33 CFR 146.405 - Safety and Security notice of arrival for vessels arriving at a place on the OCS.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or operator of that vessel must revise and re-submit the NOA within the times required in paragraph (e) of this section. An owner or operator does not need to revise and re-submit an NOA for the... site at http://www.nvmc.uscg.gov/. (e) Required reporting time of an NOA update. The owner or operator...

19 CFR 4.32 - Vessels in distress; landing of cargo.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Vessels in distress; landing of cargo. 4.32...; DEPARTMENT OF THE TREASURY VESSELS IN FOREIGN AND DOMESTIC TRADES Landing and Delivery of Cargo § 4.32 Vessels in distress; landing of cargo. (a) When a vessel from a foreign port arrives in distress at a port...

19 CFR 4.1 - Boarding of vessels; cutter and dock passes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Boarding of vessels; cutter and dock passes. 4.1 Section 4.1 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY VESSELS IN FOREIGN AND DOMESTIC TRADES Arrival and Entry of Vessels § 4.1 Boarding of...

Risk Reduction of an Invasive Insect by Targeting Surveillance Efforts with the Assistance of a Phenology Model and International Maritime Shipping Routes and Schedules.

PubMed

Gray, David R

2016-05-01

Reducing the risk of introduction to North America of the invasive Asian gypsy moth (Lymantria dispar asiatica Vnukovskij and L. d. japonica [Motschulsky]) on international maritime vessels involves two tactics: (1) vessels that wish to arrive in Canada or the United States and have visited any Asian port that is subject to regulation during designated times must obtain a predeparture inspection certificate from an approved entity; and (2) vessels with a certificate may be subjected to an additional inspection upon arrival. A decision support tool is described here with which the allocation of inspection resources at North American ports can be partitioned among multiple vessels according to estimates of the potential onboard Asian gypsy moth population and estimates of the onboard larval emergence pattern. The decision support tool assumes that port inspection is uniformly imperfect at the Asian ports and that each visit to a regulated port has potential for the vessel to be contaminated with gypsy moth egg masses. The decision support tool uses a multigenerational phenology model to estimate the potential onboard population of egg masses by calculating the temporal intersection between the dates of port visits to regulated ports and the simulated oviposition pattern in each port. The phenological development of the onboard population is simulated each day of the vessel log until the vessel arrives at the port being protected from introduction. Multiple independent simulations are used to create a probability distribution of the size and timing of larval emergence. © 2015 Society for Risk Analysis.

77 FR 41909 - Safety Zone; Port of Dutch Harbor; Dutch Harbor, AK

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-17

... the anticipated arrival of approximately twenty (20) vessels affiliated with planned offshore drilling...-yard radius of moored or anchored Shell offshore exploration or support vessels, and the navigable waters within a 100-yard radius of underway Shell offshore exploration or support vessels. The purpose of...

Tidal Analysis and Arrival Process Mining Using Automatic Identification System (AIS) Data

DTIC Science & Technology

2017-01-01

elevation at the time of vessel movement and calculating the tidal dependence (TD) parameter to 23 U.S. port areas for the years 2012– 2014. Tidal prediction...predictions, obtained from the National Oceanographic and Atmospheric Administration, are used to rank relative tidal dependence for arriving cargo and...sector traffic percentages and tidal dependence metric ............................. 11 Arrival process mining

VISIR-I: small vessels - least-time nautical routes using wave forecasts

NASA Astrophysics Data System (ADS)

Mannarini, Gianandrea; Pinardi, Nadia; Coppini, Giovanni; Oddo, Paolo; Iafrati, Alessandro

2016-05-01

A new numerical model for the on-demand computation of optimal ship routes based on sea-state forecasts has been developed. The model, named VISIR (discoVerIng Safe and effIcient Routes) is designed to support decision-makers when planning a marine voyage. The first version of the system, VISIR-I, considers medium and small motor vessels with lengths of up to a few tens of metres and a displacement hull. The model is comprised of three components: a route optimization algorithm, a mechanical model of the ship, and a processor of the environmental fields. The optimization algorithm is based on a graph-search method with time-dependent edge weights. The algorithm is also able to compute a voluntary ship speed reduction. The ship model accounts for calm water and added wave resistance by making use of just the principal particulars of the vessel as input parameters. It also checks the optimal route for parametric roll, pure loss of stability, and surfriding/broaching-to hazard conditions. The processor of the environmental fields employs significant wave height, wave spectrum peak period, and wave direction forecast fields as input. The topological issues of coastal navigation (islands, peninsulas, narrow passages) are addressed. Examples of VISIR-I routes in the Mediterranean Sea are provided. The optimal route may be longer in terms of miles sailed and yet it is faster and safer than the geodetic route between the same departure and arrival locations. Time savings up to 2.7 % and route lengthening up to 3.2 % are found for the case studies analysed. However, there is no upper bound for the magnitude of the changes of such route metrics, which especially in case of extreme sea states can be much greater. Route diversions result from the safety constraints and the fact that the algorithm takes into account the full temporal evolution and spatial variability of the environmental fields.

19 CFR 4.50 - Passenger lists.

Code of Federal Regulations, 2010 CFR

2010-04-01

... VESSELS IN FOREIGN AND DOMESTIC TRADES Passengers on Vessels § 4.50 Passenger lists. (a) The master of... passenger and crew lists, as required by § 4.7(a) of this part. If the vessel is arriving from noncontiguous... 19 Customs Duties 1 2010-04-01 2010-04-01 false Passenger lists. 4.50 Section 4.50 Customs Duties...

76 FR 2254 - Notice of Arrival on the Outer Continental Shelf

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-13

... of arrival for floating facilities, mobile offshore drilling units (MODUs), and vessels planning to... Ship Security Certificate. MMS Minerals Management Service. MODU Mobile Offshore Drilling Unit. NAICS... rule outlines the procedures that owners or operators of floating facilities, mobile offshore drilling...

Quantifying potential propagule pressure of aquatic invasive species from the commercial shipping industry in Canada.

PubMed

Lo, Veronica B; Levings, Colin D; Chan, Kai M A

2012-02-01

We quantify and compare different measures of potential propagule pressure (PPP) of aquatic invasive species (AIS) from commercial vessels in Canada. We used ship arrivals and ballast water discharge volumes as proxies for PPP from ballast water organisms, and wetted surface area (WSA) as a proxy for hull fouling PPP, to determine their relative contributions to total PPP. For three regions studied, PPP proxies correlated significantly across ports and some vessel categories. Relative contributions of ship arrivals, ballast discharge, and WSAs to PPP, evidenced by non-significant correlations across these measures, varied across regions, ports, vessel types, and seasons. Flow-through (dominant on east and west coasts) and empty-refill (in Great Lakes-St. Lawrence region) were the major ballast water exchange methods employed by the vessels surveyed. These methods have different biological efficacy for AIS removal, influencing PPP. Our study illustrates benefits and limitations of using different PPP proxies to estimate invasion risk. Copyright © 2011 Elsevier Ltd. All rights reserved.

Maritime dynamic traffic generator. Volume 3 : density data on world maps

DOT National Transportation Integrated Search

1975-06-01

The 18,000 vessels whose weekly movements are tracked by the maritime traffic generator represent 106 different countries. There are 4915 vessels five or less years old. The record for the week of January 26, 1972 includes 11,789 arrivals, 10,896 dep...

8 CFR 286.2 - Fee for arrival of passengers aboard commercial aircraft or commercial vessels.

Code of Federal Regulations, 2010 CFR

2010-01-01

... SECURITY IMMIGRATION REGULATIONS IMMIGRATION USER FEE § 286.2 Fee for arrival of passengers aboard..., per individual is charged and collected by the Commissioner for the immigration inspection of each... Act, per individual, is charged and collected by the Commissioner for the immigration inspection at a...

8 CFR 251.1 - Arrival manifests and lists.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) The prevailing practice exception for automated vessels; and (E) The reciprocity exception. (iii) If... under the reciprocity exception, the master or agent shall note on the manifest that the work will be done under the reciprocity exception, and will note the nationality of the vessel's registry and the...

8 CFR 251.1 - Arrival manifests and lists.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) The prevailing practice exception for automated vessels; and (E) The reciprocity exception. (iii) If... under the reciprocity exception, the master or agent shall note on the manifest that the work will be done under the reciprocity exception, and will note the nationality of the vessel's registry and the...

8 CFR 251.1 - Arrival manifests and lists.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) The prevailing practice exception for automated vessels; and (E) The reciprocity exception. (iii) If... under the reciprocity exception, the master or agent shall note on the manifest that the work will be done under the reciprocity exception, and will note the nationality of the vessel's registry and the...

8 CFR 251.1 - Arrival manifests and lists.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) The prevailing practice exception for automated vessels; and (E) The reciprocity exception. (iii) If... under the reciprocity exception, the master or agent shall note on the manifest that the work will be done under the reciprocity exception, and will note the nationality of the vessel's registry and the...

8 CFR 251.1 - Arrival manifests and lists.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) The prevailing practice exception for automated vessels; and (E) The reciprocity exception. (iii) If... under the reciprocity exception, the master or agent shall note on the manifest that the work will be done under the reciprocity exception, and will note the nationality of the vessel's registry and the...

33 CFR 401.65 - Communication-ports, docks and anchorages.

Code of Federal Regulations, 2010 CFR

2010-07-01

... anchorages. 401.65 Section 401.65 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT....65 Communication—ports, docks and anchorages. (a) Every vessel entering or leaving a lake port shall... the harbor entrance. (b) Every vessel arriving at a port, dock or anchorage shall report to the...

33 CFR 401.65 - Communication-ports, docks and anchorages.

Code of Federal Regulations, 2014 CFR

2014-07-01

... anchorages. 401.65 Section 401.65 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT....65 Communication—ports, docks and anchorages. (a) Every vessel entering or leaving a lake port shall... the harbor entrance. (b) Every vessel arriving at a port, dock or anchorage shall report to the...

33 CFR 401.65 - Communication-ports, docks and anchorages.

Code of Federal Regulations, 2011 CFR

2011-07-01

... anchorages. 401.65 Section 401.65 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT....65 Communication—ports, docks and anchorages. (a) Every vessel entering or leaving a lake port shall... the harbor entrance. (b) Every vessel arriving at a port, dock or anchorage shall report to the...

33 CFR 401.65 - Communication-ports, docks and anchorages.

Code of Federal Regulations, 2013 CFR

2013-07-01

... anchorages. 401.65 Section 401.65 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT....65 Communication—ports, docks and anchorages. (a) Every vessel entering or leaving a lake port shall... the harbor entrance. (b) Every vessel arriving at a port, dock or anchorage shall report to the...

33 CFR 401.65 - Communication-ports, docks and anchorages.

Code of Federal Regulations, 2012 CFR

2012-07-01

... anchorages. 401.65 Section 401.65 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT....65 Communication—ports, docks and anchorages. (a) Every vessel entering or leaving a lake port shall... the harbor entrance. (b) Every vessel arriving at a port, dock or anchorage shall report to the...

75 FR 12250 - Notification of the Imposition of Conditions of Entry for Certain Vessels Arriving to the United...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-15

... Republic of Timor-Leste. DATES: The requirements announced in this notice will become effective March 29, 2010. ADDRESSES: This notice will be available for inspection and copying at the Docket Management... arriving from ports that are not maintaining effective anti- terrorism measures and to deny entry into the...

77 FR 71608 - Notification of the Removal of Conditions of Entry on Vessels Arriving From the Republic of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-03

..., Syria, Timor-Leste, Venezuela, and Yemen. This current list is also available in the policy notice... arriving from the country of the Republic of Indonesia. DATES: The policy announced in this notice is... holidays. This policy is also available at www.homeport.uscg.mil under the Maritime Security tab...

33 CFR 117.686 - Yazoo River.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) bridge shall open on signal if at least four hours notice is given. When a vessel has given notice and fails to arrive within the four hour period specified, the drawtender shall remain on duty for two additional hours and open the draw if the requesting vessel appears. After this time, an additional four hour...

33 CFR 401.73 - Cleaning tanks-hazardous cargo vessels.

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas freeing and tank cleaning has been reported to the nearest Seaway station. (b) Hot work permission. Before any hot work, defined as any work that uses flame or that can produce a source of ignition... prior to the vessel's arrival on SLSMC approach walls or wharfs. The hot work shall not commence until...

33 CFR 401.73 - Cleaning tanks-hazardous cargo vessels.

Code of Federal Regulations, 2013 CFR

2013-07-01

... gas freeing and tank cleaning has been reported to the nearest Seaway station. (b) Hot work permission. Before any hot work, defined as any work that uses flame or that can produce a source of ignition... prior to the vessel's arrival on SLSMC approach walls or wharfs. The hot work shall not commence until...

19 CFR 4.7d - Container status messages.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 19 Customs Duties 1 2010-04-01 2010-04-01 false Container status messages. 4.7d Section 4.7d... TREASURY VESSELS IN FOREIGN AND DOMESTIC TRADES Arrival and Entry of Vessels § 4.7d Container status messages. (a) Container status messages required. In addition to the advance filing requirements pursuant...

19 CFR 4.3 - Vessels required to enter; place of entry.

Code of Federal Regulations, 2010 CFR

2010-04-01

... officer, or purser may appear in person during regular working hours to complete preliminary or formal... 48 hours after the arrival at any port or place in the United States, the following vessels are... the customhouse, and services may be requested outside of normal business hours. Customs may take...

