the proposed MSGNS algorithm over popular meta-heuristic algorithms like GA, SA and TS is demonstrated through numerical experiments.

  11. Optimal placement of tuning masses for vibration reduction in helicopter rotor blades

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1988-01-01

    Methods are presented for the reduction of helicopter rotor blade vibration through a formal mathematical optimization technique determination of optimum tuning mass sizes and locations; these are used as design variables that are systematically changed to achieve low values of shear without large mass penalty. Matrix expressions are obtained for the modal shaping parameter and modal shear amplitude that are required for FEM structural analysis of the blade as well as the optimization formulation. Sensitivity derivatives are also obtained. Three different optimization strategies are developed and tested.

  12. Optimizing biologically targeted clinical trials for neurofibromatosis

    PubMed Central

    Gutmann, David H; Blakeley, Jaishri O; Korf, Bruce R; Packer, Roger J

    2014-01-01

    Introduction The neurofibromatoses (neurofibromatosis type 1, NF1 and neurofibromatosis type 2, NF2) comprise the most common inherited conditions in which affected children and adults develop tumors of the central and peripheral nervous system. In this review, the authors discuss how the establishment of the Neurofibromatosis Clinical Trials Consortium (NFCTC) has positively impacted on the design and execution of treatment studies for individuals with NF1 and NF2. Areas covered Using an extensive PUBMED search in collaboration with select NFCTC members expert in distinct NF topics, the authors discuss the clinical features of NF1 and NF2, the molecular biology of the NF1 and NF2 genes, the development and application of clinically relevant Nf1 and Nf2 genetically engineered mouse models and the formation of the NFCTC to enable efficient clinical trial design and execution. Expert opinion The NFCTC has resulted in a more seamless integration of mouse preclinical and human clinical trials efforts. Leveraging emerging enabling resources, current research is focused on identifying subtypes of tumors in NF1 and NF2 to deliver the most active compounds to the patients most likely to respond to the targeted therapy. PMID:23425047

  13. Optimizing biologically targeted clinical trials for neurofibromatosis.

    PubMed

    Gutmann, David H; Blakeley, Jaishri O; Korf, Bruce R; Packer, Roger J

    2013-04-01

    The neurofibromatoses (neurofibromatosis type 1, NF1 and neurofibromatosis type 2, NF2) comprise the most common inherited conditions in which affected children and adults develop tumors of the central and peripheral nervous system. In this review, the authors discuss how the establishment of the Neurofibromatosis Clinical Trials Consortium (NFCTC) has positively impacted on the design and execution of treatment studies for individuals with NF1 and NF2. Using an extensive PUBMED search in collaboration with select NFCTC members expert in distinct NF topics, the authors discuss the clinical features of NF1 and NF2, the molecular biology of the NF1 and NF2 genes, the development and application of clinically relevant Nf1 and Nf2 genetically engineered mouse models and the formation of the NFCTC to enable efficient clinical trial design and execution. The NFCTC has resulted in a more seamless integration of mouse preclinical and human clinical trials efforts. Leveraging emerging enabling resources, current research is focused on identifying subtypes of tumors in NF1 and NF2 to deliver the most active compounds to the patients most likely to respond to the targeted therapy.

  14. Optimal actuator placement on an active reflector using a modified simulated annealing technique

    NASA Technical Reports Server (NTRS)

    Kuo, Chin-Po; Bruno, Robin

    1991-01-01

    The development of a lightweight actuation system for maintaining the surface accuracy of a composite honeycomb panel using piezoelectric actuators is discussed. A modified simulated annealing technique is used to optimize the problem with both combinatorial and continuous criteria and with inequality constraints. Near optimal solutions for the location of the actuators, using combinatorial optimization, and for the required actuator forces, employing continuous optimization, are sought by means of the modified simulated annealing technique. The actuator locations are determined by first seeking a near optimum solution using the modified simulated annealing technique. The final actuator configuration consists of an arrangement wherein the piezoelectric actuators are placed along six radial lines. Numerical results showing the achievable surface correction by means of this configuration are presented.

  15. Voltage stability index based optimal placement of static VAR compensator and sizing using Cuckoo search algorithm

    NASA Astrophysics Data System (ADS)

    Venkateswara Rao, B.; Kumar, G. V. Nagesh; Chowdary, D. Deepak; Bharathi, M. Aruna; Patra, Stutee

    2017-07-01

    This paper furnish the new Metaheuristic algorithm called Cuckoo Search Algorithm (CSA) for solving optimal power flow (OPF) problem with minimization of real power generation cost. The CSA is found to be the most efficient algorithm for solving single objective optimal power flow problems. The CSA performance is tested on IEEE 57 bus test system with real power generation cost minimization as objective function. Static VAR Compensator (SVC) is one of the best shunt connected device in the Flexible Alternating Current Transmission System (FACTS) family. It has capable of controlling the voltage magnitudes of buses by injecting the reactive power to system. In this paper SVC is integrated in CSA based Optimal Power Flow to optimize the real power generation cost. SVC is used to improve the voltage profile of the system. CSA gives better results as compared to genetic algorithm (GA) in both without and with SVC conditions.

  16. Evaluating the uncertainty in optimal crop management placements for bioenergy crop production

    NASA Astrophysics Data System (ADS)

    Sudheer, K. P.; Krishnan, N.; Chaubey, I.; Raj, C.

    2016-12-01

    Watershed scale simulation models are used to evaluate various `what if' questions and to make informed decisions. These mathematical models include many empirical and/or non-empirical parameters to represent various eco-hydrological processes. Parameter uncertainty is a major issue in mathematical model simulations, as often the actual parameter values are not available or are measurable. The model parameter uncertainty can affect simulation results and consequent decisions. The objective of the study was to evaluate parameter uncertainty of Soil and Water Assessment Tool (SWAT), and to evaluate potential impacts of uncertainty in model simulations on the decisions suggested for land use planning. An optimization based land use planning case study was developed to identify optimal cropping pattern including bioenergy crops in the St Joseph River watershed, IN, USA. The objective function for land use optimization included biomass production of 3,581 metric tons per day (under thermochemical conversion) minimum feasible production for a biomass processing plant, with minimum biomass production cost and maximum environmental benefits. Parameter uncertainty of the SWAT model is assessed using Shuffled Complex Evolutionary Metropolis Algorithm (SCEM). Five representative parameter sets were selected from the prediction uncertainty interval to represent the parameter uncertainty. The SWAT model was linked with AMALGAM optimizer to derive at an optimal cropping pattern for the watershed. Five sets of land use optimizations were conducted considering the five sets of parameter values, and the effects of parameter uncertainty on optimization results were quantified. The preliminary results showed that the simulation optimization results had some level of uncertainty that needed to be included in making land use decisions for bioenergy crop production.

  17. Characteristics and optimization of radar target with plasma cover

    NASA Astrophysics Data System (ADS)

    Yang, Ying-ying; Zhao, Wei-fang; Wang, Wen-ting; Yi, Xiao-jing; Ji, Jun-wen; Lin, Xue-chun

    2013-09-01

    In this paper, we investigated the characteristic of radar target, the spherical and the pyramidal missile warheads, and compared the RCS and performance of the targets with and without the cover of the plasma metamaterials. Numerical simulation is obtained by the numerical calculation Finite-difference time-domain method (FDTD). The parameters of plasmonic structures as a metamaterial cloak was designed and optimized. The relationship between the parameters of the cloak and the corresponding electromagnetic characteristic of the target are analyzed by the simulation and discussion in broadband radar signals. After optimization, the plasma cover could attenuate 40 dBsm of the radar cross section (RCS) of the targets maximally. The result shows that the anomalous phenomenon of cloaking and stealth effects induced by plasma materials for the radar target, which might have potential application of military affairs.

  18. Optimization of shunt placement for the Norwood surgery using multi-domain modeling.

    PubMed

    Moghadam, Mahdi Esmaily; Migliavacca, Francesco; Vignon-Clementel, Irene E; Hsia, Tain-Yen; Marsden, Alison L

    2012-05-01

    An idealized systemic-to-pulmonary shunt anatomy is parameterized and coupled to a closed loop, lumped parameter network (LPN) in a multidomain model of the Norwood surgical anatomy. The LPN approach is essential for obtaining information on global changes in cardiac output and oxygen delivery resulting from changes in local geometry and physiology. The LPN is fully coupled to a custom 3D finite element solver using a semi-implicit approach to model the heart and downstream circulation. This closed loop multidomain model is then integrated with a fully automated derivative-free optimization algorithm to obtain optimal shunt geometries with variable parameters of shunt diameter, anastomosis location, and angles. Three objective functions: (1) systemic; (2) coronary; and (3) combined systemic and coronary oxygen deliveries are maximized. Results show that a smaller shunt diameter with a distal shunt-brachiocephalic anastomosis is optimal for systemic oxygen delivery, whereas a more proximal anastomosis is optimal for coronary oxygen delivery and a shunt between these two anatomies is optimal for both systemic and coronary oxygen deliveries. Results are used to quantify the origin of blood flow going through the shunt and its relationship with shunt geometry. Results show that coronary artery flow is directly related to shunt position.

  19. A Topography Analysis Incorporated Optimization Method for the Selection and Placement of Best Management Practices

    PubMed Central

    Shen, Zhenyao; Chen, Lei; Xu, Liang

    2013-01-01

    Best Management Practices (BMPs) are one of the most effective methods to control nonpoint source (NPS) pollution at a watershed scale. In this paper, the use of a topography analysis incorporated optimization method (TAIOM) was proposed, which integrates topography analysis with cost-effective optimization. The surface status, slope and the type of land use were evaluated as inputs for the optimization engine. A genetic algorithm program was coded to obtain the final optimization. The TAIOM was validated in conjunction with the Soil and Water Assessment Tool (SWAT) in the Yulin watershed in Southwestern China. The results showed that the TAIOM was more cost-effective than traditional optimization methods. The distribution of selected BMPs throughout landscapes comprising relatively flat plains and gentle slopes, suggests the need for a more operationally effective scheme, such as the TAIOM, to determine the practicability of BMPs before widespread adoption. The TAIOM developed in this study can easily be extended to other watersheds to help decision makers control NPS pollution. PMID:23349917

  20. A topography analysis incorporated optimization method for the selection and placement of best management practices.

    PubMed

    Shen, Zhenyao; Chen, Lei; Xu, Liang

    2013-01-01

    Best Management Practices (BMPs) are one of the most effective methods to control nonpoint source (NPS) pollution at a watershed scale. In this paper, the use of a topography analysis incorporated optimization method (TAIOM) was proposed, which integrates topography analysis with cost-effective optimization. The surface status, slope and the type of land use were evaluated as inputs for the optimization engine. A genetic algorithm program was coded to obtain the final optimization. The TAIOM was validated in conjunction with the Soil and Water Assessment Tool (SWAT) in the Yulin watershed in Southwestern China. The results showed that the TAIOM was more cost-effective than traditional optimization methods. The distribution of selected BMPs throughout landscapes comprising relatively flat plains and gentle slopes, suggests the need for a more operationally effective scheme, such as the TAIOM, to determine the practicability of BMPs before widespread adoption. The TAIOM developed in this study can easily be extended to other watersheds to help decision makers control NPS pollution.

  1. A small perturbation based optimization approach for the frequency placement of high aspect ratio wings

    NASA Astrophysics Data System (ADS)

    Goltsch, Mandy

    Design denotes the transformation of an identified need to its physical embodiment in a traditionally iterative approach of trial and error. Conceptual design plays a prominent role but an almost infinite number of possible solutions at the outset of design necessitates fast evaluations. The corresponding practice of empirical equations and low fidelity analyses becomes obsolete in the light of novel concepts. Ever increasing system complexity and resource scarcity mandate new approaches to adequately capture system characteristics. Contemporary concerns in atmospheric science and homeland security created an operational need for unconventional configurations. Unmanned long endurance flight at high altitudes offers a unique showcase for the exploration of new design spaces and the incidental deficit of conceptual modeling and simulation capabilities. Structural and aerodynamic performance requirements necessitate light weight materials and high aspect ratio wings resulting in distinct structural and aeroelastic response characteristics that stand in close correlation with natural vibration modes. The present research effort evolves around the development of an efficient and accurate optimization algorithm for high aspect ratio wings subject to natural frequency constraints. Foundational corner stones are beam dimensional reduction and modal perturbation redesign. Local and global analyses inherent to the former suggest corresponding levels of local and global optimization. The present approach departs from this suggestion. It introduces local level surrogate models to capacitate a methodology that consists of multi level analyses feeding into a single level optimization. The innovative heart of the new algorithm originates in small perturbation theory. A sequence of small perturbation solutions allows the optimizer to make incremental movements within the design space. It enables a directed search that is free of costly gradients. System matrices are decomposed

  2. Accounting for connectivity and spatial correlation in the optimal placement of wildlife habitat

    Treesearch

    John Hof; Curtis H. Flather

    1996-01-01

    This paper investigates optimization approaches to simultaneously modelling habitat fragmentation and spatial correlation between patch populations. The problem is formulated with habitat connectivity affecting population means and variances, with spatial correlations accounted for in covariance calculations. Population with a pre-specifled confidence level is then...

  3. Optimal placement of tuning masses for vibration reduction in helicopter rotor blades

    NASA Technical Reports Server (NTRS)

    Pritchard, Jocelyn I.; Adelman, Howard M.

    1988-01-01

    Described are methods for reducing vibration in helicopter rotor blades by determining optimum sizes and locations of tuning masses through formal mathematical optimization techniques. An optimization procedure is developed which employs the tuning masses and corresponding locations as design variables which are systematically changed to achieve low values of shear without a large mass penalty. The finite-element structural analysis of the blade and the optimization formulation require development of discretized expressions for two performance parameters: modal shaping parameter and modal shear amplitude. Matrix expressions for both quantities and their sensitivity derivatives are developed. Three optimization strategies are developed and tested. The first is based on minimizing the modal shaping parameter which indirectly reduces the modal shear amplitudes corresponding to each harmonic of airload. The second strategy reduces these amplitudes directly, and the third strategy reduces the shear as a function of time during a revolution of the blade. The first strategy works well for reducing the shear for one mode responding to a single harmonic of the airload, but has been found in some cases to be ineffective for more than one mode. The second and third strategies give similar results and show excellent reduction of the shear with a low mass penalty.

  4. Improving diagnostic yield in brain biopsy: coupling spectroscopic targeting with real-time needle placement.

    PubMed

    Hall, W A; Martin, A; Liu, H; Truwit, C L

    2001-01-01

    The purpose of this study was to determine the utility of intraoperative magnetic resonance spectroscopy (MRS) for targeting during brain biopsy using a skull-mounted trajectory guide. From January 1999 to January 2001, 17 patients had intraoperative MRS-guided brain biopsy using a trajectory guide. Ten had turbo spectroscopic imaging (TSI), and seven had both SVS (single-voxel spectroscopy) and TSI. Prospective stereotaxy was used to align the device in a short-bore 1.5-T MR scanner. Areas of elevated choline relative to creatine on SVS and TSI were targeted during the biopsy. Intraoperative imaging confirmed appropriate positioning of the biopsy needle at the time of tissue sampling in all cases. All 17 biopsies (100%) yielded diagnostic tissue. Six patients (34%) had glioblastomas multiforme, three (18%) had anaplastic astrocytomas, three (18%) had anaplastic oligodendrogliomas, two (12%) had radiation necrosis, and one each (6%) had germinoma, ganglioglioma, and astrocytoma. Postoperative imaging confirmed the absence of clinically and radiographically relevant hemorrhage. The findings on SVS correlated with the pathology in all seven cases (100%). In 13 of 17 patients (76%) who had TSI, the spectra correlated well with the permanent pathologic examination. The SVS and TSI spectra were similar in six of seven (86%) cases. Intraoperative MRS-guided brain biopsy using a trajectory guide is a simple, safe, and accurate technique for accessing areas of the brain of diagnostic interest. J. Magn. Reson. Imaging 2001;13:12-15. Copyright 2001 Wiley-Liss, Inc.

  5. Optimal Well Placement for Enhanced Degradation during In Situ Groundwater Remediation

    NASA Astrophysics Data System (ADS)

    Greene, J. A.; Neupauer, R.; Piscopo, A. N.; Kasprzyk, J. R.

    2015-12-01

    Active spreading strategies have been developed to enhance contaminant degradation during in situ remediation by increasing contact of the injected treatment chemical with the contaminant plume. The contact between these reactants is increased by strategically injecting and extracting water at wells surrounding the plume to reconfigure the treatment chemical and contaminant plume in the aquifer, which leads to enhanced contaminant degradation. The distance and orientation of the wells relative to the contaminant plume affects the ability of active spreading strategies to efficiently degrade contaminant. In this study, we use a multi-objective evolutionary algorithm to optimize the distance and orientation of wells for both circular and elliptical contaminant plumes with uniform and Gaussian initial concentration distributions. The optimization yields results that maximize the amount of degradation achieved during in situ remediation while minimizing any extraction of treatment chemical.

  6. Optimal Placement of Non-Intrusive Waste Heat Recovery Devices in Exhaust Ducts

    DTIC Science & Technology

    2015-06-01

    cases, these recirculation zones create “ dead zones ” where heat transfer through the duct walls is severely restricted. In this case, these dead zones ...of recirculation thinking that they would all act as “ dead zones ” like the primary recirculation zone . Knowing that the impinging flow and local...counterintuitive because of unexpected recirculation zone effects. 14. SUBJECT TERMS Waste heat recovery, thermoelectric generator, optimization

  7. Optimal placement of trailing-edge flaps for helicopter vibration reduction using response surface methods

    NASA Astrophysics Data System (ADS)

    Viswamurthy, S. R.; Ganguli, Ranjan

    2007-03-01

    This study aims to determine optimal locations of dual trailing-edge flaps to achieve minimum hub vibration levels in a helicopter, while incurring low penalty in terms of required trailing-edge flap control power. An aeroelastic analysis based on finite elements in space and time is used in conjunction with an optimal control algorithm to determine the flap time history for vibration minimization. The reduced hub vibration levels and required flap control power (due to flap motion) are the two objectives considered in this study and the flap locations along the blade are the design variables. It is found that second order polynomial response surfaces based on the central composite design of the theory of design of experiments describe both objectives adequately. Numerical studies for a four-bladed hingeless rotor show that both objectives are more sensitive to outboard flap location compared to the inboard flap location by an order of magnitude. Optimization results show a disjoint Pareto surface between the two objectives. Two interesting design points are obtained. The first design gives 77 percent vibration reduction from baseline conditions (no flap motion) with a 7 percent increase in flap power compared to the initial design. The second design yields 70 percent reduction in hub vibration with a 27 percent reduction in flap power from the initial design.

  8. Cardiac MR in robotic heart surgery for preoperative identification of the target vessel and precise port placement--a theoretical model.

    PubMed

    Bergmann, P; Huber, S; Segl, H; Maechler, H; Reiter, U; Reiter, G; Rienmueller, R; Oberwalder, P; Rigler, B

    2003-08-01

    The identification of the ideal anastomosis site and the proper port placement are critical for the success of closed-chest robotic surgery. We investigated a new systematic procedure for precise port placement for TECABs. We used trigonometry and a human thoracic model to determine the optimal working angles between anastomotic plane, instruments, and endoscope. We then applied the results to seven human subjects as follows: 1. A navigation grid was located extrathoracically before cardiac MR examination. 2. The ideal anastomosis site was defined with the MR. Intrathoracic distances and angles were computed with cardiac MR software and projected onto the thorax. 3. The ideal port placement points were marked on the thorax. The optimal working angle between endoscope and instruments was 35 degrees. 0 degrees and 90 degrees angles were associated with a significant reduction in visualization, technical ease, quality and anastomosis time. The course of the LAD was identified in all seven volunteers with MR. Mean deviation of the endoscope port from the medioclavicular line was 4.3+/-2.1 cm and of the instrument ports from the anterior axillary line 8.4+/-2.4 cm. Cardiac MR in combination with the navigation grid proved suitable for the visualization of coronary vessels for individually calculating port placement points on the thorax.

  9. Left Ventricular Lead Placement Targeted at the Latest Activated Site Guided by Electrophysiological Mapping in Coronary Sinus Branches Improves Response to Cardiac Resynchronization Therapy.

    PubMed

    Liang, Yanchun; Yu, Haibo; Zhou, Weiwei; Xu, Guoqing; Sun, Y I; Liu, Rong; Wang, Zulu; Han, Yaling

    2015-12-01

    Electrophysiological mapping (EPM) in coronary sinus (CS) branches is feasible for guiding LV lead placement to the optimal, latest activated site at cardiac resynchronization therapy (CRT) procedures. However, whether this procedure optimizes the response to CRT has not been demonstrated. This study was to evaluate effects of targeting LV lead at the latest activated site guided by EPM during CRT. Seventy-six consecutive patients with advanced heart failure who were referred for CRT were divided into mapping (MG) and control groups (CG). In MG, the LV lead, also used as a mapping bipolar electrode, was placed at the latest activated site determined by EPM in CS branches. In CG, conventional CRT procedure was performed. Patients were followed for 6 months after CRT. Baseline characteristics were comparable between the 2 groups. In MG (n = 29), EPM was successfully performed in 85 of 91 CS branches during CRT. A LV lead was successfully placed at the latest activated site guided by EPM in 27 (93.1%) patients. Compared with CG (n = 47), MG had a significantly higher rate (86.2% vs. 63.8%, P = 0.039) of response (>15% reduction in LV end-systolic volume) to CRT, a higher percentage of patients with clinical improvement of ≥2 NYHA functional classes (72.4% vs. 44.7%, P = 0.032), and a shorter QRS duration (P = 0.004). LV lead placed at the latest activated site guided by EPM resulted in a significantly greater CRT response, and a shorter QRS duration. © 2015 Wiley Periodicals, Inc.

  10. A Clustering Based Approach for Observability and Controllability Analysis for Optimal Placement of PMU

    NASA Astrophysics Data System (ADS)

    Murthy, Ch; MIEEE; Mohanta, D. K.; SMIEE; Meher, Mahendra

    2017-08-01

    Continuous monitoring and control of the power system is essential for its healthy operation. This can be achieved by making the system observable as well as controllable. Many efforts have been made by several researchers to make the system observable by placing the Phasor Measurement Units (PMUs) at the optimal locations. But so far the idea of controllability with PMUs is not considered. This paper contributes how to check whether the system is controllable or not, if not then how make it controllable using a clustering approach. IEEE 14 bus system is considered to illustrate the concept of controllability.

  11. Optimal electrode placement for noninvasive electrical stimulation of human abdominal muscles.

    PubMed

    Lim, Julianne; Gorman, Robert B; Saboisky, Julian P; Gandevia, Simon C; Butler, Jane E

    2007-04-01

    Abdominal muscles are the most important expiratory muscles for coughing. Spinal cord-injured patients have respiratory complications because of abdominal muscle weakness and paralysis and impaired ability to cough. We aimed to determine the optimal positioning of stimulating electrodes on the trunk for the noninvasive electrical activation of the abdominal muscles. In six healthy subjects, we compared twitch pressures produced by a single electrical pulse through surface electrodes placed either posterolaterally or anteriorly on the trunk with twitch pressures produced by magnetic stimulation of nerve roots at the T(10) level. A gastroesophageal catheter measured gastric pressure (Pga) and esophageal pressure (Pes). Twitches were recorded at increasing stimulus intensities at functional residual capacity (FRC) in the seated posture. The maximal intensity used was also delivered at total lung capacity (TLC). At FRC, twitch pressures were greatest with electrical stimulation posterolaterally and magnetic stimulation at T(10) and smallest at the anterior site (Pga, 30 +/- 3 and 33 +/- 6 cm H(2)O vs. 12 +/- 3 cm H(2)O; Pes 8 +/- 2 and 11 +/- 3 cm H(2)O vs. 5 +/- 1 cm H(2)O; means +/- SE). At TLC, twitch pressures were larger. The values for posterolateral electrical stimulation were comparable to those evoked by thoracic magnetic stimulation. The posterolateral stimulation site is the optimal site for generating gastric and esophageal twitch pressures with electrical stimulation.

  12. Optimization of van der Waals Energy for Protein Side-Chain Placement and Design

    PubMed Central

    Fahmy, Amr; Wagner, Gerhard

    2011-01-01

    Computational determination of optimal side-chain conformations in protein structures has been a long-standing and challenging problem. Solving this problem is important for many applications including homology modeling, protein docking, and for placing small molecule ligands on protein-binding sites. Programs available as of this writing are very fast and reasonably accurate, as measured by deviations of side-chain dihedral angles; however, often due to multiple atomic clashes, they produce structures with high positive energies. This is problematic in applications where the energy values are important, for example when placing small molecules in docking applications; the relatively small binding energy of the small molecule is drowned by the large energy due to atomic clashes that hampers finding the lowest energy state of the docked ligand. To address this we have developed an algorithm for generating a set of side-chain conformations that is dense enough that at least one of its members would have a root mean-square deviation of no more than R Å from any possible side-chain conformation of the amino acid. We call such a set a side-chain cover set of order R for the amino acid. The size of the set is constrained by the energy of the interaction of the side chain to the backbone atoms. Then, side-chain cover sets are used to optimize the conformation of the side chains given the coordinates of the backbone of a protein. The method we use is based on a variety of dead-end elimination methods and the recently discovered dynamic programming algorithm for this problem. This was implemented in a computer program called Octopus where we use side-chain cover sets with very small values for R, such as 0.1 Å, which ensures that for each amino-acid side chain the set contains a conformation with a root mean-square deviation of, at most, R from the optimal conformation. The side-chain dihedral-angle accuracy of the program is comparable to other implementations; however

  13. Optimization of van der Waals energy for protein side-chain placement and design.

    PubMed

    Fahmy, Amr; Wagner, Gerhard

    2011-10-05

    Computational determination of optimal side-chain conformations in protein structures has been a long-standing and challenging problem. Solving this problem is important for many applications including homology modeling, protein docking, and for placing small molecule ligands on protein-binding sites. Programs available as of this writing are very fast and reasonably accurate, as measured by deviations of side-chain dihedral angles; however, often due to multiple atomic clashes, they produce structures with high positive energies. This is problematic in applications where the energy values are important, for example when placing small molecules in docking applications; the relatively small binding energy of the small molecule is drowned by the large energy due to atomic clashes that hampers finding the lowest energy state of the docked ligand. To address this we have developed an algorithm for generating a set of side-chain conformations that is dense enough that at least one of its members would have a root mean-square deviation of no more than R Å from any possible side-chain conformation of the amino acid. We call such a set a side-chain cover set of order R for the amino acid. The size of the set is constrained by the energy of the interaction of the side chain to the backbone atoms. Then, side-chain cover sets are used to optimize the conformation of the side chains given the coordinates of the backbone of a protein. The method we use is based on a variety of dead-end elimination methods and the recently discovered dynamic programming algorithm for this problem. This was implemented in a computer program called Octopus where we use side-chain cover sets with very small values for R, such as 0.1 Å, which ensures that for each amino-acid side chain the set contains a conformation with a root mean-square deviation of, at most, R from the optimal conformation. The side-chain dihedral-angle accuracy of the program is comparable to other implementations; however

  14. Optimal Placement Method of RFID Readers in Industrial Rail Transport for Uneven Rail Traflc Volume Management

    NASA Astrophysics Data System (ADS)

    Rakhmangulov, Aleksandr; Muravev, Dmitri; Mishkurov, Pavel

    2016-11-01

    The issue of operative data reception on location and movement of railcars is significant the constantly growing requirements of the provision of timely and safe transportation. The technical solution for efficiency improvement of data collection on rail rolling stock is the implementation of an identification system. Nowadays, there are several such systems, distinguished in working principle. In the authors' opinion, the most promising for rail transportation is the RFID technology, proposing the equipping of the railway tracks by the stationary points of data reading (RFID readers) from the onboard sensors on the railcars. However, regardless of a specific type and manufacturer of these systems, their implementation is affiliated with the significant financing costs for large, industrial, rail transport systems, owning the extensive network of special railway tracks with a large number of stations and loading areas. To reduce the investment costs for creation, the identification system of rolling stock on the special railway tracks of industrial enterprises has developed the method based on the idea of priority installation of the RFID readers on railway hauls, where rail traffic volumes are uneven in structure and power, parameters of which is difficult or impossible to predict on the basis of existing data in an information system. To select the optimal locations of RFID readers, the mathematical model of the staged installation of such readers has developed depending on the non-uniformity value of rail traffic volumes, passing through the specific railway hauls. As a result of that approach, installation of the numerous RFID readers at all station tracks and loading areas of industrial railway stations might be not necessary,which reduces the total cost of the rolling stock identification and the implementation of the method for optimal management of transportation process.

  15. Robust optimization of scoring functions for a target class.

    PubMed

    Seifert, Markus H J

    2009-09-01

    Target-specific optimization of scoring functions for protein-ligand docking is an effective method for significantly improving the discrimination of active and inactive molecules in virtual screening applications. Its applicability, however, is limited due to the narrow focus on, e.g., single protein structures. Using an ensemble of protein kinase structures, the publically available directory of useful decoys ligand dataset, and a novel multi-factorial optimization procedure, it is shown here that scoring functions can be tuned to multiple targets of a target class simultaneously. This leads to an improved robustness of the resulting scoring function parameters. Extensive validation experiments clearly demonstrate that (1) virtual screening performance for kinases improves significantly; (2) variations in database content affect this kind of machine-learning strategy to a lesser extent than binary QSAR models, and (3) the reweighting of interaction types is of particular importance for improved screening performance.

  16. Robust optimization of scoring functions for a target class

    NASA Astrophysics Data System (ADS)

    Seifert, Markus H. J.

    2009-09-01

    Target-specific optimization of scoring functions for protein-ligand docking is an effective method for significantly improving the discrimination of active and inactive molecules in virtual screening applications. Its applicability, however, is limited due to the narrow focus on, e.g., single protein structures. Using an ensemble of protein kinase structures, the publically available directory of useful decoys ligand dataset, and a novel multi-factorial optimization procedure, it is shown here that scoring functions can be tuned to multiple targets of a target class simultaneously. This leads to an improved robustness of the resulting scoring function parameters. Extensive validation experiments clearly demonstrate that (1) virtual screening performance for kinases improves significantly; (2) variations in database content affect this kind of machine-learning strategy to a lesser extent than binary QSAR models, and (3) the reweighting of interaction types is of particular importance for improved screening performance.

  17. Short-Term Distribution System State Forecast Based on Optimal Synchrophasor Sensor Placement and Extreme Learning Machine

    SciTech Connect

    Jiang, Huaiguang; Zhang, Yingchen

    2016-11-14

    This paper proposes an approach for distribution system state forecasting, which aims to provide an accurate and high speed state forecasting with an optimal synchrophasor sensor placement (OSSP) based state estimator and an extreme learning machine (ELM) based forecaster. Specifically, considering the sensor installation cost and measurement error, an OSSP algorithm is proposed to reduce the number of synchrophasor sensor and keep the whole distribution system numerically and topologically observable. Then, the weighted least square (WLS) based system state estimator is used to produce the training data for the proposed forecaster. Traditionally, the artificial neural network (ANN) and support vector regression (SVR) are widely used in forecasting due to their nonlinear modeling capabilities. However, the ANN contains heavy computation load and the best parameters for SVR are difficult to obtain. In this paper, the ELM, which overcomes these drawbacks, is used to forecast the future system states with the historical system states. The proposed approach is effective and accurate based on the testing results.

  18. A novel approach to optimal placement of new trauma centers within an existing trauma system using geospatial mapping.

    PubMed

    Horst, Michael A; Gross, Brian W; Cook, Alan D; Osler, Turner M; Bradburn, Eric H; Rogers, Frederick B

    2017-10-01

    Trauma system expansion is a complex process often governed by financial and health care system imperatives. We sought to propose a new, informed approach to trauma system expansion through the use of geospatial mapping. We hypothesized that geospatial mapping set to specific parameters could effectively identify optimal placement of new trauma centers (TC) within an existing trauma system. We used Pennsylvania Trauma Systems Foundation registry data of adult (age, ≥ 15 years) trauma for calendar years 2003 to 2015 (n = 408,432), hospital demographics, road networks, and US Census data files. We included TCs and zip codes outside of Pennsylvania to account for edge effects with trauma cases aggregated to the zip code centroid of residence. Our model assumptions included existing Pennsylvania Trauma Systems Foundation Level I and II TCs, a maximum travel time of 60 minutes to the TC, capacity based on mean statewide ratios of trauma cases per hospital bed size, Injury Severity Score, candidate hospitals with 200 or more licensed beds and 30 minutes or longer or 15 minutes or longer from an existing TC in nonurban/urban areas, respectively. We used the Network Analyst Location-Allocation function in ArcGIS Desktop to generate spatial models. Of the 130 candidate sites, only 14 met the bed size and travel time criteria from an existing TC. Approximately 70% of zip codes and 91% of cases were within 60 minutes of an existing TC. Adding one to six new optimally paced TCs increased to a maximum of 82% of zip codes and 96% of cases within 60 minutes of an existing TC. Changes to model assumptions had an impact on which candidate sites were selected. Intelligent trauma system design should include an objective process like geospatial to determine the optimum locations for new TCs within existing trauma networks. Epidemiological study, level III.

  19. Optimal Placement of Cerebral Oximeter Monitors to Avoid the Frontal Sinus as Determined by Computed Tomography.

    PubMed

    Gregory, Alexander J; Hatem, Muhammed A; Yee, Kevin; Grocott, Hilary P

    2016-01-01

    To determine the optimal location to place cerebral oximeter optodes to avoid the frontal sinus, using the orbit of the skull as a landmark. Retrospective observational study. Academic hospital. Fifty adult patients with previously acquired computed tomography angiography scans of the head. The distance between the superior orbit of the skull and the most superior edge of the frontal sinus was measured using imaging software. The mean (SD) frontal sinus height was 16.4 (7.2) mm. There was a nonsignificant trend toward larger frontal sinus height in men compared with women (p = 0.12). Age, height, and body surface area did not correlate with frontal sinus height. Head circumference was positively correlated (r = 0.32; p = 0.03) to frontal sinus height, with a low level of predictability based on linear regression (R(2) = 0.10; p = 0.02). Placing cerebral oximeter optodes>3 cm from the superior rim of the orbit will avoid the frontal sinus in>98% of patients. Predicting the frontal sinus height based on common patient variables is difficult. Additional studies are required to evaluate the recommended height in pediatric populations and patients of various ethnic backgrounds. The clinical relevance of avoiding the frontal sinus also needs to be further elucidated. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Target Design Optimization of KIPT Neutron Source Facility

    SciTech Connect

    Zhong, Zhaopeng; Gohar, Yousry; Merzari, Elia; Kraus, Adam; Sofu, Tanju

    2015-01-01

    Argonne National Laboratory (ANL) of the United States developed and designed a neutron source facility for Kharkov Institute of Physics and Technology (KIPT) of Ukraine. The facility was constructed at Kharkov, Ukraine and its commissioning process has been started. The facility has an electron accelerator driving a subcritical assembly. The electron beam power is 100 kW using 100 MeV electrons. The subcritical assembly has WWR-M2 fuel assemblies with U-235 enrichment of 19.7 wt%. The facility will be utilized to perform basic and applied nuclear research, to produce medical isotopes, and to train young nuclear specialists. Solid target design with stacked disks is selected and each target disk is cooled by water from both side. Tungsten or natural uranium is the target material. This paper presents the target design optimization to maximize the neutron yield and the neutron flux level of the facility while satisfying the thermal-hydraulic design criteria. Monte Carlo computer code MCNPX is utilized for the neutron yield analyses with ENDF/B-VII.0 nuclear data libraries, as a function of target thickness using a simplified target model without cladding or coolant channels. It’s found that the neutron yield saturates at target thickness 60 ~ 70 mm for both tungsten and uranium materials. For the final target design with cladding and coolant channels, the total uranium thickness is 56.5 mm, and the total tungsten thickness is only 33.0 mm. The tungsten material has a large absorption cross section for thermal neutrons. If the tungsten thickness is increased, the neutron yield gain is offset by the neutron absorption reaction. The paper presents the design optimization analyses for both target materials.

  1. Optimization of OT-MACH Filter Generation for Target Recognition

    NASA Technical Reports Server (NTRS)

    Johnson, Oliver C.; Edens, Weston; Lu, Thomas T.; Chao, Tien-Hsin

    2009-01-01

    An automatic Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter generator for use in a gray-scale optical correlator (GOC) has been developed for improved target detection at JPL. While the OT-MACH filter has been shown to be an optimal filter for target detection, actually solving for the optimum is too computationally intensive for multiple targets. Instead, an adaptive step gradient descent method was tested to iteratively optimize the three OT-MACH parameters, alpha, beta, and gamma. The feedback for the gradient descent method was a composite of the performance measures, correlation peak height and peak to side lobe ratio. The automated method generated and tested multiple filters in order to approach the optimal filter quicker and more reliably than the current manual method. Initial usage and testing has shown preliminary success at finding an approximation of the optimal filter, in terms of alpha, beta, gamma values. This corresponded to a substantial improvement in detection performance where the true positive rate increased for the same average false positives per image.

  2. An optimal velocity for online limb-target regulation processes?

    PubMed

    Tremblay, Luc; Crainic, Valentin A; de Grosbois, John; Bhattacharjee, Arindam; Kennedy, Andrew; Hansen, Steve; Welsh, Timothy N

    2017-01-01

    The utilization of visual information for the control of ongoing voluntary limb movements has been investigated for more than a century. Recently, online sensorimotor processes for the control of upper-limb reaches were hypothesized to include a distinct process related to the comparison of limb and target positions (i.e., limb-target regulation processes: Elliott et al. in Psychol Bull 136:1023-1044. doi: 10.1037/a0020958 , 2010). In the current study, this hypothesis was tested by presenting participants with brief windows of vision (20 ms) when the real-time velocity of the reaching limb rose above selected velocity criteria. One experiment tested the perceptual judgments of endpoint bias (i.e., under- vs. over-shoot), and another experiment tested the shifts in endpoint distributions following an imperceptible target jump. Both experiments revealed that limb-target regulation processes take place at an optimal velocity or "sweet spot" between movement onset and peak limb velocity (i.e., 1.0 m/s with the employed movement amplitude and duration). In contrast with pseudo-continuous models of online control (e.g., Elliott et al. in Hum Mov Sci 10:393-418. doi: 10.1016/0167-9457(91)90013-N , 1991), humans likely optimize online limb-target regulation processes by gathering visual information at a rather limited period of time, well in advance of peak limb velocity.

  3. An Optimal Initial Guess Generator for Entry Interface Targeters

    NASA Technical Reports Server (NTRS)

    Senent, Juan S.

    2009-01-01

    If a pure numerical iterative approach is used, targeting entry interface (EI) conditions for nominal and abort return trajectories or for correction maneuvers can be computationally expensive. This paper describes an algorithm to obtain an optimal impulsive maneuver that generates a trajectory satisfying a set of EI targets: inequality constraints on longitude, latitude and azimuth and a fixed flight-path angle. Most of the calculations require no iterations, making it suitable for real-time applications or large trade studies. This algorithm has been used to generate initial guesses for abort trajectories during Earth-Moon transfers.

  4. Optimal configuration of static polarization imagers for target detection.

    PubMed

    Goudail, François; Boffety, Matthieu

    2016-01-01

    We determine the set of analysis states of a static Stokes imager that maximizes target detection performance for the least favorable target-background polarimetric configuration. By using a minimax approach, we demonstrate that the optimal choice consists of four analysis states forming a regular tetrahedron in the Poincaré sphere. We also show that the value of the contrast in the best of the four Stokes channels is, in the worst case, equal to one third of that provided by a fully adaptive polarimetric imager. Static Stokes imagers thus constitute an attractive solution in applications where limited loss of discrimination ability can be tolerated.

  5. Keyword: Placement

    ERIC Educational Resources Information Center

    Cassuto, Leonard

    2012-01-01

    The practical goal of graduate education is placement of graduates. But what does "placement" mean? Academics use the word without thinking much about it. "Placement" is a great keyword for the graduate-school enterprise. For one thing, its meaning certainly gives a purpose to graduate education. Furthermore, the word is a portal into the way of…

  6. Keyword: Placement

    ERIC Educational Resources Information Center

    Cassuto, Leonard

    2012-01-01

    The practical goal of graduate education is placement of graduates. But what does "placement" mean? Academics use the word without thinking much about it. "Placement" is a great keyword for the graduate-school enterprise. For one thing, its meaning certainly gives a purpose to graduate education. Furthermore, the word is a portal into the way of…

  7. Optimization of direct drive irradiation uniformity of cylindrical target

    NASA Astrophysics Data System (ADS)

    Tian, Chao; Shan, Lianqiang; Zhou, Weimin; Liu, Dongxiao; Bi, Bi; Zhang, Feng; Wang, Weiwu; Yuan, Zongqiang; Yang, Lei; Gu, Yuqiu; Zhang, Baohan

    2017-07-01

    The irradiation uniformity of a cylindrical target directly driven by laser beams has been considered, which is relevant for fast ignition electron-transport experiments. The laser intensity distribution on the cylindrical target surface is analyzed and optimized by applying the polar direct drive technique and adjusting the laser beam parameters. Moreover, the rotation of laser spot around its propagation axis is taken into consideration. A case study based on the SG-III prototype laser configuration is presented to demonstrate the optimization approach. The irradiation uniformity is reduced from 10% to 1.6% for perfectly balanced beams, and the effects of uncertainties in beam errors (power imbalance and pointing error) are also studied. Furthermore, differences in laser absorption with different incident angles are taken into account and the results show that highly uniform energy deposition can be achieved.

  8. On-road experiment to assess drivers' detection of roadside targets as a function of headlight system, target placement, and target reflectance.

    PubMed

    Reagan, Ian J; Brumbelow, Matt; Frischmann, Tim

    2015-03-01

    Adaptive headlights swivel with steering input to keep the beams on the roadway as drivers negotiate curves. To assess the effects of this feature on driver's visual performance, a field experiment was conducted at night on a rural, unlit, and unlined two-lane road during which 20 adult participant drivers searched a set of 60 targets. High- (n=30) and low- (n=30) reflectance targets were evenly distributed on straight road sections and on the inside or outside of curves. Participants completed three target detection trials: once with adaptive high-intensity discharge (HID) headlights, once with fixed HID headlights, and once with fixed halogen headlights. Results indicated the adaptive HID headlights helped drivers detect targets that were most difficult to see (low reflectance) at the points in curves found by other researchers to be most crucial for successful navigation (inside apex). For targets placed on straight stretches of road or on the outside of curves, the adaptive feature provided no significant improvement in target detection. However, the pattern of results indicate that HID lamps whether fixed or adaptive improved target detection somewhat, suggesting that part of the real world crash reduction measured for this adaptive system (Highway Loss Data Institute (HLDI), 2012a) may be due to the differences in the light source (HID vs. halogen). Depending on the scenario, the estimated benefits to driver response time associated with the tested adaptive (swiveling HID) headlights ranged from 200 to 380ms compared with the fixed headlight systems tested.