76 FR 63935 - Notification of the Removal of Conditions of Entry on Vessels Arriving From the Republic of Congo

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-14

... arriving from the country of the Republic of Congo. DATES: The policy announced in this notice is effective... published a Notice of Policy in the Federal Register, (74 FR 45230), announcing that it had determined that... entry announced in the previously published Notice of Policy. With this notice, the current list of...

Renal contrast-enhanced MR angiography: timing errors and accurate depiction of renal artery origins.

PubMed

Schmidt, Maria A; Morgan, Robert

2008-10-01

To investigate bolus timing artifacts that impair depiction of renal arteries at contrast material-enhanced magnetic resonance (MR) angiography and to determine the effect of contrast agent infusion rates on artifact generation. Renal contrast-enhanced MR angiography was simulated for a variety of infusion schemes, assuming both correct and incorrect timing between data acquisition and contrast agent injection. In addition, the ethics committee approved the retrospective evaluation of clinical breath-hold renal contrast-enhanced MR angiographic studies obtained with automated detection of contrast agent arrival. Twenty-two studies were evaluated for their ability to depict the origin of renal arteries in patent vessels and for any signs of timing errors. Simulations showed that a completely artifactual stenosis or an artifactual overestimation of an existing stenosis at the renal artery origin can be caused by timing errors of the order of 5 seconds in examinations performed with contrast agent infusion rates compatible with or higher than those of hand injections. Lower infusion rates make the studies more likely to accurately depict the origin of the renal arteries. In approximately one-third of all clinical examinations, different contrast agent uptake rates were detected on the left and right sides of the body, and thus allowed us to confirm that it is often impossible to optimize depiction of both renal arteries. In three renal arteries, a signal void was found at the origin in a patent vessel, and delayed contrast agent arrival was confirmed. Computer simulations and clinical examinations showed that timing errors impair the accurate depiction of renal artery origins. (c) RSNA, 2008.

33 CFR 401.79 - Advance notice of arrival, vessels requiring inspection.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Notice of Arrival (NOA) prior to entering at call in point 2 (CIP 2) as follows: (1) If your voyage time to CIP 2 is 96 hours or more, you must submit an electronic NOA 96 hours before entering the Seaway at CIP 2. (2) If your voyage time to CIP 2 is less than 96 hours, you must submit an electronic NOA...

33 CFR 401.79 - Advance notice of arrival, vessels requiring inspection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Notice of Arrival (NOA) prior to entering at call in point 2 (CIP 2) as follows: (1) If your voyage time to CIP 2 is 96 hours or more, you must submit an electronic NOA 96 hours before entering the Seaway at CIP 2. (2) If your voyage time to CIP 2 is less than 96 hours, you must submit an electronic NOA...

Observations of potential acoustic cues that attract sperm whales to longline fishing in the Gulf of Alaska.

PubMed

Thode, Aaron; Straley, Janice; Tiemann, Christopher O; Folkert, Kendall; O'Connell, Victoria

2007-08-01

Sperm whales (Physeter macrocephalus) have learned to remove fish from demersal longline gear deployments off the eastern Gulf of Alaska, and are often observed to arrive at a site after a haul begins, suggesting a response to potential acoustic cues like fishing-gear strum, hydraulic winch tones, and propeller cavitation. Passive acoustic recorders attached to anchorlines have permitted continuous monitoring of the ambient noise environment before and during fishing hauls. Timing and tracking analyses of sperm whale acoustic activity during three encounters indicate that cavitation arising from changes in ship propeller speeds is associated with interruptions in nearby sperm whale dive cycles and changes in acoustically derived positions. This conclusion has been tested by cycling a vessel engine and noting the arrival of whales by the vessel, even when the vessel is not next to fishing gear. No evidence of response from activation of ship hydraulics or fishing gear strum has been found to date.

77 FR 6704 - Exemptions From Entry Requirements and Report of Arrival Requirements for Certain Department of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-09

... Missions Many vessels and aircraft that are under DoD's control and used to support DoD's missions do not... passengers supporting its missions under DoD's control through its own transportation system, the Defense... vessels and aircraft owned by, or under the complete control and management of DoD, or chartered by DoD...

Dynamics of an Overdriven Nitromethane Initiation System

NASA Astrophysics Data System (ADS)

Hároz, E. H.; Rae, P. J.; Armstrong, C. L.; Baca, E. V.; Campbell, C.; Gunderson, J. A.; Holmes, M.; Lopez-Pulliam, I.; Vaughan, L. D.; Dickson, P. M.

2017-06-01

For upcoming large-scale HE experiments, an initiation system is needed to ensure uniform and simultaneous burn. To that end, we developed an initiation system based on nitromethane. Initial, small-scale tests characterized the response of the nitromethane in the proposed cylindrical initiator geometry, indicating robust detonation under a variety of conditions such as a plane wave lenses & cylinders of PBX 9501 into a flyer plate or direct-drive. Detonation velocity, as measured by piezoelectric pin time-of-arrival measurements along the length and at bottom of vessel, shows an overdriven response. All cases show a detonation velocity faster than the literature value of 7.3 km s-1 for nitromethane, with the fastest velocity occurring for the 8-detonator, 8'' cylinder case with a velocity = 7.7 km s-1. Streak camera imaging characterized the curvature of the shock front as it arrived at the bottom of the vessel via spark gap. A final test of the initiator system looked at the expansion of the initiator vessel walls via PDV, showing velocities up to 3.5 km s-1. Finally, our initiator was placed inside a secondary vessel containing 1000 lbs of nitromethane. High-speed photography & pin data indicate complete symmetrical burn of the secondary nitromethane.

Energetic Physiology Mediates Individual Optimization of Breeding Phenology in a Migratory Arctic Seabird.

PubMed

Hennin, Holly L; Bêty, Jöel; Legagneux, Pierre; Gilchrist, H Grant; Williams, Tony D; Love, Oliver P

2016-10-01

The influence of variation in individual state on key reproductive decisions impacting fitness is well appreciated in evolutionary ecology. Rowe et al. (1994) developed a condition-dependent individual optimization model predicting that three key factors impact the ability of migratory female birds to individually optimize breeding phenology to maximize fitness in seasonal environments: arrival condition, arrival date, and ability to gain in condition on the breeding grounds. While empirical studies have confirmed that greater arrival body mass and earlier arrival dates result in earlier laying, no study has assessed whether individual variation in energetic management of condition gain effects this key fitness-related decision. Using an 8-year data set from over 350 prebreeding female Arctic common eiders (Somateria mollissima), we tested this component of the model by examining whether individual variation in two physiological traits influencing energetic management (plasma triglycerides: physiological fattening rate; baseline corticosterone: energetic demand) predicted individual variation in breeding phenology after controlling for arrival date and body mass. As predicted by the optimization model, individuals with higher fattening rates and lower energetic demand had the earliest breeding phenology (shortest delays between arrival and laying; earliest laying dates). Our results are the first to empirically determine that individual flexibility in prebreeding energetic management influences key fitness-related reproductive decisions, suggesting that individuals have the capacity to optimally manage reproductive investment.

Managing the risk of non-indigenous marine species transfer in Singapore using a study of vessel movement.

PubMed

Lim, Chin Sing; Leong, Yi Lin; Tan, Koh Siang

2017-02-15

Shipping is recognized as a major vector for the global transfer of non-indigenous marine species (NIMS). As a major transshipment port, Singapore can minimize the risk of NIMS transfer by implementing pragmatic management strategies, such as using vessel movement information to assess the risk of NIMS transfer. Findings from vessel movement information in a major port terminal in Singapore showed that vessel residence time is short, with >92% of vessels spending seven days or less. There was little variation in vessel residence time to vessel arrival numbers, while the top three last ports of call were found to be from regional ports. Using two key features obtained from vessel movement records, 1) vessel residence time and 2) biogeographic origin of the vessels' last port of call, a simple risk assessment matrix was constructed and applied to assess the level of risk of NIMS transfer by transiting vessels. Copyright © 2016 Elsevier Ltd. All rights reserved.

TRACON Aircraft Arrival Planning and Optimization Through Spatial Constraint Satisfaction

NASA Technical Reports Server (NTRS)

Bergh, Christopher P.; Krzeczowski, Kenneth J.; Davis, Thomas J.; Denery, Dallas G. (Technical Monitor)

1995-01-01

A new aircraft arrival planning and optimization algorithm has been incorporated into the Final Approach Spacing Tool (FAST) in the Center-TRACON Automation System (CTAS) developed at NASA-Ames Research Center. FAST simulations have been conducted over three years involving full-proficiency, level five air traffic controllers from around the United States. From these simulations an algorithm, called Spatial Constraint Satisfaction, has been designed, coded, undergone testing, and soon will begin field evaluation at the Dallas-Fort Worth and Denver International airport facilities. The purpose of this new design is an attempt to show that the generation of efficient and conflict free aircraft arrival plans at the runway does not guarantee an operationally acceptable arrival plan upstream from the runway -information encompassing the entire arrival airspace must be used in order to create an acceptable aircraft arrival plan. This new design includes functions available previously but additionally includes necessary representations of controller preferences and workload, operationally required amounts of extra separation, and integrates aircraft conflict resolution. As a result, the Spatial Constraint Satisfaction algorithm produces an optimized aircraft arrival plan that is more acceptable in terms of arrival procedures and air traffic controller workload. This paper discusses the current Air Traffic Control arrival planning procedures, previous work in this field, the design of the Spatial Constraint Satisfaction algorithm, and the results of recent evaluations of the algorithm.

Scenario based optimization of a container vessel with respect to its projected operating conditions

NASA Astrophysics Data System (ADS)

Wagner, Jonas; Binkowski, Eva; Bronsart, Robert

2014-06-01

In this paper the scenario based optimization of the bulbous bow of the KRISO Container Ship (KCS) is presented. The optimization of the parametrically modeled vessel is based on a statistically developed operational profile generated from noon-to-noon reports of a comparable 3600 TEU container vessel and specific development functions representing the growth of global economy during the vessels service time. In order to consider uncertainties, statistical fluctuations are added. An analysis of these data lead to a number of most probable upcoming operating conditions (OC) the vessel will stay in the future. According to their respective likeliness an objective function for the evaluation of the optimal design variant of the vessel is derived and implemented within the parametrical optimization workbench FRIENDSHIP Framework. In the following this evaluation is done with respect to vessel's calculated effective power based on the usage of potential flow code. The evaluation shows, that the usage of scenarios within the optimization process has a strong influence on the hull form.

Prehospital neurological deterioration in stroke.

PubMed

Slavin, Sabreena J; Sucharew, Heidi; Alwell, Kathleen; Moomaw, Charles J; Woo, Daniel; Adeoye, Opeolu; Flaherty, Matthew L; Ferioli, Simona; McMullan, Jason; Mackey, Jason; De Los Rios La Rosa, Felipe; Martini, Sharyl; Kissela, Brett M; Kleindorfer, Dawn O

2018-04-27

Patients with stroke can experience neurological deterioration in the prehospital setting. We evaluated patients with stroke to determine factors associated with prehospital neurological deterioration (PND). Among the Greater Cincinnati/Northern Kentucky region (population ~1.3 million), we screened all 15 local hospitals' admissions from 2010 for acute stroke and included patients aged ≥20. The GCS was compared between emergency medical services (EMS) arrival and hospital arrival, with decrease ≥2 points considered PND. Data obtained retrospectively included demographics, medical history and medication use, stroke subtype (eg, ischaemic stroke (IS), intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH)) and IS subtype (eg, small vessel, large vessel, cardioembolic), seizure at onset, time intervals between symptom onset, EMS arrival and hospital arrival, EMS level of training, and blood pressure and serum glucose on EMS arrival. Of 2708 total patients who had a stroke, 1092 patients (median (IQR) age 74 (61-83) years; 56% women; 21% black) were analysed. PND occurred in 129 cases (12%), including 9% of IS, 24% of ICH and 16% of SAH. In multivariable analysis, black race, atrial fibrillation, haemorrhagic subtype and ALS level of transport were associated with PND. Haemorrhage and atrial fibrillation is associated with PND in stroke, and further investigation is needed to establish whether PND can be predicted. Further studies are also needed to assess whether preferential transport of patients with deterioration to hospitals equipped with higher levels of care is beneficial, identify why race is associated with deterioration and to test therapies targeting PND. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

33 CFR 207.275 - McClellan-Kerr Arkansas River navigation system: use, administration, and navigation.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Vessels arriving at these markers or the mooring cells immediately upstream and downstream of the lock... mooring facilities at the junction of main stem and secondary channels are to provide temporary mooring...

Building of Reusable Reverse Logistics Model and its Optimization Considering the Decision of Backorder or Next Arrival of Goods

NASA Astrophysics Data System (ADS)

Lee, Jeong-Eun; Gen, Mitsuo; Rhee, Kyong-Gu; Lee, Hee-Hyol

This paper deals with the building of the reusable reverse logistics model considering the decision of the backorder or the next arrival of goods. The optimization method to minimize the transportation cost and to minimize the volume of the backorder or the next arrival of goods occurred by the Just in Time delivery of the final delivery stage between the manufacturer and the processing center is proposed. Through the optimization algorithms using the priority-based genetic algorithm and the hybrid genetic algorithm, the sub-optimal delivery routes are determined. Based on the case study of a distilling and sale company in Busan in Korea, the new model of the reusable reverse logistics of empty bottles is built and the effectiveness of the proposed method is verified.