  9. Optimized shapes of magnetic arrays for drug targeting applications

    NASA Astrophysics Data System (ADS)

    Barnsley, Lester C.; Carugo, Dario; Stride, Eleanor

    2016-06-01

    Arrays of permanent magnet elements have been utilized as light-weight, inexpensive sources for applying external magnetic fields in magnetic drug targeting applications, but they are extremely limited in the range of depths over which they can apply useful magnetic forces. In this paper, designs for optimized magnet arrays are presented, which were generated using an optimization routine to maximize the magnetic force available from an arbitrary arrangement of magnetized elements, depending on a set of design parameters including the depth of targeting (up to 50 mm from the magnet) and direction of force required. A method for assembling arrays in practice is considered, quantifying the difficulty of assembly and suggesting a means for easing this difficulty without a significant compromise to the applied field or force. Finite element simulations of in vitro magnetic retention experiments were run to demonstrate the capability of a subset of arrays to retain magnetic microparticles against flow. The results suggest that, depending on the choice of array, a useful proportion of particles (more than 10% ) could be retained at flow velocities up to 100 mm s-1 or to depths as far as 50 mm from the magnet. Finally, the optimization routine was used to generate a design for a Halbach array optimized to deliver magnetic force to a depth of 50 mm inside the brain.

  10. Optimization of bioenergy crop selection and placement based on a stream health indicator using an evolutionary algorithm.

    PubMed

    Herman, Matthew R; Nejadhashemi, A Pouyan; Daneshvar, Fariborz; Abouali, Mohammad; Ross, Dennis M; Woznicki, Sean A; Zhang, Zhen

    2016-10-01

    The emission of greenhouse gases continues to amplify the impacts of global climate change. This has led to the increased focus on using renewable energy sources, such as biofuels, due to their lower impact on the environment. However, the production of biofuels can still have negative impacts on water resources. This study introduces a new strategy to optimize bioenergy landscapes while improving stream health for the region. To accomplish this, several hydrological models including the Soil and Water Assessment Tool, Hydrologic Integrity Tool, and Adaptive Neruro Fuzzy Inference System, were linked to develop stream health predictor models. These models are capable of estimating stream health scores based on the Index of Biological Integrity. The coupling of the aforementioned models was used to guide a genetic algorithm to design watershed-scale bioenergy landscapes. Thirteen bioenergy managements were considered based on the high probability of adaptation by farmers in the study area. Results from two thousand runs identified an optimum bioenergy crops placement that maximized the stream health for the Flint River Watershed in Michigan. The final overall stream health score was 50.93, which was improved from the current stream health score of 48.19. This was shown to be a significant improvement at the 1% significant level. For this final bioenergy landscape the most often used management was miscanthus (27.07%), followed by corn-soybean-rye (19.00%), corn stover-soybean (18.09%), and corn-soybean (16.43%). The technique introduced in this study can be successfully modified for use in different regions and can be used by stakeholders and decision makers to develop bioenergy landscapes that maximize stream health in the area of interest.

  11. A new approach to the optimal target selection problem

    NASA Astrophysics Data System (ADS)

    Elson, E. C.; Bassett, B. A.; van der Heyden, K.; Vilakazi, Z. Z.

    2007-03-01

    Context: This paper addresses a common problem in astronomy and cosmology: to optimally select a subset of targets from a larger catalog. A specific example is the selection of targets from an imaging survey for multi-object spectrographic follow-up. Aims: We present a new heuristic optimisation algorithm, HYBRID, for this purpose and undertake detailed studies of its performance. Methods: HYBRID combines elements of the simulated annealing, MCMC and particle-swarm methods and is particularly successful in cases where the survey landscape has multiple curvature or clustering scales. Results: HYBRID consistently outperforms the other methods, especially in high-dimensionality spaces with many extrema. This means many fewer simulations must be run to reach a given performance confidence level and implies very significant advantages in solving complex or computationally expensive optimisation problems. Conclusions: .HYBRID outperforms both MCMC and SA in all cases including optimisation of high dimensional continuous surfaces indicating that HYBRID is useful far beyond the specific problem of optimal target selection. Future work will apply HYBRID to target selection for the new 10 m Southern African Large Telescope in South Africa.

  12. Time-optimal chaos control by center manifold targeting.

    PubMed

    Starrett, John

    2002-10-01

    Ott-Grebogi-Yorke control and its map-based variants work by targeting the (linear) stable subspace of the target orbit so that after one application of the control the system will be in this subspace. I propose an n-step variation, where n is the dimension of the system, that sends any initial condition in a controllable region directly to the target orbit instead of its stable subspace. This method is time optimal, in that, up to modeling and measurement error, the system is completely controlled after n iterations of the control procedure. I demonstrate the procedure using a piecewise linear and a nonlinear two-dimensional map, and indicate how the technique may be extended to maps and flows of higher dimension.

  13. Targeted Communications for Instituting Vocational Placement and Followup. Final Report and Appendixes A-C. Final Report.

    ERIC Educational Resources Information Center

    McCracken, J. David

    To provide substantive and methodological information concerning systematic vocational placement and followup to individuals responsible for educational program change, a project was conducted to develop three publications, each for different audiences: (1) school board members, (2) teacher educators, and (3) local school personnel. Information…

  14. Optimizing Interacting Potentials to Form Targeted Materials Structures

    SciTech Connect

    Torquato, Salvatore

    2015-09-28

    Conventional applications of the principles of statistical mechanics (the "forward" problems), start with particle interaction potentials, and proceed to deduce local structure and macroscopic properties. Other applications (that may be classified as "inverse" problems), begin with targeted configurational information, such as low-order correlation functions that characterize local particle order, and attempt to back out full-system configurations and/or interaction potentials. To supplement these successful experimental and numerical "forward" approaches, we have focused on inverse approaches that make use of analytical and computational tools to optimize interactions for targeted self-assembly of nanosystems. The most original aspect of our work is its inherently inverse approach: instead of predicting structures that result from given interaction potentials among particles, we determine the optimal potential that most robustly stabilizes a given target structure subject to certain constraints. Our inverse approach could revolutionize the manner in which materials are designed and fabricated. There are a number of very tangible properties (e.g. zero thermal expansion behavior), elastic constants, optical properties for photonic applications, and transport properties.

  15. Chromodomain Ligand Optimization via Target-Class Directed Combinatorial Repurposing.

    PubMed

    Barnash, Kimberly D; Lamb, Kelsey N; Stuckey, Jacob I; Norris, Jacqueline L; Cholensky, Stephanie H; Kireev, Dmitri B; Frye, Stephen V; James, Lindsey I

    2016-09-16

    Efforts to develop strategies for small-molecule chemical probe discovery against the readers of the methyl-lysine (Kme) post-translational modification have been met with limited success. Targeted disruption of these protein-protein interactions via peptidomimetic inhibitor optimization is a promising alternative to small-molecule hit discovery; however, recognition of identical peptide motifs by multiple Kme reader proteins presents a unique challenge in the development of selective Kme reader chemical probes. These selectivity challenges are exemplified by the Polycomb repressive complex 1 (PRC1) chemical probe, UNC3866, which demonstrates submicromolar off-target affinity toward the non-PRC1 chromodomains CDYL2 and CDYL. Moreover, since peptidomimetics are challenging subjects for structure-activity relationship (SAR) studies, traditional optimization of UNC3866 would prove costly and time-consuming. Herein, we report a broadly applicable strategy for the affinity-based, target-class screening of chromodomains via the repurposing of UNC3866 in an efficient, combinatorial peptide library. A first-generation library yielded UNC4991, a UNC3866 analogue that exhibits a distinct selectivity profile while maintaining submicromolar affinity toward the CDYL chromodomains. Additionally, in vitro pull-down experiments from HeLa nuclear lysates further demonstrate the selectivity and utility of this compound for future elucidation of CDYL protein function.

  16. Autonomous Optimization of Targeted Stimulation of Neuronal Networks.

    PubMed

    Kumar, Sreedhar S; Wülfing, Jan; Okujeni, Samora; Boedecker, Joschka; Riedmiller, Martin; Egert, Ulrich

    2016-08-01

    Driven by clinical needs and progress in neurotechnology, targeted interaction with neuronal networks is of increasing importance. Yet, the dynamics of interaction between intrinsic ongoing activity in neuronal networks and their response to stimulation is unknown. Nonetheless, electrical stimulation of the brain is increasingly explored as a therapeutic strategy and as a means to artificially inject information into neural circuits. Strategies using regular or event-triggered fixed stimuli discount the influence of ongoing neuronal activity on the stimulation outcome and are therefore not optimal to induce specific responses reliably. Yet, without suitable mechanistic models, it is hardly possible to optimize such interactions, in particular when desired response features are network-dependent and are initially unknown. In this proof-of-principle study, we present an experimental paradigm using reinforcement-learning (RL) to optimize stimulus settings autonomously and evaluate the learned control strategy using phenomenological models. We asked how to (1) capture the interaction of ongoing network activity, electrical stimulation and evoked responses in a quantifiable 'state' to formulate a well-posed control problem, (2) find the optimal state for stimulation, and (3) evaluate the quality of the solution found. Electrical stimulation of generic neuronal networks grown from rat cortical tissue in vitro evoked bursts of action potentials (responses). We show that the dynamic interplay of their magnitudes and the probability to be intercepted by spontaneous events defines a trade-off scenario with a network-specific unique optimal latency maximizing stimulus efficacy. An RL controller was set to find this optimum autonomously. Across networks, stimulation efficacy increased in 90% of the sessions after learning and learned latencies strongly agreed with those predicted from open-loop experiments. Our results show that autonomous techniques can exploit quantitative

  17. Autonomous Optimization of Targeted Stimulation of Neuronal Networks

    PubMed Central

    Kumar, Sreedhar S.; Wülfing, Jan; Okujeni, Samora; Boedecker, Joschka; Riedmiller, Martin

    2016-01-01

    Driven by clinical needs and progress in neurotechnology, targeted interaction with neuronal networks is of increasing importance. Yet, the dynamics of interaction between intrinsic ongoing activity in neuronal networks and their response to stimulation is unknown. Nonetheless, electrical stimulation of the brain is increasingly explored as a therapeutic strategy and as a means to artificially inject information into neural circuits. Strategies using regular or event-triggered fixed stimuli discount the influence of ongoing neuronal activity on the stimulation outcome and are therefore not optimal to induce specific responses reliably. Yet, without suitable mechanistic models, it is hardly possible to optimize such interactions, in particular when desired response features are network-dependent and are initially unknown. In this proof-of-principle study, we present an experimental paradigm using reinforcement-learning (RL) to optimize stimulus settings autonomously and evaluate the learned control strategy using phenomenological models. We asked how to (1) capture the interaction of ongoing network activity, electrical stimulation and evoked responses in a quantifiable ‘state’ to formulate a well-posed control problem, (2) find the optimal state for stimulation, and (3) evaluate the quality of the solution found. Electrical stimulation of generic neuronal networks grown from rat cortical tissue in vitro evoked bursts of action potentials (responses). We show that the dynamic interplay of their magnitudes and the probability to be intercepted by spontaneous events defines a trade-off scenario with a network-specific unique optimal latency maximizing stimulus efficacy. An RL controller was set to find this optimum autonomously. Across networks, stimulation efficacy increased in 90% of the sessions after learning and learned latencies strongly agreed with those predicted from open-loop experiments. Our results show that autonomous techniques can exploit

  18. Optimizing placements of ground-based snow sensors for areal snow cover estimation using a machine-learning algorithm and melt-season snow-LiDAR data

    NASA Astrophysics Data System (ADS)

    Oroza, C.; Zheng, Z.; Glaser, S. D.; Bales, R. C.; Conklin, M. H.

    2016-12-01

    We present a structured, analytical approach to optimize ground-sensor placements based on time-series remotely sensed (LiDAR) data and machine-learning algorithms. We focused on catchments within the Merced and Tuolumne river basins, covered by the JPL Airborne Snow Observatory LiDAR program. First, we used a Gaussian mixture model to identify representative sensor locations in the space of independent variables for each catchment. Multiple independent variables that govern the distribution of snow depth were used, including elevation, slope, and aspect. Second, we used a Gaussian process to estimate the areal distribution of snow depth from the initial set of measurements. This is a covariance-based model that also estimates the areal distribution of model uncertainty based on the independent variable weights and autocorrelation. The uncertainty raster was used to strategically add sensors to minimize model uncertainty. We assessed the temporal accuracy of the method using LiDAR-derived snow-depth rasters collected in water-year 2014. In each area, optimal sensor placements were determined using the first available snow raster for the year. The accuracy in the remaining LiDAR surveys was compared to 100 configurations of sensors selected at random. We found the accuracy of the model from the proposed placements to be higher and more consistent in each remaining survey than the average random configuration. We found that a relatively small number of sensors can be used to accurately reproduce the spatial patterns of snow depth across the basins, when placed using spatial snow data. Our approach also simplifies sensor placement. At present, field surveys are required to identify representative locations for such networks, a process that is labor intensive and provides limited guarantees on the networks' representation of catchment independent variables.

  19. Two-spoke placement optimization under explicit specific absorption rate and power constraints in parallel transmission at ultra-high field

    NASA Astrophysics Data System (ADS)

    Dupas, Laura; Massire, Aurélien; Amadon, Alexis; Vignaud, Alexandre; Boulant, Nicolas

    2015-06-01

    The spokes method combined with parallel transmission is a promising technique to mitigate the B1+ inhomogeneity at ultra-high field in 2D imaging. To date however, the spokes placement optimization combined with the magnitude least squares pulse design has never been done in direct conjunction with the explicit Specific Absorption Rate (SAR) and hardware constraints. In this work, the joint optimization of 2-spoke trajectories and RF subpulse weights is performed under these constraints explicitly and in the small tip angle regime. The problem is first considerably simplified by making the observation that only the vector between the 2 spokes is relevant in the magnitude least squares cost-function, thereby reducing the size of the parameter space and allowing a more exhaustive search. The algorithm starts from a set of initial k-space candidates and performs in parallel for all of them optimizations of the RF subpulse weights and the k-space locations simultaneously, under explicit SAR and power constraints, using an active-set algorithm. The dimensionality of the spoke placement parameter space being low, the RF pulse performance is computed for every location in k-space to study the robustness of the proposed approach with respect to initialization, by looking at the probability to converge towards a possible global minimum. Moreover, the optimization of the spoke placement is repeated with an increased pulse bandwidth in order to investigate the impact of the constraints on the result. Bloch simulations and in vivo T2∗-weighted images acquired at 7 T validate the approach. The algorithm returns simulated normalized root mean square errors systematically smaller than 5% in 10 s.

  20. Two-spoke placement optimization under explicit specific absorption rate and power constraints in parallel transmission at ultra-high field.

    PubMed

    Dupas, Laura; Massire, Aurélien; Amadon, Alexis; Vignaud, Alexandre; Boulant, Nicolas

    2015-06-01

    The spokes method combined with parallel transmission is a promising technique to mitigate the B1(+) inhomogeneity at ultra-high field in 2D imaging. To date however, the spokes placement optimization combined with the magnitude least squares pulse design has never been done in direct conjunction with the explicit Specific Absorption Rate (SAR) and hardware constraints. In this work, the joint optimization of 2-spoke trajectories and RF subpulse weights is performed under these constraints explicitly and in the small tip angle regime. The problem is first considerably simplified by making the observation that only the vector between the 2 spokes is relevant in the magnitude least squares cost-function, thereby reducing the size of the parameter space and allowing a more exhaustive search. The algorithm starts from a set of initial k-space candidates and performs in parallel for all of them optimizations of the RF subpulse weights and the k-space locations simultaneously, under explicit SAR and power constraints, using an active-set algorithm. The dimensionality of the spoke placement parameter space being low, the RF pulse performance is computed for every location in k-space to study the robustness of the proposed approach with respect to initialization, by looking at the probability to converge towards a possible global minimum. Moreover, the optimization of the spoke placement is repeated with an increased pulse bandwidth in order to investigate the impact of the constraints on the result. Bloch simulations and in vivo T2(∗)-weighted images acquired at 7 T validate the approach. The algorithm returns simulated normalized root mean square errors systematically smaller than 5% in 10 s. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Modeling of delamination in carbon/epoxy composite laminates under four point bending for damage detection and sensor placement optimization

    NASA Astrophysics Data System (ADS)

    Adu, Stephen Aboagye

    composite coupon under simply supported boundary conditions. Theoretically calculated bending stiffness's and maximum deflection were compared with that of the experimental case and the numerical. After the FEA model was properly benchmarked with test data and exact solution, data obtained from the FEM model were used for sensor placement optimization.

  2. SMET: systematic multiple enzyme targeting - a method to rationally design optimal strains for target chemical overproduction.

    PubMed

    Flowers, David; Thompson, R Adam; Birdwell, Douglas; Wang, Tsewei; Trinh, Cong T

    2013-05-01

    Identifying multiple enzyme targets for metabolic engineering is very critical for redirecting cellular metabolism to achieve desirable phenotypes, e.g., overproduction of a target chemical. The challenge is to determine which enzymes and how much of these enzymes should be manipulated by adding, deleting, under-, and/or over-expressing associated genes. In this study, we report the development of a systematic multiple enzyme targeting method (SMET), to rationally design optimal strains for target chemical overproduction. The SMET method combines both elementary mode analysis and ensemble metabolic modeling to derive SMET metrics including l-values and c-values that can identify rate-limiting reaction steps and suggest which enzymes and how much of these enzymes to manipulate to enhance product yields, titers, and productivities. We illustrated, tested, and validated the SMET method by analyzing two networks, a simple network for concept demonstration and an Escherichia coli metabolic network for aromatic amino acid overproduction. The SMET method could systematically predict simultaneous multiple enzyme targets and their optimized expression levels, consistent with experimental data from the literature, without performing an iterative sequence of single-enzyme perturbation. The SMET method was much more efficient and effective than single-enzyme perturbation in terms of computation time and finding improved solutions.

  3. Adaptive waveform optimization design for target detection in cognitive radar

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowen; Wang, Kaizhi; Liu, Xingzhao

    2017-01-01

    The problem of adaptive waveform design for target detection in cognitive radar (CR) is investigated. This problem is analyzed in signal-dependent interference, as well as additive channel noise for extended target with unknown target impulse response (TIR). In order to estimate the TIR accurately, the Kalman filter is used in target tracking. In each Kalman filtering iteration, a flexible online waveform spectrum optimization design taking both detection and range resolution into account is modeled in Fourier domain. Unlike existing CR waveform, the proposed waveform can be simultaneously updated according to the environment information fed back by receiver and radar performance demands. Moreover, the influence of waveform spectral phase to radar performance is analyzed. Simulation results demonstrate that CR with the proposed waveform performs better than a traditional radar system with a fixed waveform and offers more flexibility and suitability. In addition, waveform spectral phase will not influence tracking, detection, and range resolution performance but will greatly influence waveform forming speed and peak-to-average power ratio.

  4. Non-Invasive Fetal Monitoring: A Maternal Surface ECG Electrode Placement-Based Novel Approach for Optimization of Adaptive Filter Control Parameters Using the LMS and RLS Algorithms

    PubMed Central

    Martinek, Radek; Kahankova, Radana; Nazeran, Homer; Konecny, Jaromir; Jezewski, Janusz; Janku, Petr; Bilik, Petr; Zidek, Jan; Nedoma, Jan; Fajkus, Marcel

    2017-01-01

    This paper is focused on the design, implementation and verification of a novel method for the optimization of the control parameters (such as step size μ and filter order N) of LMS and RLS adaptive filters used for noninvasive fetal monitoring. The optimization algorithm is driven by considering the ECG electrode positions on the maternal body surface in improving the performance of these adaptive filters. The main criterion for optimal parameter selection was the Signal-to-Noise Ratio (SNR). We conducted experiments using signals supplied by the latest version of our LabVIEW-Based Multi-Channel Non-Invasive Abdominal Maternal-Fetal Electrocardiogram Signal Generator, which provides the flexibility and capability of modeling the principal distribution of maternal/fetal ECGs in the human body. Our novel algorithm enabled us to find the optimal settings of the adaptive filters based on maternal surface ECG electrode placements. The experimental results further confirmed the theoretical assumption that the optimal settings of these adaptive filters are dependent on the ECG electrode positions on the maternal body, and therefore, we were able to achieve far better results than without the use of optimization. These improvements in turn could lead to a more accurate detection of fetal hypoxia. Consequently, our approach could offer the potential to be used in clinical practice to establish recommendations for standard electrode placement and find the optimal adaptive filter settings for extracting high quality fetal ECG signals for further processing. Ultimately, diagnostic-grade fetal ECG signals would ensure the reliable detection of fetal hypoxia. PMID:28534810

  5. Non-Invasive Fetal Monitoring: A Maternal Surface ECG Electrode Placement-Based Novel Approach for Optimization of Adaptive Filter Control Parameters Using the LMS and RLS Algorithms.

    PubMed

    Martinek, Radek; Kahankova, Radana; Nazeran, Homer; Konecny, Jaromir; Jezewski, Janusz; Janku, Petr; Bilik, Petr; Zidek, Jan; Nedoma, Jan; Fajkus, Marcel

    2017-05-19

    This paper is focused on the design, implementation and verification of a novel method for the optimization of the control parameters (such as step size μ and filter order N) of LMS and RLS adaptive filters used for noninvasive fetal monitoring. The optimization algorithm is driven by considering the ECG electrode positions on the maternal body surface in improving the performance of these adaptive filters. The main criterion for optimal parameter selection was the Signal-to-Noise Ratio (SNR). We conducted experiments using signals supplied by the latest version of our LabVIEW-Based Multi-Channel Non-Invasive Abdominal Maternal-Fetal Electrocardiogram Signal Generator, which provides the flexibility and capability of modeling the principal distribution of maternal/fetal ECGs in the human body. Our novel algorithm enabled us to find the optimal settings of the adaptive filters based on maternal surface ECG electrode placements. The experimental results further confirmed the theoretical assumption that the optimal settings of these adaptive filters are dependent on the ECG electrode positions on the maternal body, and therefore, we were able to achieve far better results than without the use of optimization. These improvements in turn could lead to a more accurate detection of fetal hypoxia. Consequently, our approach could offer the potential to be used in clinical practice to establish recommendations for standard electrode placement and find the optimal adaptive filter settings for extracting high quality fetal ECG signals for further processing. Ultimately, diagnostic-grade fetal ECG signals would ensure the reliable detection of fetal hypoxia.

  6. Target delineation and optimal radiosurgical dose for pituitary tumors.

    PubMed

    Minniti, Giuseppe; Osti, Mattia Falchetto; Niyazi, Maximillian

    2016-10-11

    Stereotactic radiosurgery (SRS) delivered as either single-fraction or multi-fraction SRS (2-5 fractions) is frequently employed in patients with residual or recurrent pituitary adenoma. The most common delivery systems used for SRS include the cobalt-60 system Gamma Knife, the CyberKnife (CK) robotic radiosurgery system, or a modified conventional radiotherapy machine (linear accelerator, LINAC). Tumor control and normalization of hormone hypersecretion have been reported in 75-100 % and 25-80 % of patients, respectively. Hypopituitarism is the most commonly reported late complication of radiation treatment, whereas other toxicities occur less frequently. We have provided an overview of the recent available literature on SRS in patients with a pituitary adenoma. Critical aspects of pituitary irradiation, including target delineation and doses to organs at risk, optimal radiation dose, as well as the long-term efficacy and toxicity of SRS for either nonfunctioning or secreting pituitary adenomas are discussed. Single-fraction SRS represents an effective treatment for patients with a pituitary adenoma; however, caution should be used for lesions > 2.5-3 cm in size and/or involving the anterior optic pathway. Future studies will be necessary to optimize target doses and critical organ dose constrains in order to reduce the long-term toxicity of treatments while maintaining high efficacy.

  7. Use of spinous processes to determine the optimal trajectory for placement of lateral mass screws: technical note.

    PubMed

    Stevens, Qualls E; Majd, Mohammad E; Kattner, Keith A; Jones, Cynthia L; Holt, Richard T

    2009-07-01

    Retrospective chart analysis. In the current report, we present a new technique for the placement of lateral mass screws from C3 to C7. The safety, complications, and long-term clinical and imaging follow-up were analyzed. To address potential risk factors for this technique, relevant literature was reviewed and discussed herein. Multiple techniques have been reported to place lateral mass screws in the subaxial cervical spine. The trajectory used aims to avoid the vertebral artery and the exiting nerve root. Because of inherent differences in determining the screw trajectory for placement, there can be considerable differences among surgeons. A retrospective analysis of our experience over the period from 2003 to 2006 was undertaken. Standard practices for obtaining institutional review board approval were followed. Radiographs, hospital records, and office charts of 34 patients were reviewed. There was an equal distribution between males and females and the mean age was 56.3 years. Pain was the most frequent presentation. The indications for posterior instrumentation included instability secondary to pseudoarthrosis, infection, spondylosis, osseous metastasis, trauma, and iatrogenic etiologies. The follow-up period ranged from 1 to 30 months (average 9.1 mo). Postoperative complications included wound infection (3 cases), malpositioned screw (1 case), cerebrospinal fluid leak (1 case), and dislodged rod (1 case). There were no mortalities directly related to the procedure. This technique for placement of lateral mass screws yielded adequate fixation without any appreciable neurovascular complications. It provides a useful alternative for screw placement in patients with intact spinous processes.

  8. Is tip apex distance as important as we think? A biomechanical study examining optimal lag screw placement.

    PubMed

    Kane, Patrick; Vopat, Bryan; Heard, Wendell; Thakur, Nikhil; Paller, David; Koruprolu, Sarath; Born, Christopher

    2014-08-01

    -center group. At the time of failure, the magnitude of fracture translation was statistically significantly greater in the center-center group (20 ± 2.8 mm) compared with the low-center group (15 ± 3.4 mm; p = 0.004). Additionally, there was statistically significantly increased fracture gap distraction (center-center group, 13 ± 2.8 versus low-center group, 7 ± 4; p < 0.001) and shear fracture gap translation (center-center group, 12 ± 2.3 mm; low-center group, 6 ± 2.7 mm; p < 0.001). Positioning of the lag screw inferior in the head and neck was found to be at least as biomechanically stable as the center-center group although the tip apex distance was greater than 25 mm. Our findings challenge previously accepted principles of optimal lag screw placement.

  9. Optimal Structural Design of Mannosylated Nanocarriers for Macrophage Targeting

    PubMed Central

    Chen, Peiming; Zhang, Xiaoping; Jia, Lee; Prud’homme, Robert K.; Szekely, Zoltan; Sinko, Patrick J.

    2014-01-01

    Macrophages are involved in a number of diseases, such as HIV infection/AIDS, tuberculosis, tumor development and atherosclerosis. Macrophages possess several cell surface receptors (e.g., the mannose receptor, MR) that may serve as drug delivery cellular portals for nanocarriers (NCs). In this study, the optimal structural configuration for cell uptake of mannosylated poly(ethylene glycol)-conjugate type NCs was determined. A series NCs was synthesized to systematically evaluate the effects of the number of mannose units (Man), the PEG carrier size and the mPEG spacer length between adjacent mannose units on NC uptake into MR-expressing J774.E murine macrophage-like cells. Among NCs with 0, 1, 2 or 4 units of mannose, the uptake of (Man)2-NC was the highest, suggesting a trade-off between avidity and NC-MR clustering on the cell surface that sterically hinders endocytosis. This optimal (Man)2-NC configuration was built into subsequent NCs to optimize the other two parameters, PEG carrier size and spacer length. NCs with 0, 5, 12, 20, 30 or 40 kDa linear PEG carriers showed an inverse relationship between PEG size and uptake. The 12 kDa PEG carrier was chosen for investigating the third parameter, the Man-Man distance, since it may represent the best trade off (i.e., tissue penetration vs. systemic clearance) for in vivo macrophage targeting. Three (Man)2-PEG12kDa NCs with different Man-Man distances (39, 56 or 89 Å) were synthesized. The uptake of the NC with the 56 Å distance between mannoses was four- and two-fold higher than NCs with 39 Å and 89 Å distances, respectively. Confocal microscopy confirmed that the optimized (Man)2-PEG12kDa NC with the 56 Å Man-Man distance was internalized via endocytosis consistent with temperature-dependent active uptake. In conclusion, the optimal NC structural parameters for targeting the MR on macrophage-like J774.E cells are (i) a small PEG polymer carrier, (ii) two mannose units per NC and (iii) a 56 Å distance between

  10. Optimal structural design of mannosylated nanocarriers for macrophage targeting.

    PubMed

    Chen, Peiming; Zhang, Xiaoping; Jia, Lee; Prud'homme, Robert K; Szekely, Zoltan; Sinko, Patrick J

    2014-11-28

    Macrophages are involved in a number of diseases, such as HIV infection/AIDS, tuberculosis, tumor development and atherosclerosis. Macrophages possess several cell surface receptors (e.g., the mannose receptor, MR) that may serve as drug delivery cellular portals for nanocarriers (NCs). In this study, the optimal structural configuration for cell uptake of mannosylated poly(ethylene glycol)-conjugate type NCs was determined. A series of NCs were synthesized to systematically evaluate the effects of the number of mannose units (Man), the PEG carrier size and the mPEG spacer length between adjacent mannose units on NC uptake into MR-expressing J774.E murine macrophage-like cells. Among NCs with 0, 1, 2 or 4 units of mannose, the uptake of (Man)2-NC was the highest, suggesting a trade-off between avidity and NC-MR clustering on the cell surface that sterically hinders endocytosis. This optimal (Man)2-NC configuration was built into subsequent NCs to optimize the other two parameters, PEG carrier size and spacer length. NCs with 0, 5, 12, 20, 30 or 40 kDa linear PEG carriers showed an inverse relationship between PEG size and uptake. The 12 kDa PEG carrier was chosen for investigating the third parameter, the Man-Man distance, since it may represent the best trade off (i.e., tissue penetration vs. systemic clearance) for in vivo macrophage targeting. Three (Man)2-PEG12kDa NCs with different Man-Man distances (39, 56 or 89Å) were synthesized. The uptake of the NC with the 56Å distance between mannoses was four- and two-fold higher than NCs with 39Å and 89Å distances, respectively. Confocal microscopy confirmed that the optimized (Man)2-PEG12kDa NC with the 56Å Man-Man distance was internalized via endocytosis consistent with temperature-dependent active uptake. In conclusion, the optimal NC structural parameters for targeting the MR on macrophage-like J774.E cells are (i) a small PEG polymer carrier, (ii) two mannose units per NC and (iii) a 56Å distance between

  11. Rejuvenating cellular respiration for optimizing respiratory function: targeting mitochondria.

    PubMed

    Agrawal, Anurag; Mabalirajan, Ulaganathan

    2016-01-15

    Altered bioenergetics with increased mitochondrial reactive oxygen species production and degradation of epithelial function are key aspects of pathogenesis in asthma and chronic obstructive pulmonary disease (COPD). This motif is not unique to obstructive airway disease, reported in related airway diseases such as bronchopulmonary dysplasia and parenchymal diseases such as pulmonary fibrosis. Similarly, mitochondrial dysfunction in vascular endothelium or skeletal muscles contributes to the development of pulmonary hypertension and systemic manifestations of lung disease. In experimental models of COPD or asthma, the use of mitochondria-targeted antioxidants, such as MitoQ, has substantially improved mitochondrial health and restored respiratory function. Modulation of noncoding RNA or protein regulators of mitochondrial biogenesis, dynamics, or degradation has been found to be effective in models of fibrosis, emphysema, asthma, and pulmonary hypertension. Transfer of healthy mitochondria to epithelial cells has been associated with remarkable therapeutic efficacy in models of acute lung injury and asthma. Together, these form a 3R model--repair, reprogramming, and replacement--for mitochondria-targeted therapies in lung disease. This review highlights the key role of mitochondrial function in lung health and disease, with a focus on asthma and COPD, and provides an overview of mitochondria-targeted strategies for rejuvenating cellular respiration and optimizing respiratory function in lung diseases. Copyright © 2016 the American Physiological Society.

  12. Contact hole multiplication using grapho-epitaxy directed self-assembly: process choices, template optimization, and placement accuracy

    NASA Astrophysics Data System (ADS)

    Bekaert, Joost; Doise, Jan; Murugesan Kuppuswamy, Vijaya-Kumar; Gronheid, Roel; Chan, Boon Teik; Vandenberghe, Geert; Cao, Yi; Her, YoungJun

    2014-10-01

    Directed Self Assembly (DSA) of Block Co-Polymers (BCP) has become an intense field of study as a potential patterning solution for future generation devices. The most critical challenges that need to be understood and controlled include pattern placement accuracy, achieving low defectivity in DSA patterns and how to implement this process as a patterning solution. The DSA program at imec includes efforts on these three major topics. Specifically, in this paper the progress for the templated DSA flow within the imec program will be discussed. An experimental assessment is made based on a 37 nm BCP pitch material. In particular, the impact of different process options is illustrated, and data for CD and placement accuracy of the DSA holes in their template is provided.

  13. An optimized hydrogen target for muon catalyzed fusion

    NASA Astrophysics Data System (ADS)

    Gheisari, R.

    2011-04-01

    This paper deals with the optimization of the processes involved in muon catalyzed fusion. Muon catalyzed fusion ( μCF) is studied in all layers of the solid hydrogen structure H/0.1%T⊕D2⊕HD. The layer H/ T acts as an emitter source of energetic tμ atoms, due to the so-called Ramsauer-Townsend effect. These tμ atoms are slowed down in the second layer (degrader) and are forced to take place nuclear fusion in HD. The degrader affects time evolution of tμ atomic beam. This effect has not been considered until now in μCF-multilayered targets. Due to muon cycling and this effect, considerable reactions occur in the degrader. In our calculations, it is shown that the fusion yield equals 180±1.5. It is possible to separate events that overlap in time.

  14. A Constrained Differential Evolution Algorithm for Reservoir Management: Optimal Placement and Control of Wells for Geological Carbon Storage with Uncertainty in Reservoir Properties

    NASA Astrophysics Data System (ADS)

    Cihan, A.; Birkholzer, J. T.; Bianchi, M.

    2014-12-01

    Injection of large volume of CO2 into deep geological reservoirs for geologic carbon sequestration (GCS) is expected to cause significant pressure perturbations in subsurface. Large-scale pressure increases in injection reservoirs during GCS operations, if not controlled properly, may limit dynamic storage capacity and increase risk of environmental impacts. The high pressure may impact caprock integrity, induce fault slippage, and cause leakage of brine and/or CO2 into shallow fresh groundwater resources. Thus, monitoring and controlling pressure buildup are critically important for environmentally safe implementation of GCS projects. Extraction of native brine during GCS operations is a pressure management approach to reduce significant pressure buildup. Extracted brine can be transferred to the surface for utilization or re-injected into overlying/underlying saline aquifers. However, pumping, transportation, treatment and disposal of extracted brine can be challenging and costly. Therefore, minimizing volume of extracted brine, while maximizing CO2 storage, is an essential objective of the pressure management with brine extraction schemes. Selection of optimal well locations and extraction rates are critical for maximizing storage and minimizing brine extraction during GCS. However, placing of injection and extraction wells is not intuitive because of heterogeneity in reservoir properties and complex reservoir geometry. Efficient computerized algorithms combining reservoir models and optimization methods are needed to make proper decisions on well locations and control parameters. This study presents a global optimization methodology for pressure management during geologic CO2 sequestration. A constrained differential evolution (CDE) algorithm is introduced for solving optimization problems involving well placement and injection/extraction control. The CDE methodology is tested and applied for realistic CO2 storage scenarios with the presence of uncertainty in

  15. Optimization of Sensor Placements Using Machine Learning and LIDAR data: a Case Study for a Snow Monitoring Network in the Sierra Nevada.

    NASA Astrophysics Data System (ADS)

    Oroza, C.; Zheng, Z.; Glaser, S. D.; Bales, R. C.; Conklin, M. H.

    2014-12-01

    We present a methodology for the identification of optimal sensor placements and wireless network structure of remote wireless sensor networks. When applied to an existing snow observation network, our results suggest that greater spatial variability and more optimal networks structures could be achieved compared to existing placements. For sensor networks designed to measure spatially distributed phenomena, it is best to choose sites that capture the full range of variables explaining the underlying spatial distribution. In the context of snow depth estimation, topographical variables affecting the spatial distribution include elevation, slope, aspect, vegetation, and concavity. To extract this set of feature vectors, data is obtained from the NSF Open Topography platform, which uses LIDAR flights with 11.65 points per square meter to produce a one-meter raster for the DEM and surface models. Slope and aspect are calculated with the convolution of the elevation matrix and the Sobel operator and the vegetation layer is estimated from a two-meter height filter on the canopy height model. Two types of terrain concavity are calculated from the DEM raster: profile (parallel to the direction of maximum slope), and planform (perpendicular to the direction of maximum slope). Once this feature space is extracted from the LIDAR data, sensor placements can be found using K-means clustering. We use a normalized feature space (in which all feature vectors are scaled from zero to one, thereby evenly weighting each variable). The number of sensors, K, to be placed is taken as an input to the algorithm, which evenly partitions the data into K Voronoi cells, thereby evenly spreading the sensor locations through the space of observed variables. For regions that do not have LIDAR data, we present a methodology that uses a support vector machine algorithm with user-generated training and cross-validation points to classify vegetation from satellite imagery, and compare its accuracy

  16. Identifying optimal targets of network attack by belief propagation

    NASA Astrophysics Data System (ADS)

    Mugisha, Salomon; Zhou, Hai-Jun

    2016-07-01

    For a network formed by nodes and undirected links between pairs of nodes, the network optimal attack problem aims at deleting a minimum number of target nodes to break the network down into many small components. This problem is intrinsically related to the feedback vertex set problem that was successfully tackled by spin-glass theory and an associated belief propagation-guided decimation (BPD) algorithm [Zhou, Eur. Phys. J. B 86, 455 (2013), 10.1140/epjb/e2013-40690-1]. In the present work we apply the BPD algorithm (which has approximately linear time complexity) to the network optimal attack problem and demonstrate that it has much better performance than a recently proposed collective information algorithm [Morone and Makse, Nature 524, 65 (2015), 10.1038/nature14604] for different types of random networks and real-world network instances. The BPD-guided attack scheme often induces an abrupt collapse of the whole network, which may make it very difficult to defend.

  17. Note: Studies on target placement in TE(111) cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose.

    PubMed

    Selvakumaran, T S; Baskaran, R; Singh, A K; Sista, V L S Rao

    2010-03-01

    X-ray source based on electron cyclotron resonance principle has been constructed using TE(111) cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE(111) cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W.

  18. Note: Studies on target placement in TE{sub 111} cylindrical cavity of electron cyclotron resonance x-ray source for the enhancement of x-ray dose

    SciTech Connect

    Selvakumaran, T. S.; Baskaran, R.; Singh, A. K.; Sista, V. L. S. Rao

    2010-03-15

    X-ray source based on electron cyclotron resonance principle has been constructed using TE{sub 111} cylindrical cavity. At present the device is used to provide low energy x-ray field for thermoluminescent dosimeter badge calibration. Theoretical and experimental studies on the effect of target placement inside the TE{sub 111} cylindrical cavity for enhancing the x-ray output are carried out and the results are presented in this note. Optimum target location is identified by theoretical analysis on the electric field distribution inside the cavity using MICROWAVE STUDIO program. By modifying the magnetic field configuration, the resonance region is shifted to the optimum target location. The microwave transmission line is upgraded with a three stub tuner which improves the microwave coupling from the source to the target loaded cavity. Molybdenum target is located at a radial distance of 2.5 cm from the cavity center and the x-ray dose rate is measured at 20 cm from the exit port for different microwave power. With the introduction of the target, the x-ray output has improved nearly from 70% to 160% in the microwave power of 150-500 W.

  19. Optimized planning target volume for intact cervical cancer.

    PubMed

    Khan, Alvin; Jensen, Lindsay G; Sun, Shuai; Song, William Y; Yashar, Catheryn M; Mundt, Arno J; Zhang, Fu-Quan; Jiang, Steve B; Mell, Loren K

    2012-08-01

    To model interfraction clinical target volume (CTV) variation in patients with intact cervical cancer and design a planning target volume (PTV) that minimizes normal tissue dose while maximizing CTV coverage. We analyzed 50 patients undergoing external-beam radiotherapy for intact cervical cancer using daily online cone-beam computed tomography (CBCT). The CBCTs (n = 972) for each patient were rigidly registered to the planning CT. The CTV was delineated on the planning CT (CTV(0)) and the set of CBCTs ({CTV(1)-CTV(25)}). Manual (n = 98) and automated (n = 668) landmarks were placed over the surface of CTV(0) with reference to defined anatomic structures. Normal vectors were extended from each landmark, and the minimum length required for a given probability of encompassing CTV(1)-CTV(25) was computed. The resulting expansions were used to generate an optimized PTV. The mean (SD; range) normal vector length to ensure 95% coverage was 4.3 mm (2.7 mm; 1-16 mm). The uniform expansion required to ensure 95% probability of CTV coverage was 13 mm. An anisotropic margin of 20 mm anteriorly and posteriorly and 10 mm superiorly, inferiorly, and laterally also would have ensured a 95% probability of CTV coverage. The volume of the 95% optimized PTV (1470 cm(3)) was significantly lower than both the anisotropic PTV (2220 cm(3)) and the uniformly expanded PTV (2110 cm(3)) (p < 0.001). For a 95% probability of CTV coverage, normal lengths of 1-3 mm were found along the superior and lateral regions of CTV(0), 5-10 mm along the interfaces of CTV(0) with the bladder and rectum, and 10-14 mm along the anterior surface of CTV(0) at the level of the uterus. Optimizing PTV definition according to surface landmarking resulted in a high probability of CTV coverage with reduced PTV volumes. Our results provide data justifying planning margins to use in practice and clinical trials. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Optimized Planning Target Volume for Intact Cervical Cancer

    SciTech Connect

    Khan, Alvin; Jensen, Lindsay G.; Sun Shuai; Song, William Y.; Yashar, Catheryn M.; Mundt, Arno J.; Zhang Fuquan; Jiang, Steve B.; Mell, Loren K.

    2012-08-01

    Purpose: To model interfraction clinical target volume (CTV) variation in patients with intact cervical cancer and design a planning target volume (PTV) that minimizes normal tissue dose while maximizing CTV coverage. Methods and Materials: We analyzed 50 patients undergoing external-beam radiotherapy for intact cervical cancer using daily online cone-beam computed tomography (CBCT). The CBCTs (n = 972) for each patient were rigidly registered to the planning CT. The CTV was delineated on the planning CT (CTV{sub 0}) and the set of CBCTs ({l_brace}CTV{sub 1}-CTV{sub 25}{r_brace}). Manual (n = 98) and automated (n = 668) landmarks were placed over the surface of CTV{sub 0} with reference to defined anatomic structures. Normal vectors were extended from each landmark, and the minimum length required for a given probability of encompassing CTV{sub 1}-CTV{sub 25} was computed. The resulting expansions were used to generate an optimized PTV. Results: The mean (SD; range) normal vector length to ensure 95% coverage was 4.3 mm (2.7 mm; 1-16 mm). The uniform expansion required to ensure 95% probability of CTV coverage was 13 mm. An anisotropic margin of 20 mm anteriorly and posteriorly and 10 mm superiorly, inferiorly, and laterally also would have ensured a 95% probability of CTV coverage. The volume of the 95% optimized PTV (1470 cm{sup 3}) was significantly lower than both the anisotropic PTV (2220 cm{sup 3}) and the uniformly expanded PTV (2110 cm{sup 3}) (p < 0.001). For a 95% probability of CTV coverage, normal lengths of 1-3 mm were found along the superior and lateral regions of CTV{sub 0}, 5-10 mm along the interfaces of CTV{sub 0} with the bladder and rectum, and 10-14 mm along the anterior surface of CTV{sub 0} at the level of the uterus. Conclusion: Optimizing PTV definition according to surface landmarking resulted in a high probability of CTV coverage with reduced PTV volumes. Our results provide data justifying planning margins to use in practice and

  1. A conformal mapping based fractional order approach for sub-optimal tuning of PID controllers with guaranteed dominant pole placement

    NASA Astrophysics Data System (ADS)

    Saha, Suman; Das, Saptarshi; Das, Shantanu; Gupta, Amitava

    2012-09-01

    A novel conformal mapping based fractional order (FO) methodology is developed in this paper for tuning existing classical (Integer Order) Proportional Integral Derivative (PID) controllers especially for sluggish and oscillatory second order systems. The conventional pole placement tuning via Linear Quadratic Regulator (LQR) method is extended for open loop oscillatory systems as well. The locations of the open loop zeros of a fractional order PID (FOPID or PIλDμ) controller have been approximated in this paper vis-à-vis a LQR tuned conventional integer order PID controller, to achieve equivalent integer order PID control system. This approach eases the implementation of analog/digital realization of a FOPID controller with its integer order counterpart along with the advantages of fractional order controller preserved. It is shown here in the paper that decrease in the integro-differential operators of the FOPID/PIλDμ controller pushes the open loop zeros of the equivalent PID controller towards greater damping regions which gives a trajectory of the controller zeros and dominant closed loop poles. This trajectory is termed as "M-curve". This phenomena is used to design a two-stage tuning algorithm which reduces the existing PID controller's effort in a significant manner compared to that with a single stage LQR based pole placement method at a desired closed loop damping and frequency.