Analyses of interactions between the marine terminal and highway operations : final report.

DOT National Transportation Integrated Search

2014-04-01

Changes in vessel sizes arriving at United States ports may influence the operating regimes and schedules at the port terminals However, the impacts to highway and rail operations outside of the port terminals because of changing port terminal operat...

Vessel traffic patterns in the Port of Kaohsiung and the management implications for preventing the introduction of non-indigenous aquatic species.

PubMed

Liu, Ta-Kang; Tsai, Tzung-Kuen

2011-03-01

Data on shipping traffic in one of the busiest seaports in the world, the Port of Kaohsiung, were analyzed to evaluate the implications for ballast water management. Results show that 67% of the arriving vessels were registered to a flag of convenience, which typically have a lower degree of environmental records. The top five donor countries historically suffer from harmful algal bloom problems. The short journey and busy trading between these countries and Taiwan lead to a higher risk of inoculation. In addition, only 1.4% of all vessels visited more than once every year during the 9-year span, indicating that the port authority encounters many new vessels each year. These findings could influence the design and application of ballast water management strategies as well as highlight the challenges in their implementation. We suggest that an analysis of vessel traffic patterns should be coupled with other useful vessel information to make risk assessment successful. Copyright © 2010. Published by Elsevier Ltd.

19 CFR 4.38 - Release of cargo.

Code of Federal Regulations, 2011 CFR

2011-04-01

... for release without submission of paper documents after reviewing the entry data submitted... imported. (1) Where the cargo arrives by vessel, the report shall consist of the following data elements... following data elements: (i) Air waybill number; (ii) Quantity released; (iii) Entry number (including filer...

19 CFR 4.38 - Release of cargo.

Code of Federal Regulations, 2013 CFR

2013-04-01

... for release without submission of paper documents after reviewing the entry data submitted... imported. (1) Where the cargo arrives by vessel, the report shall consist of the following data elements... following data elements: (i) Air waybill number; (ii) Quantity released; (iii) Entry number (including filer...

19 CFR 4.38 - Release of cargo.

Code of Federal Regulations, 2012 CFR

2012-04-01

... for release without submission of paper documents after reviewing the entry data submitted... imported. (1) Where the cargo arrives by vessel, the report shall consist of the following data elements... following data elements: (i) Air waybill number; (ii) Quantity released; (iii) Entry number (including filer...

19 CFR 4.38 - Release of cargo.

Code of Federal Regulations, 2014 CFR

2014-04-01

... for release without submission of paper documents after reviewing the entry data submitted... imported. (1) Where the cargo arrives by vessel, the report shall consist of the following data elements... following data elements: (i) Air waybill number; (ii) Quantity released; (iii) Entry number (including filer...

19 CFR 4.38 - Release of cargo.

Code of Federal Regulations, 2010 CFR

2010-04-01

... for release without submission of paper documents after reviewing the entry data submitted... imported. (1) Where the cargo arrives by vessel, the report shall consist of the following data elements... following data elements: (i) Air waybill number; (ii) Quantity released; (iii) Entry number (including filer...

Simulation-based validation and arrival-time correction for Patlak analyses of Perfusion-CT scans

NASA Astrophysics Data System (ADS)

Bredno, Jörg; Hom, Jason; Schneider, Thomas; Wintermark, Max

2009-02-01

Blood-brain-barrier (BBB) breakdown is a hypothesized mechanism for hemorrhagic transformation in acute stroke. The Patlak analysis of a Perfusion Computed Tomography (PCT) scan measures the BBB permeability, but the method yields higher estimates when applied to the first pass of the contrast bolus compared to a delayed phase. We present a numerical phantom that simulates vascular and parenchymal time-attenuation curves to determine the validity of permeability measurements obtained with different acquisition protocols. A network of tubes represents the major cerebral arteries ipsi- and contralateral to an ischemic event. These tubes branch off into smaller segments that represent capillary beds. Blood flow in the phantom is freely defined and simulated as non-Newtonian tubular flow. Diffusion of contrast in the vessels and permeation through vessel walls is part of the simulation. The phantom allows us to compare the results of a permeability measurement to the simulated vessel wall status. A Patlak analysis reliably detects areas with BBB breakdown for acquisitions of 240s duration, whereas results obtained from the first pass are biased in areas of reduced blood flow. Compensating for differences in contrast arrival times reduces this bias and gives good estimates of BBB permeability for PCT acquisitions of 90-150s duration.

50 CFR 665.808 - Conditions for at-sea observer coverage.

Code of Federal Regulations, 2010 CFR

2010-10-01

... employee who is seriously injured or seriously ill. Lost fishing time is based on time traveling to and... arrive at the observer's assigned vessel 30 minutes before the time designated for departure in the... the observer. (ii) Lost fishing time arising from a seriously injured or seriously ill observer...

50 CFR 665.808 - Conditions for at-sea observer coverage.

Code of Federal Regulations, 2012 CFR

2012-10-01

... employee who is seriously injured or seriously ill. Lost fishing time is based on time traveling to and... arrive at the observer's assigned vessel 30 minutes before the time designated for departure in the... the observer. (ii) Lost fishing time arising from a seriously injured or seriously ill observer...

50 CFR 665.808 - Conditions for at-sea observer coverage.

Code of Federal Regulations, 2011 CFR

2011-10-01

... employee who is seriously injured or seriously ill. Lost fishing time is based on time traveling to and... arrive at the observer's assigned vessel 30 minutes before the time designated for departure in the... the observer. (ii) Lost fishing time arising from a seriously injured or seriously ill observer...

50 CFR 665.808 - Conditions for at-sea observer coverage.

Code of Federal Regulations, 2014 CFR

2014-10-01

... employee who is seriously injured or seriously ill. Lost fishing time is based on time traveling to and... arrive at the observer's assigned vessel 30 minutes before the time designated for departure in the... the observer. (ii) Lost fishing time arising from a seriously injured or seriously ill observer...

50 CFR 665.808 - Conditions for at-sea observer coverage.

Code of Federal Regulations, 2013 CFR

2013-10-01

... employee who is seriously injured or seriously ill. Lost fishing time is based on time traveling to and... arrive at the observer's assigned vessel 30 minutes before the time designated for departure in the... the observer. (ii) Lost fishing time arising from a seriously injured or seriously ill observer...

32 CFR 525.4 - Entry authorization (policy).

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Captains of ships and/or marine vessels planning to enter Kwajalein Missile Range shall not knowingly... when practicable). (vi) Purpose of flight. (vii) Plan of flight route, including the point of origin of flight and its designation and estimated date and times of arrival and departure of airspace covered by...

32 CFR 525.4 - Entry authorization (policy).

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Captains of ships and/or marine vessels planning to enter Kwajalein Missile Range shall not knowingly... when practicable). (vi) Purpose of flight. (vii) Plan of flight route, including the point of origin of flight and its designation and estimated date and times of arrival and departure of airspace covered by...

32 CFR 525.4 - Entry authorization (policy).

Code of Federal Regulations, 2010 CFR

2010-07-01

...) Captains of ships and/or marine vessels planning to enter Kwajalein Missile Range shall not knowingly... when practicable). (vi) Purpose of flight. (vii) Plan of flight route, including the point of origin of flight and its designation and estimated date and times of arrival and departure of airspace covered by...

32 CFR 525.4 - Entry authorization (policy).

Code of Federal Regulations, 2014 CFR

2014-07-01

... single or multiple entries. (4) Captains of ships and/or marine vessels planning to enter Kwajalein... of passengers (include list when practicable). (vi) Purpose of flight. (vii) Plan of flight route, including the point of origin of flight and its designation and estimated date and times of arrival and...

32 CFR 525.4 - Entry authorization (policy).

Code of Federal Regulations, 2013 CFR

2013-07-01

... single or multiple entries. (4) Captains of ships and/or marine vessels planning to enter Kwajalein... of passengers (include list when practicable). (vi) Purpose of flight. (vii) Plan of flight route, including the point of origin of flight and its designation and estimated date and times of arrival and...

Optimization study on structural analyses for the J-PARC mercury target vessel

NASA Astrophysics Data System (ADS)

Guan, Wenhai; Wakai, Eiichi; Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Takada, Hiroshi; Futakawa, Masatoshi

2018-06-01

The spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC) mercury target vessel is used for various materials science studies, work is underway to achieve stable operation at 1 MW. This is very important for enhancing the structural integrity and durability of the target vessel, which is being developed for 1 MW operation. In the present study, to reduce thermal stress and relax stress concentrations more effectively in the existing target vessel in J-PARC, an optimization approach called the Taguchi method (TM) is applied to thermo-mechanical analysis. The ribs and their relative parameters, as well as the thickness of the mercury vessel and shrouds, were selected as important design parameters for this investigation. According to the analytical results of 18 model types designed using the TM, the optimal design was determined. It is characterized by discrete ribs and a thicker vessel wall than the current design. The maximum thermal stresses in the mercury vessel and the outer shroud were reduced by 14% and 15%, respectively. Furthermore, it was indicated that variations in rib width, left/right rib intervals, and shroud thickness could influence the maximum thermal stress performance. It is therefore concluded that the TM was useful for optimizing the structure of the target vessel and to reduce the thermal stress in a small number of calculation cases.

A Mixed Integer Linear Program for Solving a Multiple Route Taxi Scheduling Problem

NASA Technical Reports Server (NTRS)

Montoya, Justin Vincent; Wood, Zachary Paul; Rathinam, Sivakumar; Malik, Waqar Ahmad

2010-01-01

Aircraft movements on taxiways at busy airports often create bottlenecks. This paper introduces a mixed integer linear program to solve a Multiple Route Aircraft Taxi Scheduling Problem. The outputs of the model are in the form of optimal taxi schedules, which include routing decisions for taxiing aircraft. The model extends an existing single route formulation to include routing decisions. An efficient comparison framework compares the multi-route formulation and the single route formulation. The multi-route model is exercised for east side airport surface traffic at Dallas/Fort Worth International Airport to determine if any arrival taxi time savings can be achieved by allowing arrivals to have two taxi routes: a route that crosses an active departure runway and a perimeter route that avoids the crossing. Results indicate that the multi-route formulation yields reduced arrival taxi times over the single route formulation only when a perimeter taxiway is used. In conditions where the departure aircraft are given an optimal and fixed takeoff sequence, accumulative arrival taxi time savings in the multi-route formulation can be as high as 3.6 hours more than the single route formulation. If the departure sequence is not optimal, the multi-route formulation results in less taxi time savings made over the single route formulation, but the average arrival taxi time is significantly decreased.

Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

NASA Astrophysics Data System (ADS)

Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

2016-01-01

Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.

Route Optimization for Offloading Congested Meter Fixes

NASA Technical Reports Server (NTRS)

Xue, Min; Zelinski, Shannon

2016-01-01

The Optimized Route Capability (ORC) concept proposed by the FAA facilitates traffic managers to identify and resolve arrival flight delays caused by bottlenecks formed at arrival meter fixes when there exists imbalance between arrival fixes and runways. ORC makes use of the prediction capability of existing automation tools, monitors the traffic delays based on these predictions, and searches the best reroutes upstream of the meter fixes based on the predictions and estimated arrival schedules when delays are over a predefined threshold. Initial implementation and evaluation of the ORC concept considered only reroutes available at the time arrival congestion was first predicted. This work extends previous work by introducing an additional dimension in reroute options such that ORC can find the best time to reroute and overcome the 'firstcome- first-reroute' phenomenon. To deal with the enlarged reroute solution space, a genetic algorithm was developed to solve this problem. Experiments were conducted using the same traffic scenario used in previous work, when an arrival rush was created for one of the four arrival meter fixes at George Bush Intercontinental Houston Airport. Results showed the new approach further improved delay savings. The suggested route changes from the new approach were on average 30 minutes later than those using other approaches, and fewer numbers of reroutes were required. Fewer numbers of reroutes reduce operational complexity and later reroutes help decision makers deal with uncertain situations.

U.S. Immigration Policy on Haitian Migrants

DTIC Science & Technology

2010-03-31

Mariel Policy ................................................................................................................3 Interdiction Agreement...seekers who arrived in South Florida in 1980 during the Mariel boatlift.2 The U.S. Coast Guard, as described below, has been interdicting vessels...in the years following the Mariel boatlift. Most notably, there was a drop of migrants after the Haitian elections in 1990 followed by a dramatic

NBIC: Ballast Water Reporting Forms

Science.gov Websites

for the Coast Guard's Equivalent Reporting Program (ERP). The ERP program is restricted to NON regulations, submit a BWMR at least 24 hours before the vessel arrives in Montreal, Quebec. Non-US/non | FAQ| Equivalent Reporting Program Privacy policy - Terms of Use - Contact us: nbic@ballastreport.org

19 CFR 4.36 - Delayed discharge of cargo.

Code of Federal Regulations, 2010 CFR

2010-04-01

... services are required in connection with the unlading shall, for every day consumed in unlading in excess... which has retained merchandise on board more than 25 days after the date of the vessel's arrival, their... purview of section 458, Tariff Act of 1930, 70 after the expiration of 25 days after the date of the...