  2. Enhancing potency of siRNA targeting fusion genes by optimization outside of target sequence

    PubMed Central

    Gavrilov, Kseniya; Seo, Young-Eun; Tietjen, Gregory T.; Cui, Jiajia; Cheng, Christopher J.; Saltzman, W. Mark

    2015-01-01

    Canonical siRNA design algorithms have become remarkably effective at predicting favorable binding regions within a target mRNA, but in some cases (e.g., a fusion junction site) region choice is restricted. In these instances, alternative approaches are necessary to obtain a highly potent silencing molecule. Here we focus on strategies for rational optimization of two siRNAs that target the junction sites of fusion oncogenes BCR-ABL and TMPRSS2-ERG. We demonstrate that modifying the termini of these siRNAs with a terminal G-U wobble pair or a carefully selected pair of terminal asymmetry-enhancing mismatches can result in an increase in potency at low doses. Importantly, we observed that improvements in silencing at the mRNA level do not necessarily translate to reductions in protein level and/or cell death. Decline in protein level is also heavily influenced by targeted protein half-life, and delivery vehicle toxicity can confound measures of cell death due to silencing. Therefore, for BCR-ABL, which has a long protein half-life that is difficult to overcome using siRNA, we also developed a nontoxic transfection vector: poly(lactic-coglycolic acid) nanoparticles that release siRNA over many days. We show that this system can achieve effective killing of leukemic cells. These findings provide insights into the implications of siRNA sequence for potency and suggest strategies for the design of more effective therapeutic siRNA molecules. Furthermore, this work points to the importance of integrating studies of siRNA design and delivery, while heeding and addressing potential limitations such as restricted targetable mRNA regions, long protein half-lives, and nonspecific toxicities. PMID:26627251

  3. Targeting bed nucleus of the stria terminalis for severe obsessive-compulsive disorder: more unexpected lead placement in obsessive-compulsive disorder than in surgery for movement disorders.

    PubMed

    Nuttin, Bart; Gielen, Frans; van Kuyck, Kris; Wu, Hemmings; Luyten, Laura; Welkenhuysen, Marleen; Brionne, Thomas C; Gabriëls, Loes

    2013-01-01

    In preparation for a multicenter study, a protocol was written on how to perform surgical targeting of the bed nucleus of the stria terminalis, based on the lead implantation experience in patients with treatment-refractory obsessive-compulsive disorder (OCD) at the Universitaire Ziekenhuizen Leuven (UZ Leuven). When analyzing the postoperative images, we were struck by the fact that the difference between the postoperative position of the leads and the planned position seemed larger than expected. The precision of targeting in four patients with severe OCD who received bilateral model 3391 leads (Medtronic) was compared with the precision of targeting in the last seven patients who underwent surgery at UZ Leuven for movement disorders (four with Parkinson disease and three with essential tremor; all received bilateral leads). Because the leads implanted in six of the seven patients with movement disorders were model 3387 leads (Medtronic), targeting precision was also analyzed in four patients with OCD in whom model 3387 leads were implanted in the same target as the other patients with OCD. In the patients with OCD, every implanted lead deviated at least 1.3 mm from its intended position in at least one of three directions (lateral, anteroposterior, and depth), whereas in the patients with movement disorders, the maximal deviation of any of all implanted leads was 1.3 mm. The deviations in lead placement were comparable in patients with OCD who received a model 3387 implant and patients who received a model 3391 implant. In the patients with OCD, all leads were implanted more posteriorly than planned. The cause of the posterior deviation could not be determined with certainty. The most likely cause was an increased mechanical resistance of the brain tissue along the trajectory when following the targeting protocol compared with the trajectories classically used for subthalamic nucleus or ventral intermediate nucleus of the thalamus stimulation. Copyright © 2013

  4. Effect of SRAF placement on process window for technology nodes that uses variable etch bias

    NASA Astrophysics Data System (ADS)

    Seoud, Ahmed M.; Tawfik, Tamer M.

    2009-10-01

    As technology advances to 45 nm node and below, the induced effects of etch process have an increasing contribution to the device critical dimension error budget. Traditionally, original design target shapes are drawn based on the etch target. During mask correction, etch modeling is essential to predict the new resist target that will print on the wafer. This step is known as "Model Based Retargeting" (MBR). During the initial phase of process characterization, the sub-resolution assist features (SRAF) are optimized whether based on the original design target shapes or based on a biased version of the design target (resist target). The goal of the work is to study the different possibilities of SRAF placement to maximize the accuracy and process window immunity of the final resist contour image. We will, statistically, analyze and compare process window simulation results due to various SRAFs placements by changing the reference layer used during placement.

  5. Design of a correlated validated CFD and genetic algorithm model for optimized sensors placement for indoor air quality monitoring

    NASA Astrophysics Data System (ADS)

    Mousavi, Monireh Sadat; Ashrafi, Khosro; Motlagh, Majid Shafie Pour; Niksokhan, Mohhamad Hosein; Vosoughifar, HamidReza

    2017-09-01

    In this study, coupled method for simulation of flow pattern based on computational methods for fluid dynamics with optimization technique using genetic algorithms is presented to determine the optimal location and number of sensors in an enclosed residential complex parking in Tehran. The main objective of this research is costs reduction and maximum coverage with regard to distribution of existing concentrations in different scenarios. In this study, considering all the different scenarios for simulation of pollution distribution using CFD simulations has been challenging due to extent of parking and number of cars available. To solve this problem, some scenarios have been selected based on random method. Then, maximum concentrations of scenarios are chosen for performing optimization. CFD simulation outputs are inserted as input in the optimization model using genetic algorithm. The obtained results stated optimal number and location of sensors.

  6. Optimal placement of sensors and actuators for active vibration reduction of a flexible structure using a genetic algorithm based on modified Hinfinity

    NASA Astrophysics Data System (ADS)

    Hale, J. M.; Daraji, A. H.

    2012-08-01

    This paper is concerned with active vibration reduction of a square isotropic plate, mounted rigidly along one edge to form a cantilever. Optimal placement of ten piezoelectric sensor/actuator pairs is investigated using a genetic algorithm to suppress the first six modes of vibration. A new objective function is developed based on modified Hinfinity to locate the sensor/actuator pairs. The plate, with piezoelectric sensor/actuator pairs bonded to its surfaces, is modelled using the finite element method and Hamilton's principle based on first order shear deformation theory including bending, membrane, and shear deformation effects. The effects of piezoelectric mass, stiffness and electromechanical coupling are taken into account. The first six natural frequencies are validated by comparison with the finite element ANSYS package using two dimensional SHELL63 and three dimensional SOLID45 elements and also experimentally. Vibration reduction for the cantilever plate with piezoelectric patches bonded in the optimal location was investigated to attenuate the first six modes of vibration using a linear optimal control scheme. The new fitness function has reduced the computational cost and given greater vibration reduction than other previously published results.

  7. Optimization Studies for ISOL Type High-Powered Targets

    SciTech Connect

    Remec, Igor; Ronningen, Reginald Martin

    2013-09-24

    The research studied one-step and two-step Isotope Separation on Line (ISOL) targets for future radioactive beam facilities with high driver-beam power through advanced computer simulations. As a target material uranium carbide in the form of foils was used because of increasing demand for actinide targets in rare-isotope beam facilities and because such material was under development in ISAC at TRIUMF when this project started. Simulations of effusion were performed for one-step and two step targets and the effects of target dimensions and foil matrix were studied. Diffusion simulations were limited by availability of diffusion parameters for UCx material at reduced density; however, the viability of the combined diffusion?effusion simulation methodology was demonstrated and could be used to extract physical parameters such as diffusion coefficients and effusion delay times from experimental isotope release curves. Dissipation of the heat from the isotope-producing targets is the limiting factor for high-power beam operation both for the direct and two-step targets. Detailed target models were used to simulate proton beam interactions with the targets to obtain the fission rates and power deposition distributions, which were then applied in the heat transfer calculations to study the performance of the targets. Results indicate that a direct target, with specification matching ISAC TRIUMF target, could operate in 500-MeV proton beam at beam powers up to ~40 kW, producing ~8 1013 fission/s with maximum temperature in UCx below 2200 C. Targets with larger radius allow higher beam powers and fission rates. For the target radius in the range 9-mm to 30-mm the achievable fission rate increases almost linearly with target radius, however, the effusion delay time also increases linearly with target radius.

  8. Optimal Orbital Coverage of Theater Operations and Targets

    DTIC Science & Technology

    2007-03-01

    satellites. Several different approaches to coverage optimization are used. For the case of a single satellite, the number of daylight passes made... optimization . The third approach is to prevent a gap in coverage by placing the satellites in orbits spaced evenly by longitude of the ascending node. One...balance the tradeoffs between the number of passes and slant range, an optimization algorithm was developed and implemented as a computer program

  9. A UAV routing and sensor control optimization algorithm for target search

    NASA Astrophysics Data System (ADS)

    Collins, Gaemus E.; Riehl, James R.; Vegdahl, Philip S.

    2007-04-01

    An important problem in unmanned air vehicle (UAV) and UAV-mounted sensor control is the target search problem: locating target(s) in minimum time. Current methods solve the optimization of UAV routing control and sensor management independently. While this decoupled approach makes the target search problem computationally tractable, it is suboptimal. In this paper, we explore the target search and classification problems by formulating and solving a joint UAV routing and sensor control optimization problem. The routing problem is solved on a graph using receding horizon optimal control. The graph is dynamically adjusted based on the target probability distribution function (PDF). The objective function for the routing optimization is the solution of a sensor control optimization problem. An optimal sensor schedule (in the sense of maximizing the viewed target probability mass) is constructed for each candidate flight path in the routing control problem. The PDF of the target state is represented with a particle filter and an "occupancy map" for any undiscovered targets. The tradeoff between searching for undiscovered targets and locating tracks is handled automatically and dynamically by the use of an appropriate objective function. In particular, the objective function is based on the expected amount of target probability mass to be viewed.

  10. Target optimization for the photonuclear production of radioisotopes.

    PubMed

    Howard, Sean; Starovoitova, Valeriia N

    2015-02-01

    In this paper we discuss the optimum shape of a target for photonuclear production of radioisotopes using an electron linear accelerator. Different target geometries such as right cylinder, conical frustum, Gaussian volume of revolution and semi-ellipsoid have been considered for the production of (67)Cu via (68)Zn(γ,p)(67)Cu photonuclear reaction. The specific activity (SA) of (67)Cu was simulated for each target shape. Optimum ratio of radius to height for cylindrical targets was found to be between 0.2 and 0.25 for target masses ranging from 20 g to 100 g. It was shown that while some unconventional target shapes, such as semi-elliptical volume of revolution, result in slightly higher specific activities than cylindrical targets, the advantage is not significant and is outweighed by the complexity of the target production and handling. Power deposition into the target was modeled and the trade-off between the maximization of (67)Cu yield and the minimization of target heating has been discussed. The (67)Cu case can easily be extended for production of many other isotopes.

  11. Analysis of the optimal laminated target made up of discrete set of materials

    NASA Technical Reports Server (NTRS)

    Aptukov, Valery N.; Belousov, Valentin L.

    1991-01-01

    A new class of problems was analyzed to estimate an optimal structure of laminated targets fabricated from the specified set of homogeneous materials. An approximate description of the perforation process is based on the model of radial hole extension. The problem is solved by using the needle-type variation technique. The desired optimization conditions and quantitative/qualitative estimations of optimal targets were obtained and are discussed using specific examples.

  12. A rapid application of GA-MODFLOW combined approach to optimization of well placement and operation for drought-ready groundwater reservoir design

    NASA Astrophysics Data System (ADS)

    Park, C.; Kim, Y.; Jang, H.

    2016-12-01

    Poor temporal distribution of precipitation increases winter drought risks in mountain valley areas in Korea. Since perennial streams or reservoirs for water use are rare in the areas, groundwater is usually a major water resource. Significant amount of the precipitation contributing groundwater recharge mostly occurs during the summer season. However, a volume of groundwater recharge is limited by rapid runoff because of the topographic characteristics such as steep hill and slope. A groundwater reservoir using artificial recharge method with rain water reuse can be a suitable solution to secure water resource for the mountain valley areas. Successful groundwater reservoir design depends on optimization of well placement and operation. This study introduces a combined approach using GA (Genetic Algorithm) and MODFLOW and its rapid application. The methodology is based on RAD (Rapid Application Development) concept in order to minimize the cost of implementation. DEAP (Distributed Evolutionary Algorithms in Python), a framework for prototyping and testing evolutionary algorithms, is applied for quick code development and CUDA (Compute Unified Device Architecture), a parallel computing platform using GPU (Graphics Processing Unit), is introduced to reduce runtime. The application was successfully applied to Samdeok-ri, Gosung, Korea. The site is located in a mountain valley area and unconfined aquifers are major source of water use. The results of the application produced the best location and optimized operation schedule of wells including pumping and injecting.

  13. Using initial field campaigns for optimal placement of high resolution stable water isotope and water chemistry measurements

    NASA Astrophysics Data System (ADS)

    Sahraei, Amirhossein; Kraft, Philipp; Windhorst, David; Orlowski, Natalie; Bestian, Konrad; Holly, Hartmut; Breuer, Lutz

    2017-04-01

    composition and groundwater is not reactive to the annual precipitation cycle. Consecutive runoff measurements revealed bidirectional water exchange between stream and groundwater where influent and effluent conditions occur at different stream sections during baseflow conditions. Moreover, stream water quality responds to land use with significant variation of nitrate concentration due to agricultural land use. The a priori assessment of information from various sources and methods will allow us to guide the placement of high resolution stable water isotope and water chemistry measurements. We will report on the merits and drawbacks of each approach. Results will be used to select up to 12 sampling sites for a novel self-sufficient measurement system and guide the method selection for other researchers facing a similar challenge.

  14. Optimization of cone target geometry for fast ignition

    SciTech Connect

    Nakamura, Tatsufumi; Sakagami, Hitoshi; Johzaki, Tomoyuki; Nagatomo, Hideo; Mima, Kunioki; Koga, James

    2007-10-15

    Electron energy characteristics generated by the irradiation of ultraintense laser pulses onto solid targets are controlled by using cone targets. Two parameters characterizing the laser-cone interaction are introduced, which are cone angle and the ratio of the laser spot size to the cone tip size. By changing these parameters, the energy absorption rate, laser irradiance at the cone tip, and electron acceleration at the cone tip and side wall are controlled. The optimum cone targets for fast ignition are 30 deg. cone angle with double-cone geometry, and a tip size comparable to the core size, with the irradiation of a laser pulse with a spot size of about four times the cone tip size. Cone targets have the possibility to enhance the maximum energy of laser-accelerated protons by using a smaller angle cone depending on the laser f-number.

  15. Method and apparatus for optimized sampling of volatilizable target substances

    DOEpatents

    Lindgren, Eric R.; Phelan, James M.

    2004-10-12

    An apparatus for capturing, from gases such as soil gas, target analytes. Target analytes may include emanations from explosive materials or from residues of explosive materials. The apparatus employs principles of sorption common to solid phase microextraction, and is best used in conjunction with analysis means such as a gas chromatograph. To sorb target analytes, the apparatus functions using various sorptive structures to capture target analyte. Depending upon the embodiment, those structures may include a capillary tube including an interior surface on which sorptive material (similar to that on the surface of a SPME fiber) is supported (along with means for moving gases through the capillary tube so that the gases come into close proximity to the sorptive material). In one disclosed embodiment, at least one such sorptive structure is associated with an enclosure including an opening in communication with the surface of a soil region potentially contaminated with buried explosive material such as unexploded ordnance. Emanations from explosive materials can pass into and accumulate in the enclosure where they are sorbed by the sorptive structures. Also disclosed is the use of heating means such as microwave horns to drive target analytes into the soil gas from solid and liquid phase components of the soil.

  16. Method and apparatus for optimized sampling of volatilizable target substances

    DOEpatents

    Lindgren, Eric R.; Phelan, James M.

    2002-01-01

    An apparatus for capturing, from gases such as soil gas, target analytes. Target analytes may include emanations from explosive materials or from residues of explosive materials. The apparatus employs principles of sorption common to solid phase microextraction, and is best used in conjunction with analysis means such as a gas chromatograph. To sorb target analytes, the apparatus functions using various sorptive structures to capture target analyte. Depending upon the embodiment, those structures may include 1) a conventional solid-phase microextraction (SPME) fiber, 2) a SPME fiber suspended in a capillary tube (with means provided for moving gases through the capillary tube so that the gases come into close proximity to the suspended fiber), and 3) a capillary tube including an interior surface on which sorptive material (similar to that on the surface of a SPME fiber) is supported (along with means for moving gases through the capillary tube so that the gases come into close proximity to the sorptive material). In one disclosed embodiment, at least one such sorptive structure is associated with an enclosure including an opening in communication with the surface of a soil region potentially contaminated with buried explosive material such as unexploded ordnance. Emanations from explosive materials can pass into and accumulate in the enclosure where they are sorbed by the sorptive structures. Also disclosed is the use of heating means such as microwave horns to drive target analytes into the soil gas from solid and liquid phase components of the soil.

  17. Optimizing laser-driven proton acceleration from overdense targets

    PubMed Central

    Stockem Novo, A.; Kaluza, M. C.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range. PMID:27435449

  18. Optimizing laser-driven proton acceleration from overdense targets.

    PubMed

    Stockem Novo, A; Kaluza, M C; Fonseca, R A; Silva, L O

    2016-07-20

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range.

  19. Optimizing laser-driven proton acceleration from overdense targets

    NASA Astrophysics Data System (ADS)

    Stockem Novo, A.; Kaluza, M. C.; Fonseca, R. A.; Silva, L. O.

    2016-07-01

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range.

  20. Coordinated Target Tracking via a Hybrid Optimization Approach

    PubMed Central

    Wang, Yin; Cao, Yan

    2017-01-01

    Recent advances in computer science and electronics have greatly expanded the capabilities of unmanned aerial vehicles (UAV) in both defense and civil applications, such as moving ground object tracking. Due to the uncertainties of the application environments and objects’ motion, it is difficult to maintain the tracked object always within the sensor coverage area by using a single UAV. Hence, it is necessary to deploy a group of UAVs to improve the robustness of the tracking. This paper investigates the problem of tracking ground moving objects with a group of UAVs using gimbaled sensors under flight dynamic and collision-free constraints. The optimal cooperative tracking path planning problem is solved using an evolutionary optimization technique based on the framework of chemical reaction optimization (CRO). The efficiency of the proposed method was demonstrated through a series of comparative simulations. The results show that the cooperative tracking paths determined by the newly developed method allows for longer sensor coverage time under flight dynamic restrictions and safety conditions. PMID:28264425

  1. Coordinated Target Tracking via a Hybrid Optimization Approach.

    PubMed

    Wang, Yin; Cao, Yan

    2017-02-27

    Recent advances in computer science and electronics have greatly expanded the capabilities of unmanned aerial vehicles (UAV) in both defense and civil applications, such as moving ground object tracking. Due to the uncertainties of the application environments and objects' motion, it is difficult to maintain the tracked object always within the sensor coverage area by using a single UAV. Hence, it is necessary to deploy a group of UAVs to improve the robustness of the tracking. This paper investigates the problem of tracking ground moving objects with a group of UAVs using gimbaled sensors under flight dynamic and collision-free constraints. The optimal cooperative tracking path planning problem is solved using an evolutionary optimization technique based on the framework of chemical reaction optimization (CRO). The efficiency of the proposed method was demonstrated through a series of comparative simulations. The results show that the cooperative tracking paths determined by the newly developed method allows for longer sensor coverage time under flight dynamic restrictions and safety conditions.

  2. Differential Evolution Optimization for Targeting Spacecraft Maneuver Plans

    NASA Technical Reports Server (NTRS)

    Mattern, Daniel

    2016-01-01

    Previous analysis identified specific orbital parameters as being safer for conjunction avoidance for the TDRS fleet. With TDRS-9 being considered an at-risk spacecraft, a potential conjunction concern was raised should TDRS-9 fail while at a longitude of 12W. This document summarizes the analysis performed to identify if these specific orbital parameters could be targeted using the remaining drift-termination maneuvers for the relocation of TDRS-9 from 41W longitude to 12W longitude.

  3. Pancreatic cancer: optimizing treatment options, new, and emerging targeted therapies.

    PubMed

    Chiorean, Elena Gabriela; Coveler, Andrew L

    2015-01-01

    Pancreatic cancer is the fourth leading cause of cancer death in the US and is expected to become the second leading cause of cancer-related deaths in the next decade. Despite 5-fluorouracil/leucovorin with irinotecan and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel significantly improving outcomes for metastatic cancer, refractory disease still poses significant challenges. Difficulties with early detection and the inherent chemo- and radio-resistant nature of this malignancy led to attempts to define the sequential biology of pancreatic cancer in order to improve survival outcomes. Pancreatic adenocarcinoma is characterized by several germline or acquired genetic mutations, the most common being KRAS (90%), CDK2NA (90%), TP53 (75%-90%), DPC4/SMAD4 (50%). In addition, the tumor microenvironment, chemoresistant cancer stem cells, and the desmoplastic stroma have been the target of some promising clinical investigations. Among the core pathways reproducibly shown to lead the development and progression of this disease, DNA repair, apoptosis, G1/S cell cycle transition, KRAS, Wnt, Notch, Hedgehog, TGF-beta, and other cell invasion pathways, have been the target of "precision therapeutics". No single molecularly targeted therapeutic though has been uniformly successful, probably due to the tumor heterogeneity, but biomarker research is evolving and it hopes to select more patients likely to benefit. Recent reports note activity with immunotherapies such as CD40 agonists, CCR2 inhibitors, cancer vaccines, and novel combinations against the immunosuppressive tumor milieu are ongoing. While many obstacles still exist, clearly we are making progress in deciphering the heterogeneity within pancreatic cancers. Integrating conventional and immunological targeting will be the key to effective treatment of this deadly disease.

  4. Pancreatic cancer: optimizing treatment options, new, and emerging targeted therapies

    PubMed Central

    Chiorean, Elena Gabriela; Coveler, Andrew L

    2015-01-01

    Pancreatic cancer is the fourth leading cause of cancer death in the US and is expected to become the second leading cause of cancer-related deaths in the next decade. Despite 5-fluorouracil/leucovorin with irinotecan and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel significantly improving outcomes for metastatic cancer, refractory disease still poses significant challenges. Difficulties with early detection and the inherent chemo- and radio-resistant nature of this malignancy led to attempts to define the sequential biology of pancreatic cancer in order to improve survival outcomes. Pancreatic adenocarcinoma is characterized by several germline or acquired genetic mutations, the most common being KRAS (90%), CDK2NA (90%), TP53 (75%–90%), DPC4/SMAD4 (50%). In addition, the tumor microenvironment, chemoresistant cancer stem cells, and the desmoplastic stroma have been the target of some promising clinical investigations. Among the core pathways reproducibly shown to lead the development and progression of this disease, DNA repair, apoptosis, G1/S cell cycle transition, KRAS, Wnt, Notch, Hedgehog, TGF-beta, and other cell invasion pathways, have been the target of “precision therapeutics”. No single molecularly targeted therapeutic though has been uniformly successful, probably due to the tumor heterogeneity, but biomarker research is evolving and it hopes to select more patients likely to benefit. Recent reports note activity with immunotherapies such as CD40 agonists, CCR2 inhibitors, cancer vaccines, and novel combinations against the immunosuppressive tumor milieu are ongoing. While many obstacles still exist, clearly we are making progress in deciphering the heterogeneity within pancreatic cancers. Integrating conventional and immunological targeting will be the key to effective treatment of this deadly disease. PMID:26185420

  5. Energy scaling of targeted optimal control of complex networks

    PubMed Central

    Klickstein, Isaac; Shirin, Afroza; Sorrentino, Francesco

    2017-01-01

    Recently it has been shown that the control energy required to control a dynamical complex network is prohibitively large when there are only a few control inputs. Most methods to reduce the control energy have focused on where, in the network, to place additional control inputs. Here, in contrast, we show that by controlling the states of a subset of the nodes of a network, rather than the state of every node, while holding the number of control signals constant, the required energy to control a portion of the network can be reduced substantially. The energy requirements exponentially decay with the number of target nodes, suggesting that large networks can be controlled by a relatively small number of inputs as long as the target set is appropriately sized. We validate our conclusions in model and real networks to arrive at an energy scaling law to better design control objectives regardless of system size, energy restrictions, state restrictions, input node choices and target node choices. PMID:28436417

  6. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    PubMed

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  7. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    PubMed Central

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  8. Geological aspects of model construction for well placement optimization in a mixed fluvio-aeolian reservoir, UKCS

    SciTech Connect

    Hern, C.Y.; Lewis, J.J.M.; Seifert, D.; Steel, N.C.T.

    1996-12-31

    The cost-effective development of small fields requires a thorough description of the reservoir with a strong focus on the estimation of uncertainty. In this example, 3-D reservoir models are used to define and risk optimum well trajectories in a complex, mixed fluvio-aeolian gas reservoir. Emphasis is placed on the definition and quantification of those geological factors that affect the integrity of the hybrid stochastic-deterministic reservoir model. Sequential Indicator Simulation (SIS) models conditioned to well data were constructed for target zones. Construction of geologically realistic models required identification of genetic units, an understanding of their spatial distribution and assignation of appropriate dimensions. These objectives were achieved by an integration of probe-permeametry and sedimentology data on reservoir core, and the derivation of relevant genetic unit architectures from analogous sequences at outcrop. Assignation of appropriate sizes depends on the similarity between the outcrop analogue and the subsurface reservoir. Similarity was assessed by comparison of facies types, their proportions, the vertical association of facies, types of fluvio-aeolian interaction, the size of depositional systems and general depositional environment. Outcrop data were compared to reservoir observations and sub-sampled to eliminate unrepresentative elements. The SIS models generated with this data were {open_quote}pin-cushioned{close_quote} with over 100,000 numerical {open_quotes}wells{close_quotes} of varying azimuth, length, inclination and elevation. Much improved decision support was provided through a statistical definition of the {open_quote}optimum{close_quote} well trajectory.

  9. Geological aspects of model construction for well placement optimization in a mixed fluvio-aeolian reservoir, UKCS

    SciTech Connect

    Hern, C.Y.; Lewis, J.J.M.; Seifert, D. ); Steel, N.C.T. )

    1996-01-01

    The cost-effective development of small fields requires a thorough description of the reservoir with a strong focus on the estimation of uncertainty. In this example, 3-D reservoir models are used to define and risk optimum well trajectories in a complex, mixed fluvio-aeolian gas reservoir. Emphasis is placed on the definition and quantification of those geological factors that affect the integrity of the hybrid stochastic-deterministic reservoir model. Sequential Indicator Simulation (SIS) models conditioned to well data were constructed for target zones. Construction of geologically realistic models required identification of genetic units, an understanding of their spatial distribution and assignation of appropriate dimensions. These objectives were achieved by an integration of probe-permeametry and sedimentology data on reservoir core, and the derivation of relevant genetic unit architectures from analogous sequences at outcrop. Assignation of appropriate sizes depends on the similarity between the outcrop analogue and the subsurface reservoir. Similarity was assessed by comparison of facies types, their proportions, the vertical association of facies, types of fluvio-aeolian interaction, the size of depositional systems and general depositional environment. Outcrop data were compared to reservoir observations and sub-sampled to eliminate unrepresentative elements. The SIS models generated with this data were [open quote]pin-cushioned[close quote] with over 100,000 numerical [open quotes]wells[close quotes] of varying azimuth, length, inclination and elevation. Much improved decision support was provided through a statistical definition of the [open quote]optimum[close quote] well trajectory.

  10. Targeted Structural Optimization with Additive Manufacturing of Metals

    NASA Technical Reports Server (NTRS)

    Burt, Adam; Hull, Patrick

    2015-01-01

    The recent advances in additive manufacturing (AM) of metals have now improved the state-of-the-art such that traditionally non-producible parts can be readily produced in a cost-effective way. Because of these advances in manufacturing technology, structural optimization techniques are well positioned to supplement and advance this new technology. The goal of this project is to develop a structural design, analysis, and optimization framework combined with AM to significantly light-weight the interior of metallic structures while maintaining the selected structural properties of the original solid. This is a new state-of-the-art capability to significantly reduce mass, while maintaining the structural integrity of the original design, something that can only be done with AM. In addition, this framework will couple the design, analysis, and fabrication process, meaning that what has been designed directly represents the produced part, thus closing the loop on the design cycle and removing human iteration between design and fabrication. This fundamental concept has applications from light-weighting launch vehicle components to in situ resource fabrication.

  11. Optimizing thiadiazole analogues of resveratrol versus three chemopreventive targets.

    PubMed

    Mayhoub, Abdelrahman S; Marler, Laura; Kondratyuk, Tamara P; Park, Eun-Jung; Pezzuto, John M; Cushman, Mark

    2012-01-01

    Chemoprevention is an approach to decrease cancer morbidity and mortality through inhibition of carcinogenesis and prevention of disease progression. Although the trans stilbene derivative resveratrol has chemopreventive properties, its action is compromised by weak non-specific effects on many biological targets. Replacement of the stilbene ethylenic bridge of resveratrol with a 1,2,4-thiadiazole heterocycle and modification of the substituents on the two aromatic rings afforded potential chemopreventive agents with enhanced potencies and selectivities when evaluated as inhibitors of aromatase and NF-κB and inducers of quinone reductase 1 (QR1).

  12. Targeted agents and immunotherapies: optimizing outcomes in melanoma.

    PubMed

    Luke, Jason J; Flaherty, Keith T; Ribas, Antoni; Long, Georgina V

    2017-08-01

    Treatment options for patients with metastatic melanoma, and especially BRAF-mutant melanoma, have changed dramatically in the past 5 years, with the FDA approval of eight new therapeutic agents. During this period, the treatment paradigm for BRAF-mutant disease has evolved rapidly: the standard-of-care BRAF-targeted approach has shifted from single-agent BRAF inhibition to combination therapy with a BRAF and a MEK inhibitor. Concurrently, immunotherapy has transitioned from cytokine-based treatment to antibody-mediated blockade of the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and, now, the programmed cell-death protein 1 (PD-1) immune checkpoints. These changes in the treatment landscape have dramatically improved patient outcomes, with the median overall survival of patients with advanced-stage melanoma increasing from approximately 9 months before 2011 to at least 2 years - and probably longer for those with BRAF-V600-mutant disease. Herein, we review the clinical trial data that established the standard-of-care treatment approaches for advanced-stage melanoma. Mechanisms of resistance and biomarkers of response to BRAF-targeted treatments and immunotherapies are discussed, and the contrasting clinical benefits and limitations of these therapies are explored. We summarize the state of the field and outline a rational approach to frontline-treatment selection for each individual patient with BRAF-mutant melanoma.

  13. Patient-specific targeting guides compared with traditional instrumentation for glenoid component placement in shoulder arthroplasty: a multi-surgeon study in 70 arthritic cadaver specimens.

    PubMed

    Throckmorton, Thomas W; Gulotta, Lawrence V; Bonnarens, Frank O; Wright, Stephen A; Hartzell, Jeffrey L; Rozzi, William B; Hurst, Jason M; Frostick, Simon P; Sperling, John W

    2015-06-01

    The purpose of this study was to compare the accuracy of patient-specific guides for total shoulder arthroplasty (TSA) with traditional instrumentation in arthritic cadaver shoulders. We hypothesized that the patient-specific guides would place components more accurately than standard instrumentation. Seventy cadaver shoulders with radiographically confirmed arthritis were randomized in equal groups to 5 surgeons of varying experience levels who were not involved in development of the patient-specific guidance system. Specimens were then randomized to patient-specific guides based off of computed tomography scanning, standard instrumentation, and anatomic TSA or reverse TSA. Variances in version or inclination of more than 10° and more than 4 mm in starting point were considered indications of significant component malposition. TSA glenoid components placed with patient-specific guides averaged 5° of deviation from the intended position in version and 3° in inclination; those with standard instrumentation averaged 8° of deviation in version and 7° in inclination. These differences were significant for version (P = .04) and inclination (P = .01). Multivariate analysis of variance to compare the overall accuracy for the entire cohort (TSA and reverse TSA) revealed patient-specific guides to be significantly more accurate (P = .01) for the combined vectors of version and inclination. Patient-specific guides also had fewer instances of significant component malposition than standard instrumentation did. Patient-specific targeting guides were more accurate than traditional instrumentation and had fewer instances of component malposition for glenoid component placement in this multi-surgeon cadaver study of arthritic shoulders. Long-term clinical studies are needed to determine if these improvements produce improved functional outcomes. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  14. Artificial Intelligence based technique for BTS placement

    NASA Astrophysics Data System (ADS)

    Alenoghena, C. O.; Emagbetere, J. O.; Aibinu, A. M.

    2013-12-01

    The increase of the base transceiver station (BTS) in most urban areas can be traced to the drive by network providers to meet demand for coverage and capacity. In traditional network planning, the final decision of BTS placement is taken by a team of radio planners, this decision is not fool proof against regulatory requirements. In this paper, an intelligent based algorithm for optimal BTS site placement has been proposed. The proposed technique takes into consideration neighbour and regulation considerations objectively while determining cell site. The application will lead to a quantitatively unbiased evaluated decision making process in BTS placement. An experimental data of a 2km by 3km territory was simulated for testing the new algorithm, results obtained show a 100% performance of the neighbour constrained algorithm in BTS placement optimization. Results on the application of GA with neighbourhood constraint indicate that the choices of location can be unbiased and optimization of facility placement for network design can be carried out.

  15. Tailoring peritoneal dialysis fluid for optimal acid-base targets.

    PubMed

    Feriani, Mariano

    2009-01-01

    Mild derangements of acid-base status are common features in peritoneal dialysis patients, metabolic acidosis being the most frequent alteration. One of the main tasks of dialysis is to correct these derangements and the target is the normalization of the acid-base parameters since they affect several organs and functions. Since factors affecting acid-base homeostasis are intrinsic characteristics of the individual patient (metabolic acid production, distribution space for bicarbonate, dialytic prescription, etc.), it is not surprising that only relatively few patients achieve the normal range. Only a certain modulation of buffer infusion by using different buffer concentrations in the dialysis fluid may ensure a good correction in a large percentage of patients.

  16. Study protocol: precision of a protocol for manual intramuscular needle placement checked by passive stretching and relaxing of the target muscle in the lower extremity during BTX-A treatment in children with spastic cerebral palsy, as verified by means of electrical stimulation

    PubMed Central

    2013-01-01

    Background Intramuscular injection of botulinum toxin type-A given by manual intramuscular needle placement in the lower extremity under general anaesthesia is an established treatment and standard of care in managing spasticity in children with spastic cerebral palsy. Optimal needle placement is essential. However, reports of injection and verification techniques used in previous studies have been partly incomplete and there are methodological shortcomings. This paper describes a detailed protocol for manual intramuscular needle placement checked by passive stretching and relaxing of the target muscle for each individual muscle injection location in the lower extremity during botulinum toxin type-A treatment under general anaesthesia in children with spastic cerebral palsy. It explains the design of a study to verify this protocol, which consists of an injection technique combined with a needle localizing technique, as by means of electrical stimulation to determine its precision. Methods Setting: University Medical Centre, Department of Paediatric Rehabilitation Medicine, the Netherlands. Design: prospective observational study. Participants: children with spastic cerebral palsy, aged 4 to 18 years, receiving regular botulinum toxin type-A treatment under general anaesthesia to improve their mobility, are recruited from the Department of Paediatric Rehabilitation Medicine at VU University Medical Centre, Amsterdam, the Netherlands. Method: a detailed protocol for manual intramuscular needle placement checked by passive stretching and relaxing of the target muscle has been developed for each individual muscle injection location of the adductor brevis muscle, adductor longus muscle, gracilis muscle, semimembranosus muscle, semitendinosus muscle, biceps femoris muscle, rectus femoris muscle, gastrocnemius lateralis muscle, gastrocnemius medialis muscle and soleus muscle. This protocol will be verified as by means of electrical stimulation. Technical details: 25

  17. Nonalcoholic steatohepatitis: emerging targeted therapies to optimize treatment options

    PubMed Central

    Milic, Sandra; Mikolasevic, Ivana; Krznaric-Zrnic, Irena; Stanic, Marija; Poropat, Goran; Stimac, Davor; Vlahovic-Palcevski, Vera; Orlic, Lidija

    2015-01-01

    Diet and lifestyle changes have led to worldwide increases in the prevalences of obesity and metabolic syndrome, resulting in substantially greater incidence of nonalcoholic fatty liver disease (NAFLD). NAFLD is considered a hepatic manifestation of metabolic syndrome and is related to diabetes, insulin resistance, central obesity, hyperlipidemia, and hypertension. Nonalcoholic steatohepatitis (NASH) is an entity that describes liver inflammation due to NAFLD. Growing evidence suggests that NAFLD is a multisystem disease with a clinical burden that is not only confined to liver-related morbidity and mortality, but that also affects several extra-hepatic organs and regulatory pathways. Thus, NAFLD is considered an important public health issue, but there is currently no effective therapy for all NAFLD patients in the general population. Studies seeking optimal therapy for NAFLD and NASH have not yet led to development of a universal protocol for treating this growing problem. Several pharmacological agents have been studied in an effort to improve insulin resistance and the proinflammatory mediators that may be responsible for NASH progression. Cardiovascular risk factors are highly prevalent among NASH patients, and the backbone of treatment regimens for these patients still comprises general lifestyle interventions, including dietary changes and increased physical activity. Vitamin E and thiazolidinedione derivatives are currently the most evidence-based therapeutic options, but only limited clinical evidence is available regarding their long-term efficacy and safety. Vitamin D and renin–angiotensin–aldosterone system blockers are promising drugs that are currently being intensively investigated for use in NAFLD/NASH patients. PMID:26316717

  18. Levy flights do not always optimize random blind search for sparse targets.

    PubMed

    Palyulin, Vladimir V; Chechkin, Aleksei V; Metzler, Ralf

    2014-02-25

    It is generally believed that random search processes based on scale-free, Lévy stable jump length distributions (Lévy flights) optimize the search for sparse targets. Here we show that this popular search advantage is less universal than commonly assumed. We study the efficiency of a minimalist search model based on Lévy flights in the absence and presence of an external drift (underwater current, atmospheric wind, a preference of the walker owing to prior experience, or a general bias in an abstract search space) based on two different optimization criteria with respect to minimal search time and search reliability (cumulative arrival probability). Although Lévy flights turn out to be efficient search processes when the target is far from the starting point, or when relative to the starting point the target is upstream, we show that for close targets and for downstream target positioning regular Brownian motion turns out to be the advantageous search strategy. Contrary to claims that Lévy flights with a critical exponent α = 1 are optimal for the search of sparse targets in different settings, based on our optimization parameters the optimal α may range in the entire interval (1, 2) and especially include Brownian motion as the overall most efficient search strategy.

  19. Lévy flights do not always optimize random blind search for sparse targets

    PubMed Central

    Palyulin, Vladimir V.; Chechkin, Aleksei V.; Metzler, Ralf

    2014-01-01

    It is generally believed that random search processes based on scale-free, Lévy stable jump length distributions (Lévy flights) optimize the search for sparse targets. Here we show that this popular search advantage is less universal than commonly assumed. We study the efficiency of a minimalist search model based on Lévy flights in the absence and presence of an external drift (underwater current, atmospheric wind, a preference of the walker owing to prior experience, or a general bias in an abstract search space) based on two different optimization criteria with respect to minimal search time and search reliability (cumulative arrival probability). Although Lévy flights turn out to be efficient search processes when the target is far from the starting point, or when relative to the starting point the target is upstream, we show that for close targets and for downstream target positioning regular Brownian motion turns out to be the advantageous search strategy. Contrary to claims that Lévy flights with a critical exponent α = 1 are optimal for the search of sparse targets in different settings, based on our optimization parameters the optimal α may range in the entire interval (1, 2) and especially include Brownian motion as the overall most efficient search strategy. PMID:24516153

  20. Parameter Estimation of a Ground Moving Target Using Image Sharpness Optimization.

    PubMed

    Yu, Jing; Li, Yaan

    2016-06-30

    Motion parameter estimation of a ground moving target is an important issue in synthetic aperture radar ground moving target indication (SAR-GMTI) which has significant applications for civilian and military. The SAR image of a moving target may be displaced and defocused due to the radial and along-track velocity components, respectively. The sharpness cost function presents a measure of the degree of focus of the image. In this work, a new ground moving target parameter estimation algorithm based on the sharpness optimization criterion is proposed. The relationships between the quadratic phase errors and the target's velocity components are derived. Using two-dimensional searching of the sharpness cost function, we can obtain the velocity components of the target and the focused target image simultaneously. The proposed moving target parameter estimation method and image sharpness metrics are analyzed in detail. Finally, numerical results illustrate the effective and superior velocity estimation performance of the proposed method when compared to existing algorithms.

  1. Optimizing megakaryocyte polyploidization by targeting multiple pathways of cytokinesis.

    PubMed

    Avanzi, Mauro P; Chen, Amanda; He, Wu; Mitchell, W Beau

    2012-11-01

    Large-scale in vitro production of platelets (PLTs) from cord blood stem cells is one goal of stem cell research. One step toward this goal will be to produce polyploid megakaryocytes capable of releasing high numbers of PLTs. Megakaryocyte polyploidization requires distinct cytoskeletal and cellular mechanisms, including actin polymerization, myosin activation, microtubule formation, and increased DNA production. In this study we variably combined inhibition of these principal mechanisms of cytokinesis with the goal of driving polyploidization in megakaryocytes. Megakaryocytes were derived from umbilical cord blood and cultured with reagents that inhibit distinct mechanisms of cytokinesis: Rho-Rock inhibitor (RRI), Src inhibitor (SI), nicotinamide (NIC), aurora B inhibitor (ABI), and myosin light chain kinase inhibitor (MLCKI). Combinations of reagents were used to determine their interactions and to maximize megakaryocyte ploidy. Treatment with RRI, NIC, SI, and ABI, but not with MLCKI, increased the final ploidy and RRI was the most effective single reagent. RRI and MLCKI, both inhibitors of MLC activation, resulted in opposite ploidy outcomes. Combinations of reagents also increased ploidy and the use of NIC, SI, and ABI was as effective as RRI alone. Addition of MLCKI to NIC, SI, and ABI reached the highest level of polyploidization. Megakaryocyte polyploidization results from modulation of a combination of distinct cytokinesis pathways. Reagents targeting distinct cytoskeletal pathways produced additive effects in final megakaryocyte ploidy. The RRI, however, showed no additive effect but produced a high final ploidy due to overlapping inhibition of multiple cytokinesis pathways. © 2012 American Association of Blood Banks.