78 FR 60216 - Regulated Navigation Area; Reporting Requirements for Barges Loaded With Certain Dangerous...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

... published stay (suspension) of reporting requirements under the Regulated Navigation Area (RNA) established... fleeting area managers responsible for CDC barges in the RNA from their dangerous cargo or vessel arrival... preamble as being available in the docket are part of docket USCG-2013-0760. To view documents mentioned in...

78 FR 38830 - Safety Zone; Execpro Services Fireworks Display, Lake Tahoe, Incline Village, NV

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-28

... spectators from the dangers associated with the pyrotechnics. Unauthorized persons or vessels are prohibited... pyrotechnics used in this fireworks display, the safety zone is necessary to provide for the safety of event... loading, transit and arrival of the pyrotechnics from the loading site to the launch site and until the...

75 FR 81854 - Safety Zone; New Year's Celebration for the City of San Francisco, Fireworks Display, San...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-29

... the loading, transit, and arrival of the pyrotechnics, and will extend 1,000 feet from the nearest... participants and spectators from the dangers associated with the pyrotechnics. Unauthorized persons or vessels... process would be completed. Because of the dangers posed by the pyrotechnics used in these fireworks...

78 FR 44265 - Unified Agenda of Federal Regulatory and Deregulatory Actions

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-23

... . RIN: 1625-AB27 184. Marine Vapor Control Systems Legal Authority: 33 U.S.C. 1225; 42 U.S.C. 7511b(f)(2... facility and vessel vapor control systems (VCSs). The proposed changes would make VCS requirements more... Requirements for 1625-AA99 Notices of Arrival and Departure, and Automatic Identification System. 182...

19 CFR 4.86 - Intercoastal residue-cargo procedure; optional ports.

Code of Federal Regulations, 2010 CFR

2010-04-01

... agent is unable at that time to designate the specific port or ports of discharge of that residue cargo... ports, Great Lakes coast,” as the case may be. The traveling manifest shall be similarly noted. Upon arrival of the vessel at the first port on the next coast, the master, owner, or agent must designate the...

19 CFR 4.7 - Inward foreign manifest; production on demand; contents and form; advance filing of cargo...

Code of Federal Regulations, 2011 CFR

2011-04-01

...; contents and form; advance filing of cargo declaration. 4.7 Section 4.7 Customs Duties U.S. CUSTOMS AND... and form; advance filing of cargo declaration. (a) The master of every vessel arriving in the United..., and the following documents: (1) Cargo Declaration, Customs Form 1302, (2) Ship's Stores Declaration...

19 CFR 4.7 - Inward foreign manifest; production on demand; contents and form; advance filing of cargo...

Code of Federal Regulations, 2010 CFR

2010-04-01

...; contents and form; advance filing of cargo declaration. 4.7 Section 4.7 Customs Duties U.S. CUSTOMS AND... and form; advance filing of cargo declaration. (a) The master of every vessel arriving in the United..., and the following documents: (1) Cargo Declaration, Customs Form 1302, (2) Ship's Stores Declaration...

46 CFR 42.07-10 - Submergence of load line marks.

Code of Federal Regulations, 2014 CFR

2014-10-01

... VOYAGES BY SEA Control, Enforcement, and Rights of Appeal § 42.07-10 Submergence of load line marks. (a... by sea, or on the Great Lakes, or during the voyage, or on arrival, the applicable load lines marked... when navigating the Great Lakes. (d) When a vessel departs from a port situated on a river or inland...

46 CFR 42.07-10 - Submergence of load line marks.

Code of Federal Regulations, 2011 CFR

2011-10-01

... VOYAGES BY SEA Control, Enforcement, and Rights of Appeal § 42.07-10 Submergence of load line marks. (a... by sea, or on the Great Lakes, or during the voyage, or on arrival, the applicable load lines marked... when navigating the Great Lakes. (d) When a vessel departs from a port situated on a river or inland...

46 CFR 42.07-10 - Submergence of load line marks.

Code of Federal Regulations, 2013 CFR

2013-10-01

... VOYAGES BY SEA Control, Enforcement, and Rights of Appeal § 42.07-10 Submergence of load line marks. (a... by sea, or on the Great Lakes, or during the voyage, or on arrival, the applicable load lines marked... when navigating the Great Lakes. (d) When a vessel departs from a port situated on a river or inland...

46 CFR 42.07-10 - Submergence of load line marks.

Code of Federal Regulations, 2012 CFR

2012-10-01

... VOYAGES BY SEA Control, Enforcement, and Rights of Appeal § 42.07-10 Submergence of load line marks. (a... by sea, or on the Great Lakes, or during the voyage, or on arrival, the applicable load lines marked... when navigating the Great Lakes. (d) When a vessel departs from a port situated on a river or inland...

46 CFR 42.07-10 - Submergence of load line marks.

Code of Federal Regulations, 2010 CFR

2010-10-01

... VOYAGES BY SEA Control, Enforcement, and Rights of Appeal § 42.07-10 Submergence of load line marks. (a... by sea, or on the Great Lakes, or during the voyage, or on arrival, the applicable load lines marked... when navigating the Great Lakes. (d) When a vessel departs from a port situated on a river or inland...

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel

NASA Astrophysics Data System (ADS)

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-10-01

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [ 0 m /90 n ] s , angle-ply [ ±θ] ns , [ 90/±θ] ns and [ 0/±θ] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [ ±θ] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

Optimized suspension culture: the rotating-wall vessel

NASA Technical Reports Server (NTRS)

Hammond, T. G.; Hammond, J. M.

2001-01-01

Suspension culture remains a popular modality, which manipulates mechanical culture conditions to maintain the specialized features of cultured cells. The rotating-wall vessel is a suspension culture vessel optimized to produce laminar flow and minimize the mechanical stresses on cell aggregates in culture. This review summarizes the engineering principles, which allow optimal suspension culture conditions to be established, and the boundary conditions, which limit this process. We suggest that to minimize mechanical damage and optimize differentiation of cultured cells, suspension culture should be performed in a solid-body rotation Couette-flow, zero-headspace culture vessel such as the rotating-wall vessel. This provides fluid dynamic operating principles characterized by 1) solid body rotation about a horizontal axis, characterized by colocalization of cells and aggregates of different sedimentation rates, optimally reduced fluid shear and turbulence, and three-dimensional spatial freedom; and 2) oxygenation by diffusion. Optimization of suspension culture is achieved by applying three tradeoffs. First, terminal velocity should be minimized by choosing microcarrier beads and culture media as close in density as possible. Next, rotation in the rotating-wall vessel induces both Coriolis and centrifugal forces, directly dependent on terminal velocity and minimized as terminal velocity is minimized. Last, mass transport of nutrients to a cell in suspension culture depends on both terminal velocity and diffusion of nutrients. In the transduction of mechanical culture conditions into cellular effects, several lines of evidence support a role for multiple molecular mechanisms. These include effects of shear stress, changes in cell cycle and cell death pathways, and upstream regulation of secondary messengers such as protein kinase C. The discipline of suspension culture needs a systematic analysis of the relationship between mechanical culture conditions and biological effects, emphasizing cellular processes important for the industrial production of biological pharmaceuticals and devices.

Major deepwater pipelay vessel starts work in North Sea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heerema, E.P.

1998-05-04

Industry`s deepwater pipelaying capability has received a boost this year with the entry into the world`s fleet of Solitaire, a dynamically positioned pipelay vessel of about 350 m including stinger. The converted bulk carrier, formerly the Trentwood, will arrive on station in the North Sea and begin laying pipe this month on Statoil`s Europipe II project, a 600-km, 42-in. OD gas pipeline from Norway to Germany. Next year, the vessel will install pipe for the Exxon U.S.A.`s Gulf of Mexico South Diana development (East Breaks Block 945) in a water depth of 1,643 m and for Mobil Oil Canada asmore » part of the Sable Island Offshore and Energy Project offshore Nova Scotia. Using the S-lay mode, Solitaire is particularly well-suited for laying large lines economically, including the deepwater projects anticipated for the US Gulf of Mexico. Table 1 presents Solitaire`s technical specifications. The design, construction, pipelaying, and justification for building vessels such as the Solitaire are discussed.« less

Joint Optimization of Vertical Component Gravity and Seismic P-wave First Arrivals by Simulated Annealing

NASA Astrophysics Data System (ADS)

Louie, J. N.; Basler-Reeder, K.; Kent, G. M.; Pullammanappallil, S. K.

2015-12-01

Simultaneous joint seismic-gravity optimization improves P-wave velocity models in areas with sharp lateral velocity contrasts. Optimization is achieved using simulated annealing, a metaheuristic global optimization algorithm that does not require an accurate initial model. Balancing the seismic-gravity objective function is accomplished by a novel approach based on analysis of Pareto charts. Gravity modeling uses a newly developed convolution algorithm, while seismic modeling utilizes the highly efficient Vidale eikonal equation traveltime generation technique. Synthetic tests show that joint optimization improves velocity model accuracy and provides velocity control below the deepest headwave raypath. Detailed first arrival picking followed by trial velocity modeling remediates inconsistent data. We use a set of highly refined first arrival picks to compare results of a convergent joint seismic-gravity optimization to the Plotrefa™ and SeisOpt® Pro™ velocity modeling packages. Plotrefa™ uses a nonlinear least squares approach that is initial model dependent and produces shallow velocity artifacts. SeisOpt® Pro™ utilizes the simulated annealing algorithm and is limited to depths above the deepest raypath. Joint optimization increases the depth of constrained velocities, improving reflector coherency at depth. Kirchoff prestack depth migrations reveal that joint optimization ameliorates shallow velocity artifacts caused by limitations in refraction ray coverage. Seismic and gravity data from the San Emidio Geothermal field of the northwest Basin and Range province demonstrate that joint optimization changes interpretation outcomes. The prior shallow-valley interpretation gives way to a deep valley model, while shallow antiformal reflectors that could have been interpreted as antiformal folds are flattened. Furthermore, joint optimization provides a clearer image of the rangefront fault. This technique can readily be applied to existing datasets and could replace the existing strategy of forward modeling to match gravity data.

Histological evaluation and optimization of surgical vessel sealing systems

NASA Astrophysics Data System (ADS)

Lathrop, Robert; Ryan, Thomas; Gaspredes, Jonathan; Woloszko, Jean; Coad, James E.

2017-02-01

Surgical vessel sealing systems are widely used to achieve hemostasis and dissection in open surgery and minimally invasive, laparoscopic surgery. This enabling technology was developed about 17 years ago and continues to evolve with new devices and systems achieving improved outcomes. Histopathological assessment of thermally sealed tissues is a valuable tool for refining and comparing performance among surgical vessel sealing systems. Early work in this field typically assessed seal time, burst rate, and failure rate (in-situ). Later work compared histological staining methods with birefringence to assess the extent of thermal damage to tissues adjacent to the device. Understanding the microscopic architecture of a sealed vessel is crucial to optimizing the performance of power delivery algorithms and device design parameters. Manufacturers rely on these techniques to develop new products. A system for histopathological evaluation of vessels and sealing performance was established, to enable the direct assessment of a treatment's tissue effects. The parameters included the commonly used seal time, pressure burst rate and failure rate, as well as extensions of the assessment to include its likelihood to form steam vacuoles, adjacent thermal effect near the device, and extent of thermally affected tissue extruded back into the vessel lumen. This comprehensive assessment method provides an improved means of assessing the quality of a sealed vessel and understanding the exact mechanisms which create an optimally sealed vessel.

78 FR 27336 - Drawbridge Operation Regulation; Wolf River, Gills Landing and Winneconne, WI

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-10

... clearance allows most of the vessel traffic to pass under the bridge without an opening. The Canadian... boat. A 12- hours advance notice from October 16 to April 19 would be required for openings. Currently...-hour advance notice of arrival for openings from May 1 to October 31 between the hours of 11 p.m. to 7...

76 FR 30954 - Notification of the Imposition of Conditions of Entry for Certain Vessels Arriving to the United...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-27

...-Leste, and Venezuela. This current list is also available in the policy notice available on the Homeport... Union of the Comoros and the Republic of Cote d'Ivoire. DATES: The policy announced in this notice will..., except Federal holidays. The telephone number is 202-366-9329. This policy is also available at http...

77 FR 53901 - Notification of the Imposition of Conditions of Entry for Certain Vessels Arriving to the United...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-04

... Principe, Syria, Timor-Leste, Venezuela, and Yemen. This current list is also available in the policy... Hodeidah. DATES: The policy announced in this notice will become effective September 18, 2012. ADDRESSES... telephone number is 202-366-9329. This policy is also available at www.homeport.uscg.mil under the Maritime...