  2. Echolocating bats use future-target information for optimal foraging

    PubMed Central

    Fujioka, Emyo; Aihara, Ikkyu; Sumiya, Miwa; Aihara, Kazuyuki; Hiryu, Shizuko

    2016-01-01

    When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat’s attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics. PMID:27071082

  3. Echolocating bats use future-target information for optimal foraging.

    PubMed

    Fujioka, Emyo; Aihara, Ikkyu; Sumiya, Miwa; Aihara, Kazuyuki; Hiryu, Shizuko

    2016-04-26

    When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat's attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics.

  4. Advanced Algorithm for Optimal Sensor-Target and Weapon-Target Pairings in Dynamic Collaborative Engagement

    DTIC Science & Technology

    2008-12-01

    assignment optimization problem in mathematics (Bertsekas, 1990, 1992a, 1992b; Castanon, 1993; Galil , 1986; Hopcroft and Karp,1973; Micali and Vazirani... Galil Z., 1986: Efficient Algorithms for Finding Maximum Matchings in Graphs. ACM Computing Surveys, 18, 23-38. Karmarkar N., 1984: A New

  5. CT-Finder: A Web Service for CRISPR Optimal Target Prediction and Visualization.

    PubMed

    Zhu, Houxiang; Misel, Lauren; Graham, Mitchell; Robinson, Michael L; Liang, Chun

    2016-05-23

    The CRISPR system holds much promise for successful genome engineering, but therapeutic, industrial, and research applications will place high demand on improving the specificity and efficiency of this tool. CT-Finder (http://bioinfolab.miamioh.edu/ct-finder) is a web service to help users design guide RNAs (gRNAs) optimized for specificity. CT-Finder accommodates the original single-gRNA Cas9 system and two specificity-enhancing paired-gRNA systems: Cas9 D10A nickases (Cas9n) and dimeric RNA-guided FokI nucleases (RFNs). Optimal target candidates can be chosen based on the minimization of predicted off-target effects. Graphical visualization of on-target and off-target sites in the genome is provided for target validation. Major model organisms are covered by this web service.

  6. Multivalency: the hallmark of antibodies used for optimization of tumor targeting by design.

    PubMed

    Deyev, Sergey M; Lebedenko, Ekaterina N

    2008-09-01

    High-precision tumor targeting with conventional therapeutics is based on the concept of the ideal drug as a "magic bullet"; this became possible after techniques were developed for production of monoclonal antibodies (mAbs). Innovative DNA technologies have revolutionized this area and enhanced clinical efficiency of mAbs. The experience of applying small-size recombinant antibodies (monovalent binding fragments and their derivatives) to cancer targeting showed that even high-affinity monovalent interactions provide fast blood clearance but only modest retention time on the target antigen. Conversion of recombinant antibodies into multivalent format increases their functional affinity, decreases dissociation rates for cell-surface and optimizes biodistribution. In addition, it allows the creation of bispecific antibody molecules that can target two different antigens simultaneously and do not exist in nature. Different multimerization strategies used now in antibody engineering make it possible to optimize biodistribution and tumor targeting of recombinant antibody constructs for cancer diagnostics and therapy.

  7. CT-Finder: A Web Service for CRISPR Optimal Target Prediction and Visualization

    PubMed Central

    Zhu, Houxiang; Misel, Lauren; Graham, Mitchell; Robinson, Michael L.; Liang, Chun

    2016-01-01

    The CRISPR system holds much promise for successful genome engineering, but therapeutic, industrial, and research applications will place high demand on improving the specificity and efficiency of this tool. CT-Finder (http://bioinfolab.miamioh.edu/ct-finder) is a web service to help users design guide RNAs (gRNAs) optimized for specificity. CT-Finder accommodates the original single-gRNA Cas9 system and two specificity-enhancing paired-gRNA systems: Cas9 D10A nickases (Cas9n) and dimeric RNA-guided FokI nucleases (RFNs). Optimal target candidates can be chosen based on the minimization of predicted off-target effects. Graphical visualization of on-target and off-target sites in the genome is provided for target validation. Major model organisms are covered by this web service. PMID:27210050

  8. Electronic Attack Platform Placement Optimization

    DTIC Science & Technology

    2014-09-01

    SECURITY CLASSIFICATION OF REPORT Unclassified 18. SECURITY CLASSIFICATION OF THIS PAGE Unclassified 19. SECURITY CLASSIFICATION OF...GB DDR3) Display 10.1” (IPS, 1366 X 768) Multi-touch HD display Operating System Windows 8 Storage 256 GB SSD (SATA-III) Network Intel WLAN ...programming the GPU: 1) security and 2) determining when the GPU is advantageous. Security is a problem applicable to all software development. With the

  9. Multi-Robot, Multi-Target Particle Swarm Optimization Search in Noisy Wireless Environments

    SciTech Connect

    Kurt Derr; Milos Manic

    2009-05-01

    Multiple small robots (swarms) can work together using Particle Swarm Optimization (PSO) to perform tasks that are difficult or impossible for a single robot to accomplish. The problem considered in this paper is exploration of an unknown environment with the goal of finding a target(s) at an unknown location(s) using multiple small mobile robots. This work demonstrates the use of a distributed PSO algorithm with a novel adaptive RSS weighting factor to guide robots for locating target(s) in high risk environments. The approach was developed and analyzed on multiple robot single and multiple target search. The approach was further enhanced by the multi-robot-multi-target search in noisy environments. The experimental results demonstrated how the availability of radio frequency signal can significantly affect robot search time to reach a target.

  10. Identification of Metabolic Engineering Targets through Analysis of Optimal and Sub-Optimal Routes

    PubMed Central

    Soons, Zita I. T. A.; Ferreira, Eugénio C.

    2013-01-01

    Identification of optimal genetic manipulation strategies for redirecting substrate uptake towards a desired product is a challenging task owing to the complexity of metabolic networks, esp. in terms of large number of routes leading to the desired product. Algorithms that can exploit the whole range of optimal and suboptimal routes for product formation while respecting the biological objective of the cell are therefore much needed. Towards addressing this need, we here introduce the notion of structural flux, which is derived from the enumeration of all pathways in the metabolic network in question and accounts for the contribution towards a given biological objective function. We show that the theoretically estimated structural fluxes are good predictors of experimentally measured intra-cellular fluxes in two model organisms, namely, Escherichia coli and Saccharomyces cerevisiae. For a small number of fluxes for which the predictions were poor, the corresponding enzyme-coding transcripts were also found to be distinctly regulated, showing the ability of structural fluxes in capturing the underlying regulatory principles. Exploiting the observed correspondence between in vivo fluxes and structural fluxes, we propose an in silico metabolic engineering approach, iStruF, which enables the identification of gene deletion strategies that couple the cellular biological objective with the product flux while considering optimal as well as sub-optimal routes and their efficiency. PMID:23626708

  11. Reformulated Kemeny optimal aggregation with application in consensus ranking of microRNA targets.

    PubMed

    Sengupta, Debarka; Pyne, Aroonalok; Maulik, Ujjwal; Bandyopadhyay, Sanghamitra

    2013-01-01

    MicroRNAs are very recently discovered small noncoding RNAs, responsible for negative regulation of gene expression. Members of this endogenous family of small RNA molecules have been found implicated in many genetic disorders. Each microRNA targets tens to hundreds of genes. Experimental validation of target genes is a time- and cost-intensive procedure. Therefore, prediction of microRNA targets is a very important problem in computational biology. Though, dozens of target prediction algorithms have been reported in the past decade, they disagree significantly in terms of target gene ranking (based on predicted scores). Rank aggregation is often used to combine multiple target orderings suggested by different algorithms. This technique has been used in diverse fields including social choice theory, meta search in web, and most recently, in bioinformatics. Kemeny optimal aggregation (KOA) is considered the more profound objective for rank aggregation. The consensus ordering obtained through Kemeny optimal aggregation incurs minimum pairwise disagreement with the input orderings. Because of its computational intractability, heuristics are often formulated to obtain a near optimal consensus ranking. Unlike its real time use in meta search, there are a number of scenarios in bioinformatics (e.g., combining microRNA target rankings, combining disease-related gene rankings obtained from microarray experiments) where evolutionary approaches can be afforded with the ambition of better optimization. We conjecture that an ideal consensus ordering should have its total disagreement shared, as equally as possible, with the input orderings. This is also important to refrain the evolutionary processes from getting stuck to local extremes. In the current work, we reformulate Kemeny optimal aggregation while introducing a trade-off between the total pairwise disagreement and its distribution. A simulated annealing-based implementation of the proposed objective has been found

  12. An Optimized System for Interventional MRI Guided Stereotactic Surgery: Preliminary Evaluation of Targeting Accuracy

    PubMed Central

    Larson, Paul S.; Starr, Philip A.; Bates, Geoffrey; Tansey, Lisa; Richardson, R. Mark; Martin, Alastair J.

    2011-01-01

    Background Deep brain stimulation (DBS) electrode placement using interventional MRI has been previously reported using a commercially available skull mounted aiming device (Medtronic Nexframe MR) and native MRI scanner software. This first-generation method has technical limitations that are inherent to the hardware and software used. A novel system (SurgiVision ClearPoint) consisting of an aiming device (SMARTFrame) and software has been developed specifically for iMRI interventions including DBS. Objective A series of phantom and cadaver tests were performed to determine the system’s capability, preliminary accuracy and workflow. Methods 18 experiments using a water phantom were used to determine predictive accuracy of the software. 16 experiments using a gelatin-filled skull phantom were used to determine targeting accuracy of the aiming device. 6 procedures in three cadaver heads were performed to compare workflow and accuracy of ClearPoint with Nexframe MR. Results Software prediction experiments showed an average error of 0.9±0.5 mm in magnitude in pitch and roll (mean pitch error −0.2±0.7 mm, mean roll error +0.2±0.7 mm) and an average error of 0.7±0.3 mm in X-Y translation with a slight anterior (0.5±0.3 mm) and lateral (0.4±0.3mm) bias. Targeting accuracy experiments showed average radial error of 0.5±0.3 mm. Cadaver experiments showed a radial error of 0.2±0.1 mm with the ClearPoint system (average procedure time 88±14 minutes) vs 0.6±0.2 mm with the Nexframe MR (average procedure time 92±12 minutes). Conclusion This novel system provides the submillimetric accuracy required for stereotactic interventions including DBS placement. It also overcomes technical limitations inherent in the first-generation iMRI system. PMID:21796000

  13. Characterizations of PAPR-Constrained Radar Waveforms for Optimal Target Detection

    SciTech Connect

    Sen, Satyabrata

    2014-01-01

    We propose to design a peak-to-average power ratio (PAPR) constrained transmit waveform that achieves the optimal performance (following the Neyman Pearson lemma) in detecting a target in the presence of signal-dependent interference. The direct time-domain approach allows straightforward characterizations of the correlation and PAPR properties of the designed signals, which are critically important to analyze the system performance in the presence of multiple targets and to assess the transmitter power-utilization, respectively. Therefore, instead of designing a transmit signal only for the optimal detection performance, we solve a biobjective Pareto-optimization problem, subjecting to the PAPR and total energy constraints, in order to simultaneously optimize the detection and cross-correlation performances. With extensive numerical examples, we demonstrate that PAPR-constrained signals produce nearly optimum detection performance even with a strict PAPR requirement, and also highlight the conflicting behavior of the detection and correlation performances.

  14. Performance consequences of parity placement in disk arrays

    NASA Technical Reports Server (NTRS)

    Lee, Edward K.; Katz, Randy H.

    1991-01-01

    The performance of a variety of parity placement schemes are defined and investigated to demonstrate that, at relatively large request sizes of hundreds of kilobytes, the choice of parity placement significantly affects performance (20 to 30 percent for the disk array configurations that are common today). It is shown that the left-symmetric, extended-left-symmetric and flat-left-symmetric are the best RAID level 5 parity placements. The placement with the highest read performance, flat-left-symmetric, has the lowest write performance, while the placement with the lowest read performance, left-symmetric, has the highest write performance. Suggestions for optimizing parity placements are included.

  15. Anatomical targeting of the optimal location for thalamic deep brain stimulation in patients with essential tremor.

    PubMed

    King, Nicolas K K; Krishna, Vibhor; Sammartino, Francesco; Bari, Ausaf; Reddy, Gaddum Duemani; Hodaie, Mojgan; Kalia, Suneil K; Fasano, Alfonso; Munhoz, Renato P; Lozano, Andres M; Hamani, Clement

    2017-07-31

    Thalamic deep brain stimulation (DBS) is an effective strategy for the treatment of essential tremor (ET). With limitations of imaging modalities, targeting largely relies on indirect methods. This study was designed to determine the optimal target for DBS in ET and construct a targeting method based on probabilistic maps. Patients with ET who had sustained tremor reduction at 1-year and optimal microelectrode recordings were selected. Stimulation volume was individually modeled in standard space and a final optimal region was derived for the whole population. A fornix (Fx) targeting method was developed to determine the location of the optimal stimulation site relative to the fornix and posterior commissure (PC) in the anteroposterior plane, the border between the thalamus and internal capsule in the mediolateral plane, and the anterior-posterior commissure (AC-PC) plane in the dorsalventral axis. Following comparative analyses with other standard indirect methods (25% of AC-PC, and PC+6mm), the Fx-method was studied in relation to diffusion tensor imaging. Using the Fx-method, we found that the optimal stimulation site was at the intersection of the 2/3 and 1/3 of the PC-Fx distance (mean of 28±1.5% AC-PC length), and 4mm medial to the lateral border of the thalamus. Compared to previously used methods, there was a significant reduction in variability of the optimal stimulation site with the Fx-method. The target defined using this strategy was found to be within the boundaries of the dentato-rubro-thalamic tract. The Fx-method may be an additional targeting strategy in patients undergoing thalamic surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Maximize, minimize or target - optimization for a fitted response from a designed experiment

    DOE PAGES

    Anderson-Cook, Christine Michaela; Cao, Yongtao; Lu, Lu

    2016-04-01

    One of the common goals of running and analyzing a designed experiment is to find a location in the design space that optimizes the response of interest. Depending on the goal of the experiment, we may seek to maximize or minimize the response, or set the process to hit a particular target value. After the designed experiment, a response model is fitted and the optimal settings of the input factors are obtained based on the estimated response model. Furthermore, the suggested optimal settings of the input factors are then used in the production environment.

  17. Maximize, minimize or target - optimization for a fitted response from a designed experiment

    SciTech Connect

    Anderson-Cook, Christine Michaela; Cao, Yongtao; Lu, Lu

    2016-04-01

    One of the common goals of running and analyzing a designed experiment is to find a location in the design space that optimizes the response of interest. Depending on the goal of the experiment, we may seek to maximize or minimize the response, or set the process to hit a particular target value. After the designed experiment, a response model is fitted and the optimal settings of the input factors are obtained based on the estimated response model. Furthermore, the suggested optimal settings of the input factors are then used in the production environment.

  18. Development of an uncertainty technique using Bayesian methods to study the impact of climate change and land use change on solutions obtained by the BMP selection and placement optimization tool

    NASA Astrophysics Data System (ADS)

    Maringanti, C.; Chaubey, I.

    2009-12-01

    A multi-objective genetic algorithm (NSGA-II) in combination with a watershed model (Soil and Water Assessment Tool (SWAT)) is used in an optimization framework for making the Best Management Practices (BMP) selection and placement decisions to reduce the nonpoint source (NPS) pollutants and the net cost for implementation of BMPs. Shuffled complex evolutionary metropolis uncertainty analysis (SCEM-UA) method will be used to quantify the uncertainty of the BMP selection and placement tool. The sources of input uncertainty for the tool include the uncertainties in the estimation of economic costs for the implementation of BMPs, and input SWAT model predictions at field level. The SWAT model predictions are in turn influenced by the model parameters and the input climate forcing such as precipitation and temperature which in turn are affected due to the changing climate, and the changing land use in the watershed. The optimization tool is also influenced by the operational parameters of the genetic algorithm. The SCEM-UA method will be initiated using a uniform distribution for the range of the model parameters and the input sources of uncertainty to estimate the posterior probability distribution of the model response variables. This methodology will be applied to estimate the uncertainty in the BMP selection and placement in Wildcat Creek Watershed located in northcentral Indiana. Nitrogen, phosphorus, sediment, and pesticide are the various NPS pollutants that will be reduced through implementation of BMPs in the watershed. The uncertainty bounds around the Pareto-optimal fronts after the optimization will provide the watershed management groups a clear insight on how the desired water quality goals could be realistically met for the least amount of money that is available for BMP implementation in the watershed.

  19. Paleoclimate Sampling as a Sensor Placement Problem

    NASA Astrophysics Data System (ADS)

    Comboul, M.; Emile-Geay, J.; Hakim, G. J.; Evans, M. N.

    2014-12-01

    We treat paleoclimatic sampling as a sensor placement problem, attempting to find the locations where observations would optimally characterize the variability of climate fields of interest. Starting from a set of realistically-constrained, predefined potential sampling locations and observational uncertainties, we formulate optimized observing networks as the solution to a data-assimilation problem: given a stochastic representation of the Gaussian-distributed climate states of interest, which are linked to direct climate observations via a proxy system model, we may update the distribution and quantify the information gain from each possible sensor network. Furthermore, using submodular cost functions considerably reduces the size of the numerical optimization problem, as it enables iterative addition of sensors to the network. We illustrate this process with the design of an optimal network of coral δ18O used to jointly infer sea surface temperature and sea surface salinity fields. For example, given the current coral network, we show that an additional 25 to 75 observations would greatly improve the SST field reconstruction with the resampling rate being the highest in the central Pacific region. We analyze the impact of various design choices on the resulting optimal sensor network, such as the cost function formulation, the quantification of uncertainty within the proxy system model and the targeted fields. We conclude with a discussion of applications to other proxy classes.

  20. Optimal In Silico Target Gene Deletion through Nonlinear Programming for Genetic Engineering

    PubMed Central

    Hong, Chung-Chien; Song, Mingzhou

    2010-01-01

    Background Optimal selection of multiple regulatory genes, known as targets, for deletion to enhance or suppress the activities of downstream genes or metabolites is an important problem in genetic engineering. Such problems become more feasible to address in silico due to the availability of more realistic dynamical system models of gene regulatory and metabolic networks. The goal of the computational problem is to search for a subset of genes to knock out so that the activity of a downstream gene or a metabolite is optimized. Methodology/Principal Findings Based on discrete dynamical system modeling of gene regulatory networks, an integer programming problem is formulated for the optimal in silico target gene deletion problem. In the first result, the integer programming problem is proved to be NP-hard and equivalent to a nonlinear programming problem. In the second result, a heuristic algorithm, called GKONP, is designed to approximate the optimal solution, involving an approach to prune insignificant terms in the objective function, and the parallel differential evolution algorithm. In the third result, the effectiveness of the GKONP algorithm is demonstrated by applying it to a discrete dynamical system model of the yeast pheromone pathways. The empirical accuracy and time efficiency are assessed in comparison to an optimal, but exhaustive search strategy. Significance Although the in silico target gene deletion problem has enormous potential applications in genetic engineering, one must overcome the computational challenge due to its NP-hardness. The presented solution, which has been demonstrated to approximate the optimal solution in a practical amount of time, is among the few that address the computational challenge. In the experiment on the yeast pheromone pathways, the identified best subset of genes for deletion showed advantage over genes that were selected empirically. Once validated in vivo, the optimal target genes are expected to achieve higher

  1. Optimal in silico target gene deletion through nonlinear programming for genetic engineering.

    PubMed

    Hong, Chung-Chien; Song, Mingzhou

    2010-02-24

    Optimal selection of multiple regulatory genes, known as targets, for deletion to enhance or suppress the activities of downstream genes or metabolites is an important problem in genetic engineering. Such problems become more feasible to address in silico due to the availability of more realistic dynamical system models of gene regulatory and metabolic networks. The goal of the computational problem is to search for a subset of genes to knock out so that the activity of a downstream gene or a metabolite is optimized. Based on discrete dynamical system modeling of gene regulatory networks, an integer programming problem is formulated for the optimal in silico target gene deletion problem. In the first result, the integer programming problem is proved to be NP-hard and equivalent to a nonlinear programming problem. In the second result, a heuristic algorithm, called GKONP, is designed to approximate the optimal solution, involving an approach to prune insignificant terms in the objective function, and the parallel differential evolution algorithm. In the third result, the effectiveness of the GKONP algorithm is demonstrated by applying it to a discrete dynamical system model of the yeast pheromone pathways. The empirical accuracy and time efficiency are assessed in comparison to an optimal, but exhaustive search strategy. Although the in silico target gene deletion problem has enormous potential applications in genetic engineering, one must overcome the computational challenge due to its NP-hardness. The presented solution, which has been demonstrated to approximate the optimal solution in a practical amount of time, is among the few that address the computational challenge. In the experiment on the yeast pheromone pathways, the identified best subset of genes for deletion showed advantage over genes that were selected empirically. Once validated in vivo, the optimal target genes are expected to achieve higher genetic engineering effectiveness than a trial

  2. Patient-specific port placement for laparoscopic surgery using atlas-based registration

    NASA Astrophysics Data System (ADS)

    Enquobahrie, Andinet; Shivaprabhu, Vikas; Aylward, Stephen; Finet, Julien; Cleary, Kevin; Alterovitz, Ron

    2013-03-01

    Laparoscopic surgery is a minimally invasive surgical approach, in which abdominal surgical procedures are performed through trocars via small incisions. Patients benefit by reduced postoperative pain, shortened hospital stays, improved cosmetic results, and faster recovery times. Optimal port placement can improve surgeon dexterity and avoid the need to move the trocars, which would cause unnecessary trauma to the patient. We are building an intuitive open source visualization system to help surgeons identify ports. Our methodology is based on an intuitive port placement visualization module and atlas-based registration algorithm to transfer port locations to individual patients. The methodology follows three steps:1) Use a port placement visualization module to manually place ports in an abdominal organ atlas. This step generates port-augmented abdominal atlas. This is done only once for a given patient population. 2) Register the atlas data with the patient CT data, to transfer the prescribed ports to the individual patient 3) Review and adjust the transferred port locations using the port placement visualization module. Tool maneuverability and target reachability can be tested using the visualization system. Our methodology would decrease the amount of physician input necessary to optimize port placement for each patient case. In a follow up work, we plan to use the transferred ports as starting point for further optimization of the port locations by formulating a cost function that will take into account factors such as tool dexterity and likelihood of collision between instruments.

  3. Optimization of self-directed target coverage in wireless multimedia sensor network.

    PubMed

    Yang, Yang; Wang, Yufei; Pi, Dechang; Wang, Ruchuan

    2014-01-01

    Video and image sensors in wireless multimedia sensor networks (WMSNs) have directed view and limited sensing angle. So the methods to solve target coverage problem for traditional sensor networks, which use circle sensing model, are not suitable for WMSNs. Based on the FoV (field of view) sensing model and FoV disk model proposed, how expected multimedia sensor covers the target is defined by the deflection angle between target and the sensor's current orientation and the distance between target and the sensor. Then target coverage optimization algorithms based on expected coverage value are presented for single-sensor single-target, multisensor single-target, and single-sensor multitargets problems distinguishingly. Selecting the orientation that sensor rotated to cover every target falling in the FoV disk of that sensor for candidate orientations and using genetic algorithm to multisensor multitargets problem, which has NP-complete complexity, then result in the approximated minimum subset of sensors which covers all the targets in networks. Simulation results show the algorithm's performance and the effect of number of targets on the resulting subset.

  4. Targeted Learning of the Mean Outcome under an Optimal Dynamic Treatment Rule.

    PubMed

    van der Laan, Mark J; Luedtke, Alexander R

    2015-03-01

    We consider estimation of and inference for the mean outcome under the optimal dynamic two time-point treatment rule defined as the rule that maximizes the mean outcome under the dynamic treatment, where the candidate rules are restricted to depend only on a user-supplied subset of the baseline and intermediate covariates. This estimation problem is addressed in a statistical model for the data distribution that is nonparametric beyond possible knowledge about the treatment and censoring mechanism. This contrasts from the current literature that relies on parametric assumptions. We establish that the mean of the counterfactual outcome under the optimal dynamic treatment is a pathwise differentiable parameter under conditions, and develop a targeted minimum loss-based estimator (TMLE) of this target parameter. We establish asymptotic linearity and statistical inference for this estimator under specified conditions. In a sequentially randomized trial the statistical inference relies upon a second-order difference between the estimator of the optimal dynamic treatment and the optimal dynamic treatment to be asymptotically negligible, which may be a problematic condition when the rule is based on multivariate time-dependent covariates. To avoid this condition, we also develop TMLEs and statistical inference for data adaptive target parameters that are defined in terms of the mean outcome under the estimate of the optimal dynamic treatment. In particular, we develop a novel cross-validated TMLE approach that provides asymptotic inference under minimal conditions, avoiding the need for any empirical process conditions. We offer simulation results to support our theoretical findings.

  5. MUSCLE: automated multi-objective evolutionary optimization of targeted LC-MS/MS analysis.

    PubMed

    Bradbury, James; Genta-Jouve, Grégory; Allwood, J William; Dunn, Warwick B; Goodacre, Royston; Knowles, Joshua D; He, Shan; Viant, Mark R

    2015-03-15

    Developing liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses of (bio)chemicals is both time consuming and challenging, largely because of the large number of LC and MS instrument parameters that need to be optimized. This bottleneck significantly impedes our ability to establish new (bio)analytical methods in fields such as pharmacology, metabolomics and pesticide research. We report the development of a multi-platform, user-friendly software tool MUSCLE (multi-platform unbiased optimization of spectrometry via closed-loop experimentation) for the robust and fully automated multi-objective optimization of targeted LC-MS/MS analysis. MUSCLE shortened the analysis times and increased the analytical sensitivities of targeted metabolite analysis, which was demonstrated on two different manufacturer's LC-MS/MS instruments.

  6. Optimization of vascular-targeting drugs in a computational model of tumor growth

    NASA Astrophysics Data System (ADS)

    Gevertz, Jana

    2012-04-01

    A biophysical tool is introduced that seeks to provide a theoretical basis for helping drug design teams assess the most promising drug targets and design optimal treatment strategies. The tool is grounded in a previously validated computational model of the feedback that occurs between a growing tumor and the evolving vasculature. In this paper, the model is particularly used to explore the therapeutic effectiveness of two drugs that target the tumor vasculature: angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs). Using sensitivity analyses, the impact of VDA dosing parameters is explored, as is the effects of administering a VDA with an AI. Further, a stochastic optimization scheme is utilized to identify an optimal dosing schedule for treatment with an AI and a chemotherapeutic. The treatment regimen identified can successfully halt simulated tumor growth, even after the cessation of therapy.

  7. Toward 3D-guided prostate biopsy target optimization: an estimation of tumor sampling probabilities

    NASA Astrophysics Data System (ADS)

    Martin, Peter R.; Cool, Derek W.; Romagnoli, Cesare; Fenster, Aaron; Ward, Aaron D.

    2014-03-01

    Magnetic resonance imaging (MRI)-targeted, 3D transrectal ultrasound (TRUS)-guided "fusion" prostate biopsy aims to reduce the ~23% false negative rate of clinical 2D TRUS-guided sextant biopsy. Although it has been reported to double the positive yield, MRI-targeted biopsy still yields false negatives. Therefore, we propose optimization of biopsy targeting to meet the clinician's desired tumor sampling probability, optimizing needle targets within each tumor and accounting for uncertainties due to guidance system errors, image registration errors, and irregular tumor shapes. We obtained multiparametric MRI and 3D TRUS images from 49 patients. A radiologist and radiology resident contoured 81 suspicious regions, yielding 3D surfaces that were registered to 3D TRUS. We estimated the probability, P, of obtaining a tumor sample with a single biopsy. Given an RMS needle delivery error of 3.5 mm for a contemporary fusion biopsy system, P >= 95% for 21 out of 81 tumors when the point of optimal sampling probability was targeted. Therefore, more than one biopsy core must be taken from 74% of the tumors to achieve P >= 95% for a biopsy system with an error of 3.5 mm. Our experiments indicated that the effect of error along the needle axis on the percentage of core involvement (and thus the measured tumor burden) was mitigated by the 18 mm core length.

  8. Optimal Multicarrier Phase-Coded Waveform Design for Detection of Extended Targets

    SciTech Connect

    Sen, Satyabrata; Glover, Charles Wayne

    2013-01-01

    We design a parametric multicarrier phase-coded (MCPC) waveform that achieves the optimal performance in detecting an extended target in the presence of signal-dependent interference. Traditional waveform design techniques provide only the optimal energy spectral density of the transmit waveform and suffer a performance loss in the synthesis process of the time-domain signal. Therefore, we opt for directly designing an MCPC waveform in terms of its time-frequency codes to obtain the optimal detection performance. First, we describe the modeling assumptions considering an extended target buried within the signal-dependent clutter with known power spectral density, and deduce the performance characteristics of the optimal detector. Then, considering an MCPC signal transmission, we express the detection characteristics in terms of the phase-codes of the MCPC waveform and propose to optimally design the MCPC signal by maximizing the detection probability. Our numerical results demonstrate that the designed MCPC signal attains the optimal detection performance and requires a lesser computational time than the other parametric waveform design approach.

  9. Navigated marker placement for motion compensation in radiotherapy

    NASA Astrophysics Data System (ADS)

    Winterstein, A.; März, K.; Franz, A. M.; Hafezi, M.; Fard, N.; Sterzing, F.; Mehrabi, A.; Maier-Hein, L.

    2015-03-01

    Radiotherapy is frequently used to treat unoperated or partially resected tumors. Tumor movement, e.g. caused by respiration, is a major challenge in this context. Markers can be implanted around the tumor prior to radiation therapy for accurate tracking of tumor movement. However, accurate placement of these markers while keeping a secure margin around the target and while taking into account critical structures is a difficult task. Computer-assisted needle insertion has been an active field of research in the past decades. However, the challenge of navigated marker placement for motion compensated radiotherapy has not yet been addressed. This work presents a system to support marker implantation for radiotherapy under consideration of safety margins and optimal marker configuration. It is designed to allow placement of markers both percutaneously and during an open liver surgery. To this end, we adapted the previously proposed EchoTrack system which integrates ultrasound (US) imaging and electromagnetic (EM) tracking in a single mobile modality. The potential of our new marker insertion concept was evaluated in a phantom study by inserting sets of three markers around dedicated targets (n=22) simultaneously spacing the markers evenly around the target as well as placing the markers in a defined distance to the target. In all cases the markers were successfully placed in a configuration fulfilling the predefined criteria. This includes a minimum distance of 18.9 ± 2.4 mm between marker and tumor as well as a divergence of 2.1 ± 1.5 mm from the planned marker positions. We conclude that our system has high potential to facilitate the placement of markers in suitable configurations for surgeons without extensive experience in needle punctions as high quality configurations were obtained even by medical non-experts.

  10. Optimization of the photoneutron target geometry for e-accelerator based BNCT

    PubMed Central

    Chegeni, Nahid; Pur, Saleh Boveiry; Razmjoo, Sasan; Hoseini, Seydeh Khadijed

    2017-01-01

    Background and aim Today, electron accelerators are taken into consideration as photoneutron sources. Therefore, for maximum production of epithermal neutron flux, designing a photoneutron target is of significant importance. In this paper, the effect of thickness and geometric shape of a photoneutron target on neutron output were investigated. Methods In this study, a pencil photon source with 13, 15, 18, 20 and 25 MeV energies and a diameter of 2 mm was investigated using Monte Carlo simulation method using MCNP code. To optimize the design of the photoneutron target, the tungsten target with various geometries and thicknesses was investigated. Results The maximum neutron flux produced for all target geometries and thicknesses occurred at neutron energy peak of around 0.46 MeV. As the thickness increased to 2 cm, neutron flux increased and then a decreasing trend was observed. For various geometrical shapes, the determining factor in photoneutron output was the effective target thickness in the photon interaction path that increased by the increase in the area of interaction. Another factor was the angle of the photon’s incidence with the target surface that resulted in a significant decrease in photoneutron output in cone-shaped targets Conclusion Three factors including the total neutron flux, neutrons energy spectrum, and convergence of neutrons plays an important role in the selection of geometry and shape of the target that should be investigated considering beam shaping assembly (BSA) shape. PMID:28848635

  11. Optimization of the photoneutron target geometry for e-accelerator based BNCT.

    PubMed

    Chegeni, Nahid; Pur, Saleh Boveiry; Razmjoo, Sasan; Hoseini, Seydeh Khadijed

    2017-06-01

    Today, electron accelerators are taken into consideration as photoneutron sources. Therefore, for maximum production of epithermal neutron flux, designing a photoneutron target is of significant importance. In this paper, the effect of thickness and geometric shape of a photoneutron target on neutron output were investigated. In this study, a pencil photon source with 13, 15, 18, 20 and 25 MeV energies and a diameter of 2 mm was investigated using Monte Carlo simulation method using MCNP code. To optimize the design of the photoneutron target, the tungsten target with various geometries and thicknesses was investigated. The maximum neutron flux produced for all target geometries and thicknesses occurred at neutron energy peak of around 0.46 MeV. As the thickness increased to 2 cm, neutron flux increased and then a decreasing trend was observed. For various geometrical shapes, the determining factor in photoneutron output was the effective target thickness in the photon interaction path that increased by the increase in the area of interaction. Another factor was the angle of the photon's incidence with the target surface that resulted in a significant decrease in photoneutron output in cone-shaped targets. Three factors including the total neutron flux, neutrons energy spectrum, and convergence of neutrons plays an important role in the selection of geometry and shape of the target that should be investigated considering beam shaping assembly (BSA) shape.

  12. Quantitative control of active targeting of nanocarriers to tumor cells through optimization of folate ligand density.

    PubMed

    Tang, Zhaomin; Li, Dan; Sun, Huili; Guo, Xing; Chen, Yuping; Zhou, Shaobing

    2014-09-01

    The active targeting delivery system has been widely studied in cancer therapy by utilizing folate (FA) ligands to generate specific interaction between nanocarriers and folate receptors (FRs) on tumor cell. However, there is little work that has been published to investigate the influence of the definite density of the FA ligands on the active targeting of nanocarriers. In this study, we have combined magnetic-guided iron oxide nanoparticles with FA ligands, adjusted the FA ligand density and then studied the resulting effects on the active targeting ability of this dual-targeting drug delivery system to tumor cells. We have also optimized the FA ligand density of the drug delivery system for their active targeting to FR-overexpressing tumor cells in vitro. Prussian blue staining, semi-thin section of cells observed with transmission electron microscopy (TEM) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) have shown that the optimal FA density is from 2.3 × 10(18) to 2.5 × 10(18) per gram nanoparticles ((g·NPs)(-1)). We have further tried to qualitatively and quantitatively control the active targeting and delivering of drugs to tumors on 4T1-bearing BALB/c mice. As expected, the in vivo experimental results have also demonstrated that the FA density of the magnetic nanoparticles (MNPs) could be optimized for a more easily binding to tumor cells via the multivalent linkages and more readily internalization through the FR-mediated endocytosis. Our study can provide a strategy to quantitatively control the active targeting of nanocarriers to tumor cells for cancer therapy.

  13. The optimal target for acute glycemic control in critically ill patients: a network meta-analysis.

    PubMed

    Yatabe, Tomoaki; Inoue, Shigeaki; Sakaguchi, Masahiko; Egi, Moritoki

    2017-01-01

    The optimal target blood glucose concentration for acute glycemic control remains unclear because few studies have directly compared 144-180 with 110-144 or >180 mg/dL. Accordingly, we performed a network meta-analysis to compare four different target blood glucose levels (<110, 110-144, 144-180, and >180 mg/dL) in terms of the benefit and risk of insulin therapy. We included all of the studies from three systematic reviews and searched the PubMed and Cochrane databases for other studies investigating glucose targets among critically ill patients. The primary outcome was hospital mortality, and the secondary outcomes were sepsis or bloodstream infection and the risk of hypoglycemia. Network meta-analysis to identify an optimal target glucose concentration. The network meta-analysis included 18,098 patients from 35 studies. There were no significant differences in the risk of mortality and infection among the four blood glucose ranges overall or in subgroup analysis. Conversely, target concentrations of <110 and 110-144 mg/dL were associated with a four to ninefold increase in the risk of hypoglycemia compared with 144-180 and >180 mg/dL. However, there were no significant differences between the target concentrations of 144-180 and >180 mg/dL. This network meta-analysis found no significant difference in the risk of mortality and infection among four target blood glucose ranges in critically ill patients, but indicated that target blood glucose levels of <110 and 110-144 mg/dL were associated with a higher risk of hypoglycemia than target levels of 144-180 and >180 mg/dL. Further studies are required to refute or confirm our findings.

  14. Genetic Algorithm Approaches for Actuator Placement

    NASA Technical Reports Server (NTRS)

    Crossley, William A.

    2000-01-01

    This research investigated genetic algorithm approaches for smart actuator placement to provide aircraft maneuverability without requiring hinged flaps or other control surfaces. The effort supported goals of the Multidisciplinary Design Optimization focus efforts in NASA's Aircraft au program. This work helped to properly identify various aspects of the genetic algorithm operators and parameters that allow for placement of discrete control actuators/effectors. An improved problem definition, including better definition of the objective function and constraints, resulted from this research effort. The work conducted for this research used a geometrically simple wing model; however, an increasing number of potential actuator placement locations were incorporated to illustrate the ability of the GA to determine promising actuator placement arrangements. This effort's major result is a useful genetic algorithm-based approach to assist in the discrete actuator/effector placement problem.

  15. Application of the theory of optimal experiments to adaptive electromagnetic-induction sensing of buried targets.

    PubMed

    Liao, Xuejun; Carin, Lawrence

    2004-08-01

    A mobile electromagnetic-induction (EMI) sensor is considered for detection and characterization of buried conducting and/or ferrous targets. The sensor may be placed on a robot and, here, we consider design of an optimal adaptive-search strategy. A frequency-dependent magnetic-dipole model is used to characterize the target at EMI frequencies. The goal of the search is accurate characterization of the dipole-model parameters, denoted bythe vector theta; the target position and orientation are a subset of theta. The sensor position and operating frequency are denoted by the parameter vector p and a measurement is represented by the pair (p, O), where O denotes the observed data. The parametersp are fixed for a given measurement, but, in the context of a sequence of measurements p may be changed adaptively. In a locally optimal sequence of measurements, we desire the optimal sensor parameters, P(N+1) for estimation of theta, based on the previous measurements (p(n), On)n=1,N. The search strategy is based on the theory of optimal experiments, as discussed in detail and demonstrated via several numerical examples.

  16. A Placement Advisory Test

    ERIC Educational Resources Information Center

    Hughes, Chris

    2010-01-01

    The primary method of placement at Portland CC (PCC) is the Compass Placement test. For the most part, students are placed correctly, but there are cases when students feel that they have been placed too low. In such cases we use our newly created Placement Advisory Test (PAT) to help us place them appropriately. (Contains 2 figures.)

  17. A Placement Advisory Test

    ERIC Educational Resources Information Center

    Hughes, Chris

    2010-01-01

    The primary method of placement at Portland CC (PCC) is the Compass Placement test. For the most part, students are placed correctly, but there are cases when students feel that they have been placed too low. In such cases we use our newly created Placement Advisory Test (PAT) to help us place them appropriately. (Contains 2 figures.)

  18. Job Placement Handbook.

    ERIC Educational Resources Information Center

    Los Angeles Unified School District, CA. Div. of Career and Continuing Education.

    Designed to serve as a guide for job placement personnel, this handbook is written from the point of view of a school or job preparation facility, based on methodology applicable to the placement function in any setting. Factors identified as critical to a successful placement operation are utilization of a systems approach, establishment of…

  19. Increasing quality and quantity of student placements in smaller rural health services: It can be done.

    PubMed

    Smith, Morgan; Lloyd, Gerry; Lobzin, Stefanie; Bartel, Christine; Medlicott, Kym

    2015-08-01

    Future rural nursing and midwifery workforce shortage and current shortage of placements for undergraduate nursing and midwifery students. Developmental evaluation. Five small hospitals and a regional community health service. Increased number of placements available for students; sustainable, quality clinical placement system in place for the future. Clinical facilitators developed a clinical facilitation model and resources that increased quality and quantity of student placements, assisted clinicians to provide higher quality teaching to students, enabled students to develop skills in rural health care service provision and enhanced knowledge around future career options. Placement targets were met and all health services involved chose to continue the model of clinical facilitation developed after project funding ceased. The clinical education skills developed by staff under the project remain in the region to support future students. It is possible to create a sustainable, high-quality, rural placement experience for larger numbers of nursing and midwifery students. Funding sources are available to continue the clinical facilitation model in to the future, but for it to work optimally, a steady supply of students across the year is required. © 2015 National Rural Health Alliance Inc.

  20. Optimization of a Multi-Stage ATR System for Small Target Identification

    NASA Technical Reports Server (NTRS)

    Lin, Tsung-Han; Lu, Thomas; Braun, Henry; Edens, Western; Zhang, Yuhan; Chao, Tien- Hsin; Assad, Christopher; Huntsberger, Terrance

    2010-01-01

    An Automated Target Recognition system (ATR) was developed to locate and target small object in images and videos. The data is preprocessed and sent to a grayscale optical correlator (GOC) filter to identify possible regionsof- interest (ROIs). Next, features are extracted from ROIs based on Principal Component Analysis (PCA) and sent to neural network (NN) to be classified. The features are analyzed by the NN classifier indicating if each ROI contains the desired target or not. The ATR system was found useful in identifying small boats in open sea. However, due to "noisy background," such as weather conditions, background buildings, or water wakes, some false targets are mis-classified. Feedforward backpropagation and Radial Basis neural networks are optimized for generalization of representative features to reduce false-alarm rate. The neural networks are compared for their performance in classification accuracy, classifying time, and training time.

  1. Optimal Intermittence in Search Strategies under Speed-Selective Target Detection

    NASA Astrophysics Data System (ADS)

    Campos, Daniel; Méndez, Vicenç; Bartumeus, Frederic

    2012-01-01

    Random search theory has been previously explored for both continuous and intermittent scanning modes with full target detection capacity. Here we present a new class of random search problems in which a single searcher performs flights of random velocities, the detection probability when it passes over a target location being conditioned to the searcher speed. As a result, target detection involves an N-passage process for which the mean search time is here analytically obtained through a renewal approximation. We apply the idea of speed-selective detection to random animal foraging since a fast movement is known to significantly degrade perception abilities in many animals. We show that speed-selective detection naturally introduces an optimal level of behavioral intermittence in order to solve the compromise between fast relocations and target detection capability.