A predictive software tool for optimal timing in contrast enhanced carotid MR angiography

NASA Astrophysics Data System (ADS)

Moghaddam, Abbas N.; Balawi, Tariq; Habibi, Reza; Panknin, Christoph; Laub, Gerhard; Ruehm, Stefan; Finn, J. Paul

2008-03-01

A clear understanding of the first pass dynamics of contrast agents in the vascular system is crucial in synchronizing data acquisition of 3D MR angiography (MRA) with arrival of the contrast bolus in the vessels of interest. We implemented a computational model to simulate contrast dynamics in the vessels using the theory of linear time-invariant systems. The algorithm calculates a patient-specific impulse response for the contrast concentration from time-resolved images following a small test bolus injection. This is performed for a specific region of interest and through deconvolution of the intensity curve using the long division method. Since high spatial resolution 3D MRA is not time-resolved, the method was validated on time-resolved arterial contrast enhancement in Multi Slice CT angiography. For 20 patients, the timing of the contrast enhancement of the main bolus was predicted by our algorithm from the response to the test bolus, and then for each case the predicted time of maximum intensity was compared to the corresponding time in the actual scan which resulted in an acceptable agreement. Furthermore, as a qualitative validation, the algorithm's predictions of the timing of the carotid MRA in 20 patients with high quality MRA were correlated with the actual timing of those studies. We conclude that the above algorithm can be used as a practical clinical tool to eliminate guesswork and to replace empiric formulae by a priori computation of patient-specific timing of data acquisition for MR angiography.

An evaluation of descent strategies for TNAV-equipped aircraft in an advanced metering environment

NASA Technical Reports Server (NTRS)

Izumi, K. H.; Schwab, R. W.; Groce, J. L.; Coote, M. A.

1986-01-01

Investigated were the effects on system throughput and fleet fuel usage of arrival aircraft utilizing three 4D RNAV descent strategies (cost optimal, clean-idle Mach/CAS and constant descent angle Mach/CAS), both individually and in combination, in an advanced air traffic control metering environment. Results are presented for all mixtures of arrival traffic consisting of three Boeing commercial jet types and for all combinations of the three descent strategies for a typical en route metering airport arrival distribution.

Online stochastic optimization of radiotherapy patient scheduling.

PubMed

Legrain, Antoine; Fortin, Marie-Andrée; Lahrichi, Nadia; Rousseau, Louis-Martin

2015-06-01

The effective management of a cancer treatment facility for radiation therapy depends mainly on optimizing the use of the linear accelerators. In this project, we schedule patients on these machines taking into account their priority for treatment, the maximum waiting time before the first treatment, and the treatment duration. We collaborate with the Centre Intégré de Cancérologie de Laval to determine the best scheduling policy. Furthermore, we integrate the uncertainty related to the arrival of patients at the center. We develop a hybrid method combining stochastic optimization and online optimization to better meet the needs of central planning. We use information on the future arrivals of patients to provide an accurate picture of the expected utilization of resources. Results based on real data show that our method outperforms the policies typically used in treatment centers.

Trauma deaths in the first hour: are they all unsalvageable injuries?

PubMed

MacLeod, Jana B A; Cohn, Stephen M; Johnson, E William; McKenney, Mark G

2007-02-01

With the advent of trauma systems, time to definitive care has been decreased. We hypothesized that a subset of patients who are in extremis from the time of prehospital transport to arrival at the trauma center, and who ultimately die early after arrival, may in fact have a potentially salvageable single-organ injury. We reviewed all deaths that occurred in the first hour after hospital admission. Trauma registry, medical records, and autopsy reports for 556 patients were evaluated. The median time to arrival was 39 minutes, and the median Injury Severity Score was 29. Blunt injuries (53%) were most commonly auto-accident injuries (134 of 285 patients; 47%). Penetrating wounds (42%) were mostly gunshot wounds to the chest (73 of 233 patients; 31%). For patients with initial vital signs, the most common cause of death was isolated brain injury (26 patients; 28%). Possibly survivable injuries (single organ or vessel) occurred in 35 (38%) patients, of which 4 were isolated spleen injuries (4%). Some patients with potentially survivable single organ injuries did not have associated head injuries. An aggressive approach is warranted on patients with detectable vital signs on at least one occasion in the field but who arrive at the trauma center in extremis.

Sound System Engineering & Optimization: The effects of multiple arrivals on the intelligibility of reinforced speech

NASA Astrophysics Data System (ADS)

Ryan, Timothy James

The effects of multiple arrivals on the intelligibility of speech produced by live-sound reinforcement systems are examined. The intent is to determine if correlations exist between the manipulation of sound system optimization parameters and the subjective attribute speech intelligibility. Given the number, and wide range, of variables involved, this exploratory research project attempts to narrow the focus of further studies. Investigated variables are delay time between signals arriving from multiple elements of a loudspeaker array, array type and geometry and the two-way interactions of speech-to-noise ratio and array geometry with delay time. Intelligibility scores were obtained through subjective evaluation of binaural recordings, reproduced via headphone, using the Modified Rhyme Test. These word-score results are compared with objective measurements of Speech Transmission Index (STI). Results indicate that both variables, delay time and array geometry, have significant effects on intelligibility. Additionally, it is seen that all three of the possible two-way interactions have significant effects. Results further reveal that the STI measurement method overestimates the decrease in intelligibility due to short delay times between multiple arrivals.

Optimizing the recovery efficiency of Finnish oil combating vessels in the Gulf of Finland using Bayesian Networks.

PubMed

Lehikoinen, Annukka; Luoma, Emilia; Mäntyniemi, Samu; Kuikka, Sakari

2013-02-19

Oil transport has greatly increased in the Gulf of Finland over the years, and risks of an oil accident occurring have risen. Thus, an effective oil combating strategy is needed. We developed a Bayesian Network (BN) to examine the recovery efficiency and optimal disposition of the Finnish oil combating vessels in the Gulf of Finland (GoF), Eastern Baltic Sea. Four alternative home harbors, five accident points, and ten oil combating vessels were included in the model to find the optimal disposition policy that would maximize the recovery efficiency. With this composition, the placement of the oil combating vessels seems not to have a significant effect on the recovery efficiency. The process seems to be strongly controlled by certain random factors independent of human action, e.g. wave height and stranding time of the oil. Therefore, the success of oil combating is rather uncertain, so it is also important to develop activities that aim for preventing accidents. We found that the model developed is suitable for this type of multidecision optimization. The methodology, results, and practices are further discussed.

Pulmonary vessel segmentation utilizing curved planar reformation and optimal path finding (CROP) in computed tomographic pulmonary angiography (CTPA) for CAD applications

NASA Astrophysics Data System (ADS)

Zhou, Chuan; Chan, Heang-Ping; Kuriakose, Jean W.; Chughtai, Aamer; Wei, Jun; Hadjiiski, Lubomir M.; Guo, Yanhui; Patel, Smita; Kazerooni, Ella A.

2012-03-01

Vessel segmentation is a fundamental step in an automated pulmonary embolism (PE) detection system. The purpose of this study is to improve the segmentation scheme for pulmonary vessels affected by PE and other lung diseases. We have developed a multiscale hierarchical vessel enhancement and segmentation (MHES) method for pulmonary vessel tree extraction based on the analysis of eigenvalues of Hessian matrices. However, it is difficult to segment the pulmonary vessels accurately under suboptimal conditions, such as vessels occluded by PEs, surrounded by lymphoid tissues or lung diseases, and crossing with other vessels. In this study, we developed a new vessel refinement method utilizing curved planar reformation (CPR) technique combined with optimal path finding method (MHES-CROP). The MHES segmented vessels straightened in the CPR volume was refined using adaptive gray level thresholding where the local threshold was obtained from least-square estimation of a spline curve fitted to the gray levels of the vessel along the straightened volume. An optimal path finding method based on Dijkstra's algorithm was finally used to trace the correct path for the vessel of interest. Two and eight CTPA scans were randomly selected as training and test data sets, respectively. Forty volumes of interest (VOIs) containing "representative" vessels were manually segmented by a radiologist experienced in CTPA interpretation and used as reference standard. The results show that, for the 32 test VOIs, the average percentage volume error relative to the reference standard was improved from 32.9+/-10.2% using the MHES method to 9.9+/-7.9% using the MHES-CROP method. The accuracy of vessel segmentation was improved significantly (p<0.05). The intraclass correlation coefficient (ICC) of the segmented vessel volume between the automated segmentation and the reference standard was improved from 0.919 to 0.988. Quantitative comparison of the MHES method and the MHES-CROP method with the reference standard was also evaluated by the Bland-Altman plot. This preliminary study indicates that the MHES-CROP method has the potential to improve PE detection.

Integrated Arrival and Departure Schedule Optimization Under Uncertainty

NASA Technical Reports Server (NTRS)

Xue, Min; Zelinski, Shannon

2014-01-01

In terminal airspace, integrating arrivals and departures with shared waypoints provides the potential of improving operational efficiency by allowing direct routes when possible. Incorporating stochastic evaluation as a post-analysis process of deterministic optimization, and imposing a safety buffer in deterministic optimization, are two ways to learn and alleviate the impact of uncertainty and to avoid unexpected outcomes. This work presents a third and direct way to take uncertainty into consideration during the optimization. The impact of uncertainty was incorporated into cost evaluations when searching for the optimal solutions. The controller intervention count was computed using a heuristic model and served as another stochastic cost besides total delay. Costs under uncertainty were evaluated using Monte Carlo simulations. The Pareto fronts that contain a set of solutions were identified and the trade-off between delays and controller intervention count was shown. Solutions that shared similar delays but had different intervention counts were investigated. The results showed that optimization under uncertainty could identify compromise solutions on Pareto fonts, which is better than deterministic optimization with extra safety buffers. It helps decision-makers reduce controller intervention while achieving low delays.

19 CFR 4.7 - Inward foreign manifest; production on demand; contents and form; advance filing of cargo...

Code of Federal Regulations, 2014 CFR

2014-04-01

... as homogeneous cargo that is stowed loose in the hold and is not enclosed in any container such as a...; contents and form; advance filing of cargo declaration. 4.7 Section 4.7 Customs Duties U.S. CUSTOMS AND... and form; advance filing of cargo declaration. (a) The master of every vessel arriving in the United...

19 CFR 4.7 - Inward foreign manifest; production on demand; contents and form; advance filing of cargo...

Code of Federal Regulations, 2012 CFR

2012-04-01

... enclosed in any container such as a box, bale, bag, cask, or the like. Such cargo is also described as bulk...; contents and form; advance filing of cargo declaration. 4.7 Section 4.7 Customs Duties U.S. CUSTOMS AND... and form; advance filing of cargo declaration. (a) The master of every vessel arriving in the United...

19 CFR 4.7 - Inward foreign manifest; production on demand; contents and form; advance filing of cargo...

Code of Federal Regulations, 2013 CFR

2013-04-01

... as homogeneous cargo that is stowed loose in the hold and is not enclosed in any container such as a...; contents and form; advance filing of cargo declaration. 4.7 Section 4.7 Customs Duties U.S. CUSTOMS AND... and form; advance filing of cargo declaration. (a) The master of every vessel arriving in the United...

33 CFR Appendix D to Part 157 - Example of a Procedure for Dedicated Clean Ballast Tanks Operations

Code of Federal Regulations, 2010 CFR

2010-07-01

... Dedicated Clean Ballast Tanks Operations D Appendix D to Part 157 Navigation and Navigable Waters COAST... ENVIRONMENT RELATING TO TANK VESSELS CARRYING OIL IN BULK Pt. 157, App. D Appendix D to Part 157—Example of a.... (3) Ensure that all valves in the dedicated clean ballast tanks are closed. (d) Before arrival at the...

A Constrained Least Squares Approach to Mobile Positioning: Algorithms and Optimality

NASA Astrophysics Data System (ADS)

Cheung, KW; So, HC; Ma, W.-K.; Chan, YT

2006-12-01

The problem of locating a mobile terminal has received significant attention in the field of wireless communications. Time-of-arrival (TOA), received signal strength (RSS), time-difference-of-arrival (TDOA), and angle-of-arrival (AOA) are commonly used measurements for estimating the position of the mobile station. In this paper, we present a constrained weighted least squares (CWLS) mobile positioning approach that encompasses all the above described measurement cases. The advantages of CWLS include performance optimality and capability of extension to hybrid measurement cases (e.g., mobile positioning using TDOA and AOA measurements jointly). Assuming zero-mean uncorrelated measurement errors, we show by mean and variance analysis that all the developed CWLS location estimators achieve zero bias and the Cramér-Rao lower bound approximately when measurement error variances are small. The asymptotic optimum performance is also confirmed by simulation results.

An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT

PubMed Central

Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan

2016-01-01

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process. PMID:27827909

An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT.

PubMed

Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan

2016-11-04

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.

Throughput-optimal scheduling for broadcast channels

NASA Astrophysics Data System (ADS)

Eryilmaz, Atilla; Srikant, Rayadurgam; Perkins, James R.

2001-07-01

In this paper, we consider a degraded Gaussian broadcast channel, where the transmitter maintains separate queues for each receiver. We present throughput optimal policies that stabilize the queues without knowing the statistics of the arrival processes to these queues.

Role of Arrival Time Difference Between Lesions and Lung Tissue on Contrast-Enhanced Sonography in the Differential Diagnosis of Subpleural Pulmonary Lesions.

PubMed

Bai, Jing; Yang, Wei; Wang, Song; Guan, Rui-Hong; Zhang, Hui; Fu, Jing-Jing; Wu, Wei; Yan, Kun

2016-07-01

The purpose of this study was to explore the diagnostic value of the arrival time difference between lesions and surrounding lung tissue on contrast-enhanced sonography of subpleural pulmonary lesions. A total of 110 patients with subpleural pulmonary lesions who underwent both conventional and contrast-enhanced sonography and had a definite diagnosis were enrolled. After contrast agent injection, the arrival times in the lesion, lung, and chest wall were recorded. The arrival time differences between various tissues were also calculated. Statistical analysis showed a significant difference in the lesion arrival time, the arrival time difference between the lesion and lung, and the arrival time difference between the chest wall and lesion (all P < .001) for benign and malignant lesions. Receiver operating characteristic curve analysis revealed that the optimal diagnostic criterion was the arrival time difference between the lesion and lung, and that the best cutoff point was 2.5 seconds (later arrival signified malignancy). This new diagnostic criterion showed superior diagnostic accuracy (97.1%) compared to conventional diagnostic criteria. The individualized diagnostic method based on an arrival time comparison using contrast-enhanced sonography had high diagnostic accuracy (97.1%) with good feasibility and could provide useful diagnostic information for subpleural pulmonary lesions.

Retinal blood vessel extraction using tunable bandpass filter and fuzzy conditional entropy.

PubMed

Sil Kar, Sudeshna; Maity, Santi P

2016-09-01

Extraction of blood vessels on retinal images plays a significant role for screening of different opthalmologic diseases. However, accurate extraction of the entire and individual type of vessel silhouette from the noisy images with poorly illuminated background is a complicated task. To this aim, an integrated system design platform is suggested in this work for vessel extraction using a sequential bandpass filter followed by fuzzy conditional entropy maximization on matched filter response. At first noise is eliminated from the image under consideration through curvelet based denoising. To include the fine details and the relatively less thick vessel structures, the image is passed through a bank of sequential bandpass filter structure optimized for contrast enhancement. Fuzzy conditional entropy on matched filter response is then maximized to find the set of multiple optimal thresholds to extract the different types of vessel silhouettes from the background. Differential Evolution algorithm is used to determine the optimal gain in bandpass filter and the combination of the fuzzy parameters. Using the multiple thresholds, retinal image is classified as the thick, the medium and the thin vessels including neovascularization. Performance evaluated on different publicly available retinal image databases shows that the proposed method is very efficient in identifying the diverse types of vessels. Proposed method is also efficient in extracting the abnormal and the thin blood vessels in pathological retinal images. The average values of true positive rate, false positive rate and accuracy offered by the method is 76.32%, 1.99% and 96.28%, respectively for the DRIVE database and 72.82%, 2.6% and 96.16%, respectively for the STARE database. Simulation results demonstrate that the proposed method outperforms the existing methods in detecting the various types of vessels and the neovascularization structures. The combination of curvelet transform and tunable bandpass filter is found to be very much effective in edge enhancement whereas fuzzy conditional entropy efficiently distinguishes vessels of different widths. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Optimizing Mars Sphere of Influence Maneuvers for NASA's Evolvable Mars Campaign

NASA Technical Reports Server (NTRS)

Merrill, Raymond G.; Komar, D. R.; Chai, Patrick; Qu, Min

2016-01-01

NASA's Human Spaceflight Architecture Team is refining human exploration architectures that will extend human presence to the Martian surface. For both Mars orbital and surface missions, NASA's Evolvable Mars Campaign assumes that cargo and crew can be delivered repeatedly to the same destination. Up to this point, interplanetary trajectories have been optimized to minimize the total propulsive requirements of the in-space transportation systems, while the pre-deployed assets and surface systems are optimized to minimize their respective propulsive requirements separate from the in-space transportation system. There is a need to investigate the coupled problem of optimizing the interplanetary trajectory and optimizing the maneuvers within Mars's sphere of influence. This paper provides a description of the ongoing method development, analysis and initial results of the effort to resolve the discontinuity between the interplanetary trajectory and the Mars sphere of influence trajectories. Assessment of Phobos and Deimos orbital missions shows the in-space transportation and crew taxi allocations are adequate for missions in the 2030s. Because the surface site has yet to be selected, the transportation elements must be sized to provide enough capability to provide surface access to all landing sites under consideration. Analysis shows access to sites from elliptical parking orbits with a lander that is designed for sub-periapsis landing location is either infeasible or requires expensive orbital maneuvers for many latitude ranges. In this case the locus of potential arrival perigee vectors identifies the potential maximum north or south latitudes accessible. Higher arrival velocities can decrease reorientation costs and increase landing site availability. Utilizing hyperbolic arrival and departure vectors in the optimization scheme will increase transportation site accessibility and provide more optimal solutions.

Optimal Time Advance In Terminal Area Arrivals: Throughput vs. Fuel Savings

NASA Technical Reports Server (NTRS)

Sadovsky, Alexander V .; Swenson, Harry N.; Haskell, William B.; Rakas, Jasenka

2011-01-01

The current operational practice in scheduling air traffic arriving at an airport is to adjust flight schedules by delay, i.e. a postponement of an aircrafts arrival at a scheduled location, to manage safely the FAA-mandated separation constraints between aircraft. To meet the observed and forecast growth in traffic demand, however, the practice of time advance (speeding up an aircraft toward a scheduled location) is envisioned for future operations as a practice additional to delay. Time advance has two potential advantages. The first is the capability to minimize, or at least reduce, the excess separation (the distances between pairs of aircraft immediately in-trail) and thereby to increase the throughput of the arriving traffic. The second is to reduce the total traffic delay when the traffic sample is below saturation density. A cost associated with time advance is the fuel expenditure required by an aircraft to speed up. We present an optimal control model of air traffic arriving in a terminal area and solve it using the Pontryagin Maximum Principle. The admissible controls allow time advance, as well as delay, some of the way. The cost function reflects the trade-off between minimizing two competing objectives: excess separation (negatively correlated with throughput) and fuel burn. A number of instances are solved using three different methods, to demonstrate consistency of solutions.

Coronary artery segmentation in X-ray angiograms using gabor filters and differential evolution.

PubMed

Cervantes-Sanchez, Fernando; Cruz-Aceves, Ivan; Hernandez-Aguirre, Arturo; Solorio-Meza, Sergio; Cordova-Fraga, Teodoro; Aviña-Cervantes, Juan Gabriel

2018-08-01

Segmentation of coronary arteries in X-ray angiograms represents an essential task for computer-aided diagnosis, since it can help cardiologists in diagnosing and monitoring vascular abnormalities. Due to the main disadvantages of the X-ray angiograms are the nonuniform illumination, and the weak contrast between blood vessels and image background, different vessel enhancement methods have been introduced. In this paper, a novel method for blood vessel enhancement based on Gabor filters tuned using the optimization strategy of Differential evolution (DE) is proposed. Because the Gabor filters are governed by three different parameters, the optimal selection of those parameters is highly desirable in order to maximize the vessel detection rate while reducing the computational cost of the training stage. To obtain the optimal set of parameters for the Gabor filters, the area (Az) under the receiver operating characteristics curve is used as objective function. In the experimental results, the proposed method achieves an A z =0.9388 in a training set of 40 images, and for a test set of 40 images it obtains the highest performance with an A z =0.9538 compared with six state-of-the-art vessel detection methods. Finally, the proposed method achieves an accuracy of 0.9423 for vessel segmentation using the test set. In addition, the experimental results have also shown that the proposed method can be highly suitable for clinical decision support in terms of computational time and vessel segmentation performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Computational analysis of the effectiveness of blood flushing with saline injection from an intravascular diagnostic catheter

PubMed Central

Ghata, Narugopal; Aldredge, Ralph C.; Bec, Julien; Marcu, Laura

2015-01-01

SUMMARY Optical techniques including fluorescence lifetime spectroscopy have demonstrated potential as a tool for study and diagnosis of arterial vessel pathologies. However, their application in the intravascular diagnostic procedures has been hampered by the presence of blood hemoglobin that affects the light delivery to and the collection from the vessel wall. We report a computational fluid dynamics model that allows for the optimization of blood flushing parameters in a manner that minimizes the amount of saline needed to clear the optical field of view and reduces any adverse effects caused by the external saline jet. A 3D turbulence (k−ω) model was employed for Eulerian–Eulerian two-phase flow to simulate the flow inside and around a side-viewing fiber-optic catheter. Current analysis demonstrates the effects of various parameters including infusion and blood flow rates, vessel diameters, and pulsatile nature of blood flow on the flow structure around the catheter tip. The results from this study can be utilized in determining the optimal flushing rate for given vessel diameter, blood flow rate, and maximum wall shear stress that the vessel wall can sustain and subsequently in optimizing the design parameters of optical-based intravascular catheters. PMID:24953876

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nose, Y.

Methods were developed for generating an integrated, statistical model of the anatomical structures within the human thorax relevant to radioisotope powered artificial heart implantation. These methods involve measurement and analysis of anatomy in four areas: chest wall, pericardium, vascular connections, and great vessels. A model for the prediction of thorax outline from radiograms was finalized. These models were combined with 100 radiograms to arrive at a size distribution representing the adult male and female populations. (CH)

Global Optimization of Interplanetary Trajectories in the Presence of Realistic Mission Contraints

NASA Technical Reports Server (NTRS)

Hinckley, David, Jr.; Englander, Jacob; Hitt, Darren

2015-01-01

Interplanetary missions are often subject to difficult constraints, like solar phase angle upon arrival at the destination, velocity at arrival, and altitudes for flybys. Preliminary design of such missions is often conducted by solving the unconstrained problem and then filtering away solutions which do not naturally satisfy the constraints. However this can bias the search into non-advantageous regions of the solution space, so it can be better to conduct preliminary design with the full set of constraints imposed. In this work two stochastic global search methods are developed which are well suited to the constrained global interplanetary trajectory optimization problem.

Maritime transportation of illegal drugs from South America.

PubMed

Atkinson, Michael P; Kress, Moshe; Szechtman, Roberto

2017-01-01

The US invests considerable effort in searching and interdicting drug-trafficking vessels in the Caribbean and Eastern Pacific regions. While some vessels are indeed interdicted, resulting in confiscation of substantial quantities of drugs, many such vessels manage to avoid detection and arrive safely at their destinations in Central America and Mexico with their drug load intact. The agency in charge of interdicting this traffic, Joint Interagency Task Force South-JIATF-S, sends out both aerial and surface assets for search and interdiction missions. An important parameter for planning search and interdiction missions is an estimate of the expected steady-state number of the various types of drug trafficking vessels present in the search regions at any given time. In this paper we use various publicly available sources to estimate these numbers. We estimate that the number of drug shipments initiated per month ranges between four and six dozen, and at any given time there are between two and four vessels, of all types, on the high seas. These estimates remain quite robust over a relatively large range of assumptions and estimates regarding the size and distribution of the drug flow, mix of vessel types, and physical characteristics of those vessels. Our analysis provides insight for how to allocate assets to search, detect, and interdict drug trafficking vessels. The results can also be useful to vet informants to check if their information is consistent with our flow estimates. To the best of our knowledge this is the first time such flow estimates appear in the open literature. Published by Elsevier B.V.

Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

PubMed

Joshi, Vinayak S; Reinhardt, Joseph M; Garvin, Mona K; Abramoff, Michael D

2014-01-01

The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.

Power Allocation Based on Data Classification in Wireless Sensor Networks

PubMed Central

Wang, Houlian; Zhou, Gongbo

2017-01-01

Limited node energy in wireless sensor networks is a crucial factor which affects the monitoring of equipment operation and working conditions in coal mines. In addition, due to heterogeneous nodes and different data acquisition rates, the number of arriving packets in a queue network can differ, which may lead to some queue lengths reaching the maximum value earlier compared with others. In order to tackle these two problems, an optimal power allocation strategy based on classified data is proposed in this paper. Arriving data is classified into dissimilar classes depending on the number of arriving packets. The problem is formulated as a Lyapunov drift optimization with the objective of minimizing the weight sum of average power consumption and average data class. As a result, a suboptimal distributed algorithm without any knowledge of system statistics is presented. The simulations, conducted in the perfect channel state information (CSI) case and the imperfect CSI case, reveal that the utility can be pushed arbitrarily close to optimal by increasing the parameter V, but with a corresponding growth in the average delay, and that other tunable parameters W and the classification method in the interior of utility function can trade power optimality for increased average data class. The above results show that data in a high class has priorities to be processed than data in a low class, and energy consumption can be minimized in this resource allocation strategy. PMID:28498346

The effect of early berthing prospects on the energy efficiency operational index in oil tanker vessels

NASA Astrophysics Data System (ADS)

Acomi, N.; Acomi, O. C.

2016-08-01

Marine pollution is one of the main concerns of our society. In order to reduce air pollution produced by ships, the International Maritime Organization has developed technical, operational and management measures. Part of the operational measures refers to CO2 emissions that contribute to the energy efficiency of the vessel. The difficulty in assessing the energy efficiency of the vessel rests with the diversity of voyage parameters, including quantity of cargo, distance and type of fuel in use. Assessing the energy efficiency of the vessel is thus not a matter of determining the absolute value of the CO2, but of providing a meaningful construct to enable tracking performance trends over time, for the same ship, a fleet of ships or across the industry. This concept is the Energy Efficiency Operational Index, EEOI. The purpose of this study is to analyse the influence of a well predicted voyage on the EEOI value. The method used consists in a comparative analysis of two situations regarding berthing prospects: the real passage plan and an early prediction that supposes the vessel to arrive on time as required. The results of the study represent a monitoring tool for the ship owners to assess the EEOI from the early stage of designing the berthing prospects.

Energy Optimal Path Planning: Integrating Coastal Ocean Modelling with Optimal Control

NASA Astrophysics Data System (ADS)

Subramani, D. N.; Haley, P. J., Jr.; Lermusiaux, P. F. J.