  2. Experimental evaluation of a robust optimization method for IMRT of moving targets

    NASA Astrophysics Data System (ADS)

    Vrančić, Christian; Trofimov, Alexei; Chan, Timothy C. Y.; Sharp, Gregory C.; Bortfeld, Thomas

    2009-05-01

    Internal organ motion during radiation therapy, if not considered appropriately in the planning process, has been shown to reduce target coverage and increase the dose to healthy tissues. Standard planning approaches, which use safety margins to handle intrafractional movement of the tumor, are typically designed based on the maximum amplitude of motion, and are often overly conservative. Comparable coverage and reduced dose to healthy organs appear achievable with robust motion-adaptive treatment planning, which considers the expected probability distribution of the average target position and the uncertainty of its realization during treatment delivery. A dosimetric test of a robust optimization method for IMRT was performed, using patient breathing data. External marker motion data acquired from respiratory-gated radiotherapy patients were used to build and test the framework for robust optimization. The motion trajectories recorded during radiation treatment itself are not strictly necessary to generate the initial version of a robust treatment plan, but can be used to adapt the plan during the course of treatment. Single-field IMRT plans were optimized to deliver a uniform dose to a rectangular area. During delivery on a linear accelerator, a computer-driven motion phantom reproduced the patients' breathing patterns and a two-dimensional ionization detector array measured the dose delivered. The dose distributions from robust-optimized plans were compared to those from standard plans, which used a margin expansion. Dosimetric tests confirmed the improved sparing of the non-target area with robust planning, which was achieved without compromising the target coverage. The maximum dose in robust plans did not exceed 110% of the prescription, while the minimum target doses were comparable in standard and robust plans. In test courses, optimized for a simplified target geometry, and delivered to a phantom that moved in one dimension with an average amplitude of 17

  3. Microfluidic platform for combinatorial synthesis and optimization of targeted nanoparticles for cancer therapy.

    PubMed

    Valencia, Pedro M; Pridgen, Eric M; Rhee, Minsoung; Langer, Robert; Farokhzad, Omid C; Karnik, Rohit

    2013-12-23

    Taking a nanoparticle (NP) from discovery to clinical translation has been slow compared to small molecules, in part by the lack of systems that enable their precise engineering and rapid optimization. In this work we have developed a microfluidic platform for the rapid, combinatorial synthesis and optimization of NPs. The system takes in a number of NP precursors from which a library of NPs with varying size, surface charge, target ligand density, and drug load is produced in a reproducible manner. We rapidly synthesized 45 different formulations of poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) NPs of different size and surface composition and screened and ranked the NPs for their ability to evade macrophage uptake in vitro. Comparison of the results to pharmacokinetic studies in vivo in mice revealed a correlation between in vitro screen and in vivo behavior. Next, we selected NP synthesis parameters that resulted in longer blood half-life and used the microfluidic platform to synthesize targeted NPs with varying targeting ligand density (using a model targeting ligand against cancer cells). We screened NPs in vitro against prostate cancer cells as well as macrophages, identifying one formulation that exhibited high uptake by cancer cells yet similar macrophage uptake compared to nontargeted NPs. In vivo, the selected targeted NPs showed a 3.5-fold increase in tumor accumulation in mice compared to nontargeted NPs. The developed microfluidic platform in this work represents a tool that could potentially accelerate the discovery and clinical translation of NPs.

  4. Improvement of in-hospital telemetry monitoring in coronary care units: an intervention study for achieving optimal electrode placement and attachment, hygiene and delivery of critical information to patients.

    PubMed

    Pettersen, Trond R; Fålun, Nina; Norekvål, Tone M

    2014-12-01

    In-hospital telemetry monitoring is important for diagnosis and treatment of patients at risk of developing life-threatening arrhythmias. It is widely used in critical and non-critical care wards. Nurses are responsible for correct electrode placement, thus ensuring optimal quality of the monitoring. The aims of this study were to determine whether a complex educational intervention improves (a) optimal electrode placement, (b) hygiene, and (c) delivery of critical information to patients (reason for monitoring, limitations in cellular phone use, and not to leave the ward without informing a member of staff). A prospective interventional study design was used, with data collection occurring over two six-week periods: before implementation of the intervention (n=201) and after the intervention (n=165). Standard abstraction forms were used to obtain data on patients' clinical characteristics, and 10 variables related to electrode placement and attachment, hygiene and delivery of critical information. At pre-intervention registration, 26% of the electrodes were misplaced. Twelve per cent of the patients received information about limiting their cellular phone use while monitored, 70% were informed of the purpose of monitoring, and 71% used a protective cover for their unit. Post-intervention, outcome measures for the three variables improved significantly: use of protective cover (p<0.001), information about the purpose of monitoring (p=0.005) and information about limitations in cellular phone use (p=0.003). Nonetheless, 23% of the electrodes were still misplaced. The study highlights the need for better, continued education for in-hospital telemetry monitoring in coronary care units, and other units that monitor patients with telemetry. © The European Society of Cardiology 2013.

  5. Advanced Targeting Cost Function Design for Evolutionary Optimization of Control of Logistic Equation

    NASA Astrophysics Data System (ADS)

    Senkerik, Roman; Zelinka, Ivan; Davendra, Donald; Oplatkova, Zuzana

    2010-06-01

    This research deals with the optimization of the control of chaos by means of evolutionary algorithms. This work is aimed on an explanation of how to use evolutionary algorithms (EAs) and how to properly define the advanced targeting cost function (CF) securing very fast and precise stabilization of desired state for any initial conditions. As a model of deterministic chaotic system, the one dimensional Logistic equation was used. The evolutionary algorithm Self-Organizing Migrating Algorithm (SOMA) was used in four versions. For each version, repeated simulations were conducted to outline the effectiveness and robustness of used method and targeting CF.

  6. Parameter Estimation of a Ground Moving Target Using Image Sharpness Optimization

    PubMed Central

    Yu, Jing; Li, Yaan

    2016-01-01

    Motion parameter estimation of a ground moving target is an important issue in synthetic aperture radar ground moving target indication (SAR-GMTI) which has significant applications for civilian and military. The SAR image of a moving target may be displaced and defocused due to the radial and along-track velocity components, respectively. The sharpness cost function presents a measure of the degree of focus of the image. In this work, a new ground moving target parameter estimation algorithm based on the sharpness optimization criterion is proposed. The relationships between the quadratic phase errors and the target’s velocity components are derived. Using two-dimensional searching of the sharpness cost function, we can obtain the velocity components of the target and the focused target image simultaneously. The proposed moving target parameter estimation method and image sharpness metrics are analyzed in detail. Finally, numerical results illustrate the effective and superior velocity estimation performance of the proposed method when compared to existing algorithms. PMID:27376294

  7. Optimal target VOI size for accurate 4D coregistration of DCE-MRI

    NASA Astrophysics Data System (ADS)

    Park, Brian; Mikheev, Artem; Zaim Wadghiri, Youssef; Bertrand, Anne; Novikov, Dmitry; Chandarana, Hersh; Rusinek, Henry

    2016-03-01

    Dynamic contrast enhanced (DCE) MRI has emerged as a reliable and diagnostically useful functional imaging technique. DCE protocol typically lasts 3-15 minutes and results in a time series of N volumes. For automated analysis, it is important that volumes acquired at different times be spatially coregistered. We have recently introduced a novel 4D, or volume time series, coregistration tool based on a user-specified target volume of interest (VOI). However, the relationship between coregistration accuracy and target VOI size has not been investigated. In this study, coregistration accuracy was quantitatively measured using various sized target VOIs. Coregistration of 10 DCE-MRI mouse head image sets were performed with various sized VOIs targeting the mouse brain. Accuracy was quantified by measures based on the union and standard deviation of the coregistered volume time series. Coregistration accuracy was determined to improve rapidly as the size of the VOI increased and approached the approximate volume of the target (mouse brain). Further inflation of the VOI beyond the volume of the target (mouse brain) only marginally improved coregistration accuracy. The CPU time needed to accomplish coregistration is a linear function of N that varied gradually with VOI size. From the results of this study, we recommend the optimal size of the VOI to be slightly overinclusive, approximately by 5 voxels, of the target for computationally efficient and accurate coregistration.

  8. Targeting blood–brain barrier changes during inflammatory pain: an opportunity for optimizing CNS drug delivery

    PubMed Central

    Ronaldson, Patrick T; Davis, Thomas P

    2012-01-01

    The blood–brain barrier (BBB) is the most significant obstacle to effective CNS drug delivery. It possesses structural and biochemical features (i.e., tight-junction protein complexes and, influx and efflux transporters) that restrict xenobiotic permeation. Pathophysiological stressors (i.e., peripheral inflammatory pain) can alter BBB tight junctions and transporters, which leads to drug-permeation changes. This is especially critical for opioids, which require precise CNS concentrations to be safe and effective analgesics. Recent studies have identified molecular targets (i.e., endogenous transporters and intracellular signaling systems) that can be exploited for optimization of CNS drug delivery. This article summarizes current knowledge in this area and emphasizes those targets that present the greatest opportunity for controlling drug permeation and/or drug transport across the BBB in an effort to achieve optimal CNS opioid delivery. PMID:22468221

  9. Adaptive bi-level programming for optimal gene knockouts for targeted overproduction under phenotypic constraints

    PubMed Central

    2013-01-01

    Background Optimization procedures to identify gene knockouts for targeted biochemical overproduction have been widely in use in modern metabolic engineering. Flux balance analysis (FBA) framework has provided conceptual simplifications for genome-scale dynamic analysis at steady states. Based on FBA, many current optimization methods for targeted bio-productions have been developed under the maximum cell growth assumption. The optimization problem to derive gene knockout strategies recently has been formulated as a bi-level programming problem in OptKnock for maximum targeted bio-productions with maximum growth rates. However, it has been shown that knockout mutants in fact reach the steady states with the minimization of metabolic adjustment (MOMA) from the corresponding wild-type strains instead of having maximal growth rates after genetic or metabolic intervention. In this work, we propose a new bi-level computational framework--MOMAKnock--which can derive robust knockout strategies under the MOMA flux distribution approximation. Methods In this new bi-level optimization framework, we aim to maximize the production of targeted chemicals by identifying candidate knockout genes or reactions under phenotypic constraints approximated by the MOMA assumption. Hence, the targeted chemical production is the primary objective of MOMAKnock while the MOMA assumption is formulated as the inner problem of constraining the knockout metabolic flux to be as close as possible to the steady-state phenotypes of wide-type strains. As this new inner problem becomes a quadratic programming problem, a novel adaptive piecewise linearization algorithm is developed in this paper to obtain the exact optimal solution to this new bi-level integer quadratic programming problem for MOMAKnock. Results Our new MOMAKnock model and the adaptive piecewise linearization solution algorithm are tested with a small E. coli core metabolic network and a large-scale iAF1260 E. coli metabolic network

  10. NCCN Task Force Report: Optimizing Treatment of Advanced Renal Cell Carcinoma With Molecular Targeted Therapy

    PubMed Central

    Hudes, Gary R.; Carducci, Michael A.; Choueiri, Toni K.; Esper, Peg; Jonasch, Eric; Kumar, Rashmi; Margolin, Kim A.; Michaelson, M. Dror; Motzer, Robert J.; Pili, Roberto; Roethke, Susan; Srinivas, Sandy

    2015-01-01

    The outcome of patients with metastatic renal cell carcinoma has been substantially improved with administration of the currently available molecularly targeted therapies. However, proper selection of therapy and management of toxicities remain challenging. NCCN convened a multidisciplinary task force panel to address the clinical issues associated with these therapies in attempt to help practicing oncologists optimize patient outcomes. This report summarizes the background data presented at the task force meeting and the ensuing discussion. PMID:21335444

  11. Optimal snake-based segmentation of a random luminance target on a spatially disjoint background

    NASA Astrophysics Data System (ADS)

    Germain, Olivier; Réfrégier, Philippe

    1996-11-01

    We describe a segmentation processor that is optimal for tracking the shape of a target with random white Gaussian intensity appearing on a random white Gaussian spatially disjoint background. This algorithm, based on an active contours model (snakes), consists of correlations of binary references with preprocessed versions of the scene image. This result can provide a practical method to adapt the reference image to correlation techniques.

  12. Microfluidic Platform for Combinatorial Synthesis and Optimization of Targeted Nanoparticles for Cancer Therapy

    PubMed Central

    Valencia, Pedro M.; Pridgen, Eric M.; Rhee, Minsoung; Langer, Robert; Farokhzad, Omid C.; Karnik, Rohit

    2014-01-01

    Taking a nanoparticle (NP) from discovery to clinical translation has been slow compared to small molecules, in part by the lack of systems that enable their precise engineering and rapid optimization. In this work we have developed a microfluidic platform for the rapid, combinatorial synthesis and optimization of NPs. The system takes in a number of NP precursors from which a library of NPs with varying size, surface charge, target ligand density, and drug load is produced in a reproducible manner. We rapidly synthesized 45 different formulations of poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) NPs of different size and surface composition, and screened and ranked the NPs for their ability to evade macrophage uptake in vitro. Comparison of the results to pharmacokinetic studies in vivo in mice revealed a correlation between in vitro screen and in vivo behavior. Next, we selected NP synthesis parameters that resulted in longer blood half-life and used the microfluidic platform to synthesize targeted NPs with varying targeting ligand density (using a model targeting ligand against cancer cells). We screened NPs in vitro against prostate cancer cells as well as macrophages, identifying one formulation that exhibited high uptake by cancer cells yet similar macrophage uptake compared to non-targeted NPs. In vivo, the selected targeted NPs showed a 3.5-fold increase in tumor accumulation in mice compared to non-targeted NPs. The developed microfluidic platform in this work represents a tool that could potentially accelerate the discovery and clinical translation of NPs. PMID:24215426

  13. Constant-Envelope Waveform Design for Optimal Target-Detection and Autocorrelation Performances

    SciTech Connect

    Sen, Satyabrata

    2013-01-01

    We propose an algorithm to directly synthesize in time-domain a constant-envelope transmit waveform that achieves the optimal performance in detecting an extended target in the presence of signal-dependent interference. This approach is in contrast to the traditional indirect methods that synthesize the transmit signal following the computation of the optimal energy spectral density. Additionally, we aim to maintain a good autocorrelation property of the designed signal. Therefore, our waveform design technique solves a bi-objective optimization problem in order to simultaneously improve the detection and autocorrelation performances, which are in general conflicting in nature. We demonstrate this compromising characteristics of the detection and autocorrelation performances with numerical examples. Furthermore, in the absence of the autocorrelation criterion, our designed signal is shown to achieve a near-optimum detection performance.

  14. Flexible Fusion Structure-Based Performance Optimization Learning for Multisensor Target Tracking.

    PubMed

    Ge, Quanbo; Wei, Zhongliang; Cheng, Tianfa; Chen, Shaodong; Wang, Xiangfeng

    2017-05-06

    Compared with the fixed fusion structure, the flexible fusion structure with mixed fusion methods has better adjustment performance for the complex air task network systems, and it can effectively help the system to achieve the goal under the given constraints. Because of the time-varying situation of the task network system induced by moving nodes and non-cooperative target, and limitations such as communication bandwidth and measurement distance, it is necessary to dynamically adjust the system fusion structure including sensors and fusion methods in a given adjustment period. Aiming at this, this paper studies the design of a flexible fusion algorithm by using an optimization learning technology. The purpose is to dynamically determine the sensors' numbers and the associated sensors to take part in the centralized and distributed fusion processes, respectively, herein termed sensor subsets selection. Firstly, two system performance indexes are introduced. Especially, the survivability index is presented and defined. Secondly, based on the two indexes and considering other conditions such as communication bandwidth and measurement distance, optimization models for both single target tracking and multi-target tracking are established. Correspondingly, solution steps are given for the two optimization models in detail. Simulation examples are demonstrated to validate the proposed algorithms.

  15. Intracellular protein target detection by quantum dots optimized for live cell imaging.

    PubMed

    Choi, Youngseon; Kim, Keumhyun; Hong, Sukmin; Kim, Hichul; Kwon, Yong-Jun; Song, Rita

    2011-08-17

    Imaging of specific intracellular target proteins in living cells has been of great challenge and importance for understanding intracellular events and elucidating various biological phenomena. Highly photoluminescent and water-soluble semiconductor nanocrystal quantum dots (QDs) have been extensively applied to various cellular imaging applications due to the long-term photostability and the tunable narrow emission spectra with broad excitation. Despite the great success of various bioimaging and diagnostic applications, visualization of intracellular targets in live cells still has been of great challenge. Nonspecific binding, difficulty of intracellular delivery, or endosomal trapping of nanosized QDs are the main reasons to hamper specific target binding in live cells. In this context, we prepared the polymer-coated QDs (pcQD) of which the surface was optimized for specific intracellular targeting in live cells. Efficient intracellular delivery was achieved through PEGylation and subsequent cell penetrating peptide (i.e., TAT) conjugation to the pcQD in order to avoid significant endosomal sequestration and to facilitate internalization of the QDs, respectively. In this study, we employed HEK293 cell line overexpressing endothelin A receptor (ET(A)R), a family of G-protein coupled receptor (GPCR), of which the cytosolic c-terminal site is genetically engineered to possess green fluorescent protein (GFP) as our intracellular protein target. The fluorescence signal of the target protein and the well-defined intracellular behavior of the GPCR help to evaluate the targeting specificity of QDs in living cells. To test the hypothesis that the TAT-QDs conjugated with antibody against intracellular target of interest can find the target, we conjugated anti-GFP antibody to TAT-PEG-pcQD using heterobifunctional linkers. Compared to the TAT-PEG-pcQD, which was distributed throughout the cytoplasm, the antiGFP-functionalized TAT-PEG-pcQD could penetrate the cell membrane

  16. Optimal marker-strategy clinical trial design to detect predictive markers for targeted therapy.

    PubMed

    Zang, Yong; Liu, Suyu; Yuan, Ying

    2016-07-01

    In developing targeted therapy, the marker-strategy design (MSD) provides an important approach to evaluate the predictive marker effect. This design first randomizes patients into non-marker-based or marker-based strategies. Patients allocated to the non-marker-based strategy are then further randomized to receive either the standard or targeted treatments, while patients allocated to the marker-based strategy receive treatments based on their marker statuses. Little research has been done on the statistical properties of the MSD, which has led to some widespread misconceptions and placed clinical researchers at high risk of using inefficient designs. In this article, we show that the commonly used between-strategy comparison has low power to detect the predictive effect and is valid only under a restrictive condition that the randomization ratio within the non-marker-based strategy matches the marker prevalence. We propose a Wald test that is generally valid and also uniformly more powerful than the between-strategy comparison. Based on that, we derive an optimal MSD that maximizes the power to detect the predictive marker effect by choosing the optimal randomization ratios between the two strategies and treatments. Our numerical study shows that using the proposed optimal designs can substantially improve the power of the MSD to detect the predictive marker effect. We use a lung cancer trial to illustrate the proposed optimal designs.

  17. Methods for joint optimization of mask and design targets for improving lithographic process window

    NASA Astrophysics Data System (ADS)

    Banerjee, Shayak; Agarwal, Kanak B.; Orshansky, Michael

    2013-04-01

    Low-k1 lithography results in features that suffer from poor lithographic yield in the presence of process variation. The problem is especially pronounced for lower-level metals used for local routing, where bi-directionality and tight pitches give rise to lithography unfriendly layout patterns. However, there exists inherent unutilized flexibility in design shapes, e.g., one can modify such wires without significantly affecting design behavior. We develop two different techniques to simultaneously modify mask and design shapes during optical proximity correction (OPC) to improve lithographic yield of low-level metal layers. The methods utilize image slope information, which is available during OPC image simulations at no extra cost, as a measure of lithographic process window. We first propose a method that identifies fragments with low normalized image log slope (NILS) and then use this NILS information to guide dynamic target modification between iterations of OPC. The method uses a pre-characterized lookup table to assign a different magnitude of local target correction to different NILS bins. Next we develop an optimization flow where we derive a cost function that maximizes both contour fidelity and robustness to drive our simultaneous mask and target optimization (SMATO) method. We develop analytical equations to predict the cost for a given mask and target modification and use a fast algorithm to minimize this cost function to obtain an optimal mask and target solution. Our experiments on sample 1× (M1) layouts show that the use of SMATO reduces the process manufacturability index (PMI) by 15.4% compared with OPC, which further leads to 69% reduction in the number of layout hotspots. Additionally, such improvement is obtained at low average runtime overhead (5.5%). Compared with process window optical proximity correction (PWOPC), we observe 4.6% improvement in PMI at large (2.6×) improvement in runtime.

  18. Interpolating between random walks and optimal transportation routes: Flow with multiple sources and targets

    NASA Astrophysics Data System (ADS)

    Guex, Guillaume

    2016-05-01

    In recent articles about graphs, different models proposed a formalism to find a type of path between two nodes, the source and the target, at crossroads between the shortest-path and the random-walk path. These models include a freely adjustable parameter, allowing to tune the behavior of the path toward randomized movements or direct routes. This article presents a natural generalization of these models, namely a model with multiple sources and targets. In this context, source nodes can be viewed as locations with a supply of a certain good (e.g. people, money, information) and target nodes as locations with a demand of the same good. An algorithm is constructed to display the flow of goods in the network between sources and targets. With again a freely adjustable parameter, this flow can be tuned to follow routes of minimum cost, thus displaying the flow in the context of the optimal transportation problem or, by contrast, a random flow, known to be similar to the electrical current flow if the random-walk is reversible. Moreover, a source-targetcoupling can be retrieved from this flow, offering an optimal assignment to the transportation problem. This algorithm is described in the first part of this article and then illustrated with case studies.

  19. Strategies and Advancement in Antibody-Drug Conjugate Optimization for Targeted Cancer Therapeutics

    PubMed Central

    Kim, Eunhee G.; Kim, Kristine M.

    2015-01-01

    Antibody-drug conjugates utilize the antibody as a delivery vehicle for highly potent cytotoxic molecules with specificity for tumor-associated antigens for cancer therapy. Critical parameters that govern successful antibody-drug conjugate development for clinical use include the selection of the tumor target antigen, the antibody against the target, the cytotoxic molecule, the linker bridging the cytotoxic molecule and the antibody, and the conjugation chemistry used for the attachment of the cytotoxic molecule to the antibody. Advancements in these core antibody-drug conjugate technology are reflected by recent approval of Adectris® (anti-CD30-drug conjugate) and Kadcyla® (anti-HER2 drug conjugate). The potential approval of an anti-CD22 conjugate and promising new clinical data for anti-CD19 and anti-CD33 conjugates are additional advancements. Enrichment of antibody-drug conjugates with newly developed potent cytotoxic molecules and linkers are also in the pipeline for various tumor targets. However, the complexity of antibody-drug conjugate components, conjugation methods, and off-target toxicities still pose challenges for the strategic design of antibody-drug conjugates to achieve their fullest therapeutic potential. This review will discuss the emergence of clinical antibody-drug conjugates, current trends in optimization strategies, and recent study results for antibody-drug conjugates that have incorporated the latest optimization strategies. Future challenges and perspectives toward making antibody-drug conjugates more amendable for broader disease indications are also discussed. PMID:26535074

  20. Drug Target Optimization in Chronic Myeloid Leukemia Using Innovative Computational Platform

    NASA Astrophysics Data System (ADS)

    Chuang, Ryan; Hall, Benjamin A.; Benque, David; Cook, Byron; Ishtiaq, Samin; Piterman, Nir; Taylor, Alex; Vardi, Moshe; Koschmieder, Steffen; Gottgens, Berthold; Fisher, Jasmin

    2015-02-01

    Chronic Myeloid Leukemia (CML) represents a paradigm for the wider cancer field. Despite the fact that tyrosine kinase inhibitors have established targeted molecular therapy in CML, patients often face the risk of developing drug resistance, caused by mutations and/or activation of alternative cellular pathways. To optimize drug development, one needs to systematically test all possible combinations of drug targets within the genetic network that regulates the disease. The BioModelAnalyzer (BMA) is a user-friendly computational tool that allows us to do exactly that. We used BMA to build a CML network-model composed of 54 nodes linked by 104 interactions that encapsulates experimental data collected from 160 publications. While previous studies were limited by their focus on a single pathway or cellular process, our executable model allowed us to probe dynamic interactions between multiple pathways and cellular outcomes, suggest new combinatorial therapeutic targets, and highlight previously unexplored sensitivities to Interleukin-3.

  1. Optimization of yeast surface-displayed cDNA library screening for low abundance targets.

    PubMed

    Kim, Juh-Yung; Kim, Hyung Kyu; Jang, Hye Jeong; Kim, Eun-Kyung; Kim, Moon Kyu

    2015-04-01

    The yeast surface-displayed cDNA library has been used to identify unknown antigens. However, when unknown target antigens show moderate-to-low abundance, some modifications are needed in the screening process. In this study, a directional random-primed cDNA library was used to increase the number of candidates for the unknown antigen. To avoid the loss of target yeast clones that express proteins at a low frequency in the cDNA library, a comprehensive monitoring system based on magnetic-activated cell sorting, fluorescence-activated cell sorting, and immunofluorescence was established, and a small number of target yeast cells was successfully enriched. These results showed that our optimized method has potential application for identifying rare unknown antigens of the human monoclonal antibody.

  2. Multi-objective optimization for RNA design with multiple target secondary structures.

    PubMed

    Taneda, Akito

    2015-09-03

    RNAs are attractive molecules as the biological parts for synthetic biology. In particular, the ability of conformational changes, which can be encoded in designer RNAs, enables us to create multistable molecular switches that function in biological circuits. Although various algorithms for designing such RNA switches have been proposed, the previous algorithms optimize the RNA sequences against the weighted sum of objective functions, where empirical weights among objective functions are used. In addition, an RNA design algorithm for multiple pseudoknot targets is currently not available. We developed a novel computational tool for automatically designing RNA sequences which fold into multiple target secondary structures. Our algorithm designs RNA sequences based on multi-objective genetic algorithm, by which we can explore the RNA sequences having good objective function values without empirical weight parameters among the objective functions. Our algorithm has great flexibility by virtue of this weight-free nature. We benchmarked our multi-target RNA design algorithm with the datasets of two, three, and four target structures and found that our algorithm shows better or comparable design performances compared with the previous algorithms, RNAdesign and Frnakenstein. In addition to the benchmarks with pseudoknot-free datasets, we benchmarked MODENA with two-target pseudoknot datasets and found that MODENA can design the RNAs which have the target pseudoknotted secondary structures whose free energies are close to the lowest free energy. Moreover, we applied our algorithm to a ribozyme-based ON-switch which takes a ribozyme-inactive secondary structure when the theophylline aptamer structure is assumed. Currently, MODENA is the only RNA design software which can be applied to multiple pseudoknot targets. Successful design results for the multiple targets and an RNA device indicate usefulness of our multi-objective RNA design algorithm.

  3. Optimization of the combined proton acceleration regime with a target composition scheme

    NASA Astrophysics Data System (ADS)

    Yao, W. P.; Li, B. W.; Zheng, C. Y.; Liu, Z. J.; Yan, X. Q.; Qiao, B.

    2016-01-01

    A target composition scheme to optimize the combined proton acceleration regime is presented and verified by two-dimensional particle-in-cell simulations by using an ultra-intense circularly polarized (CP) laser pulse irradiating an overdense hydrocarbon (CH) target, instead of a pure hydrogen (H) one. The combined acceleration regime is a two-stage proton acceleration scheme combining the radiation pressure dominated acceleration (RPDA) stage and the laser wakefield acceleration (LWFA) stage sequentially together. Protons get pre-accelerated in the first stage when an ultra-intense CP laser pulse irradiating an overdense CH target. The wakefield is driven by the laser pulse after penetrating through the overdense CH target and propagating in the underdense tritium plasma gas. With the pre-accelerate stage, protons can now get trapped in the wakefield and accelerated to much higher energy by LWFA. Finally, protons with higher energies (from about 20 GeV up to about 30 GeV) and lower energy spreads (from about 18% down to about 5% in full-width at half-maximum, or FWHM) are generated, as compared to the use of a pure H target. It is because protons can be more stably pre-accelerated in the first RPDA stage when using CH targets. With the increase of the carbon-to-hydrogen density ratio, the energy spread is lower and the maximum proton energy is higher. It also shows that for the same laser intensity around 1022 W cm-2, using the CH target will lead to a higher proton energy, as compared to the use of a pure H target. Additionally, proton energy can be further increased by employing a longitudinally negative gradient of a background plasma density.

  4. Opposed optimal strategies of weighting somatosensory inputs for planning reaching movements toward visual and proprioceptive targets.

    PubMed

    Blouin, Jean; Saradjian, Anahid H; Lebar, Nicolas; Guillaume, Alain; Mouchnino, Laurence

    2014-11-01

    Behavioral studies have suggested that the brain uses a visual estimate of the hand to plan reaching movements toward visual targets and somatosensory inputs in the case of somatosensory targets. However, neural correlates for distinct coding of the hand according to the sensory modality of the target have not yet been identified. Here we tested the twofold hypothesis that the somatosensory input from the reaching hand is facilitated and inhibited, respectively, when planning movements toward somatosensory (unseen fingers) or visual targets. The weight of the somatosensory inputs was assessed by measuring the amplitude of the somatosensory evoked potential (SEP) resulting from vibration of the reaching finger during movement planning. The target sensory modality had no significant effect on SEP amplitude. However, Spearman's analyses showed significant correlations between the SEPs and reaching errors. When planning movements toward proprioceptive targets without visual feedback of the reaching hand, participants showing the greater SEPs were those who produced the smaller directional errors. Inversely, participants showing the smaller SEPs when planning movements toward visual targets with visual feedback of the reaching hand were those who produced the smaller directional errors. No significant correlation was found between the SEPs and radial or amplitude errors. Our results indicate that the sensory strategy for planning movements is highly flexible among individuals and also for a given sensory context. Most importantly, they provide neural bases for the suggestion that optimization of movement planning requires the target and the reaching hand to both be represented in the same sensory modality. Copyright © 2014 the American Physiological Society.

  5. Optimization of the combined proton acceleration regime with a target composition scheme

    SciTech Connect

    Yao, W. P.; Li, B. W.; Zheng, C. Y.; Liu, Z. J.; Yan, X. Q.; Qiao, B.

    2016-01-15

    A target composition scheme to optimize the combined proton acceleration regime is presented and verified by two-dimensional particle-in-cell simulations by using an ultra-intense circularly polarized (CP) laser pulse irradiating an overdense hydrocarbon (CH) target, instead of a pure hydrogen (H) one. The combined acceleration regime is a two-stage proton acceleration scheme combining the radiation pressure dominated acceleration (RPDA) stage and the laser wakefield acceleration (LWFA) stage sequentially together. Protons get pre-accelerated in the first stage when an ultra-intense CP laser pulse irradiating an overdense CH target. The wakefield is driven by the laser pulse after penetrating through the overdense CH target and propagating in the underdense tritium plasma gas. With the pre-accelerate stage, protons can now get trapped in the wakefield and accelerated to much higher energy by LWFA. Finally, protons with higher energies (from about 20 GeV up to about 30 GeV) and lower energy spreads (from about 18% down to about 5% in full-width at half-maximum, or FWHM) are generated, as compared to the use of a pure H target. It is because protons can be more stably pre-accelerated in the first RPDA stage when using CH targets. With the increase of the carbon-to-hydrogen density ratio, the energy spread is lower and the maximum proton energy is higher. It also shows that for the same laser intensity around 10{sup 22} W cm{sup −2}, using the CH target will lead to a higher proton energy, as compared to the use of a pure H target. Additionally, proton energy can be further increased by employing a longitudinally negative gradient of a background plasma density.

  6. Distributed bees algorithm parameters optimization for a cost efficient target allocation in swarms of robots.

    PubMed

    Jevtić, Aleksandar; Gutiérrez, Alvaro

    2011-01-01

    Swarms of robots can use their sensing abilities to explore unknown environments and deploy on sites of interest. In this task, a large number of robots is more effective than a single unit because of their ability to quickly cover the area. However, the coordination of large teams of robots is not an easy problem, especially when the resources for the deployment are limited. In this paper, the distributed bees algorithm (DBA), previously proposed by the authors, is optimized and applied to distributed target allocation in swarms of robots. Improved target allocation in terms of deployment cost efficiency is achieved through optimization of the DBA's control parameters by means of a genetic algorithm. Experimental results show that with the optimized set of parameters, the deployment cost measured as the average distance traveled by the robots is reduced. The cost-efficient deployment is in some cases achieved at the expense of increased robots' distribution error. Nevertheless, the proposed approach allows the swarm to adapt to the operating conditions when available resources are scarce.

  7. Optimizing drugs to reach treatment targets for children and adolescents living with HIV.

    PubMed

    Penazzato, Martina; Lee, Janice; Capparelli, Edmund; Essajee, Shaffiq; Ford, Nathan; Ojoo, Atieno; Pascual, Fernando; Sugandhi, Nandita; Lallemant, Marc

    2015-01-01

    As the global community makes progress towards the 90-90-90 targets by 2020, a key challenge is ensuring that antiretroviral drugs for children and adolescents are suitable to the context of resource-limited settings. Drug optimization aims to support the expanded use of more simplified, less toxic drug regimens with high barriers to drug resistance that require minimal clinical monitoring while maintaining therapeutic efficacy. This manuscript summarizes the progress made and outlines further critical steps required to ensure that the right drugs are available to start children and adolescents on treatment and to keep them virologically suppressed. Building upon previous work in drug optimization, several important steps were taken in 2014 to ensure alignment between WHO dosing recommendations and the requirements of regulatory bodies, to accelerate drug development, to reduce intellectual property barriers to generic production of combined formulations and rationalize drug selection in countries. The priority for the future is to improve access to antiretroviral therapy (ART) at the two ends of the paediatric age spectrum--infants and adolescents--where the treatment gap is greatest, and optimize drug sequencing with better use of available medicines for second- and third-line ART. Future efforts in this area will require continuous collaboration and coordination, and the promotion of innovative approaches to accelerate access to new drugs and formulations. While significant progress has been made, additional efforts are needed to ensure that treatment targets are reached by 2020.

  8. Topology of classical molecular optimal control landscapes for multi-target objectives

    SciTech Connect

    Joe-Wong, Carlee; Ho, Tak-San; Rabitz, Herschel; Wu, Rebing

    2015-04-21

    This paper considers laser-driven optimal control of an ensemble of non-interacting molecules whose dynamics lie in classical phase space. The molecules evolve independently under control to distinct final states. We consider a control landscape defined in terms of multi-target (MT) molecular states and analyze the landscape as a functional of the control field. The topology of the MT control landscape is assessed through its gradient and Hessian with respect to the control. Under particular assumptions, the MT control landscape is found to be free of traps that could hinder reaching the objective. The Hessian associated with an optimal control field is shown to have finite rank, indicating an inherent degree of robustness to control noise. Both the absence of traps and rank of the Hessian are shown to be analogous to the situation of specifying multiple targets for an ensemble of quantum states. Numerical simulations are presented to illustrate the classical landscape principles and further characterize the system behavior as the control field is optimized.

  9. Target point correction optimized based on the dose distribution of each fraction in daily IGRT

    NASA Astrophysics Data System (ADS)

    Stoll, Markus; Giske, Kristina; Stoiber, Eva M.; Schwarz, Michael; Bendl, Rolf

    2014-03-01

    Purpose: To use daily re-calculated dose distributions for optimization of target point corrections (TPCs) in image guided radiation therapy (IGRT). This aims to adapt fractioned intensity modulated radiation therapy (IMRT) to changes in the dose distribution induced by anatomical changes. Methods: Daily control images from an in-room on-rail spiral CT-Scanner of three head-and-neck cancer patients were analyzed. The dose distribution was re-calculated on each control CT after an initial TPC, found by a rigid image registration method. The clinical target volumes (CTVs) were transformed from the planning CT to the rigidly aligned control CTs using a deformable image registration method. If at least 95% of each transformed CTV was covered by the initially planned D95 value, the TPC was considered acceptable. Otherwise the TPC was iteratively altered to maximize the dose coverage of the CTVs. Results: In 14 (out of 59) fractions the criterion was already fulfilled after the initial TPC. In 10 fractions the TPC can be optimized to fulfill the coverage criterion. In 31 fractions the coverage can be increased but the criterion is not fulfilled. In another 4 fractions the coverage cannot be increased by the TPC optimization. Conclusions: The dose coverage criterion allows selection of patients who would benefit from replanning. Using the criterion to include daily re-calculated dose distributions in the TPC reduces the replanning rate in the analysed three patients from 76% to 59% compared to the rigid image registration TPC.

  10. Distributed Bees Algorithm Parameters Optimization for a Cost Efficient Target Allocation in Swarms of Robots

    PubMed Central

    Jevtić, Aleksandar; Gutiérrez, Álvaro

    2011-01-01

    Swarms of robots can use their sensing abilities to explore unknown environments and deploy on sites of interest. In this task, a large number of robots is more effective than a single unit because of their ability to quickly cover the area. However, the coordination of large teams of robots is not an easy problem, especially when the resources for the deployment are limited. In this paper, the Distributed Bees Algorithm (DBA), previously proposed by the authors, is optimized and applied to distributed target allocation in swarms of robots. Improved target allocation in terms of deployment cost efficiency is achieved through optimization of the DBA’s control parameters by means of a Genetic Algorithm. Experimental results show that with the optimized set of parameters, the deployment cost measured as the average distance traveled by the robots is reduced. The cost-efficient deployment is in some cases achieved at the expense of increased robots’ distribution error. Nevertheless, the proposed approach allows the swarm to adapt to the operating conditions when available resources are scarce. PMID:22346677

  11. Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

    SciTech Connect

    Simakov, Andrei N. Wilson, Douglas C.; Yi, Sunghwan A.; Kline, John L.; Batha, Steven H.; Clark, Daniel S.; Milovich, Jose L.; Salmonson, Jay D.

    2014-02-15

    For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer.

  12. Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Simakov, Andrei N.; Wilson, Douglas C.; Yi, Sunghwan A.; Kline, John L.; Clark, Daniel S.; Milovich, Jose L.; Salmonson, Jay D.; Batha, Steven H.

    2014-02-01

    For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer.

  13. Optimization of cell receptor-specific targeting through multivalent surface decoration of polymeric nanocarriers

    PubMed Central

    D’Addio, Suzanne M.; Baldassano, Steven; Shi, Lei; Cheung, Lila; Adamson, Douglas H.; Bruzek, Matthew; Anthony, John E.; Laskin, Debra L.; Sinko, Patrick J.; Prud’homme, Robert K.

    2013-01-01

    characterization of nanocarrier uptake and targeting provides promise for optimizing drug delivery to macrophages for TB treatment and establishes a general route for optimizing targeted formulations of nanocarriers for specific delivery at targeted sites. PMID:23419950

  14. Optimization of cell receptor-specific targeting through multivalent surface decoration of polymeric nanocarriers.

    PubMed

    D'Addio, Suzanne M; Baldassano, Steven; Shi, Lei; Cheung, Lila; Adamson, Douglas H; Bruzek, Matthew; Anthony, John E; Laskin, Debra L; Sinko, Patrick J; Prud'homme, Robert K

    2013-05-28

    characterization of nanocarrier uptake and targeting provides promise for optimizing drug delivery to macrophages for TB treatment and establishes a general route for optimizing targeted formulations of nanocarriers for specific delivery at targeted sites.

  15. Strategies for recruiting and targeting dendritic cells for optimizing HIV vaccines.

    PubMed

    Ahlers, Jeffrey D; Belyakov, Igor M

    2009-06-01

    The natural immune response against HIV and other pathogens that cause chronic infection is insufficient for protection. Novel vaccine design and delivery strategies for optimization of HIV vaccines are urgently needed. These will require a better understanding of a number of factors including: the interplay between dendritic cells (DCs) and multiple cell types in linking innate signals that orchestrate subsequent adaptive immune responses; the regulation of DC function by viral and bacterial vectors, adjuvants and immunomodulatory molecules; and the temporal and synergistic relationships between C-type lectins, Toll-like receptors, NOD-like receptors and RIG-1-like receptors, chemokines and cytokines in enhancing immune responses. Here, we discuss current vaccine strategies for optimizing the induction of immune responses by the recruitment of DCs and the targeting of vaccine antigens to DCs.

  16. Efficient and Targeted Transduction of Nonhuman Primate Liver With Systemically Delivered Optimized AAV3B Vectors.

    PubMed

    Li, Shaoyong; Ling, Chen; Zhong, Li; Li, Mengxin; Su, Qin; He, Ran; Tang, Qiushi; Greiner, Dale L; Shultz, Leonard D; Brehm, Michael A; Flotte, Terence R; Mueller, Christian; Srivastava, Arun; Gao, Guangping

    2015-12-01

    Recombinant adeno-associated virus serotype 3B (rAAV3B) can transduce cultured human liver cancer cells and primary human hepatocytes efficiently. Serine (S)- and threonine (T)-directed capsid modifications further augment its transduction efficiency. Systemically delivered capsid-optimized rAAV3B vectors can specifically target cancer cells in a human liver cancer xenograft model, suggesting their potential use for human liver-directed gene therapy. Here, we compared transduction efficiencies of AAV3B and AAV8 vectors in cultured primary human hepatocytes and cancer cells as well as in human and mouse hepatocytes in a human liver xenograft NSG-PiZ mouse model. We also examined the safety and transduction efficacy of wild-type (WT) and capsid-optimized rAAV3B in the livers of nonhuman primates (NHPs). Intravenously delivered S663V+T492V (ST)-modified self-complementary (sc) AAV3B-EGFP vectors led to liver-targeted robust enhanced green fluorescence protein (EGFP) expression in NHPs without apparent hepatotoxicity. Intravenous injections of both WT and ST-modified rAAV3B.ST-rhCG vectors also generated stable super-physiological levels of rhesus chorionic gonadotropin (rhCG) in NHPs. The vector genome predominantly targeted the liver. Clinical chemistry and histopathology examinations showed no apparent vector-related toxicity. Our studies should be important and informative for clinical development of optimized AAV3B vectors for human liver-directed gene therapy.

  17. Artificially-induced organelles are optimal targets for optical trapping experiments in living cells

    PubMed Central

    López-Quesada, C.; Fontaine, A.-S.; Farré, A.; Joseph, M.; Selva, J.; Egea, G.; Ludevid, M. D.; Martín-Badosa, E.; Montes-Usategui, M.

    2014-01-01

    Optical trapping supplies information on the structural, kinetic or rheological properties of inner constituents of the cell. However, the application of significant forces to intracellular objects is notoriously difficult due to a combination of factors, such as the small difference between the refractive indices of the target structures and the cytoplasm. Here we discuss the possibility of artificially inducing the formation of spherical organelles in the endoplasmic reticulum, which would contain densely packed engineered proteins, to be used as optimized targets for optical trapping experiments. The high index of refraction and large size of our organelles provide a firm grip for optical trapping and thereby allow us to exert large forces easily within safe irradiation limits. This has clear advantages over alternative probes, such as subcellular organelles or internalized synthetic beads. PMID:25071944

  18. Artificially-induced organelles are optimal targets for optical trapping experiments in living cells.

    PubMed

    López-Quesada, C; Fontaine, A-S; Farré, A; Joseph, M; Selva, J; Egea, G; Ludevid, M D; Martín-Badosa, E; Montes-Usategui, M

    2014-07-01

    Optical trapping supplies information on the structural, kinetic or rheological properties of inner constituents of the cell. However, the application of significant forces to intracellular objects is notoriously difficult due to a combination of factors, such as the small difference between the refractive indices of the target structures and the cytoplasm. Here we discuss the possibility of artificially inducing the formation of spherical organelles in the endoplasmic reticulum, which would contain densely packed engineered proteins, to be used as optimized targets for optical trapping experiments. The high index of refraction and large size of our organelles provide a firm grip for optical trapping and thereby allow us to exert large forces easily within safe irradiation limits. This has clear advantages over alternative probes, such as subcellular organelles or internalized synthetic beads.