2016-02-01

A stochastic optimization methodology is formulated for computing energy-optimal paths from among time-optimal paths of autonomous vehicles navigating in a dynamic flow field. To set up the energy optimization, the relative vehicle speed and headings are considered to be stochastic, and new stochastic Dynamically Orthogonal (DO) level-set equations that govern their stochastic time-optimal reachability fronts are derived. Their solution provides the distribution of time-optimal reachability fronts and corresponding distribution of time-optimal paths. An optimization is then performed on the vehicle's energy-time joint distribution to select the energy-optimal paths for each arrival time, among all stochastic time-optimal paths for that arrival time. The accuracy and efficiency of the DO level-set equations for solving the governing stochastic level-set reachability fronts are quantitatively assessed, including comparisons with independent semi-analytical solutions. Energy-optimal missions are studied in wind-driven barotropic quasi-geostrophic double-gyre circulations, and in realistic data-assimilative re-analyses of multiscale coastal ocean flows. The latter re-analyses are obtained from multi-resolution 2-way nested primitive-equation simulations of tidal-to-mesoscale dynamics in the Middle Atlantic Bight and Shelbreak Front region. The effects of tidal currents, strong wind events, coastal jets, and shelfbreak fronts on the energy-optimal paths are illustrated and quantified. Results showcase the opportunities for longer-duration missions that intelligently utilize the ocean environment to save energy, rigorously integrating ocean forecasting with optimal control of autonomous vehicles.

Energy optimization for upstream data transfer in 802.15.4 beacon-enabled star formulation

NASA Astrophysics Data System (ADS)

Liu, Hua; Krishnamachari, Bhaskar

2008-08-01

Energy saving is one of the major concerns for low rate personal area networks. This paper models energy consumption for beacon-enabled time-slotted media accessing control cooperated with sleeping scheduling in a star network formulation for IEEE 802.15.4 standard. We investigate two different upstream (data transfer from devices to a network coordinator) strategies: a) tracking strategy: the devices wake up and check status (track the beacon) in each time slot; b) non-tracking strategy: nodes only wake-up upon data arriving and stay awake till data transmitted to the coordinator. We consider the tradeoff between energy cost and average data transmission delay for both strategies. Both scenarios are formulated as optimization problems and the optimal solutions are discussed. Our results show that different data arrival rate and system parameters (such as contention access period interval, upstream speed etc.) result in different strategies in terms of energy optimization with maximum delay constraints. Hence, according to different applications and system settings, different strategies might be chosen by each node to achieve energy optimization for both self-interested view and system view. We give the relation among the tunable parameters by formulas and plots to illustrate which strategy is better under corresponding parameters. There are two main points emphasized in our results with delay constraints: on one hand, when the system setting is fixed by coordinator, nodes in the network can intelligently change their strategies according to corresponding application data arrival rate; on the other hand, when the nodes' applications are known by the coordinator, the coordinator can tune the system parameters to achieve optimal system energy consumption.

Optimization of a vacuum chamber for vibration measurements.

PubMed

Danyluk, Mike; Dhingra, Anoop

2011-10-01

A 200 °C high vacuum chamber has been built to improve vibration measurement sensitivity. The optimized design addresses two significant issues: (i) vibration measurements under high vacuum conditions and (ii) use of design optimization tools to reduce operating costs. A test rig consisting of a cylindrical vessel with one access port has been constructed with a welded-bellows assembly used to seal the vessel and enable vibration measurements in high vacuum that are comparable with measurements in air. The welded-bellows assembly provides a force transmissibility of 0.1 or better at 15 Hz excitation under high vacuum conditions. Numerical results based on design optimization of a larger diameter chamber are presented. The general constraints on the new design include material yield stress, chamber first natural frequency, vibration isolation performance, and forced convection heat transfer capabilities over the exterior of the vessel access ports. Operating costs of the new chamber are reduced by 50% compared to a preexisting chamber of similar size and function.

Strategic Mobility 21: SM21 CONOPS Revised - Phase II, Joint Force Deployment and Distribution Support Platform: Joint Operational Concept

DTIC Science & Technology

2009-12-02

an overarching regional information technology architecture to synchronize the vessel arrival and departure schedules with marine terminal, short... wakeup call for the rest of the nation’s ports and regions. The impacts of these disruptions are felt throughout the supply chain - in the national...and equipment repositioning. Supply chain unreliability wreaks havoc with planning, scheduling , purchasing, sales, and distribution. Suppliers are

Dynamics of different-sized solid-state nanocrystals as tracers for a drug-delivery system in the interstitium of a human tumor xenograft

PubMed Central

Kawai, Masaaki; Higuchi, Hideo; Takeda, Motohiro; Kobayashi, Yoshio; Ohuchi, Noriaki

2009-01-01

Introduction Recent anticancer drugs have been made larger to pass selectively through tumor vessels and stay in the interstitium. Understanding drug movement in association with its size at the single-molecule level and estimating the time needed to reach the targeted organ is indispensable for optimizing drug delivery because single cell-targeted therapy is the ongoing paradigm. This report describes the tracking of single solid nanoparticles in tumor xenografts and the estimation of arrival time. Methods Different-sized nanoparticles measuring 20, 40, and 100 nm were injected into the tail vein of the female Balb/c nu/nu mice bearing human breast cancer on their backs. The movements of the nanoparticles were visualized through the dorsal skin-fold chamber with the high-speed confocal microscopy that we manufactured. Results An analysis of the particle trajectories revealed diffusion to be inversely related to the particle size and position in the tumor, whereas the velocity of the directed movement was related to the position. The difference in the velocity was the greatest for 40-nm particles in the perivascular to the intercellular region: difference = 5.8 nm/s. The arrival time of individual nanoparticles at tumor cells was simulated. The estimated times for the 20-, 40-, and 100-nm particles to reach the tumor cells were 158.0, 218.5, and 389.4 minutes, respectively, after extravasation. Conclusions This result suggests that the particle size can be individually designed for each goal. These data and methods are also important for understanding drug pharmacokinetics. Although this method may be subject to interference by surface molecules attached on the particles, it has the potential to elucidate the pharmacokinetics involved in constructing novel drug-delivery systems involving cell-targeted therapy. PMID:19575785

Lung vessel segmentation in CT images using graph-cuts

NASA Astrophysics Data System (ADS)

Zhai, Zhiwei; Staring, Marius; Stoel, Berend C.

2016-03-01

Accurate lung vessel segmentation is an important operation for lung CT analysis. Filters that are based on analyzing the eigenvalues of the Hessian matrix are popular for pulmonary vessel enhancement. However, due to their low response at vessel bifurcations and vessel boundaries, extracting lung vessels by thresholding the vesselness is not sufficiently accurate. Some methods turn to graph-cuts for more accurate segmentation, as it incorporates neighbourhood information. In this work, we propose a new graph-cuts cost function combining appearance and shape, where CT intensity represents appearance and vesselness from a Hessian-based filter represents shape. Due to the amount of voxels in high resolution CT scans, the memory requirement and time consumption for building a graph structure is very high. In order to make the graph representation computationally tractable, those voxels that are considered clearly background are removed from the graph nodes, using a threshold on the vesselness map. The graph structure is then established based on the remaining voxel nodes, source/sink nodes and the neighbourhood relationship of the remaining voxels. Vessels are segmented by minimizing the energy cost function with the graph-cuts optimization framework. We optimized the parameters used in the graph-cuts cost function and evaluated the proposed method with two manually labeled sub-volumes. For independent evaluation, we used 20 CT scans of the VESSEL12 challenge. The evaluation results of the sub-volume data show that the proposed method produced a more accurate vessel segmentation compared to the previous methods, with F1 score 0.76 and 0.69. In the VESSEL12 data-set, our method obtained a competitive performance with an area under the ROC curve of 0.975, especially among the binary submissions.

Augmented Lagrange Programming Neural Network for Localization Using Time-Difference-of-Arrival Measurements.

PubMed

Han, Zifa; Leung, Chi Sing; So, Hing Cheung; Constantinides, Anthony George

2017-08-15

A commonly used measurement model for locating a mobile source is time-difference-of-arrival (TDOA). As each TDOA measurement defines a hyperbola, it is not straightforward to compute the mobile source position due to the nonlinear relationship in the measurements. This brief exploits the Lagrange programming neural network (LPNN), which provides a general framework to solve nonlinear constrained optimization problems, for the TDOA-based localization. The local stability of the proposed LPNN solution is also analyzed. Simulation results are included to evaluate the localization accuracy of the LPNN scheme by comparing with the state-of-the-art methods and the optimality benchmark of Cramér-Rao lower bound.

Energy-optimal path planning by stochastic dynamically orthogonal level-set optimization

NASA Astrophysics Data System (ADS)

Subramani, Deepak N.; Lermusiaux, Pierre F. J.

2016-04-01

A stochastic optimization methodology is formulated for computing energy-optimal paths from among time-optimal paths of autonomous vehicles navigating in a dynamic flow field. Based on partial differential equations, the methodology rigorously leverages the level-set equation that governs time-optimal reachability fronts for a given relative vehicle-speed function. To set up the energy optimization, the relative vehicle-speed and headings are considered to be stochastic and new stochastic Dynamically Orthogonal (DO) level-set equations are derived. Their solution provides the distribution of time-optimal reachability fronts and corresponding distribution of time-optimal paths. An optimization is then performed on the vehicle's energy-time joint distribution to select the energy-optimal paths for each arrival time, among all stochastic time-optimal paths for that arrival time. Numerical schemes to solve the reduced stochastic DO level-set equations are obtained, and accuracy and efficiency considerations are discussed. These reduced equations are first shown to be efficient at solving the governing stochastic level-sets, in part by comparisons with direct Monte Carlo simulations. To validate the methodology and illustrate its accuracy, comparisons with semi-analytical energy-optimal path solutions are then completed. In particular, we consider the energy-optimal crossing of a canonical steady front and set up its semi-analytical solution using a energy-time nested nonlinear double-optimization scheme. We then showcase the inner workings and nuances of the energy-optimal path planning, considering different mission scenarios. Finally, we study and discuss results of energy-optimal missions in a wind-driven barotropic quasi-geostrophic double-gyre ocean circulation.

Estimating Controller Intervention Probabilities for Optimized Profile Descent Arrivals

NASA Technical Reports Server (NTRS)

Meyn, Larry A.; Erzberger, Heinz; Huynh, Phu V.

2011-01-01

Simulations of arrival traffic at Dallas/Fort-Worth and Denver airports were conducted to evaluate incorporating scheduling and separation constraints into advisories that define continuous descent approaches. The goal was to reduce the number of controller interventions required to ensure flights maintain minimum separation distances of 5 nmi horizontally and 1000 ft vertically. It was shown that simply incorporating arrival meter fix crossing-time constraints into the advisory generation could eliminate over half of the all predicted separation violations and more than 80% of the predicted violations between two arrival flights. Predicted separation violations between arrivals and non-arrivals were 32% of all predicted separation violations at Denver and 41% at Dallas/Fort-Worth. A probabilistic analysis of meter fix crossing-time errors is included which shows that some controller interventions will still be required even when the predicted crossing-times of the advisories are set to add a 1 or 2 nmi buffer above the minimum in-trail separation of 5 nmi. The 2 nmi buffer was shown to increase average flight delays by up to 30 sec when compared to the 1 nmi buffer, but it only resulted in a maximum decrease in average arrival throughput of one flight per hour.

Hemipelvectomy images of loss caused by war

PubMed Central

Salamon, Tal; Kassis, Shokrey; Lerner, Alexander

2014-01-01

As we treat our 230th patient from the Syrian conflict, the pathology we see is more debilitating and the humanitarian needs of the wounded have become even more obvious. This case presents some graphic images of the realities of war. Care in the most advanced units cannot restore broken limbs, let alone broken lives. We present a case of a young war-injured man, who suffered severe crush injury to the pelvis and lower limb, arriving at our medical facility after a delay of hours. The lower limb was shattered from the pelvis down (essentially a traumatic hemipelvectomy). His life had been saved in Syria by ligation of the femoral vessels in an unknown facility by an unknown medical team. On arrival in a centre in Israel for definitive care of an unsalvageable leg, formal hemipelvectomy was performed. PMID:25008336

Survey of optimization techniques for nonlinear spacecraft trajectory searches

NASA Technical Reports Server (NTRS)

Wang, Tseng-Chan; Stanford, Richard H.; Sunseri, Richard F.; Breckheimer, Peter J.

1988-01-01

Mathematical analysis of the optimal search of a nonlinear spacecraft trajectory to arrive at a set of desired targets is presented. A high precision integrated trajectory program and several optimization software libraries are used to search for a converged nonlinear spacecraft trajectory. Several examples for the Galileo Jupiter Orbiter and the Ocean Topography Experiment (TOPEX) are presented that illustrate a variety of the optimization methods used in nonlinear spacecraft trajectory searches.

Visualization of Porphyrin-Based Photosensitizer Distribution from Fluorescence Images In Vivo Using an Optimized RGB Camera

NASA Astrophysics Data System (ADS)

Liu, L.; Huang, Zh.; Qiu, Zh.; Li, B.