  19. Optimal design of TIR prism for the infrared target simulator based on DMD

    NASA Astrophysics Data System (ADS)

    Liu, Fang; Sun, Dan; Gao, Jiaobo; Zheng, Yawei; Hu, Yu; Zhang, Fang; Wang, Xicheng

    2016-10-01

    Overall structure of the infrared target simulator system and the principle of DMD are introduced. When DMD is on "open" state, all of the incidence light can rip into the pupil of the projection system. In addition, when it is on "close" state or "flat" state, all of the incident light can't rip into the pupil of the projection system. Based on this principle, with a specific infrared target simulator, TIR prism with BaF2 as material is designed. And then, this design is improved by ZnSe material instead of BaF2. ZnSe transmission rate is very well in the range of 0.6 microns to 14 microns and the infrared target simulator in this project requires 3 to 5 microns and 8 to 14 microns wavelength. This material is hard and easy to be processed. The design idea and design process are introduced in details in this paper and angle parameters are obtained. To improve light utilization and image quality in infrared target simulator system, two types of thin film on TIR prism different surfaces are designed. One is high transmittance with incidence angle of 0° and 24° - the other is 55°. Finally, this scheme is simulated and optimized by Tracepro software. Approving results were acquired.

  20. Optimized ion acceleration using high repetition rate, variable thickness liquid crystal targets

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Andereck, C. David; Schumacher, Douglass

    2015-11-01

    Laser-based ion acceleration is a widely studied plasma physics topic for its applications to secondary radiation sources, advanced imaging, and cancer therapy. Recent work has centered on investigating new acceleration mechanisms that promise improved ion energy and spectrum. While the physics of these mechanisms is not yet fully understood, it has been observed to dominate for certain ranges of target thickness, where the optimum thickness depends on laser conditions including energy, pulse width, and contrast. The study of these phenomena is uniquely facilitated by the use of variable-thickness liquid crystal films, first introduced in P. L. Poole et al. PoP21, 063109 (2014). Control of the formation parameters of these freely suspended films such as volume, temperature, and draw speed allows on-demand thickness variability between 10 nanometers and several 10s of microns, fully encompassing the currently studied thickness regimes with a single target material. The low vapor pressure of liquid crystal enables in-situ film formation and unlimited vacuum use of these targets. Details on the selection and optimization of ion acceleration mechanism with target thickness will be presented, including recent experiments on the Scarlet laser facility and others. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  1. Threshold size for optimal passive pulmonary targeting and retention of rigid microparticles in rats

    PubMed Central

    Kutscher, Hilliard L.; Chao, Piyun; Deshmukh, Manjeet; Singh, Yashveer; Hu, Peidi; Joseph, Laurie B.; Reimer, David C.; Stein, Stanley; Laskin, Debra L.; Sinko, Patrick J.

    2010-01-01

    The relationship between microparticle (MP) size and lung targeting efficiency, intra-lung distribution and retention time was systematically studied after intravenous administration of rigid fluorescent polystyrene MPs of various sizes (2, 3, 6 and 10μm) to Sprague-Dawley rats. Total fluorescence was assessed and it was found that 2μm and 3μm MPs readily passed through the lung to the liver and spleen while 10μm MPs were completely entrapped in the lung for the one-week duration of the study. Approximately 84% of 6μm MPs that were initially entrapped in the lung were cleared over the next 2 days and 15% were cleared over the remaining 5 days. A Caliper IVIS® 100 small animal imaging system confirmed that 3μm MPs were not retained in the lung but that 6μm and 10μm MPs were widely distributed throughout the lung. Moreover, histologic examination showed MP entrapment in capillaries but not arterioles. These studies suggest that for rigid MPs the optimal size range required to achieve transient but highly efficiently targeting to pulmonary capillaries after IV injection is >6μm but <10μm in rats and that systemic administration of optimally sized MPs may be an efficient alternative to currently used inhalation-based delivery to the lung. PMID:20043961

  2. Soay rams target reproductive activity towards promiscuous females' optimal insemination period.

    PubMed

    Preston, B T; Stevenson, I R; Wilson, K

    2003-10-07

    Female promiscuity is thought to have resulted in the evolution of male behaviours that confer advantages in the sperm competition that ensues. In mammalian species, males can gain a post-copulatory advantage in this sperm 'raffle' by inseminating females at the optimal time relative to ovulation, leading to the prediction that males should preferentially associate and copulate with females at these times. To the best of our knowledge, we provide the first high-resolution test of this prediction using feral Soay sheep, which have a mating system characterized by male competition for access to highly promiscuous females. We find that competitive males time their mate guarding (and hence copulations) to occur close to the optimal insemination period (OIP), when females are also increasingly likely to 'cooperate' with copulation attempts. Subordinate males practice an alternative mating tactic, where they break the integrity of the consort pair and force copulations on females. The timing of these forced copulations is also targeted towards the OIP. We thus provide quantitative evidence that female promiscuity has resulted in the evolution of reproductive strategies in which males 'load' the sperm raffle by targeting their mating activity towards female OIPs, when the probability of sperm-competition success is at its greatest.

  3. Formulation, Evaluation and Optimization of Pectin- Bora Rice Beads for Colon Targeted Drug Delivery System

    PubMed Central

    Ramteke, Kuldeep Hemraj; Nath, Lilakant

    2014-01-01

    Purpose: The purpose of this research was to established new polysaccharide for the colon targeted drug delivery system, its formulation and in vitro and in vivo evaluation. Methods: Microspheres containing pectin and bora rice were prepared by ionotropic gelation technique using zinc acetate as cross linking agent and model drug used was glipizide. A 32 full factorial design was employed to study the effect of independent variables, polymer to drug ratio (A), and concentration of cross linking agent (B) on dependent variables, particle size, swelling index, drug entrapment efficiency and percentage drug release. Results: Results of trial batches indicated that polymer to drug ratio and concentration of cross linking agent affects characteristics of beads. Beads were discrete, spherical and free flowing. Beads exhibited small particle size and showed higher percentage of drug entrapment efficiency. The optimized batch P2 exhibited satisfactory drug entrapment efficiency 68% and drug release was also controlled for more than 24 hours. The polymer to drug ratio had a more significant effect on the dependent variables. In vivo gamma scintigraphy study of optimized pectin-bora rice beads demonstrated degradation of beads whenever they reached to the colon. Conclusion: Bora rice is potential polysaccharide for colon targeted drug delivery system. PMID:24511481

  4. LEO cooperative multi-spacecraft refueling mission optimization considering J2 perturbation and target's surplus propellant constraint

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Zhang, Jin; Li, Hai-yang; Zhou, Jian-yong

    2017-01-01

    The optimization of an LEO cooperative multi-spacecraft refueling mission considering the J2 perturbation and target's surplus propellant constraint is studied in the paper. First, a mission scenario is introduced. One service spacecraft and several target spacecraft run on an LEO near-circular orbit, the service spacecraft rendezvouses with some service positions one by one, and target spacecraft transfer to corresponding service positions respectively. Each target spacecraft returns to its original position after obtaining required propellant and the service spacecraft returns to its original position after refueling all target spacecraft. Next, an optimization model of this mission is built. The service sequence, orbital transfer time, and service position are used as deign variables, whereas the propellant cost is used as the design objective. The J2 perturbation, time constraint and the target spacecraft's surplus propellant capability constraint are taken into account. Then, a hybrid two-level optimization approach is presented to solve the formulated mixed integer nonlinear programming (MINLP) problem. A hybrid-encoding genetic algorithm is adopted to seek the near optimal solution in the up-level optimization, while a linear relative dynamic equation considering the J2 perturbation is used to obtain the impulses of orbital transfer in the low-level optimization. Finally, the effectiveness of the proposed model and method is validated by numerical examples.

  5. Optimization of electrical geophysical survey design for hydrogeological applications and subsurface target discrimination

    NASA Astrophysics Data System (ADS)

    Goode, Tomas Charles

    Geophysical imaging methods significantly enhance our knowledge of subsurface characteristics and their use has become prevalent over a range of subsurface investigations. These methods facilitate the detection and characterization of both metallic and nonmetallic subsurface targets, and can provide spatially extensive information on subsurface structure and characteristics that is often impractical to obtain using standard drilling and sampling procedures alone. Electrical imaging methods such as electrical resistivity tomography (ERT) have proven to be particularly useful in hydrogeologic and geotechnical investigations because of the strong dependence of the electrical properties of soils to water saturation, soil texture, and solute concentration. Given the available geophysical tools as well as their applications, the selection of the appropriate geophysical survey design is an essential part of every subsurface geophysical investigation. Where investigations are located in an area with subsurface information already available, this information may be used as a guide for the design of a geophysical survey. In some instances, no subsurface information is available and a survey must be designed to cover a range of possible circumstances. Yet, in other instances, there may be significant subsurface information available, but because of subsurface complexities, a geophysical survey must still be designed to cover a broad range of possibilities. Demonstrating the application and limitations of ERT in a specific field application, the first investigation presented in this document provides guidance for developing methods to improve the design and implementation of ERT surveys in a complex subsurface environment. The two investigations that follow present the development of a relatively simple optimization approach based on limited forward modeling of the geophysical response for both static and mobile surveys. This process is demonstrated through examples of

  6. Optimal Target Region for Subject Classification on the Basis of Amyloid PET Images.

    PubMed

    Carbonell, Felix; Zijdenbos, Alex P; Charil, Arnaud; Grand'Maison, Marilyn; Bedell, Barry J

    2015-09-01

    Classification of subjects on the basis of amyloid PET scans is increasingly being used in research studies and clinical practice. Although qualitative, visual assessment is currently the gold standard approach, automated classification techniques are inherently more reproducible and efficient. The objective of this work was to develop a statistical approach for the automated classification of subjects with different levels of cognitive impairment into a group with low amyloid levels (AβL) and a group with high amyloid levels (AβH) through the use of amyloid PET data from the Alzheimer Disease Neuroimaging Initiative study. In our framework, an iterative, voxelwise, regularized discriminant analysis is combined with a receiver operating characteristic approach that optimizes the selection of a region of interest (ROI) and a cutoff value for the automated classification of subjects into the AβL and AβH groups. The robustness, spatial stability, and generalization of the resulting target ROIs were evaluated by use of the standardized uptake value ratio for (18)F-florbetapir PET images from subjects who served as healthy controls, subjects who had mild cognitive impairment, and subjects who had Alzheimer disease and were participating in the Alzheimer Disease Neuroimaging Initiative study. We determined that several iterations of the discriminant analysis improved the classification of subjects into the AβL and AβH groups. We found that an ROI consisting of the posterior cingulate cortex/precuneus and the medial frontal cortex yielded optimal group separation and showed good stability across different reference regions and cognitive cohorts. A key step in this process was the automated determination of the cutoff value for group separation, which was dependent on the reference region used for the standardized uptake value ratio calculation and which was shown to have a relatively narrow range across subject groups. We developed a data-driven approach for the

  7. Optimizing nerve cuff stimulation of targeted regions through use of genetic algorithms.

    PubMed

    Brill, Natalie; Tyler, Dustin

    2011-01-01

    A nerve cuff electrode is a viable technology for use in a neuroprostheses system to restore loss of function due to neurological injury. The Flat Interface Nerve Electrode (FINE) is a nerve cuff that gently reshapes the nerve to bring the axons closer to the stimulating contacts. The overall goal of this work is to optimize nerve cuff stimulation in upper extremity nerves. Recently, highly efficient and accurate linear models of neuronal activation have been developed in our lab. Using the fast calculations from the newly developed linear activation method, nerve stimulation parameters such as current pulse width and pulse amplitude at many electrode contacts can be explored by employing optimization algorithms. Finite element nerve models with high density electrodes were constructed based on upper extremity cadaveric nerve cross sections. An objective function was developed to target specific groups of nerve fascicles and minimize overlap amongst these groups. By changing the objective function and using a genetic search algorithm, stimulation parameters can be optimized for many contacts.

  8. Multivariate Optimization of Rizatriptan Benzoate-Loaded Solid Lipid Nanoparticles for Brain Targeting and Migraine Management.

    PubMed

    Girotra, Priti; Singh, Shailendra Kumar

    2017-02-01

    The present investigation aimed at development of brain-targeted rizatriptan benzoate-loaded solid lipid nanoparticles (RB-SLNs) by design of experiment, for improvement of its anti-migraine potential. Several formulation variables affecting the fabrication of RB-SLNs were screened using the Plackett-Burman design (PBD). The PBD results demonstrated lipid (Precirol® ATO 5) concentration, co-surfactant (Phospholipon® 90 H) concentration and temperature of lipid melt to be the critical variables, having a significant effect on the achievement of minimum particle size, maximum entrapment efficiency coupled with sustained drug release. The interactions between these formulation parameters and the variability between the batches were further explored employing the Box-Behnken design (BBD). The BBD results were validated by fabricating the suggested optimized solution, which yielded 220.4 ± 2.3 nm particle size with a sufficiently high entrapment efficiency of 71.8 ± 1.9% and 45.9 ± 2.7% cumulative drug release in 8 h. The optimized formulation was, thereafter, characterized by FTIR spectroscopy, wide angle XRD, thermal analysis and TEM imaging technique. The in vivo studies revealed the brain uptake potential of optimized RB-SLNs to be 18.43-folds higher with respect to the pure drug in its free form, post 2 h of oral drug administration. The significant anti-migraine efficacy of RB-SLNs was corroborated through the pharmacodynamic studies on adult male Swiss albino mice. The results hence explicate that RB-SLNs have distinctly improved brain target ability and offer an apt approach for the efficient therapeutic management of migraine.

  9. Optimizing the implementation of the target motion sampling temperature treatment technique - How fast can it get?

    SciTech Connect

    Tuomas, V.; Jaakko, L.

    2013-07-01

    This article discusses the optimization of the target motion sampling (TMS) temperature treatment method, previously implemented in the Monte Carlo reactor physics code Serpent 2. The TMS method was introduced in [1] and first practical results were presented at the PHYSOR 2012 conference [2]. The method is a stochastic method for taking the effect of thermal motion into account on-the-fly in a Monte Carlo neutron transport calculation. It is based on sampling the target velocities at collision sites and then utilizing the 0 K cross sections at target-at-rest frame for reaction sampling. The fact that the total cross section becomes a distributed quantity is handled using rejection sampling techniques. The original implementation of the TMS requires 2.0 times more CPU time in a PWR pin-cell case than a conventional Monte Carlo calculation relying on pre-broadened effective cross sections. In a HTGR case examined in this paper the overhead factor is as high as 3.6. By first changing from a multi-group to a continuous-energy implementation and then fine-tuning a parameter affecting the conservativity of the majorant cross section, it is possible to decrease the overhead factors to 1.4 and 2.3, respectively. Preliminary calculations are also made using a new and yet incomplete optimization method in which the temperature of the basis cross section is increased above 0 K. It seems that with the new approach it may be possible to decrease the factors even as low as 1.06 and 1.33, respectively, but its functionality has not yet been proven. Therefore, these performance measures should be considered preliminary. (authors)

  10. Optimal antisense target reducing INS intron 1 retention is adjacent to a parallel G quadruplex

    PubMed Central

    Kralovicova, Jana; Lages, Ana; Patel, Alpa; Dhir, Ashish; Buratti, Emanuele; Searle, Mark; Vorechovsky, Igor

    2014-01-01

    Splice-switching oligonucleotides (SSOs) have been widely used to inhibit exon usage but antisense strategies that promote removal of entire introns to increase splicing-mediated gene expression have not been developed. Here we show reduction of INS intron 1 retention by SSOs that bind transcripts derived from a human haplotype expressing low levels of proinsulin. This haplotype is tagged by a polypyrimidine tract variant rs689 that decreases the efficiency of intron 1 splicing and increases the relative abundance of mRNAs with extended 5' untranslated region (5' UTR), which curtails translation. Co-expression of haplotype-specific reporter constructs with SSOs bound to splicing regulatory motifs and decoy splice sites in primary transcripts revealed a motif that significantly reduced intron 1-containing mRNAs. Using an antisense microwalk at a single nucleotide resolution, the optimal target was mapped to a splicing silencer containing two pseudoacceptor sites sandwiched between predicted RNA guanine (G) quadruplex structures. Circular dichroism spectroscopy and nuclear magnetic resonance of synthetic G-rich oligoribonucleotide tracts derived from this region showed formation of a stable parallel 2-quartet G-quadruplex on the 3' side of the antisense retention target and an equilibrium between quadruplexes and stable hairpin-loop structures bound by optimal SSOs. This region interacts with heterogeneous nuclear ribonucleoproteins F and H that may interfere with conformational transitions involving the antisense target. The SSO-assisted promotion of weak intron removal from the 5' UTR through competing noncanonical and canonical RNA structures may facilitate development of novel strategies to enhance gene expression. PMID:24944197

  11. Efficient sensor placement for state estimation in structural dynamics

    NASA Astrophysics Data System (ADS)

    Hernandez, Eric M.

    2017-02-01

    This paper derives a computationally efficient algorithm to determine optimal sequential sensor placement for state estimation in linear structural systems subjected to unmeasured excitations and noise contaminated measurements. The proposed algorithm is developed within the context of the Kalman filter and it minimizes the variance of the state estimate among all possible sequential sensor locations. The paper investigates the effects of measurement type, covariance matrix partition selection, spatial correlation of excitation and model selection on optimal sensor placement. The paper shows that the sequential approach reaches the optimal sensor placement as the number of sensor increases.

  12. Optimal Length of Conformational Transition Region in Protein Search for Targets on DNA.

    PubMed

    Kochugaeva, Maria P; Berezhkovskii, Alexander M; Kolomeisky, Anatoly B

    2017-09-07

    The starting point of many fundamental biological processes is associated with protein molecules finding and recognizing specific sites on DNA. However, despite a large number of experimental and theoretical studies on protein search for targets on DNA, many molecular aspects of underlying mechanisms are still not well understood. Experiments show that proteins bound to DNA can switch between slow recognition and fast search conformations. However, from a theoretical point of view, such conformational transitions should slow down the protein search for specific sites on DNA, in contrast to available experimental observations. In addition, experiments indicate that the nucleotide composition near the target site is more symmetrically homogeneous, leading to stronger effective interactions between proteins and DNA at these locations. However, as has been shown theoretically, this should also make the search less efficient, which is not observed. We propose a possible resolution of these problems by suggesting that conformational transitions occur only within a segment around the target where stronger interactions between proteins and DNA are observed. Two theoretical methods, based on continuum and discrete-state stochastic calculations, are developed, allowing us to obtain a comprehensive dynamic description for the protein search process in this system. The existence of an optimal length of the conformational transition zone with the shortest mean search time is predicted.

  13. An optimized transit peptide for effective targeting of diverse foreign proteins into chloroplasts in rice

    PubMed Central

    Shen, Bo-Ran; Zhu, Cheng-Hua; Yao, Zhen; Cui, Li-Li; Zhang, Jian-Jun; Yang, Cheng-Wei; He, Zheng-Hui; Peng, Xin-Xiang

    2017-01-01

    Various chloroplast transit peptides (CTP) have been used to successfully target some foreign proteins into chloroplasts, but for other proteins these same CTPs have reduced localization efficiencies or fail completely. The underlying cause of the failures remains an open question, and more effective CTPs are needed. In this study, we initially observed that two E.coli enzymes, EcTSR and EcGCL, failed to be targeted into rice chloroplasts by the commonly-used rice rbcS transit peptide (rCTP) and were subsequently degraded. Further analyses revealed that the N-terminal unfolded region of cargo proteins is critical for their localization capability, and that a length of about 20 amino acids is required to attain the maximum localization efficiency. We considered that the unfolded region may alleviate the steric hindrance produced by the cargo protein, by functioning as a spacer to which cytosolic translocators can bind. Based on this inference, an optimized CTP, named RC2, was constructed. Analyses showed that RC2 can more effectively target diverse proteins, including EcTSR and EcGCL, into rice chloroplasts. Collectively, our results provide further insight into the mechanism of CTP-mediated chloroplastic localization, and more importantly, RC2 can be widely applied in future chloroplastic metabolic engineering, particularly for crop plants. PMID:28397859

  14. Optimization of antibody-conjugated magnetic nanoparticles for target preconcentration and immunoassays

    PubMed Central

    Smith, Joshua E.; Sapsford, Kim E.; Tan, Weihong; Ligler, Frances S.

    2013-01-01

    Biosensors based on antibody recognition have a wide range of monitoring applications that apply to clinical, environmental, homeland security, and food problems. In an effort to improve the limit of detection of the Naval Research Laboratory (NRL) Array Biosensor, magnetic nanoparticles (MNPs) were designed and tested using a fluorescence-based array biosensor. The MNPs were coated with the fluorescently labeled protein, AlexaFluor647–chicken IgG (Alexa647–chick IgG). Antibody-labeled MNPs (Alexa647–chick–MNPs) were used to preconcentrate the target via magnetic separation and as the tracer to demonstrate binding to slides modified with anti-chicken IgG as a capture agent. A full optimization study of the antibody-modified MNPs and their use in the biosensor was performed. This investigation looked at the Alexa647–chick–MNP composition, MNP surface modifications, target preconcentration conditions, and the effect that magnetic extraction has on the Alexa647–chick–MNP binding with the array surface. The results demonstrate the impact of magnetic extraction using the MNPs labeled with fluorescent proteins both for target preconcentration and for subsequent integration into immunoassays performed under flow conditions for enhanced signal generation. PMID:21078282

  15. Optimization of antibody-conjugated magnetic nanoparticles for target preconcentration and immunoassays.

    PubMed

    Smith, Joshua E; Sapsford, Kim E; Tan, Weihong; Ligler, Frances S

    2011-03-01

    Biosensors based on antibody recognition have a wide range of monitoring applications that apply to clinical, environmental, homeland security, and food problems. In an effort to improve the limit of detection of the Naval Research Laboratory (NRL) Array Biosensor, magnetic nanoparticles (MNPs) were designed and tested using a fluorescence-based array biosensor. The MNPs were coated with the fluorescently labeled protein, AlexaFluor647-chicken IgG (Alexa647-chick IgG). Antibody-labeled MNPs (Alexa647-chick-MNPs) were used to preconcentrate the target via magnetic separation and as the tracer to demonstrate binding to slides modified with anti-chicken IgG as a capture agent. A full optimization study of the antibody-modified MNPs and their use in the biosensor was performed. This investigation looked at the Alexa647-chick-MNP composition, MNP surface modifications, target preconcentration conditions, and the effect that magnetic extraction has on the Alexa647-chick-MNP binding with the array surface. The results demonstrate the impact of magnetic extraction using the MNPs labeled with fluorescent proteins both for target preconcentration and for subsequent integration into immunoassays performed under flow conditions for enhanced signal generation.

  16. Heuristics for Effective Actuator and Sensor Placement in Feedback Flow Control

    NASA Astrophysics Data System (ADS)

    Chen, Kevin; Rowley, Clarence

    2014-11-01

    Actuator and sensor placement can be just as consequential for the performance of localized feedback flow control as controller design. Yet, effective placement is not well understood, and the use of suboptimal placements is common. We report descriptions and characteristics of effective actuator and sensor placements for optimal flow control. We review optimal placements in the linearized Ginzburg-Landau and Orr-Sommerfeld/Squire models of fluid flow. We then analyze the feedback control of these models by relating physical observations with mathematical tools. Although these tools do not fully predict optimal placements, they do reveal patterns that most or all effective placements share. Most notably, effective actuator-sensor placements provide good authority over unstable modes and transient growth, and avoid large time lags between inputs and outputs. This work was supported by the National Science Foundation's Graduate Research Fellowship Program and Grant CMMI-0932928.

  17. Optimization of Direct Ionization of CO2 by Controlling the Gas Flow Inside of a Beam-Target

    SciTech Connect

    Salazar Quintero, G A; Ognibene, T

    2011-03-07

    We designed and optimized a target that directs a CO{sub 2} pulse onto a Ti surface where a Cs{sup +} sputtering beam ionizes the CO{sub 2} to generate C{sup -}. These targets will be used for the direct ionization of CO{sub 2} pulses to enable the measurement of carbon isotope ratios in real time. The design was based on the results of Comsol{trademark} simulations of the target configurations.

  18. Targeted optimization of central carbon metabolism for engineering succinate production in Escherichia coli.

    PubMed

    Zhao, Ying; Wang, Chang-Song; Li, Fei-Fei; Liu, Zhen-Ning; Zhao, Guang-Rong

    2016-06-24

    Succinate is a kind of industrially important C4 platform chemical for synthesis of high value added products. Due to the economical and environmental advantages, considerable efforts on metabolic engineering and synthetic biology have been invested for bio-based production of succinate. Precursor phosphoenolpyruvate (PEP) is consumed for transport and phosphorylation of glucose, and large amounts of byproducts are produced, which are the crucial obstacles preventing the improvement of succinate production. In this study, instead of deleting genes involved in the formation of lactate, acetate and formate, we optimized the central carbon metabolism by targeting at metabolic node PEP to improve succinate production and decrease accumulation of byproducts in engineered E. coli. By deleting ptsG, ppc, pykA, maeA and maeB, we constructed the initial succinate-producing strain to achieve succinate yield of 0.22 mol/mol glucose, which was 2.1-fold higher than that of the parent strain. Then, by targeting at both reductive TCA arm and PEP carboxylation, we deleted sdh and co-overexpressed pck and ecaA, which led to a significant improvement in succinate yield of 1.13 mol/mol glucose. After fine-tuning of pykF expression by anti-pykF sRNA, yields of lactate and acetate were decreased by 43.48 and 38.09 %, respectively. The anaerobic stoichiometric model on metabolic network showed that the carbon fraction to succinate of engineered strains was significantly increased at the expense of decreased fluxes to lactate and acetate. In batch fermentation, the optimized strain BKS15 produced succinate with specific productivity of 5.89 mmol gDCW(-1) h(-1). This report successfully optimizes succinate production by targeting at PEP of the central carbon metabolism. Co-overexpressing pck-ecaA, deleting sdh and finely tuning pykF expression are efficient strategies for improving succinate production and minimizing accumulation of lactate and acetate in metabolically engineered E

  19. JS ISH-ISN-3 OPTIMAL TARGETS FOR BP CONTROL IN CKD.

    PubMed

    Wheeler, David

    2016-09-01

    Hypertension is the most prevalent complication of chronic kidney disease (CKD). Lowering high blood pressure slows progressive loss of kidney function and may also reduce the associated risk of cardiovascular complications, a common cause of premature death in CKD patients.Current International Guidelines produced by Kidney Disease: Improving Global Outcomes (KDIGO) acknowledges that no single BP target is optimal for all CKD patients, and encourages individualization of treatment depending on age, the severity of albuminuria and comorbidities. When published in 2012, the available evidence indicated that in CKD patients without albuminuria, the target BP should be ≤140 mmHg systolic and ≤90 mmHg diastolic. However, in most patients with an albumin excretion rate of ≥30 mg/24 h (i.e., those with both micro- and macroalbuminuria), a lower target of ≤130 mmHg systolic and ≤80 mmHg diastolic was suggested. In achieving BP control, the value of lifestyle changes and the need for multiple pharmacological agents was acknowledged. Use of agents that block the renin-angiotensin-aldosterone system was recommended or suggested in all patients with an albumin excretion rate of ≥30 mg/24 h. Recommendations are almost identical in CKD patients with and without diabetes.Recent data from SPRINT (which included CKD patients) and other clinical trials has led nephrologists to ask whether targets lower than those recommend by KDIGO are appropriate and the guidelines are currently undergoing an update. Controversies remain around discontinuation of ACE/ARB in patients with stage 4-5 CKD and dual renin-angiotensin-aldosterone system blockade.

  20. Optimization and in Vivo Validation of Peptide Vectors Targeting the LDL Receptor.

    PubMed

    Jacquot, Guillaume; Lécorché, Pascaline; Malcor, Jean-Daniel; Laurencin, Mathieu; Smirnova, Maria; Varini, Karine; Malicet, Cédric; Gassiot, Fanny; Abouzid, Karima; Faucon, Aude; David, Marion; Gaudin, Nicolas; Masse, Maxime; Ferracci, Géraldine; Dive, Vincent; Cisternino, Salvatore; Khrestchatisky, Michel

    2016-12-05

    Active targeting and delivery to pathophysiological organs of interest is of paramount importance to increase specific accumulation of therapeutic drugs or imaging agents while avoiding systemic side effects. We recently developed a family of new peptide ligands of the human and rodent LDL receptor (LDLR), an attractive cell-surface receptor with high uptake activity and local enrichment in several normal or pathological tissues (Malcor et al., J. Med. Chem. 2012, 55 (5), 2227). Initial chemical optimization of the 15-mer, all natural amino acid compound 1/VH411 (DSGL[CMPRLRGC]cDPR) and structure-activity relationship (SAR) investigation led to the cyclic 8 amino acid analogue compound 22/VH445 ([cMPRLRGC]c) which specifically binds hLDLR with a KD of 76 nM and has an in vitro blood half-life of ∼3 h. Further introduction of non-natural amino acids led to the identification of compound 60/VH4106 ([(d)-"Pen"M"Thz"RLRGC]c), which showed the highest KD value of 9 nM. However, this latter analogue displayed the lowest in vitro blood half-life (∼1.9 h). In the present study, we designed a new set of peptide analogues, namely, VH4127 to VH4131, with further improved biological properties. Detailed analysis of the hLDLR-binding kinetics of previous and new analogues showed that the latter all displayed very high on-rates, in the 10(6) s(-1.)M(-1) range, and off-rates varying from the low 10(-2) s(-1) to the 10(-1) s(-1) range. Furthermore, all these new analogues showed increased blood half-lives in vitro, reaching ∼7 and 10 h for VH4129 and VH4131, respectively. Interestingly, we demonstrate in cell-based assays using both VH445 and the most balanced optimized analogue VH4127 ([cM"Thz"RLRG"Pen"]c), showing a KD of 18 nM and a blood half-life of ∼4.3 h, that its higher on-rate correlated with a significant increase in both the extent of cell-surface binding to hLDLR and the endocytosis potential. Finally, intravenous injection of tritium-radiolabeled (3)H-VH4127

  1. ESL Placement and Schools

    PubMed Central

    Callahan, Rebecca; Wilkinson, Lindsey; Muller, Chandra; Frisco, Michelle

    2010-01-01

    In this study, the authors explore English as a Second Language (ESL) placement as a measure of how schools label and process immigrant students. Using propensity score matching and data from the Adolescent Health and Academic Achievement Study and the National Longitudinal Study of Adolescent Health, the authors estimate the effect of ESL placement on immigrant achievement. In schools with more immigrant students, the authors find that ESL placement results in higher levels of academic performance; in schools with few immigrant students, the effect reverses. This is not to suggest a one-size-fits-all policy; many immigrant students, regardless of school composition, generational status, or ESL placement, struggle to achieve at levels sufficient for acceptance to a 4-year university. This study offers several factors to be taken into consideration as schools develop policies and practices to provide immigrant students opportunities to learn. PMID:20617111

  2. Fiducial Marker Placement

    MedlinePlus

    ... Media Computed Tomography (CT) - Body General Ultrasound Ultrasound - Prostate Introduction to Cancer Therapy (Radiation Oncology) Proton Therapy Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT) Images related to Fiducial Marker Placement Sponsored by ...

  3. Gastrostomy tube placement - slideshow

    MedlinePlus

    ... presentations/100125.htm Gastrostomy tube placement - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...

  4. Targeting B cells in relapsing–remitting multiple sclerosis: from pathophysiology to optimal clinical management

    PubMed Central

    Bittner, Stefan; Ruck, Tobias; Wiendl, Heinz; Grauer, Oliver M.; Meuth, Sven G.

    2016-01-01

    Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease that is caused by an autoimmune response against central nervous system (CNS) structures. Traditionally considered a T-cell-mediated disorder, the contribution of B cells to the pathogenesis of MS has long been debated. Based on recent promising clinical results from CD20-depleting strategies by three therapeutic monoclonal antibodies in clinical phase II and III trials (rituximab, ocrelizumab and ofatumumab), targeting B cells in MS is currently attracting growing interest among basic researchers and clinicians. Many questions about the role of B and plasma cells in MS remain still unanswered, ranging from the role of specific B-cell subsets and functions to the optimal treatment regimen of B-cell depletion and monitoring thereafter. Here, we will assess our current knowledge of the mechanisms implicating B cells in multiple steps of disease pathology and examine current and future therapeutic approaches for the treatment of MS. PMID:28450895

  5. Optimization of the Target Subsystem for the New g-2 Experiment

    SciTech Connect

    Yoshikawa, C.; Leveling, A.; Mokhov, N.V.; Morgan, J.; Neuffer, D.; Striganov, S.; /Fermilab

    2012-05-01

    A precision measurement of the muon anomalous magnetic moment, a{sub {mu}} = (g-2)/2, was previously performed at BNL with a result of 2.2-2.7 standard deviations above the Standard Model (SM) theoretical calculations. The same experimental apparatus is being planned to run in the new Muon Campus at Fermilab, where the muon beam is expected to have less pion contamination and the extended dataset may provide a possible 7.5{sigma} deviation from the SM, creating a sensitive and complementary benchmark for proposed SM extensions. We report here on a preliminary simulation study of the target subsystem where the apparatus is optimized for pions that have favourable phase space to create polarized daughter muons around the magic momentum of 3.094 GeV/c, which is needed by the downstream g 2 muon ring.

  6. Optimization of Isocenter Location for Intensity Modulated Stereotactic Treatment of Small Intracranial Targets

    SciTech Connect

    Salter, Bill J. Fuss, Martin; Sarkar, Vikren; Wang, Brian; Rassiah-Szegedi, Prema; Papanikolaou, Niko; Hollingshaus, Scott; Shrieve, Dennis C.

    2009-02-01

    Purpose: To quantify the impact of isocenter location on treatment plan quality for intensity-modulated stereotactic treatment of small intracranial lesions. Methods and Materials: For 18 patients previously treated by stereotactic-intensity modulated radiosurgery (IMRS) or intensity-modulated radiation therapy (IMRT), a retrospective virtual planning study was conducted wherein the impact of isocenter location on plan quality was measured. Treatment indications studied included six arteriovenous malformations, six acoustic neuromas, and six intracranial metastases, ranging in volume from 0.71 to 3.21 cm{sup 3} (mean = 2.26 cm{sup 3}), 1.08 to 2.84 cm{sup 3} (mean = 1.73 cm{sup 3}), and 0.19 to 2.30 cm{sup 3} (mean = 0.79 cm{sup 3}), respectively. Variation of isocenter location causes the geometric grid of pencil beams into which the target is segmented for intensity-modulated treatment to be altered. The impact of this pencil-beam-grid redefinition on achievable conformity index was quantified for three collimators (Varian Millennium 120; BrainLab MM3; Nomos binary Mimic) and three treatment planning systems (TPS; Varian Eclipse v6.5; BrainLab BrainScan v5.31; Best-Nomos Corvus v6.2), resulting in the evaluation of 3,446 treatment plans. Results: For all patients, collimator, and TPS combinations studied, a significant variation in plan quality was observed as a function of isocenter and pencil-beam-grid relocation. Optimization of isocenter location resulted in treatment plan conformity variations as large as 109% (min = 15%, mean = 51%, max = 109%). Conclusion: Optimization of isocenter location for IMRT/IMRS treatment of small intracranial lesions in which pencil-beam dimensions are comparable to target dimensions, can result in significant improvements in treatment plan quality.

  7. Optimization of isocenter location for intensity modulated stereotactic treatment of small intracranial targets.

    PubMed

    Salter, Bill J; Fuss, Martin; Sarkar, Vikren; Wang, Brian; Rassiah-Szegedi, Prema; Papanikolaou, Niko; Hollingshaus, Scott; Shrieve, Dennis C

    2009-02-01

    To quantify the impact of isocenter location on treatment plan quality for intensity-modulated stereotactic treatment of small intracranial lesions. For 18 patients previously treated by stereotactic-intensity modulated radiosurgery (IMRS) or intensity-modulated radiation therapy (IMRT), a retrospective virtual planning study was conducted wherein the impact of isocenter location on plan quality was measured. Treatment indications studied included six arteriovenous malformations, six acoustic neuromas, and six intracranial metastases, ranging in volume from 0.71 to 3.21 cm(3) (mean = 2.26 cm(3)), 1.08 to 2.84 cm(3) (mean = 1.73 cm(3)), and 0.19 to 2.30 cm(3) (mean = 0.79 cm(3)), respectively. Variation of isocenter location causes the geometric grid of pencil beams into which the target is segmented for intensity-modulated treatment to be altered. The impact of this pencil-beam-grid redefinition on achievable conformity index was quantified for three collimators (Varian Millennium 120; BrainLab MM3; Nomos binary Mimic) and three treatment planning systems (TPS; Varian Eclipse v6.5; BrainLab BrainScan v5.31; Best-Nomos Corvus v6.2), resulting in the evaluation of 3,446 treatment plans. For all patients, collimator, and TPS combinations studied, a significant variation in plan quality was observed as a function of isocenter and pencil-beam-grid relocation. Optimization of isocenter location resulted in treatment plan conformity variations as large as 109% (min = 15%, mean = 51%, max = 109%). Optimization of isocenter location for IMRT/IMRS treatment of small intracranial lesions in which pencil-beam dimensions are comparable to target dimensions, can result in significant improvements in treatment plan quality.

  8. Optimization of brain targeted gallic acid nanoparticles for improved antianxiety-like activity.

    PubMed

    Nagpal, Kalpana; Singh, S K; Mishra, D N

    2013-06-01

    Ligand coated nanoparticles may improve brain uptake of drugs. To formulate brain targeted nanoparticles of gallic acid (GA) for improving its antianxiety-like activity. The nanoparticles were prepared and optimized to minimize particle size and maximize percent drug entrapment efficiency using two factor three level (3(2)) central composite design. Pure GA, optimized ligand coated nanoparticles of GA (cGANP) and corresponding uncoated nanoparticles (GANP) were administered to Swiss albino mice for seven consecutive days and evaluated in vivo for their antianxiety-like activity. Behavioral studies revealed that cGANP significantly improved antianxiety-like activity in mice. The plasma nitrite level decreased with GA, GANP and cGANP (most pronounced for cGANP) treated group as compared to saline treated control group while no change in plasma corticosterone levels was observed in any treatment. The treatments (except alprazolam) did not show any significant effect on locomotor activity of mice. The antianxiety-like activity may be attributed to decreased plasma nitrite level and effect was improved by enhanced brain uptake of GA via ligand coated nanoparticles. Thus antianxiety-like activity of GA was significantly improved formulating it as ligand coated nanoparticles. On the other hand, no significant difference was observed between antianxiety-like activity by administration of pure GA and GANP. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. The effect of target group size on risk judgments and comparative optimism: the more, the riskier.

    PubMed

    Price, Paul C; Smith, Andrew R; Lench, Heather C

    2006-03-01

    In 5 experiments, college students exhibited a group size effect on risk judgments. As the number of individuals in a target group increased, so did participants' judgments of the risk of the average member of the group for a variety of negative life events. This happened regardless of whether the stimuli consisted of photographs of real peers or stick-figure representations of peers. As a result, the degree to which participants exhibited comparative optimism (i.e., judged themselves to be at lower risk than their peers) also increased as the size of the comparison group increased. These results suggest that the typical comparative optimism effect reported so often in the literature might be, at least in part, a group size effect. Additional results include a group size effect on judgments of the likelihood that the average group member will experience positive and neutral events and a group size effect on perceptual judgments of the heights of stick figures. These latter results, in particular, support the existence of a simple, general cognitive mechanism that integrates stimulus numerosity into quantitative judgments about that stimulus.

  10. Trade-offs and efficiencies in optimal budget-constrained multispecies corridor networks

    Treesearch

    Bistra Dilkina; Rachel Houtman; Carla P. Gomes; Claire A. Montgomery; Kevin S. McKelvey; Katherine Kendall; Tabitha A. Graves; Richard Bernstein; Michael K. Schwartz

    2016-01-01

    Conservation biologists recognize that a system of isolated protected areas will be necessary but insufficient to meet biodiversity objectives. Current approaches to connecting core conservation areas through corridors consider optimal corridor placement based on a single optimization goal: commonly, maximizing the movement for a target species across a...

  11. Optimal target grasping of a flexible space manipulator for a class of objectives

    NASA Astrophysics Data System (ADS)

    Toglia, Chiara; Sabatini, Marco; Gasbarri, Paolo; Palmerini, Giovanni B.

    2011-04-01

    Space graspers are complex systems, composed by robotic arms placed on an orbiting platform. In order to fulfil the manoeuvres' requirements, it is necessary to properly model all the forces acting on the space robot. A fully nonlinear model is used to describe the dynamics, based on a multibody approach. The model includes the orbital motion, the gravity gradient, the aerodynamic effects, as well as the flexibility of the links. The present paper aims to design, thanks to nonlinear optimization algorithms, a class of manoeuvres that, given the same target to be grasped, are characterized by different mission objectives. The grasping mission can be performed with the objective to minimize the power consumption. Collision avoidance constraints can be also added when the target is equipped with solar panels or other appendices. In some cases, large elastic displacements should be expected, possibly leading to an inaccurate positioning of the end-effector. Therefore, different design strategies can require that the manoeuvre is accomplished with minimum vibrations' amplitude at the end-effector. Performance of the different strategies is analyzed in terms of control effort, trajectory errors, and flexible response of the manipulator.

  12. Structure-based virtual screening and optimization of modulators targeting Hsp90-Cdc37 interaction.

    PubMed

    Wang, Lei; Li, Li; Zhou, Zi-Han; Jiang, Zheng-Yu; You, Qi-Dong; Xu, Xiao-Li

    2017-08-18

    Identification of novel Hsp90 inhibitors to disrupt Hsp90-Cdc37 protein-protein interaction (PPI) could be an alternative strategy to achieve Hsp90 inhibition. In this paper, a series of small molecules targeting Hsp90-Cdc37 complex are addressed and characterized. The molecules' key characters are determined by utilizing a structure-based virtual screening workflow, derivatives synthesis, and biological evaluation. Structural optimization and structure-activity relationship (SAR) analysis were then carried out on the virtual hit of VS-8 with potent activity, which resulted in the discovery of compound 10 as a more potent regulator of Hsp90-Cdc37 interaction with a promising inhibitory effect (IC50 = 27 μM), a moderate binding capacity (KD = 40 μM) and a preferable antiproliferative activity against several cancer lines including MCF-7, SKBR3 and A549 cell lines (IC50 = 26 μM, 15 μM and 38 μM respectively). All the data suggest that compound 10 exhibits moderate inhibitory effect on Hsp90-Cdc37 and could be regard as a first evidence of a non-natural compound targeting Hsp90-Cdc37 PPI. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Navigating later lines of treatment for advanced colorectal cancer - optimizing targeted biological therapies to improve outcomes.

    PubMed

    Gill, Sharlene; Dowden, Scot; Colwell, Bruce; Collins, Loretta L; Berry, Scott

    2014-12-01

    Colorectal cancer (CRC) is the third most commonly diagnosed cancer among males and second among females worldwide. The treatment landscape for advanced CRC (aCRC) is rapidly evolving and there are now a number of randomized trials assessing treatment of aCRC beyond first-line, prompting important questions about how to optimize therapy and maximize benefit. The availability of targeted agents has increased the complexity of post-progression treatment of aCRC. Targeted biological agents with varying modes of action are now approved for use in second-line and beyond, including the VEGF-inhibitors bevacizumab and aflibercept, the VEGFR/multikinase-inhibitor regorafenib, and the EGFR-inhibitors cetuximab and panitumumab. This article provides a systematic overview of the available phase III trial data, discusses biomarkers predictive of response to treatment, addresses safety concerns associated with specific agents, and provides practical, evidence-based recommendations for the later lines of treatment for patients with unresectable aCRC. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. [Optimized definition and delineation of supraclavicular lymph nodes target in postmastectomy radiotherapy for breast cancer patients].

    PubMed

    Huang, Shujing; Huang, Xiaobo; Wang, Xicheng; Zhang, Yujing; Sun, Jiayuan; He, Liru; Wen, Ge; He, Zhichun

    2014-07-01

    To explore the optimized methods to define and delineate supraclavicular lymph nodal target in postmastectomy radiotherapy for breast cancer patients. From September 2012 to August 2013, a total of 10 breast cancer patients at Sun Yan-sen University Cancer were selected for mastectomy plus postoperative radiotherapy. The clinical target volume (CTV) of every patient was delineated on CT-slices after computed tomography (CT) simulation by 6 radiation oncologists. Then the coverage discrepancy in anatomic lymphatic drainage subregions was analyzed among both CTVs by different oncologists and CTVs for patients with different clinical characters. The average volume of SCLN-CTVs was 110 ± 28 cm(3). All SCLN, neck-IV and axilla III regions were covered in CTV, none of axillaIregion. The covergy rates of nonsurgery-axillaII, Rotter-LN, intraclavicular-LN, neck-Vb, scalenus gap, neck-III and surgery-axilla IIregions was 75%, 85%, 73%, 88%, 68%, 10%, 17% , respectively. SCLN, neck-IV and axilla III regions should be covered according to consensus. However, the opinions of nonsurgery-axillaII, Rotter-LN, intraclavicular-LN, neck-Vb, scalenus gap, neck-III and surgery-axilla IIremain divisive.

  15. Optimization of Morpholino Antisense Oligonucleotides Targeting the Intronic Repressor Element1 in Spinal Muscular Atrophy.

    PubMed

    Osman, Erkan Y; Washington, Charles W; Kaifer, Kevin A; Mazzasette, Chiara; Patitucci, Teresa N; Florea, Kyra M; Simon, Madeline E; Ko, Chien-Ping; Ebert, Allison D; Lorson, Christian L

    2016-09-01

    Loss of Survival Motor Neuron-1 (SMN1) causes Spinal Muscular Atrophy, a devastating neurodegenerative disease. SMN2 is a nearly identical copy gene; however SMN2 cannot prevent disease development in the absence of SMN1 since the majority of SMN2-derived transcripts are alternatively spliced, encoding a truncated, unstable protein lacking exon 7. Nevertheless, SMN2 retains the ability to produce low levels of functional protein. Previously we have described a splice-switching Morpholino antisense oligonucleotide (ASO) sequence that targets a potent intronic repressor, Element1 (E1), located upstream of SMN2 exon 7. In this study, we have assessed a novel panel of Morpholino ASOs with the goal of optimizing E1 ASO activity. Screening for efficacy in the SMNΔ7 mouse model, a single ASO variant was more active in vivo compared with the original E1(MO)-ASO. Sequence variant eleven (E1(MOv11)) consistently showed greater efficacy by increasing the lifespan of severe Spinal Muscular Atrophy mice after a single intracerebroventricular injection in the central nervous system, exhibited a strong dose-response across an order of magnitude, and demonstrated excellent target engagement by partially reversing the pathogenic SMN2 splicing event. We conclude that Morpholino modified ASOs are effective in modifying SMN2 splicing and have the potential for future Spinal Muscular Atrophy clinical applications.

  16. An Optimal t-{Delta}v Guidance Law for Intercepting a Boosting Target

    SciTech Connect

    Ng, L.C.; Breitfeller, E.; Ledebuhr, A.G.

    2002-06-30

    Lawrence Livermore National Laboratory (LLNL) have developed a new missile guidance law for intercepting a missile during boost phase. Unlike other known missile guidance laws being used today, the new t-{Delta}v guidance law optimally trades an interceptor's onboard fuel capacity against time-to-go before impact. In particular, this guidance law allows a missile designer to program the interceptor to maximally impact a boosting missile before burnout or burn termination and thus negating its ability to achieve the maximum kinetic velocity. For an intercontinental range ballistic missile (ICBM), it can be shown that for every second of earlier intercept prior to burnout, the ICBM ground range is reduced by 350 km. Therefore, intercepting a mere 15 seconds earlier would result in amiss of 5,250 km from the intended target or approximately a distance across the continental US. This paper also shows how the t-{Delta}v guidance law can incorporate uncertainties in target burnout time, predicted intercept point (PIP) error, time-to-go error, and other track estimation errors. The authors believe that the t-{Delta}v guidance law is a step toward the development of a new and smart missile guidance law that would enhance the probability of achieving a boost phase intercept.

  17. A real-time brain-machine interface combining motor target and trajectory intent using an optimal feedback control design.

    PubMed

    Shanechi, Maryam M; Williams, Ziv M; Wornell, Gregory W; Hu, Rollin C; Powers, Marissa; Brown, Emery N

    2013-01-01

    Real-time brain-machine interfaces (BMI) have focused on either estimating the continuous movement trajectory or target intent. However, natural movement often incorporates both. Additionally, BMIs can be modeled as a feedback control system in which the subject modulates the neural activity to move the prosthetic device towards a desired target while receiving real-time sensory feedback of the state of the movement. We develop a novel real-time BMI using an optimal feedback control design that jointly estimates the movement target and trajectory of monkeys in two stages. First, the target is decoded from neural spiking activity before movement initiation. Second, the trajectory is decoded by combining the decoded target with the peri-movement spiking activity using an optimal feedback control design. This design exploits a recursive Bayesian decoder that uses an optimal feedback control model of the sensorimotor system to take into account the intended target location and the sensory feedback in its trajectory estimation from spiking activity. The real-time BMI processes the spiking activity directly using point process modeling. We implement the BMI in experiments consisting of an instructed-delay center-out task in which monkeys are presented with a target location on the screen during a delay period and then have to move a cursor to it without touching the incorrect targets. We show that the two-stage BMI performs more accurately than either stage alone. Correct target prediction can compensate for inaccurate trajectory estimation and vice versa. The optimal feedback control design also results in trajectories that are smoother and have lower estimation error. The two-stage decoder also performs better than linear regression approaches in offline cross-validation analyses. Our results demonstrate the advantage of a BMI design that jointly estimates the target and trajectory of movement and more closely mimics the sensorimotor control system.

  18. Serum Stability and Affinity Optimization of an M2 Macrophage-Targeting Peptide (M2pep)

    PubMed Central

    Ngambenjawong, Chayanon; Gustafson, Heather H.; Pineda, Julio M.; Kacherovsky, Nataly A.; Cieslewicz, Maryelise; Pun, Suzie H.

    2016-01-01

    Tumor associated macrophages (TAMs) are a major stromal component of the tumor microenvironment in several cancers. TAMs are a potential target for adjuvant cancer therapies due to their established roles in promoting proliferation of cancer cells, angiogenesis, and metastasis. We previously discovered an M2 macrophage-targeting peptide (M2pep) which was successfully used to target and deliver a pro-apoptotic KLA peptide to M2-like TAMs in a CT-26 colon carcinoma model. However, the effectiveness of in vivo TAM-targeting using M2pep is limited by its poor serum stability and low binding affinity. In this study, we synthesized M2pep derivatives with the goals of increasing serum stability and binding affinity. Serum stability evaluation of M2pepBiotin confirmed its rapid degradation attributed to exolytic cleavage from the N-terminus and endolytic cleavages at the W10/W11 and S16/K17 sites. N-terminal acetylation of M2pepBiotin protected the peptide against the exolytic degradation while W10w and K(17,18,19)k substitutions were able to effectively protect endolytic degradation at their respective cleavage sites. However, no tested amino acid changes at the W10 position resulted in both protease resistance at that site and retention of binding activity. Therefore, cyclization of M2pep was investigated. Cyclized M2pep better resisted serum degradation without compromising binding activity to M2 macrophages. During the serum stability optimization process, we also discovered that K9R and W10Y substitutions significantly enhanced binding affinity of M2pep. In an in vitro binding study of different M2pep analogs pre-incubated in mouse serum, cyclic M2pep with K9R and W10Y modifications (cyclic M2pep(RY)) retained the highest binding activity to M2 macrophages over time due to its improved serum stability. Finally, we evaluated the in vivo accumulation of sulfo-Cy5-labeled M2pep and cyclic M2pep(RY) in both the CT-26 and 4T1 breast carcinoma models. Cyclic M2pep

  19. Weighted Optimization-Based Distributed Kalman Filter for Nonlinear Target Tracking in Collaborative Sensor Networks.

    PubMed

    Chen, Jie; Li, Jiahong; Yang, Shuanghua; Deng, Fang

    2016-07-21

    The identification of the nonlinearity and coupling is crucial in nonlinear target tracking problem in collaborative sensor networks. According to the adaptive Kalman filtering (KF) method, the nonlinearity and coupling can be regarded as the model noise covariance, and estimated by minimizing the innovation or residual errors of the states. However, the method requires large time window of data to achieve reliable covariance measurement, making it impractical for nonlinear systems which are rapidly changing. To deal with the problem, a weighted optimization-based distributed KF algorithm (WODKF) is proposed in this paper. The algorithm enlarges the data size of each sensor by the received measurements and state estimates from its connected sensors instead of the time window. A new cost function is set as the weighted sum of the bias and oscillation of the state to estimate the "best" estimate of the model noise covariance. The bias and oscillation of the state of each sensor are estimated by polynomial fitting a time window of state estimates and measurements of the sensor and its neighbors weighted by the measurement noise covariance. The best estimate of the model noise covariance is computed by minimizing the weighted cost function using the exhaustive method. The sensor selection method is in addition to the algorithm to decrease the computation load of the filter and increase the scalability of the sensor network. The existence, suboptimality and stability analysis of the algorithm are given. The local probability data association method is used in the proposed algorithm for the multitarget tracking case. The algorithm is demonstrated in simulations on tracking examples for a random signal, one nonlinear target, and four nonlinear targets. Results show the feasibility and superiority of WODKF against other filtering algorithms for a large class of systems.

  20. Optimal Dosing for Targeted Therapies in Oncology: Drug Development Cases Leading by Example.

    PubMed

    Sachs, Jeffrey R; Mayawala, Kapil; Gadamsetty, Satvik; Kang, Soonmo Peter; de Alwis, Dinesh P

    2016-03-15

    One of the key objectives of oncology first-in-human trials has often been to establish the maximum tolerated dose (MTD). However, targeted therapies might not exhibit dose-limiting toxicities (DLT) at doses significantly higher than sufficiently active doses, and there is frequently a limited ability to objectively quantify adverse events. Thus, while MTD-based determination of recommended phase II dose may have yielded appropriate dosing for some cytotoxics, targeted therapeutics (including monoclonal antibodies and/or immunotherapies) sometimes need alternative or complementary strategies to help identify dose ranges for a randomized dose-ranging study. One complementary strategy is to define a biologically efficacious dose (BED) using an "effect marker." An effect marker could be a target engagement, pharmacodynamic, or disease progression marker (change in tumor size for solid tumors or bone marrow blast count for some hematologic tumors). Although the concept of BED has been discussed extensively, we review specific examples in which the approach influenced oncology clinical development. Data extracted from the literature and the examples support improving dose selection strategies to benefit patients, providers, and the biopharmaceutical industry. Although the examples illustrate key contributions of effect markers in dose selection, no one-size-fits-all approach to dosing can be justified. Higher-than-optimal dosing can increase toxicity in later trials (and in clinical use), which can have a negative impact on efficacy (via lower adherence or direct sequelae of toxicities). Proper dose selection in oncology should follow a multifactorial decision process leading to a randomized, dose-ranging study instead of a single phase II dose. ©2015 American Association for Cancer Research.

  1. Spectral optimization studies and schemes to enhance target detection and display for a three-band staring LWIR sensor

    NASA Astrophysics Data System (ADS)

    Mayer, Rulon R.; Waterman, James; Schuler, Jonathon; Scribner, Dean

    2003-12-01

    To achieve enhanced target discrimination, prototype three- band long wave infrared (LWIR) focal plane arrays (FPA) for missile defense applications have recently been constructed. The cutoff wavelengths, widths, and spectral overlap of the bands are critical parameters for the multicolor sensor design. Previous calculations for sensor design did not account for target and clutter spectral features in determining the optimal band characteristics. The considerable spectral overlap and correlation between the bands and attendant reduction in color contrast is another unexamined issue. To optimize and simulate the projected behavior of three-band sensors, this report examined a hyperspectral LWIR image cube. Our study starts with 30 bands of the LWIR spectra of three man-made targets and natural backgrounds that were binned to 3 bands using weighted band binning. This work achieves optimal binning by using a genetic algorithm approach and the target-to-clutter-ratio (TCR) as the optimization criterion. Another approach applies a genetic algorithm to maximize discrimination among the spectral reflectivities in the Non-conventional Exploitation Factors Data System (NEFDS) library. Each candidate band was weighted using a Fermi function to represent four interacting band edges for three- bands. It is found that choice of target can significantly influence the optimal choice of bands as expressed through the TCR and the Receiver Operator Characteristic curve. This study shows that whitening the image data prominently displays targets relative to backgrounds by increasing color contrast and also maintains color constancy. Three-color images are displayed by assigning red, green, blue colors directly to the whitened data set. Achieving constant colors of targets and backgrounds over time can greatly aid human viewers in the interpretation of the images and discriminate targets.

  2. Spectral optimization studies and schemes to enhance target detection and display for a three-band staring LWIR sensor

    NASA Astrophysics Data System (ADS)

    Mayer, Rulon R.; Waterman, James; Schuler, Jonathon; Scribner, Dean

    2004-01-01

    To achieve enhanced target discrimination, prototype three- band long wave infrared (LWIR) focal plane arrays (FPA) for missile defense applications have recently been constructed. The cutoff wavelengths, widths, and spectral overlap of the bands are critical parameters for the multicolor sensor design. Previous calculations for sensor design did not account for target and clutter spectral features in determining the optimal band characteristics. The considerable spectral overlap and correlation between the bands and attendant reduction in color contrast is another unexamined issue. To optimize and simulate the projected behavior of three-band sensors, this report examined a hyperspectral LWIR image cube. Our study starts with 30 bands of the LWIR spectra of three man-made targets and natural backgrounds that were binned to 3 bands using weighted band binning. This work achieves optimal binning by using a genetic algorithm approach and the target-to-clutter-ratio (TCR) as the optimization criterion. Another approach applies a genetic algorithm to maximize discrimination among the spectral reflectivities in the Non-conventional Exploitation Factors Data System (NEFDS) library. Each candidate band was weighted using a Fermi function to represent four interacting band edges for three- bands. It is found that choice of target can significantly influence the optimal choice of bands as expressed through the TCR and the Receiver Operator Characteristic curve. This study shows that whitening the image data prominently displays targets relative to backgrounds by increasing color contrast and also maintains color constancy. Three-color images are displayed by assigning red, green, blue colors directly to the whitened data set. Achieving constant colors of targets and backgrounds over time can greatly aid human viewers in the interpretation of the images and discriminate targets.

  3. Bi-objective optimization of a multiple-target active debris removal mission

    NASA Astrophysics Data System (ADS)

    Bérend, Nicolas; Olive, Xavier

    2016-05-01

    The increasing number of space debris in Low-Earth Orbit (LEO) raises the question of future Active Debris Removal (ADR) operations. Typical ADR scenarios rely on an Orbital Transfer Vehicle (OTV) using one of the two following disposal strategies: the first one consists in attaching a deorbiting kit, such as a solid rocket booster, to the debris after rendezvous; with the second one, the OTV captures the debris and moves it to a low-perigee disposal orbit. For multiple-target ADR scenarios, the design of such a mission is very complex, as it involves two optimization levels: one for the space debris sequence, and a second one for the "elementary" orbit transfer strategy from a released debris to the next one in the sequence. This problem can be seen as a Time-Dependant Traveling Salesman Problem (TDTSP) with two objective functions to minimize: the total mission duration and the total propellant consumption. In order to efficiently solve this problem, ONERA has designed, under CNES contract, TOPAS (Tool for Optimal Planning of ADR Sequence), a tool that implements a Branch & Bound method developed in previous work together with a dedicated algorithm for optimizing the "elementary" orbit transfer. A single run of this tool yields an estimation of the Pareto front of the problem, which exhibits the trade-off between mission duration and propellant consumption. We first detail our solution to cope with the combinatorial explosion of complex ADR scenarios with 10 debris. The key point of this approach is to define the orbit transfer strategy through a small set of parameters, allowing an acceptable compromise between the quality of the optimum solution and the calculation cost. Then we present optimization results obtained for various 10 debris removal scenarios involving a 15-ton OTV, using either the deorbiting kit or the disposal orbit strategy. We show that the advantage of one strategy upon the other depends on the propellant margin, the maximum duration allowed

  4. Amikacin Optimal Exposure Targets in the Hollow-Fiber System Model of Tuberculosis

    PubMed Central

    Srivastava, Shashikant; Modongo, Chawanga; Siyambalapitiyage Dona, Chandima W.; Pasipanodya, Jotam G.; Deshpande, Devyani

    2016-01-01

    Aminoglycosides such as amikacin are currently used for the treatment of multidrug-resistant tuberculosis (MDR-TB). However, formal pharmacokinetic/pharmacodynamic (PK/PD) studies to identify amikacin exposures and dosing schedules that optimize Mycobacterium tuberculosis killing have not been performed. It is believed that aminoglycosides do not work well under acidic conditions, which, if true, would mean poor sterilizing activity against semidormant bacilli at low pH. We performed time-kill studies to compare the bactericidal effect of amikacin in log-phase-growth bacilli with the sterilizing effect in semidormant bacilli at pH 5.8 in broth. In log-phase M. tuberculosis at normal pH versus semidormant M. tuberculosis at pH 5.8, the maximal kill (Emax) estimate and 95% confidence interval (CI) were 5.39 (95% CI, 4.91 to 5.63) versus 4.88 (CI, 4.46 to 5.22) log10 CFU/ml, while the concentration mediating 50% of Emax (EC50) was 1.0 (CI, 0. 0.86 to 1.12) versus 0.60 (CI, 0.50 to 0.66) times the MIC, respectively. Thus, the optimal exposures and kill rates identified for log-phase M. tuberculosis will be optimal even for semidormant bacilli. Next, we performed exposure-response and dose-scheduling studies in the hollow-fiber system model of tuberculosis using log-phase M. tuberculosis. We recapitulated the amikacin concentration-time profiles observed in lungs of patients treated over 28 days. The PK/PD index linked to M. tuberculosis kill was the peak concentration (Cmax)-to-MIC ratio (r2 > 0.99), closely followed by the area under the concentration-time curve from 0 to 24 h (AUC0–24)-to-MIC ratio (r2 = 0.98). The EC90 was a Cmax/MIC ratio of 10.13 (95% CI, 7.73 to 12.48). The EC90 is the dosing target for intermittent therapy that optimizes cure in TB programs for MDR-TB patients. PMID:27458215

  5. Four-Dimensional Phase Contrast Magnetic Resonance Imaging Protocol Optimization Using Patient-Specific 3-Dimensional Printed Replicas for In Vivo Imaging Before and After Flow Diverter Placement.

    PubMed

    Karmonik, Christof; Anderson, Jeff R; Elias, Saba; Klucznik, Richard; Diaz, Orlando; Zhang, Yi Jonathan; Grossman, Robert G; Britz, Gavin W

    2017-09-01

    Hemodynamics in cerebral aneurysms are currently investigated toward clinical efficacy using nonstandardized computational simulation techniques. At the same time, flow patterns and velocities are accessible by 4-dimensional phase contrast magnetic resonance imaging (4D pcMRI). Complexity of protocol design and imaging duration has limited the use of this technique in clinical imaging. A new approach is presented to overcome these limitations. Three-dimensional (3D) replicas of 2 cerebral aneurysms were fabricated by fused deposition prototyping (3D printing) and imaged using 4D pcMRI while connected to a magnetic resonance imaging-compatible continuous flow loop. Acquisition parameters were optimized with imaging times not to exceed 10 minutes. Six patients harboring cerebral aneurysms with sizes ranging from 4.7 to 13.8 mm were imaged with the optimized 4D pcMRI protocol. After treatment with the pipeline embolization device (PED), 4D pcMRI examinations were repeated in 3 patients. In all cases, major flow patterns were visualized well; smaller aneurysms posed a challenge because of limited spatial resolution, whereas larger aneurysms contained regions of low velocity resulting in limited contrast in the flow-sensitive images. After PED placement, ordered aneurysmal flow was disrupted and intra-aneurysmal velocity was reduced on average by 24.5% (range, 12.9-31.5%). Exploratory statistical analysis yielded a positive significant correlation (P < 0.01) between changes in inflow velocity and posttreatment intra-aneurysmal flow velocity. 4D pcMRI flow imaging in cerebral aneurysms within a time frame suitable for clinical imaging applications is feasible with optimized acquisition parameters, thereby enabling quantification of intra-aneurysmal flow changes after flow diverter device treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Optimization of a Novel Peptide Ligand Targeting Human Carbonic Anhydrase IX

    PubMed Central

    Rana, Shoaib; Nissen, Felix; Marr, Annabell; Markert, Annette; Altmann, Annette; Mier, Walter; Debus, Juergen; Haberkorn, Uwe; Askoxylakis, Vasileios

    2012-01-01

    Background Carbonic anhydrase IX (CA IX) is a hypoxia-regulated transmembrane protein over-expressed in various types of human cancer. Recently, a new peptide with affinity for human carbonic anhydrase IX (CaIX-P1) was identified using the phage display technology. Aim of the present study is to characterize the binding site in the sequence of CaIX-P1, in order to optimize the binding and metabolic properties and use it for targeting purposes. Methodology/Principal Findings Various fragments of CaIX-P1 were synthesized on solid support using Fmoc chemistry. Alanine scanning was performed for identification of the amino acids crucial for target binding. Derivatives with increased binding affinity were radiolabeled and in vitro studies were carried out on the CA IX positive human renal cell carcinoma cell line SKRC 52 and the CA IX negative human pancreatic carcinoma cell line BxPC3. Metabolic stability was investigated in cell culture medium and human serum. Organ distribution and planar scintigraphy studies were performed in Balb/c nu/nu mice carrying subcutaneously transplanted SKRC 52 tumors. The results of our studies clearly identified amino acids that are important for target binding. Among various fragments and derivatives the ligand CaIX-P1-4-10 (NHVPLSPy) was found to possess increased binding potential in SKRC 52 cells, whereas no binding capacity for BxPC3 cells was observed. Binding of radiolabeled CaIX-P1-4-10 on CA IX positive cells could be inhibited by both the unlabeled and the native CaIX-P1 peptide but not by control peptides. Stability experiments indicated the degradation site in the sequence of CaIX-P1-4-10. Biodistribution studies showed a higher in vivo accumulation in the tumor than in most healthy tissues. Conclusions Our data reveal modifications in the sequence of the CA IX affine ligand CaIX-P1 that might be favorable for improvement of target affinity and metabolic stability, which are necessary prior to the use of the ligand in

  7. Comparison of optimization-algorithm based feature extraction from time data or time-frequency data for target recognition purposes

    NASA Astrophysics Data System (ADS)

    Strifors, H. C.; Abrahamson, S.; Andersson, T.; Gaunaurd, G. C.

    2006-05-01

    Ultra-wideband ground penetrating radar (GPR) systems have proved useful for extracting and displaying information for target recognition purposes. Target signatures whether in the time, frequency, or joint time-frequency domains, will substantially depend on the target's burial conditions such as the type of soil, burial depth, and the soil's moisture content. That dependence can be utilized for target recognition purposes as we have demonstrated previously. The signature template of each target was computed in the time-frequency domain from the returned echo when the target was buried at a known depth in the soil with a known moisture content. Then, for any returned echo the relative difference between the similarly computed target signature and a selected signature template was computed. A global optimization method together with our (approximate) target translation method (TTM) that signature difference, chosen as object function, was minimized by adjusting the depth and moisture content, now taken to be unknown parameters. The template that gave the smallest value of the minimized object function for the returned echo was taken as target classification and the corresponding values of the depth and moisture parameters as estimates of the target's burial conditions. This optimization technique can also be applied to time-series data, avoiding the need for time-frequency analysis. It is then of interest to evaluate the relative merits of time data and time-frequency data for target recognition. Such a comparison is here preformed using signals returned from dummy mines buried underground. The results of the analysis serve to assess the intrinsic worth of data in the time domain and in the time-frequency domain for identifying subsurface targets using a GPR. The targets are buried in a test field at the Swedish Explosive Ordnance Disposal and Demining Center (SWEDEC) at Eksjo, Sweden.

  8. ECG-Based Detection of Early Myocardial Ischemia in a Computational Model: Impact of Additional Electrodes, Optimal Placement, and a New Feature for ST Deviation

    PubMed Central

    Schulze, Walther H. W.; Jiang, Yuan; Wilhelms, Mathias; Luik, Armin; Dössel, Olaf; Seemann, Gunnar

    2015-01-01

    In case of chest pain, immediate diagnosis of myocardial ischemia is required to respond with an appropriate treatment. The diagnostic capability of the electrocardiogram (ECG), however, is strongly limited for ischemic events that do not lead to ST elevation. This computational study investigates the potential of different electrode setups in detecting early ischemia at 10 minutes after onset: standard 3-channel and 12-lead ECG as well as body surface potential maps (BSPMs). Further, it was assessed if an additional ECG electrode with optimized position or the right-sided Wilson leads can improve sensitivity of the standard 12-lead ECG. To this end, a simulation study was performed for 765 different locations and sizes of ischemia in the left ventricle. Improvements by adding a single, subject specifically optimized electrode were similar to those of the BSPM: 2–11% increased detection rate depending on the desired specificity. Adding right-sided Wilson leads had negligible effect. Absence of ST deviation could not be related to specific locations of the ischemic region or its transmurality. As alternative to the ST time integral as a feature of ST deviation, the K point deviation was introduced: the baseline deviation at the minimum of the ST-segment envelope signal, which increased 12-lead detection rate by 7% for a reasonable threshold. PMID:26587538

  9. Analyzing the multiple-target-multiple-agent scenario using optimal assignment algorithms

    SciTech Connect

    Kwok, K.S.; Driessen, B.J.; Phillips, C.A.; Tovey, C.A.

    1997-10-01

    This work considers the problem of maximum utilization of a set of mobile robots with limited sensor-range capabilities and limited travel distances. The robots are initially in random positions. A set of robots properly guards or covers a region if every point within the region is within the effective sensor range of at least one vehicle. The authors wish to move the vehicles into surveillance positions so as to guard or cover a region, while minimizing the maximum distance traveled by any vehicle. This problem can be formulated as an assignment problem, in which they must optimally decide which robot to assign to which slot of a desired matrix of grid points. The cost function is the maximum distance traveled by any robot. Assignment problems can be solved very efficiently. Solutions times for one hundred robots took only seconds on a Silicon Graphics Crimson workstation. The initial positions of all the robots can be sampled by a central base station and their newly assigned positions communicated back to the robots. Alternatively, the robots can establish their own coordinate system with the origin fixed at one of the robots and orientation determined by the compass bearing of another robot relative to this robot. This paper presents example solutions to the multiple-target-multiple-agent scenario using a matching algorithm. Two separate cases with one hundred agents in each were analyzed using this method. They have found these mobile robot problems to be a very interesting application of network optimization methods, and they expect this to be a fruitful area for future research.

  10. Establishment of a biophysical model to optimize endoscopic targeting of magnetic nanoparticles for cancer treatment

    PubMed Central

    Baumann, Martin; Alizai, Patrick H; Schmeding, Maximilian; Guentherodt, Gernot; Schmitz-Rode, Thomas; Neumann, Ulf P

    2017-01-01

    Superparamagnetic iron oxide nanoparticles (SPION) may be used for local tumor treatment by coupling them to a drug and accumulating them locally with magnetic field traps, that is, a combination of permanent magnets and coils. Thereafter, an alternating magnetic field generates heat which may be used to release the thermosensitively bound drug and for hyperthermia. Until today, only superficial tumors can be treated with this method. Our aim was to transfer this method into an endoscopic setting to also reach the majority of tumors located inside the body. To find the ideal endoscopic magnetic field trap, which accumulates the most SPION, we first developed a biophysical model considering anatomical as well as physical conditions. Entities of choice were esophageal and prostate cancer. The magnetic susceptibilities of different porcine and rat tissues were measured with a superconducting quantum interference device. All tissues showed diamagnetic behavior. The evaluation of clinical data (computed tomography scan, endosonography, surgical reports, pathological evaluation) of patients gave insight into the topographical relationship between the tumor and its surroundings. Both were used to establish the biophysical model of the tumors and their surroundings, closely mirroring the clinical situation, in which we could virtually design, place and evaluate different electromagnetic coil configurations to find optimized magnetic field traps for each tumor entity. By simulation, we could show that the efficiency of the magnetic field traps can be enhanced by 38-fold for prostate and 8-fold for esophageal cancer. Therefore, our approach of endoscopic targeting is an improvement of the magnetic drug-targeting setups for SPION tumor therapy as it holds the possibility of reaching tumors inside the body in a minimal-invasive way. Future animal experiments must prove these findings in vivo. PMID:28860758

  11. Construction of a directed hammerhead ribozyme library: towards the identification of optimal target sites for antisense-mediated gene inhibition.

    PubMed Central

    Pierce, M L; Ruffner, D E

    1998-01-01

    Antisense-mediated gene inhibition uses short complementary DNA or RNA oligonucleotides to block expression of any mRNA of interest. A key parameter in the success or failure of an antisense therapy is the identification of a suitable target site on the chosen mRNA. Ultimately, the accessibility of the target to the antisense agent determines target suitability. Since accessibility is a function of many complex factors, it is currently beyond our ability to predict. Consequently, identification of the most effective target(s) requires examination of every site. Towards this goal, we describe a method to construct directed ribozyme libraries against any chosen mRNA. The library contains nearly equal amounts of ribozymes targeting every site on the chosen transcript and the library only contains ribozymes capable of binding to that transcript. Expression of the ribozyme library in cultured cells should allow identification of optimal target sites under natural conditions, subject to the complexities of a fully functional cell. Optimal target sites identified in this manner should be the most effective sites for therapeutic intervention. PMID:9801305

  12. Characterizing and optimizing human anticancer drug targets based on topological properties in the context of biological pathways.

    PubMed

    Zhang, Jian; Wang, Yan; Shang, Desi; Yu, Fulong; Liu, Wei; Zhang, Yan; Feng, Chenchen; Wang, Qiuyu; Xu, Yanjun; Liu, Yuejuan; Bai, Xuefeng; Li, Xuecang; Li, Chunquan

    2015-04-01

    One of the challenging problems in drug discovery is to identify the novel targets for drugs. Most of the traditional methods for drug targets optimization focused on identifying the particular families of "druggable targets", but ignored their topological properties based on the biological pathways. In this study, we characterized the topological properties of human anticancer drug targets (ADTs) in the context of biological pathways. We found that the ADTs tended to present the following seven topological properties: influence the number of the pathways related to cancer, be localized at the start or end of the pathways, interact with cancer related genes, exhibit higher connectivity, vulnerability, betweenness, and closeness than other genes. We first ranked ADTs based on their topological property values respectively, then fused them into one global-rank using the joint cumulative distribution of an N-dimensional order statistic to optimize human ADTs. We applied the optimization method to 13 anticancer drugs, respectively. Results demonstrated that over 70% of known ADTs were ranked in the top 20%. Furthermore, the performance for mercaptopurine was significant: 6 known targets (ADSL, GMPR2, GMPR, HPRT1, AMPD3, AMPD2) were ranked in the top 15 and other four out of the top 15 (MAT2A, CDKN1A, AREG, JUN) have the potentialities to become new targets for cancer therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. How visual perceptual grouping influences foot placement

    PubMed Central

    Fennell, John; Goodwin, Charlotte; Burn, Jeremy F.; Leonards, Ute

    2015-01-01

    Everybody would agree that vision guides locomotion; but how does vision influence choice when there are different solutions for possible foot placement? We addressed this question by investigating the impact of perceptual grouping on foot placement in humans. Participants performed a stepping stone task in which pathways consisted of target stones in a spatially regular path of foot falls and visual distractor stones in their proximity. Target and distractor stones differed in shape and colour so that each subset of stones could be easily grouped perceptually. In half of the trials, one target stone swapped shape and colour with a distractor in its close proximity. We show that in these ‘swapped’ conditions, participants chose the perceptually groupable, instead of the spatially regular, stepping location in over 40% of trials, even if the distance between perceptually groupable steps was substantially larger than normal step width/length. This reveals that the existence of a pathway that could be traversed without spatial disruption to periodic stepping is not sufficient to guarantee participants will select it and suggests competition between different types of visual input when choosing foot placement. We propose that a bias in foot placement choice in favour of visual grouping exists as, in nature, sudden changes in visual characteristics of the ground increase the uncertainty for stability. PMID:26587273

  14. Indiana Invitational Conference on Placement. Report. (Smithville, Indiana, June 25-27, 1975).

    ERIC Educational Resources Information Center

    Indiana State Board of Vocational and Technical Education, Indianapolis.

    These 10 presentations were made at a State conference to explore the problems and possibilities of job placement as background for implementing a Statewide guidance program with emphasis on counseling, placement, and followup for selected target groups. Focus is on three issues of job placement: (1) Where do the responsibilities for job placement…

  15. Critical Path-Based Thread Placement for NUMA Systems

    SciTech Connect

    Su, C Y; Li, D; Nikolopoulos, D S; Grove, M; Cameron, K; de Supinski, B R

    2011-11-01

    Multicore multiprocessors use a Non Uniform Memory Architecture (NUMA) to improve their scalability. However, NUMA introduces performance penalties due to remote memory accesses. Without efficiently managing data layout and thread mapping to cores, scientific applications, even if they are optimized for NUMA, may suffer performance loss. In this paper, we present algorithms and a runtime system that optimize the execution of OpenMP applications on NUMA architectures. By collecting information from hardware counters, the runtime system directs thread placement and reduces performance penalties by minimizing the critical path of OpenMP parallel regions. The runtime system uses a scalable algorithm that derives placement decisions with negligible overhead. We evaluate our algorithms and runtime system with four NPB applications implemented in OpenMP. On average the algorithms achieve between 8.13% and 25.68% performance improvement compared to the default Linux thread placement scheme. The algorithms miss the optimal thread placement in only 8.9% of the cases.

  16. From in vivo gene targeting of oestrogen receptors to optimization of their modulation in menopause

    PubMed Central

    Arnal, Jean-François; Lenfant, Françoise; Flouriot, Gilles; Tremollières, Florence; Laurell, Henrik; Fontaine, Coralie; Krust, Andrée; Chambon, Pierre; Gourdy, Pierre

    2012-01-01

    The ancestral status of oestrogen receptor (ER) in the family of the steroid receptors has probably contributed to the pleiotropic actions of oestrogens, and in particular, that of 17β-oestradiol (E2). Indeed, in addition to their well-described role in sexual development and reproduction, they influence most of the physiological processes. The pathophysiological counterpart of these actions includes prevention of osteoporosis, atheroma and type 2 diabetes, and also the promotion of uterus and breast cancer growth. Thus, the major challenge consists in uncoupling some beneficial actions from other deleterious ones, that is, selective ER modulation. Tamoxifen and raloxifene are already used, as they prevent the recurrence of breast cancer and mimic oestrogen action mainly on bone. Both E2 and tamoxifen exhibit a proliferative and, thus, a protumoural action on the endometrium. Activation of ERα and ERβ regulates target gene transcription (genomic action) through two independent activation functions, AF-1 and AF-2, but can also elicit rapid membrane-initiated steroid signals. In the present review, we attempted to summarize recent advances provided by the in vivo molecular ‘dissection’ of ERα, allowing the uncoupling of some of its actions and potentially paving the way to optimized selective ER modulators. PMID:21671899

  17. Improved Plant-based Production of E1 endoglucanase Using Potato: Expression Optimization and Tissue Targeting

    SciTech Connect

    Dai, Ziyu; Hooker, Brian S.; Anderson, Daniel B.; Thomas, Steven R.

    2000-06-01

    Optimization of Acidothermus cellulolyticus endoglucanase (E1) gene expression in transgenic potato (Solanum tuberosum L.) was examined in this study, where the E1 coding sequence was transcribed under control of a leaf specific promoter (tomato RbcS-3C) or the Mac promoter (a hybrid promoter of mannopine synthase promoter and cauliflower mosaic virus 35S promoter enhancer region). Average E1 activity in leaf extracts of potato transformants, in which E1 protein was targeted by a chloroplast signal peptide and an apoplast signal peptide were much higher than those by an E1 native signal peptide and a vacuole signal peptide. E1 protein accumulated up to 2.6% of total leaf soluble protein, where E1 gene was under control of the RbcS-3C promoter, alfalfa mosaic virus 5-untranslated leader, and RbcS-2A signal peptide. E1 protein production, based on average E1 activity and E1 protein accumulation in leaf extracts, is higher in potato than those measured previously in transgenic tobacco bearing the same transgene constructs. Comparisons of E1 activity, protein accumulation, and relative mRNA levels showed that E1 expression under control of tomato RbcS-3C promoter was specifically localized in leaf tissues, while E1 gene was expressed in both leaf and tuber tissues under control of Mac promoter. This suggests dual-crop applications in which potato vines serve as enzyme production `bioreactors' while tubers are preserved for culinary applications.

  18. Heritability of targeted gene modifications induced by plant-optimized CRISPR systems.

    PubMed

    Mao, Yanfei; Botella, Jose Ramon; Zhu, Jian-Kang

    2017-03-01

    The Streptococcus-derived CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 (CRISPR-associated protein 9) system has emerged as a very powerful tool for targeted gene modifications in many living organisms including plants. Since the first application of this system for plant gene modification in 2013, this RNA-guided DNA endonuclease system has been extensively engineered to meet the requirements of functional genomics and crop trait improvement in a number of plant species. Given its short history, the emphasis of many studies has been the optimization of the technology to improve its reliability and efficiency to generate heritable gene modifications in plants. Here we review and analyze the features of customized CRISPR/Cas9 systems developed for plant genetic studies and crop breeding. We focus on two essential aspects: the heritability of gene modifications induced by CRISPR/Cas9 and the factors affecting its efficiency, and we provide strategies for future design of systems with improved activity and heritability in plants.

  19. (90)Y Radioembolization: Multimodality Imaging Pattern Approach with Angiographic Correlation for Optimized Target Therapy Delivery.

    PubMed

    Camacho, Juan C; Moncayo, Valeria; Kokabi, Nima; Reavey, Hamilton E; Galt, James R; Yamada, Kei; Kies, Darren D; Williams, Roger S; Kim, Hyun S; Schuster, David M

    2015-01-01

    Primary and metastatic liver cancers are responsible for considerable morbidity and mortality, and many patients are not curable at presentation. Therefore, new therapies such as radioembolization with yttrium 90 ((90)Y)-labeled microspheres are an alternative method to treat patients with unresectable primary or secondary liver tumors. Patient selection, treatment technique, and early recognition of potential complications are the keys for successful patient outcomes. The activity of administered (90)Y microspheres depends on multiple variables, including the tumor burden, the volume of the liver lobe to be treated, the type of (90)Y microspheres, and the hepatopulmonary shunt fraction. Preprocedural planning relies on the results of cross-sectional imaging to determine the extent of disease, tumoral and nontumoral liver volumes, patency of the portal vein, and the degree of extrahepatic disease. A multidisciplinary approach that combines expertise in cross-sectional imaging, nuclear medicine, and flow dynamics is critical to adequately target malignant tissue. Preprocedural multimodality imaging, particularly combined single photon emission computed tomography (SPECT) and computed tomography (CT) imaging (SPECT/CT), may be used to identify nontarget imaging patterns that, if recognized, can potentially be corrected with either branch vessel embolization or catheter repositioning. Postprocedural multimodality imaging is also useful to confirm the appropriate delivery of (90)Y microspheres, enabling early identification of potential complications and the adequacy of microsphere distribution, thereby optimizing planning for subsequent therapies.

  20. Benefit on optimal cerebral perfusion pressure targeted treatment for traumatic brain injury patients.

    PubMed

    Petkus, Vytautas; Preiksaitis, Aidanas; Krakauskaite, Solventa; Zubaviciute, Erika; Rocka, Saulius; Rastenyte, Daiva; Vosylius, Saulius; Ragauskas, Arminas

    2017-04-23

    The maintenance of patient-specific optimal cerebral perfusion pressure (CPPopt) is crucial for patients with traumatic brain injury (TBI). The goal of the study was to explore the influence of CPP declination from CPPopt value on the TBI patients' outcome. The CPP and cerebrovascular autoregulation (CA) monitoring of 52 TBI patients was performed. Patient-specific CPPopt has been identified and the associations between the patients' outcome and complex influence of time of CPP declination from CPPopt value, age, and the duration of CA impairment episodes has been analyzed. The multiple correlation coefficient between the Glasgow outcome scale (GOS), duration of CA impairment events and percentage time, when 0<ΔCPPopt<10mmHg was r=-0.643 (P<0.001). The multiple correlation coefficients between GOS, age, and percentage time of ΔCPPopt when 0<ΔCPPopt<10mmHg was r=-0.587 (P<0.001). The CPPopt-targeted patient-specific management might be useful for stabilizing CA in TBI patients as well as for improving their outcome. Better outcomes were obtained by maintaining CPP in light hyperperfusion condition (up to 10mmHg above CPPopt) when CPPopt is in the range of 60-80mmHg, and keeping CPP within the range of CPPopt +/-5mmHg when CPPopt is above 80mmHg. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Development of an Optimized Activatable MMP-14 targeted SPECT Imaging Probe

    PubMed Central

    Watkins, Gregory A.; Jones, Ella Fung; Shell, M. Scott; VanBrocklin, Henry F.; Pan, Mei-Hsiu; Hanrahan, Stephen M.; Feng, Jin Jin; He, Jiang; Sounni, Nor Eddine; Dill, Ken A.; Contag, Christopher H.; Coussens, Lisa M.; Franc, Benjamin L.

    2008-01-01

    Matrix Metalloproteinase-14 (MT1-MMP or MMP-14) is a membrane-associated protease implicated in a variety of tissue remodeling processes and a molecular hallmark of select metastatic cancers. The ability to detect MMP-14 in vivo would be useful in studying its role in pathologic processes and may potentially serve as a guide for the development of targeted molecular therapies. Four MMP-14 specific probes containing a positively charged cell penetrating peptide (CPP) d-arginine octamer (r8) linked with a MMP-14 peptide substrate and attenuating sequences with glutamate (8e, 4e) or glutamate-glycine (4eg and 4egg) repeating units were modeled using an AMBER force field method. The probe with 4egg attenuating sequence exhibited the highest CPP/attenuator interaction, predicting minimized cellular uptake until cleaved. The in vitro MMP-14-mediated cleavage studies using the human recombinant MMP-14 catalytic domain revealed an enhanced cleavage rate that directly correlated with the linearity of the embedded peptide substrate sequence. Successful cleavage and uptake of a technetium-99m labeled version of the optimal probe was demonstrated in MMP-14 transfected human breast cancer cells. Two- fold reduction of cellular uptake was found in the presence of a broad spectrum MMP inhibitor. The combination of computational chemistry, parallel synthesis and biochemical screening, therefore, shows promise as a set of tools for developing new radiolabeled probes that are sensitive to protease activity. PMID:19109023

  2. An approach to optimal hyperspectral and multispectral signature and image fusion for detecting hidden targets on shorelines

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R.

    2015-10-01

    Hyperspectral and multispectral imagery of shorelines collected from airborne and shipborne platforms are used following pushbroom imagery corrections using inertial motion motions units and augmented global positioning data and Kalman filtering. Corrected radiance or reflectance images are then used to optimize synthetic high spatial resolution spectral signatures resulting from an optimized data fusion process. The process demonstrated utilizes littoral zone features from imagery acquired in the Gulf of Mexico region. Shoreline imagery along the Banana River, Florida, is presented that utilizes a technique that makes use of numerically embedded targets in both higher spatial resolution multispectral images and lower spatial resolution hyperspectral imagery. The fusion process developed utilizes optimization procedures that include random selection of regions and pixels in the imagery, and minimizing the difference between the synthetic signatures and observed signatures. The optimized data fusion approach allows detection of spectral anomalies in the resolution enhanced data cubes. Spectral-spatial anomaly detection is demonstrated using numerically embedded line targets within actual imagery. The approach allows one to test spectral signature anomaly detection and to identify features and targets. The optimized data fusion techniques and software allows one to perform sensitivity analysis and optimization in the singular value decomposition model building process and the 2-D Butterworth cutoff frequency and order numerical selection process. The data fusion "synthetic imagery" forms a basis for spectral-spatial resolution enhancement for optimal band selection and remote sensing algorithm development within "spectral anomaly areas". Sensitivity analysis demonstrates the data fusion methodology is most sensitive to (a) the pixels and features used in the SVD model building process and (b) the 2-D Butterworth cutoff frequency optimized by application of K

  3. Hard target penetrator explosive development optimization of fragment, blast and survivability properties of explosives for hard target applications

    SciTech Connect

    Simpson, R. L., LLNL

    1997-05-01

    Several new explosives have been developed for hard target and related applications. Materials having energy densities as high as 20 KJ/cc have been made. Mid-scale field trials have been carried out at Eglin Air Force Base. Fragmentation improvements 150% that of Tritonal have been attained.

  4. Back to the Future: Lessons Learned in Modern Target-based and Whole-Cell Lead Optimization of Antimalarials

    PubMed Central

    Chatterjee, Arnab K; Yeung, Bryan KS

    2012-01-01

    Antimalarial drug discovery has historically benefited from the whole-cell (phenotypic) screening approach to identify lead molecules in the search for new drugs. However over the past two decades there has been a shift in the pharmaceutical industry to move away from whole-cell screening to target-based approaches. As part of a Wellcome Trust and Medicines for Malaria Venture (MMV) funded consortium to discover new blood-stage antimalarials, we used both approaches to identify new antimalarial chemotypes, two of which have progressed beyond the lead optimization phase and display excellent in vivo efficacy in mice. These two advanced series were identified through a cell-based optimization devoid of target information and in this review we summarize the advantages of this approach versus a target-based optimization. Although the each lead optimization required slightly different medicinal chemistry strategies, we observed some common issues across the different the scaffolds which could be applied to other cell based lead optimization programs. PMID:22242845

  5. Left ventricular lead placement in the latest activated region guided by coronary venous electroanatomic mapping.

    PubMed

    Rad, Masih Mafi; Blaauw, Yuri; Dinh, Trang; Pison, Laurent; Crijns, Harry J; Prinzen, Frits W; Vernooy, Kevin

    2015-01-01

    Left ventricular (LV) lead placement in the latest activated region is an important determinant of response to cardiac resynchronization therapy (CRT). We investigated the feasibility of coronary venous electroanatomic mapping (EAM) to guide LV lead placement to the latest activated region. Twenty-five consecutive CRT candidates with left bundle-branch block underwent intra-procedural coronary venous EAM using EnSite NavX. A guidewire was used to map the coronary veins during intrinsic activation, and to test for phrenic nerve stimulation (PNS). The latest activated region, defined as the region with an electrical delay >75% of total QRS duration, was located anterolaterally in 18 (basal, n = 10; mid, n = 8) and inferolaterally in 6 (basal, n = 3; mid, n = 3). In one patient, identification of the latest activated region was impeded by limited coronary venous anatomy. In patients with >1 target vein (n = 12), the anatomically targeted inferolateral vein was rarely the vein with maximal electrical delay (n = 3). A concordant LV lead position was achieved in 18 of 25 patients. In six patients, this was hampered by PNS (n = 4), lead instability (n = 1), and coronary vein stenosis (n = 1). Coronary venous EAM can be used intraprocedurally to guide LV lead placement to the latest activated region free of PNS. This approach especially contributes to optimization of LV lead electrical delay in patients with multiple target veins. Conventional anatomical LV lead placement strategy does not target the vein with maximal electrical delay in many of these patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  6. Optimal Placement of Pressure Monitoring Wells for CO2 Leakage Detection based on a Kalman filter and a Multi-Objective Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Nogues, J. P.; Nordbotten, J. M.; Celia, M. A.

    2012-12-01

    Measurement of pressure changes in monitoring wells located in a formation overlying an injection formation can provide an early warning for CO2 or brine leakage. If this strategy is to be part of an overall monitoring framework, then questions about how many monitoring wells are needed to detect a leakage event, and where should these well be placed, need to be addressed. In this study we present a methodology that uses a combination of a Kalman filter, a physically-based analytical model that solves for pressure propagation across old/abandoned leaky wells in a multi-formation system, and a multi-objective genetic algorithm, to answer the questions of how many wells should be used and where should they be placed. The Kalman filter is used to explore the covariance reduction based on possible well positions. The physically-based model is used to simulate, in a Monte Carlo scheme, a wide range of possible leakage scenarios where the random variable is the permeability of the old/abandoned leaky wells. The multi-objective genetic algorithm employed in this work is the Non-dominated Sorting Genetic Algorithm (NSGA-II), which is used to optimize three objectives: (i)The reduction of the total variance of the pressure field, (ii) the reduction of the number of wells used to detect a leakage event, and (iii) the reduction of the detection of leakage events which are not "harmful". In this work a "harmful" leakage event refers to an event in which the pressure change in the monitoring formation is large enough to induce leakage into the deepest potable water formation. The methodology is applied to a synthetic case study, which serves to prove the applicability of the methods and to gather insights on the strengths and weaknesses of using pressure monitoring wells to detect a CO2 leakage event.

  7. Research: Hyperactivity, Placement Centers

    ERIC Educational Resources Information Center

    Nation's Schools and Colleges, 1975

    1975-01-01

    A diet that emphasizes the elimination of food containing artificial coloring and flavoring from meals served to hyperactive children has met with success in preliminary studies; college placement centers are advised to shift their emphasis from job research and counseling. (Author/MLF)

  8. Optimal Systolic Blood Pressure Target After SPRINT: Insights from a Network Meta-Analysis of Randomized Trials.

    PubMed

    Bangalore, Sripal; Toklu, Bora; Gianos, Eugenia; Schwartzbard, Arthur; Weintraub, Howard; Ogedegbe, Gbenga; Messerli, Franz H

    2017-06-01

    The optimal on-treatment blood pressure (BP) target has been a matter of debate. The recent SPRINT trial showed significant benefits of a BP target of <120 mm Hg, albeit with an increase in serious adverse effects related to low BP. PubMed, EMBASE, and CENTRAL were searched for randomized trials comparing treating with different BP targets. Trial arms were grouped into 5 systolic BP target categories: 1) <160 mm Hg, 2) <150 mm Hg, 3) <140 mm Hg, 4) <130 mm Hg, and 5) <120 mm Hg. Efficacy outcomes of stroke, myocardial infarction, death, cardiovascular death, heart failure, and safety outcomes of serious adverse effects were evaluated using a network meta-analysis. Seventeen trials that enrolled 55,163 patients with 204,103 patient-years of follow-up were included. There was a significant decrease in stroke (rate ratio [RR] 0.54; 95% confidence interval [CI], 0.29-1.00) and myocardial infarction (RR 0.68; 95% CI, 0.47-1.00) with systolic BP <120 mm Hg (vs <160 mm Hg). Sensitivity analysis using achieved systolic BP showed a 72%, 97%, and 227% increase in stroke with systolic BP of <140 mm Hg, <150 mm Hg, and <160 mm, respectively, when compared with systolic BP <120 mm Hg. There was no difference in death, cardiovascular death, or heart failure when comparing any of the BP targets. However, the point estimate favored lower BP targets (<120 mm Hg, <130 mm Hg) when compared with higher BP targets (<140 mm Hg or <150 mm Hg). BP targets of <120 mm Hg and <130 mm Hg ranked #1 and #2, respectively, as the most efficacious target. There was a significant increase in serious adverse effects with systolic BP <120 mm Hg vs <150 mm Hg (RR 1.83; 95% CI, 1.05-3.20) or vs <140 mm Hg (RR 2.12; 95% CI, 1.46-3.08). BP targets of <140 mm Hg and <150 mm Hg ranked #1 and #2, respectively, as the safest target for the outcome of serious adverse effects. Cluster plots for combined efficacy and safety showed that a systolic BP target of <130 mm Hg had optimal balance between efficacy

  9. College Placement in Today's Economy.

    ERIC Educational Resources Information Center

    Galloway, James L.

    1982-01-01

    Analyzed the effects of reduced financing on college placement items such as services, staffing, fees, conference attendance, travel, recruitment, and salaries. Placement personnel (N=224) responded to a questionnaire. Results indicated that budgets have generally remained the same. (RC)

  10. Optimal Proteinuria Target for Renoprotection in Patients with IgA Nephropathy

    PubMed Central

    Nam, Ki Heon; Kie, Jeong Hae; Lee, Mi Jung; Chang, Tae-Ik; Kang, Ea Wha; Kim, Dong Wook; Lim, Beom Jin; Park, Jung Tak; Kwon, Young Eun; Kim, Yung Ly; Park, Kyoung Sook; An, Seong Yeong; Oh, Hyung Jung; Yoo, Tae-Hyun; Kang, Shin-Wook; Choi, Kyu Hun; Jeong, Hyeon Joo; Han, Dae-Suk; Han, Seung Hyeok

    2014-01-01

    Background Proteinuria is a target for renoprotection in kidney diseases. However, optimal level of proteinuria reduction in IgA nephropathy (IgAN) is unknown. Methods We conducted a retrospective observational study in 500 patients with biopsy-proven IgAN. Time-averaged proteinuria (TA-P) was calculated as the mean of every 6 month period of measurements of spot urine protein-to-creatinine ratio. The study endpoints were a 50% decline in estimated glomerular filtration rate (eGFR), onset of end-stage renal disease (ESRD), and slope of eGFR. Results During a median follow-up duration of 65 (12–154) months, a 50% decline in eGFR occurred in 1 (0.8%) patient with TA-P of <0.3 g/g compared to 6 (2.7%) patients with TA-P of 0.3–0.99 g/g (hazard ratio, 2.82; P = 0.35). Risk of reaching a 50% decline in eGFR markedly increased in patients with TA-P of 1.0–2.99 g/g (P = 0.002) and those with TA-P≥3.0 g/g (P<0.001). ESRD did not occur in patients with TA-P<1.0 g/g compared to 26 (20.0%) and 8 (57.1%) patients with TA-P of 1.0–2.99 and ≥3.0 g/g, respectively. Kidney function of these two groups deteriorated faster than those with TA-P<1.0 g/g (P<0.001). However, patients with TA-P of 0.3–0.99 g/g had a greater decline of eGFR than patients with TA-P<0.3 g/g (−0.41±1.68 vs. −0.73±2.82 ml/min/1.73 m2/year, P = 0.03). Conclusion In this study, patients with TA-P<1.0 g/g show favorable outcomes. However, given the faster eGFR decline in patients with TA-P of 0.3–0.99 g/g than in patients with TA-P<0.3 g/g, the ultimate optimal goal of proteinuria reduction can be lowered in the management of IgAN. PMID:25003873

  11. Validation and scopolamine-reversal of latent learning in the water maze utilizing a revised direct platform placement procedure.

    PubMed

    Malin, David H; Schaar, Krystal L; Izygon, Jonathan J; Nghiem, Duyen M; Jabitta, Sikirat Y; Henceroth, Mallori M; Chang, Yu-Hsuan; Daggett, Jenny M; Ward, Christopher P

    2015-08-01

    The Morris water maze is routinely used to explore neurobiological mechanisms of working memory. Humans can often acquire working memory relevant to performing a task by mere sensory observation, without having to actually perform the task followed by reinforcement. This can be modeled in the water maze through direct placement of a rat on the escape platform so that it can observe the location, and then assessing the subject's performance in swimming back to the platform. However, direct placement procedures have hardly been studied for two decades, reflecting a controversy about whether direct placement resulted in sufficiently rapid and direct swims back to the platform. In the present study, utilizing revised training methods, a more comprehensive measure of trajectory directness, a more rigorous sham-trained control procedure and an optimal placement-test interval, rats swam almost directly back to the platform in under 4s, significantly more quickly and directly than sham-trained subjects. Muscarinic cholinergic mechanisms, which are inactivated by scopolamine, are essential to memory for standard learning paradigms in the water maze. This experiment determined whether this would also be true for latent learning. ANOVA revealed significant negative effects of scopolamine on both speed and accuracy of trajectory, as well as significant positive effects of direct placement training vs. sham-training. In a probe trial, placement-trained animals without scopolamine spent significantly more time and path length in the target quadrant than trained rats with scopolamine and sham-trained rats without scopolamine. Scopolamine impairments are likely due to effects on memory, since the same dose had little effect on performance with a visible platform. The revised direct placement model offers a means of further comparing the neural mechanisms of latent learning with those of standard instrumental learning.

  12. Optimization of targeted two-photon PDT triads for the treatment of head and neck cancers

    NASA Astrophysics Data System (ADS)

    Spangler, Charles W.; Starkey, Jean R.; Dubinina, Galyna; Fahlstrom, Carl; Shepard, Joyce

    2012-02-01

    Synthesis of new PDT triads that incorporate a tumor-killing porphyrin with large two-photon cross-section for 150 fs laser pulses (2000 GM) in the Near-infrared (NIR) at 840 nm, a NIR imaging agent, and a small peptide that targets over-expressed EGF receptors on the tumor surface. This triad formulation has been optimized over the past year to treat FADU Head and Neck SCC xenograft tumors in SCID mice. Effective PDT triad dose (1-10 mg/Kg) and laser operating parameters (840 nm, 15-45 min, 900 mW) have been established. Light, dark and PDT treatment toxicities were determined, showing no adverse effects. Previous experiments in phantom and mouse models indicate that tumors can be treated directly through the skin to effective depths between 2 and 5 cm. Treated mice demonstrated rapid tumor regression with some complete cures in as little as 15-20 days. No adverse effects were observed in any healthy tissue through which the focused laser beam passed before reaching the tumor site, and excellent healing occurred post treatment including rapid hair re-growth. Not all irradiation protocols lead to complete cures. Since two-photon PDT is carried out by rastering focused irradiation throughout the tumor, there is the possibility that as the treatment depth increases, some parts of the tumor may escape irradiation due to increased scattering, thus raising the possibility that tumor re-growth could be triggered by small islands of untreated cells, especially at the rapidly growing tumor margins, a problem we hope to alleviate by using image-guided two-photon PDT.

  13. Georgia Guidebook: Job Placement Services.

    ERIC Educational Resources Information Center

    Anderson, Grady L.; Riordan, Richard J.

    Intended for potential and current job placement coordinators, this guidebook describes Georgia's placement service activities in the following five areas: (1) organization of a placement service, (2) developmental activities, (3) testing, (4) individual and group work activities, and (5) followup evaluation and research. The test's introductory…

  14. Career Planning & Placement Survey, 1991.

    ERIC Educational Resources Information Center

    College Placement Council, Bethlehem, PA.

    In 1991, survey questionnaires were completed by 823 out of 1,518 College Placement Council college members in a study assessing the status of career planning and placement activities. The results revealed that 87% of the responding offices were centralized. The 1991 survey results showed a continuation of the decline in the use of "placement"…

  15. Optimization of Landscape Phage Fusion Protein-Modified Polymeric PEG-PE Micelles for Improved Breast Cancer Cell Targeting

    PubMed Central

    Wang, Tao; Petrenko, Valery A.; Torchilin, Vladimir P.

    2015-01-01

    Amphiphilic landscape phage fusion proteins with high affinity and selectivity towards breast cancer MCF-7 (Michigan Cancer Foundation-7) cells self-assemble with polymeric PEG-PE conjugates to form mixed micelles (phage-micelles) capable of cancer cell-targeted delivery of poorly-soluble drugs. While the PEG corona provides the stability and longevity to the micelles, its presence is a potential steric difficulties for the interaction of phage fusion protein with cell surface targets. We attempted to address this problem by controlling the length of the PEG block and the phage fusion protein quantity, selecting the optimal ones to produce a reasonable retention of the targeting affinity and selectivity of the MCF-7-specific phage fusion protein. Three PEG-PE conjugates with different PEG lengths were used to construct phage- and plain-micelles, followed by FACS analysis of the effect of the PEG length on their binding affinity and selectivity towards target MCF-7 cells using either a MCF-7 cell monoculture or a cell co-culture model composed of target cancer MCF-7 cells and non-target, non-cancer C166 cells expressing GFP (Green Fluorescent Protein). Both, the length of PEG and quantity of phage fusion protein had a profound impact on the targetability of the phage-micelles. Phage-micelles prepared with PEG2k-PE achieved a desirable binding affinity and selectivity. Incorporation of a minimal concentration of phage protein, up to 0.5%, produced maximal targeting efficiency towards MCF-7 cells. Overall, phage-micelles with PEG2k-PE and 0.5% of phage protein represent the optimal formulation for targeting towards breast cancer cells. PMID:26451274

  16. VLSI Cells Placement Using the Neural Networks

    SciTech Connect

    Azizi, Hacene; Zouaoui, Lamri; Mokhnache, Salah

    2008-06-12

    The artificial neural networks have been studied for several years. Their effectiveness makes it possible to expect high performances. The privileged fields of these techniques remain the recognition and classification. Various applications of optimization are also studied under the angle of the artificial neural networks. They make it possible to apply distributed heuristic algorithms. In this article, a solution to placement problem of the various cells at the time of the realization of an integrated circuit is proposed by using the KOHONEN network.

  17. Treatment Optimization Using Computed Tomography-Delineated Targets Should be Used for Supraclavicular Irradiation for Breast Cancer

    SciTech Connect

    Liengsawangwong, Raweewan; Yu, T.-K.; Sun, T.-L.; Erasmus, Jeremy J.; Perkins, George H.; Tereffe, Welela; Oh, Julia L.; Woodward, Wendy A.; Strom, Eric A.; Salephour, Mohammad; Buchholz, Thomas A.

    2007-11-01

    Background: The purpose of this study was to determine whether the use of optimized CT treatment planning offered better coverage of axillary level III (LIII)/supraclavicular (SC) targets than the empirically derived dose prescription that are commonly used. Materials/Methods: Thirty-two consecutive breast cancer patients who underwent CT treatment planning of a SC field were evaluated. Each patient was categorized according to body mass index (BMI) classes: normal, overweight, or obese. The SC and LIII nodal beds were contoured, and four treatment plans for each patient were generated. Three of the plans used empiric dose prescriptions, and these were compared with a CT-optimized plan. Each plan was evaluated by two criteria: whether 98% of target volume receive >90% of prescribed dose and whether < 5% of the irradiated volume received 105% of prescribed dose. Results: The mean depth of SC and LIII were 3.2 cm (range, 1.4-6.7 cm) and 3.1 (range, 1.7-5.8 cm). The depth of these targets varied according across BMI classes (p = 0.01). Among the four sets of plans, the CT-optimized plans were the most successful at achieving both of the dosimetry objectives for every BMI class (normal BMI, p = .003; overweight BMI, p < .0001; obese BMI, p < .001). Conclusions: Across all BMI classes, routine radiation prescriptions did not optimally cover intended targets for every patient. Optimized CT-based treatment planning generated the most successful plans; therefore, we recommend the use of routine CT simulation and treatment planning of SC fields in breast cancer.

  18. Optimizing MRI-targeted fusion prostate biopsy: the effect of systematic error and anisotropy on tumor sampling

    NASA Astrophysics Data System (ADS)

    Martin, Peter R.; Cool, Derek W.; Romagnoli, Cesare; Fenster, Aaron; Ward, Aaron D.

    2015-03-01

    Magnetic resonance imaging (MRI)-targeted, 3D transrectal ultrasound (TRUS)-guided "fusion" prostate biopsy aims to reduce the 21-47% false negative rate of clinical 2D TRUS-guided sextant biopsy. Although it has been reported to double the positive yield, MRI-targeted biopsy still has a substantial false negative rate. Therefore, we propose optimization of biopsy targeting to meet the clinician's desired tumor sampling probability, optimizing needle targets within each tumor and accounting for uncertainties due to guidance system errors, image registration errors, and irregular tumor shapes. As a step toward this optimization, we obtained multiparametric MRI (mpMRI) and 3D TRUS images from 49 patients. A radiologist and radiology resident contoured 81 suspicious regions, yielding 3D surfaces that were registered to 3D TRUS. We estimated the probability, P, of obtaining a tumor sample with a single biopsy, and investigated the effects of systematic errors and anisotropy on P. Our experiments indicated that a biopsy system's lateral and elevational errors have a much greater effect on sampling probabilities, relative to its axial error. We have also determined that for a system with RMS error of 3.5 mm, tumors of volume 1.9 cm3 and smaller may require more than one biopsy core to ensure 95% probability of a sample with 50% core involvement, and tumors 1.0 cm3 and smaller may require more than two cores.

  19. Impacted material placement plans

    SciTech Connect

    Hickey, M.J.

    1997-01-29

    Impacted material placement plans (IMPP) are documents identifying the essential elements in placing remediation wastes into disposal facilities. Remediation wastes or impacted material(s) are those components used in the construction of the disposal facility exclusive of the liners and caps. The components might include soils, concrete, rubble, debris, and other regulatory approved materials. The IMPP provides the details necessary for interested parties to understand the management and construction practices at the disposal facility. The IMPP should identify the regulatory requirements from applicable DOE Orders, the ROD(s) (where a part of a CERCLA remedy), closure plans, or any other relevant agreements or regulations. Also, how the impacted material will be tracked should be described. Finally, detailed descriptions of what will be placed and how it will be placed should be included. The placement of impacted material into approved on-site disposal facilities (OSDF) is an integral part of gaining regulatory approval. To obtain this approval, a detailed plan (Impacted Material Placement Plan [IMPP]) was developed for the Fernald OSDF. The IMPP provides detailed information for the DOE, site generators, the stakeholders, regulatory community, and the construction subcontractor placing various types of impacted material within the disposal facility.

  20. Sensor Networks for Optimal Target Localization with Bearings-Only Measurements in Constrained Three-Dimensional Scenarios

    PubMed Central

    Moreno-Salinas, David; Pascoal, Antonio; Aranda, Joaquin

    2013-01-01

    In this paper, we address the problem of determining the optimal geometric configuration of an acoustic sensor network that will maximize the angle-related information available for underwater target positioning. In the set-up adopted, a set of autonomous vehicles carries a network of acoustic units that measure the elevation and azimuth angles between a target and each of the receivers on board the vehicles. It is assumed that the angle measurements are corrupted by white Gaussian noise, the variance of which is distance-dependent. Using tools from estimation theory, the problem is converted into that of minimizing, by proper choice of the sensor positions, the trace of the inverse of the Fisher Information Matrix (also called the Cramer-Rao Bound matrix) to determine the sensor configuration that yields the minimum possible covariance of any unbiased target estimator. It is shown that the optimal configuration of the sensors depends explicitly on the intensity of the measurement noise, the constraints imposed on the sensor configuration, the target depth and the probabilistic distribution that defines the prior uncertainty in the target position. Simulation examples illustrate the key results derived. PMID:23941912

  1. Spatial targeting of agri-environmental policy using bilevel evolutionary optimization

    USDA-ARS?s Scientific Manuscript database

    In this study we describe the optimal designation of agri-environmental policy as a bilevel optimization problem and propose an integrated solution method using a hybrid genetic algorithm. The problem is characterized by a single leader, the agency, that establishes a policy with the goal of optimiz...

  2. Optimized sgRNA design to maximize activity and minimize off-target effects of CRISPR-Cas9

    PubMed Central

    Donovan, Katherine F.; Smith, Ian; Tothova, Zuzana; Wilen, Craig; Orchard, Robert; Virgin, Herbert W.; Root, David E.

    2015-01-01

    CRISPR-Cas9-based genetic screens are a powerful new tool in biology. By simply altering the sequence of the single-guide RNA (sgRNA), Cas9 can be reprogrammed to target different sites in the genome with relative ease, but the on-target activity and off-target effects of individual sgRNAs can vary widely. Here, we use recently-devised sgRNA design rules to create human and mouse genome-wide libraries, perform positive and negative selection screens and observe that the use of these rules produced improved results. Additionally, we profile the off-target activity of thousands of sgRNAs and develop a metric to predict off-target sites. We incorporate these findings from large-scale, empirical data to improve our computational design rules and create optimized sgRNA libraries that maximize on-target activity and minimize off-target effects to enable more effective and efficient genetic screens and genome engineering. PMID:26780180

  3. Joint optimization of logistics infrastructure investments and subsidies in a regional logistics network with CO2 emission reduction targets

    DOE PAGES

    Zhang, Dezhi; Zhan, Qingwen; Chen, Yuche; ...

    2016-03-14

    This study proposes an optimization model that simultaneously incorporates the selection of logistics infrastructure investments and subsidies for green transport modes to achieve specific CO2 emission targets in a regional logistics network. The proposed model is formulated as a bi-level formulation, in which the upper level determines the optimal selection of logistics infrastructure investments and subsidies for green transport modes such that the benefit-cost ratio of the entire logistics system is maximized. The lower level describes the selected service routes of logistics users. A genetic and Frank-Wolfe hybrid algorithm is introduced to solve the proposed model. The proposed model ismore » applied to the regional logistics network of Changsha City, China. Findings show that using the joint scheme of the selection of logistics infrastructure investments and green subsidies is more effective than using them solely. In conclusion, carbon emission reduction targets can significantly affect logistics infrastructure investments and subsidy levels.« less

  4. Optimal selection and placement of green infrastructure to reduce impacts of land use change and climate change on hydrology and water quality: An application to the Trail Creek Watershed, Indiana.

    PubMed

    Liu, Yaoze; Theller, Lawrence O; Pijanowski, Bryan C; Engel, Bernard A

    2016-05-15

    The adverse impacts of urbanization and climate change on hydrology and water quality can be mitigated by applying green infrastructure practices. In this study, the impacts of land use change and climate change on hydrology and water quality in the 153.2 km(2) Trail Creek watershed located in northwest Indiana were estimated using the Long-Term Hydrologic Impact Assessment-Low Impact Development 2.1 (L-THIA-LID 2.1) model for the following environmental concerns: runoff volume, Total Suspended Solids (TSS), Total Phosphorous (TP), Total Kjeldahl Nitrogen (TKN), and Nitrate+Nitrite (NOx). Using a recent 2001 land use map and 2050 land use forecasts, we found that land use change resulted in increased runoff volume and pollutant loads (8.0% to 17.9% increase). Climate change reduced runoff and nonpoint source pollutant loads (5.6% to 10.2% reduction). The 2050 forecasted land use with current rainfall resulted in the largest runoff volume and pollutant loads. The optimal selection and placement of green infrastructure practices using L-THIA-LID 2.1 model were conducted. Costs of applying green infrastructure were estimated using the L-THIA-LID 2.1 model considering construction, maintenance, and opportunity costs. To attain the same runoff volume and pollutant loads as in 2001 land uses for 2050 land uses, the runoff volume, TSS, TP, TKN, and NOx for 2050 needed to be reduced by 10.8%, 14.4%, 13.1%, 15.2%, and 9.0%, respectively. The corresponding annual costs of implementing green infrastructure to achieve the goals were $2.1, $0.8, $1.6, $1.9, and $0.8 million, respectively. Annual costs of reducing 2050 runoff volume/pollutant loads were estimated, and results show green infrastructure annual cost greatly increased for larger reductions in runoff volume and pollutant loads. During optimization, the most cost-efficient green infrastructure practices were selected and implementation levels increased for greater reductions of runoff and nonpoint source pollutants

  5. Optimizing the Colour and Fabric of Targets for the Control of the Tsetse Fly Glossina fuscipes fuscipes

    PubMed Central

    Lindh, Jenny M.; Goswami, Parikshit; Blackburn, Richard S.; Arnold, Sarah E. J.; Vale, Glyn A.; Lehane, Mike J.; Torr, Steve J.

    2012-01-01

    Background Most cases of human African trypanosomiasis (HAT) start with a bite from one of the subspecies of Glossina fuscipes. Tsetse use a range of olfactory and visual stimuli to locate their hosts and this response can be exploited to lure tsetse to insecticide-treated targets thereby reducing transmission. To provide a rational basis for cost-effective designs of target, we undertook studies to identify the optimal target colour. Methodology/Principal Findings On the Chamaunga islands of Lake Victoria , Kenya, studies were made of the numbers of G. fuscipes fuscipes attracted to targets consisting of a panel (25 cm square) of various coloured fabrics flanked by a panel (also 25 cm square) of fine black netting. Both panels were covered with an electrocuting grid to catch tsetse as they contacted the target. The reflectances of the 37 different-coloured cloth panels utilised in the study were measured spectrophotometrically. Catch was positively correlated with percentage reflectance at the blue (460 nm) wavelength and negatively correlated with reflectance at UV (360 nm) and green (520 nm) wavelengths. The best target was subjectively blue, with percentage reflectances of 3%, 29%, and 20% at 360 nm, 460 nm and 520 nm respectively. The worst target was also, subjectively, blue, but with high reflectances at UV (35% reflectance at 360 nm) wavelengths as well as blue (36% reflectance at 460 nm); the best low UV-reflecting blue caught 3× more tsetse than the high UV-reflecting blue. Conclusions/Significance Insecticide-treated targets to control G. f. fuscipes should be blue with low reflectance in both the UV and green bands of the spectrum. Targets that are subjectively blue will perform poorly if they also reflect UV strongly. The selection of fabrics for targets should be guided by spectral analysis of the cloth across both the spectrum visible to humans and the UV region. PMID:22666511

  6. Optimized concept design of the target station of Chinese spallation neutron source

    NASA Astrophysics Data System (ADS)

    Yan, Q. W.; Yin, W.; Yu, B. L.

    2005-08-01

    CSNS (Chinese spallation neutron source) target station, with proton beam power of 100 kW, consists of Tungsten rectangular target surrounded by a beryllium/steel reflector, three wing-moderators and the shield having 18 beam tubes. The leakage neutron intensity from the target (with reflector) and heat deposition on the target, reflector and shield were calculated using Monte Carlo code NMTC/JAM respectively. It is reported that the target having rectangular section will produce more leakage neutron intensity than a square one for the same proton power. The temperature and thermal stress distribution in the target disks were calculated by the finite element method. The performances of moderators were calculated using MCNP-4A code.

  7. Optimal Placement of Origins for DNA Replication

    NASA Astrophysics Data System (ADS)

    Karschau, Jens; Blow, J. Julian; de Moura, Alessandro P. S.

    2012-02-01

    DNA replication is an essential process in biology and its timing must be robust so that cells can divide properly. Random fluctuations in the formation of replication starting points, called origins, and the subsequent activation of proteins lead to variations in the replication time. We analyze these stochastic properties of DNA and derive the positions of origins corresponding to the minimum replication time. We show that under some conditions the minimization of replication time leads to the grouping of origins, and relate this to experimental data in a number of species showing origin grouping.

  8. Optimal Transmitter Placement in Wireless Mesh Networks

    DTIC Science & Technology

    2009-06-01

    DSSS – direct sequence spread spectrum DTED – digital elevation terrain data ECO – Enhanced Company Operations FDMA – frequency division multiple...Frequency Division Multiple Access ( FDMA ) divides the available bandwidth into channels, and assigns a channel to devices that wish to communicate

  9. Optimal placement of origins for DNA replication.

    PubMed

    Karschau, Jens; Blow, J Julian; de Moura, Alessandro P S

    2012-02-03

    DNA replication is an essential process in biology and its timing must be robust so that cells can divide properly. Random fluctuations in the formation of replication starting points, called origins, and the subsequent activation of proteins lead to variations in the replication time. We analyze these stochastic properties of DNA and derive the positions of origins corresponding to the minimum replication time. We show that under some conditions the minimization of replication time leads to the grouping of origins, and relate this to experimental data in a number of species showing origin grouping.

  10. Optimizing Restriction Site Placement for Synthetic Genomes

    NASA Astrophysics Data System (ADS)

    Montes, Pablo; Memelli, Heraldo; Ward, Charles; Kim, Joondong; Mitchell, Joseph S. B.; Skiena, Steven

    Restriction enzymes are the workhorses of molecular biology. We introduce a new problem that arises in the course of our project to design virus variants to serve as potential vaccines: we wish to modify virus-length genomes to introduce large numbers of unique restriction enzyme recognition sites while preserving wild-type function by substitution of synonymous codons. We show that the resulting problem is NP-Complete, give an exponential-time algorithm, and propose effective heuristics, which we show give excellent results for five sample viral genomes. Our resulting modified genomes have several times more unique restriction sites and reduce the maximum gap between adjacent sites by three to nine-fold.

  11. Optimization of Passive Coherent Receiver System Placement

    DTIC Science & Technology

    2013-09-01

    from satellites can be considered to cover the entirety of the area of interest. In an effort to increase the range of their signals, many cell...broadcasting jazz and pop music tend to have more clearly defined peaks than those stations broadcasting rock or news radio [9]. These ambiguities can

  12. Optimizing Airborne Area Surveillance Asset Placement

    DTIC Science & Technology

    2011-07-28

    rowinci(*), kk REAL colsum(*), rowsum(*), TGTVAL(*) REAL CM(ntgt,ncsp), ttv INTEGER aspt , Xj, Oset(*), inset, Overrun 77 REAL Tj(*), Sj(*), Astar...CONTINUE aspt 1 DO 1405 j = 2, ncolA IF (Tjoj).GT.Tj( aspt )) THEN aspt =j ENDIrF 1405 CONTINUE DO 1406 i 1, nrowA Astar(i) =CM(i, aspt ) R(i,Xj) =Astar(i...1406 CONTINUE Oset(Xj) = aspt C *** STEP 3 ** 990 CONTINUE DO 1407 j = 1, ncolA inset = 0 Sjoj) = 0.0 DO 1408 k= 1, Xj IF (j.EQ.Oset(k)) THEN inset

  13. Low-Z target optimization for spatial resolution improvement in megavoltage imaging.

    PubMed

    Connell, Tanner; Robar, James L

    2010-01-01

    Recently, several authors have shown contrast improvements in megavoltage portal imaging and cone-beam computed tomography using low atomic number (Z) targets. This work compliments previous studies by investigating the effects of varying different beam production parameters including target atomic number, target thickness, and incident electron energy on spatial resolution. Target materials of beryllium, aluminum, and tungsten were investigated over a range of thicknesses between 10% and 100% of the continuous slowing down approximation range of electrons. Incident electron kinetic energies of 4.5 and 7.0 MeV were used, in conjunction with custom targets installed above the carousel of a modern radiotherapy linear accelerator. Monte Carlo simulations of the accelerator were constructed and compared to the experimental results. The results showed that thinner targets, as well higher incident electron energies, generally produce more favorable modulation transfer function (MTF) curves. Due to an MTF dependence of the detector system on the photon energy, the experimental results showed that low-Z targets produced superior MTF curves. Simulations showed 14.5% and 21.5% increases in f50 for the 7.0 and 4.5 MeV targets (A1; 60% R% CSDA), respectively, when moved from the carousel to the location of the clinical target. f50 values for the custom targets were compared to the clinical 6 MV beam and were found to be between 10.4% lower (4.5 MeV/W) and 15.5% higher (7.0 MeV/Be). Integration of low-Z external targets into the treatment head of a medical linear was achieved with only minor modifications. It was shown that reasonably high resolution images on par or better than those acquired with the clinical 6 MV beam can be achieved using external low-Z targets.

  14. Optimization of multifocal transcranial current stimulation for weighted cortical pattern targeting from realistic modeling of electric fields

    PubMed Central

    Ruffini, Giulio; Fox, Michael D.; Ripolles, Oscar; Miranda, Pedro Cavaleiro; Pascual-Leone, Alvaro

    2014-01-01

    Recently, multifocal transcranial current stimulation (tCS) devices using several relatively small electrodes have been used to achieve more focal stimulation of specific cortical targets. However, it is becoming increasingly recognized that many behavioral manifestations of neurological and psychiatric disease are not solely the result of abnormality in one isolated brain region but represent alterations in brain networks. In this paper we describe a method for optimizing the configuration of multifocal tCS for stimulation of brain networks, represented by spatially extended cortical targets. We show how, based on fMRI, PET, EEG or other data specifying a target map on the cortical surface for excitatory, inhibitory or neutral stimulation and a constraint of the maximal number of electrodes, a solution can be produced with the optimal currents and locations of the electrodes. The method described here relies on a fast calculation of multifocal tCS electric fields (including components normal and tangential to the cortical boundaries) using a five layer finite element model of a realistic head. Based on the hypothesis that the effects of current stimulation are to first order due to the interaction of electric fields with populations of elongated cortical neurons, it is argued that the optimization problem for tCS stimulation can be defined in terms of the component of the electric field normal to the cortical surface. Solutions are found using constrained least squares to optimize current intensities, while electrode number and their locations are selected using a genetic algorithm. For direct current tCS (tDCS) applications, we provide some examples of this technique using an available tCS system providing 8 small Ag/AgCl stimulation electrodes. We demonstrate the approach both for localized and spatially extended targets defined using rs-fcMRI and PET data, with clinical applications in stroke and depression. Finally, we extend these ideas to more general

  15. Targeted Deposition of Antibodies on a Multiplex CMOS Microarray and Optimization of a Sensitive Immunoassay Using Electrochemical Detection

    DTIC Science & Technology

    2010-03-19

    sandwich immunoassay used a capture Ab adsorbed to the Ppy and a reporter Ab labeled for fluorescence detection or ECD, and results from these methods of...Targeted Deposition of Antibodies on a Multiplex CMOS Microarray and Optimization of a Sensitive Immunoassay Using Electrochemical Detection John...Sensitive Immunoassay Using Electrochemical Detection 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT

  16. Selecting Optimal Peptides for Targeted Proteomic Experiments in Human Plasma Using in vitro Synthesized Proteins as Analytical Standards

    PubMed Central

    Bollinger, James G.; Stergachis, Andrew B.; Johnson, Richard S.; Egertson, Jarrett D.; MacCoss, Michael J.

    2017-01-01

    Summary In targeted proteomics, the development of robust methodologies is dependent upon the selection of a set of optimal peptides for each protein-of-interest. Unfortunately, predicting which peptides and respective product ion transitions provide the greatest signal-to-noise ratio in a particular assay matrix is complicated. Using in vitro synthesized proteins as analytical standards, we report here an empirically driven method for the selection of said peptides in a human plasma assay matrix. PMID:26867746

  17. Selecting Optimal Peptides for Targeted Proteomic Experiments in Human Plasma Using In Vitro Synthesized Proteins as Analytical Standards.

    PubMed

    Bollinger, James G; Stergachis, Andrew B; Johnson, Richard S; Egertson, Jarrett D; MacCoss, Michael J

    2016-01-01

    In targeted proteomics, the development of robust methodologies is dependent upon the selection of a set of optimal peptides for each protein-of-interest. Unfortunately, predicting which peptides and respective product ion transitions provide the greatest signal-to-noise ratio in a particular assay matrix is complicated. Using in vitro synthesized proteins as analytical standards, we report here an empirically driven method for the selection of said peptides in a human plasma assay matrix.

  18. Preparation, Evaluation and Optimization of Multiparticulate System of Mebendazole for Colon Targeted Drug Delivery by Using Natural Polysaccharides

    PubMed Central

    Hemraj Ramteke, Kuldeep; Balaji Jadhav, Varsha; Kulkarni, Nilesh Shrikant; Kharat, Amol Rameshrao; Diwate, Sonali Bhima

    2015-01-01

    Purpose: A Multiparticulate system of Mebendazole was developed for colon targeted drug delivery by using natural polysaccharides like Chitosan and Sodium-alginate beads. Methods: Chitosan microspheres were formulated by using Emulsion crosslinking method using Glutaraldehyde as crosslinking agent. Sodium-alginate beads were formulated by using Calcium chloride as gelling agent. Optimization for Chitosan microspheres was carried out by using 23 full factorial design. 32 full factorial design was used for the optimization of Sodium-alginate beads. The formulated batches were evaluated for percentage yield, particle size measurement, flow properties, percent entrapment efficiency, Swelling studies. The formulations were subjected to Stability studies and In-vitro release study (with and without rat caecal content). Release kinetics data was subjected to different dissolution models. Results: The formulated batches showed acceptable particle size range as well as excellent flow properties. Entrapment efficiency for optimized batches of Chitosan microspheres and sodium alginate beads was found to be 74.18% and 88.48% respectively. In-vitro release of drug for the optimized batches was found to be increased in presence of rat caecal content. The best-fit models were koresmeyer-peppas for Chitosan microspheres and zero order for sodium-alginate beads. Conclusion: Chitosan and Sodium-alginate was used successfully for the formulation of Colon targeted Multiparticulate system. PMID:26504758

  19. The optimization of intensity modulated radiotherapy in cases where the planning target volume extends into the build-up region.

    PubMed

    Nguyen, T B; Hoole, A C F; Burnet, N G; Thomas, S J

    2009-04-21

    A common clinical problem in IMRT, especially when treating head and neck cases, is that the clinical target volume (CTV) stops short of the skin surface, whilst the margin for geometric uncertainties may take the planning target volume (PTV) to the skin surface or beyond. In these cases, optimization leads to over-dosing of the skin, unless the planner resorts to procedural tricks to avoid this, such as the use of pretend bolus or reduction of the PTV followed by adding 'flash' after optimization. This paper describes a method of avoiding the need for these tricks by using a multiple-isocentre CTV-based objective function. This enables plans to be produced that will give good coverage of the CTV for all the geometrical uncertainties that would have been covered by the PTV without causing the problem of over-dosing the skin. Eight isocentre shifts, equally distributed on the surface of a sphere with a radius equal to the CTV-PTV margin, are shown to be adequate for the optimization process. The resulting fluence maps are much simpler than those resulting from PTV optimization and will therefore be simpler to deliver. The method also permits better sparing of organs at risk such as the spinal cord.

  20. The optimization of intensity modulated radiotherapy in cases where the planning target volume extends into the build-up region

    NASA Astrophysics Data System (ADS)

    Nguyen, T. B.; Hoole, A. C. F.; Burnet, N. G.; Thomas, S. J.

    2009-04-01

    A common clinical problem in IMRT, especially when treating head and neck cases, is that the clinical target volume (CTV) stops short of the skin surface, whilst the margin for geometric uncertainties may take the planning target volume (PTV) to the skin surface or beyond. In these cases, optimization leads to over-dosing of the skin, unless the planner resorts to procedural tricks to avoid this, such as the use of pretend bolus or reduction of the PTV followed by adding 'flash' after optimization. This paper describes a method of avoiding the need for these tricks by using a multiple-isocentre CTV-based objective function. This enables plans to be produced that will give good coverage of the CTV for all the geometrical uncertainties that would have been covered by the PTV without causing the problem of over-dosing the skin. Eight isocentre shifts, equally distributed on the surface of a sphere with a radius equal to the CTV-PTV margin, are shown to be adequate for the optimization process. The resulting fluence maps are much simpler than those resulting from PTV optimization and will therefore be simpler to deliver. The method also permits better sparing of organs at risk such as the spinal cord.