2018-01-01

A handheld RGB camera was developed to monitor the in vivo distribution of porphyrin-based photosensitizer (PS) hematoporphyrin monomethyl ether (HMME) in blood vessels during photodynamic therapy (PDT). The focal length, f-number, International Standardization Organization (ISO) sensitivity, and shutter speed of the camera were optimized for the solution sample with various HMME concentrations. After the parameter optimization, it was found that the red intensity value of the fluorescence image was linearly related to the fluorescence intensity under investigated conditions. The RGB camera was then used to monitor the in vivo distribution of HMME in blood vessels in a skin-fold window chamber model. The red intensity value of the recorded RGB fluorescence image was found to be linearly correlated to HMME concentrations in the range 0-24 μM. Significant differences in the red to green intensity ratios were observed between the blood vessels and the surrounding tissue.

Galileo 1989 VEEGA trajectory design. [Venus-Earth-Earth-Gravity-Assist

NASA Technical Reports Server (NTRS)

D'Amario, Louis A.; Byrnes, Dennis V.; Johannesen, Jennie R.; Nolan, Brian G.

1989-01-01

The new baseline for the Galileo Mission is a 1989 Venus-earth-earth gravity-assist (VEEGA) trajectory, which utilizes three gravity-assist planetary flybys in order to reduce launch energy requirements significantly compared to other earth-Jupiter transfer modes. The launch period occurs during October-November 1989. The total flight time is about 6 years, with November 1995 as the most likely choice for arrival at Jupiter. Optimal 1989 VEEGA trajectories have been generated for a wide range of earth launch dates and Jupiter arrival dates. Launch/arrival space contour plots are presented for various trajectory parameters, including propellant margin, which is used to measure mission performance. The accessible region of the launch/arrival space is defined by propellant margin and launch energy constraints; the available launch period is approximately 1.5 months long.

A conflict analysis of 4D descent strategies in a metered, multiple-arrival route environment

NASA Technical Reports Server (NTRS)

Izumi, K. H.; Harris, C. S.

1990-01-01

A conflict analysis was performed on multiple arrival traffic at a typical metered airport. The Flow Management Evaluation Model (FMEM) was used to simulate arrival operations using Denver Stapleton's arrival route structure. Sensitivities of conflict performance to three different 4-D descent strategies (clear-idle Mach/Constant AirSpeed (CAS), constant descent angle Mach/CAS and energy optimal) were examined for three traffic mixes represented by those found at Denver Stapleton, John F. Kennedy and typical en route metering (ERM) airports. The Monte Carlo technique was used to generate simulation entry point times. Analysis results indicate that the clean-idle descent strategy offers the best compromise in overall performance. Performance measures primarily include susceptibility to conflict and conflict severity. Fuel usage performance is extrapolated from previous descent strategy studies.

An Exploration Of Fuel Optimal Two-impulse Transfers To Cyclers in the Earth-Moon System

NASA Astrophysics Data System (ADS)

Hosseinisianaki, Saghar

2011-12-01

This research explores the optimum two-impulse transfers between a low Earth orbit and cycler orbits in the Earth-Moon circular restricted three-body framework, emphasizing the optimization strategy. Cyclers are those types of periodic orbits that meet both the Earth and the Moon periodically. A spacecraft on such trajectories are under the influence of both the Earth and the Moon gravitational fields. Cyclers have gained recent interest as baseline orbits for several Earth-Moon mission concepts, notably in relation to human exploration. In this thesis it is shown that a direct optimization starting from the classic lambert initial guess may not be adequate for these problems and propose a three-step optimization solver to improve the domain of convergence toward an optimal solution. The first step consists of finding feasible trajectories with a given transfer time. I employ Lambert's problem to provide initial guess to optimize the error in arrival position. This includes the analysis of the liability of Lambert's solution as an initial guess. Once a feasible trajectory is found, the velocity impulse is only a function of transfer time, departure, and arrival points' phases. The second step consists of the optimization of impulse over transfer time which results in the minimum impulse transfer for fixed end points. Finally, the third step is mapping the optimal solutions as the end points are varied.

An Exploration Of Fuel Optimal Two-impulse Transfers To Cyclers in the Earth-Moon System

NASA Astrophysics Data System (ADS)

Hosseinisianaki, Saghar

This research explores the optimum two-impulse transfers between a low Earth orbit and cycler orbits in the Earth-Moon circular restricted three-body framework, emphasizing the optimization strategy. Cyclers are those types of periodic orbits that meet both the Earth and the Moon periodically. A spacecraft on such trajectories are under the influence of both the Earth and the Moon gravitational fields. Cyclers have gained recent interest as baseline orbits for several Earth-Moon mission concepts, notably in relation to human exploration. In this thesis it is shown that a direct optimization starting from the classic lambert initial guess may not be adequate for these problems and propose a three-step optimization solver to improve the domain of convergence toward an optimal solution. The first step consists of finding feasible trajectories with a given transfer time. I employ Lambert's problem to provide initial guess to optimize the error in arrival position. This includes the analysis of the liability of Lambert's solution as an initial guess. Once a feasible trajectory is found, the velocity impulse is only a function of transfer time, departure, and arrival points' phases. The second step consists of the optimization of impulse over transfer time which results in the minimum impulse transfer for fixed end points. Finally, the third step is mapping the optimal solutions as the end points are varied.

Balanced MR cholangiopancreatography with motion-sensitized driven-equilibrium (MSDE) preparation: Feasibility and optimization of imaging parameters.

PubMed

Nakayama, Tomohiro; Nishie, Akihiro; Yoshiura, Takashi; Asayama, Yoshiki; Ishigami, Kousei; Kakihara, Daisuke; Obara, Makoto; Honda, Hiroshi

2015-12-01

To show the feasibility of motion-sensitized driven-equilibrium-balanced magnetic resonance cholangiopancreatography and to determine the optimal velocity encoding (VENC) value. Sixteen healthy volunteers underwent MRI study using a 1.5-T clinical unit and a 32-channel body array coil. For each volunteer, images were obtained using the following seven respiratory-triggered sequences: (1) balanced magnetic resonance cholangiopancreatography without motion-sensitized driven-equilibrium, and (2)-(7) balanced magnetic resonance cholangiopancreatography with motion-sensitized driven-equilibrium, with VENC=1, 3, 5, 7, 9 and ∞cm/s for the x-, y-, and z-directions, respectively. Quantitative evaluation was obtained by measuring the maximum signal intensity of the common hepatic duct, portal vein, liver tissue including visible peripheral vessels, and liver tissue excluding visible peripheral vessels that were evaluated. We compared the contrast ratios of portal vein/common hepatic duct, liver tissue including visible peripheral vessels/common hepatic duct and liver tissue excluding visible peripheral vessels/common hepatic duct among the five finite sequences (VENC=1, 3, 5, 7, and 9cm/s). Statistical comparisons were performed using the t-test for paired data with the Bonferroni correction. Suppression of blood vessel signals was achieved with motion-sensitized driven-equilibrium sequences. We found the optimal VENC values to be either 3 or 5cm/s with the best suppression of relative vessel signals to bile ducts. At a lower VENC value (1cm/s), the bile duct signal was reduced, presumably due to minimal biliary flow. The feasibility of motion-sensitized driven-equilibrium-balanced magnetic resonance cholangiopancreatography was suggested. The optimal VENC value was considered to be either 3 or 5cm/s. The clinical usefulness of this new magnetic resonance cholangiopancreatography sequence needs to be verified by further studies. Copyright © 2015 Elsevier Inc. All rights reserved.

Apollo 12 Crewmembers - Greeting - Family - Arrival - Ellington AFB (EAFB), TX

NASA Image and Video Library

1969-11-29

S69-60759 (29 Nov. 1969) --- Members of the Apollo 12 lunar landing mission's crew are greeted by their wives and children at the front of a large crowd on hand to welcome the three home. The Mobile Quarantine Facility (MQF), with the crew inside, arrived at Ellington Air Force Base aboard a United States Air Force C-141 transport jet in the early morning hours of Nov. 29, 1969. The crew men, looking out the MQF window at the crowd, are from left to right, astronauts Charles Conrad Jr., Richard F. Gordon Jr. and Alan L. Bean. Their wives are, from left to right, Mrs. Barbara Gordon, Mrs. Jane Conrad and Mrs. Sue Bean. The women are wearing lei's, an Hawaiian tradition. The crew members were taken to Hawaii from their Pacific Ocean recovery site aboard the USS Hornet, prime recovery vessel for the mission.

BPC 157 and blood vessels.

PubMed

Seiwerth, Sven; Brcic, Luka; Vuletic, Lovorka Batelja; Kolenc, Danijela; Aralica, Gorana; Misic, Marija; Zenko, Anita; Drmic, Domagoj; Rucman, Rudolf; Sikiric, Predrag

2014-01-01

This review focuses on the described effects of BPC 157 on blood vessels after different types of damage, and elucidate by investigating different aspects of vascular response to injury (endothelium damage, clotting, thrombosis, vasoconstriction, vasodilatation, vasculoneogenesis and edema formation) especially in connection to the healing processes. In this respect, BPC 157 was concluded to be the most potent angiomodulatory agent, acting through different vasoactive pathways and systems (e.g. NO, VEGF, FAK) and leading to optimization of the vascular response followed, as it has to be expected, by optimization of the healing process. Formation of new blood vessels involves two main, partly overlapping mechanisms, angiogenesis and vasculogenesis. The additional mechanism of arteriogenesis is involved in the formation of collaterals. In conjunction with blood vessel function, we at least have to consider leakage of fluid/proteins/plasma, resulting in edema/exudate formation as well as thrombogenesis. Blood vessels are also strongly involved in tumor biology. In this aspect, we have neoangiogenesis resulting in pathological vascularization, vascular invasion resulting in release of metastatic cells and the phenomenon of homing resulting in formation of secondary tumors--metastases.

Optimal trajectories for solar bow shock mission

NASA Astrophysics Data System (ADS)

Pizzurro, S.; Circi, C.

2012-11-01

This paper deals a Solar Bow Shock mission, a phenomenon of interaction between the solar wind and the interstellar medium, due to the relative motion of our star with respect to the enormous interstellar matter cloud that contains it. This phenomenon occurs at boundary of the solar system (200 AU), and it is preferable a mission in situ that could examine in detail what actually happens on-the-spot, to understand its effect on the planets of the solar system. Voyager 1 & 2 reached the area where the phenomenon takes place after 30 years. The target is to arrive there optimizing both the transfer time, and the propellant mass consumption. Therefore, the trajectory will be optimized using different propulsion systems and appropriate flyby sequences.. The approach techniques that will be used foresee executions of impulsive or ballistic gravity assists with the utilisation of high thrust engine only, or low thrust engine only, or both engines in two different phases of the mission. By comparing all the solutions obtained imposing different initial conditions the optimal trajectory to arrive at Solar Bow Shock is presented.

PBF Reactor Building (PER620). Camera on main floor faces south ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PBF Reactor Building (PER-620). Camera on main floor faces south (open) doorway. In foreground is canal gate, lined with stainless steel and painted with protective coatings. Reactor pit is round with protective coatings. Reactor put is round form discernible beyond. Lifting beams and rigging are in place for a load test before reactor vessel arrives. Photographer: John Capek. Date: January 26, 1970. INEEL negative no. 70-347 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

Complications of vessel architecture and the the reason that cylindrical electrodes are generally not effective

NASA Astrophysics Data System (ADS)

Pearce, John; Thomsen, Sharon

2017-02-01

Large vessels can be reliably sealed with radio frequency current. High apposition pressures are necessary to ensure a high probability of a successful seal. However, the complex architecture of the vessels, particularly arteries, means that results can vary substantially even with similar thermal histories. The relative volume fractions and spatial distributions of collagen, elastin, and smooth muscle dominate the vessel function in vivo and can even vary from proximal to distal locations in the same vessel. We begin by reviewing the architectural features characteristic of porcine and canine large vessels and conclude with an experimental and numerical modeling demonstration of the reasons why cylindrical electrodes are a sub-optimal choice.

Energy-optimal path planning in the coastal ocean

NASA Astrophysics Data System (ADS)

Subramani, Deepak N.; Haley, Patrick J.; Lermusiaux, Pierre F. J.

2017-05-01

We integrate data-driven ocean modeling with the stochastic Dynamically Orthogonal (DO) level-set optimization methodology to compute and study energy-optimal paths, speeds, and headings for ocean vehicles in the Middle-Atlantic Bight (MAB) region. We hindcast the energy-optimal paths from among exact time-optimal paths for the period 28 August 2006 to 9 September 2006. To do so, we first obtain a data-assimilative multiscale reanalysis, combining ocean observations with implicit two-way nested multiresolution primitive-equation simulations of the tidal-to-mesoscale dynamics in the region. Second, we solve the reduced-order stochastic DO level-set partial differential equations (PDEs) to compute the joint probability of minimum arrival time, vehicle-speed time series, and total energy utilized. Third, for each arrival time, we select the vehicle-speed time series that minimize the total energy utilization from the marginal probability of vehicle-speed and total energy. The corresponding energy-optimal path and headings are obtained through the exact particle-backtracking equation. Theoretically, the present methodology is PDE-based and provides fundamental energy-optimal predictions without heuristics. Computationally, it is 3-4 orders of magnitude faster than direct Monte Carlo methods. For the missions considered, we analyze the effects of the regional tidal currents, strong wind events, coastal jets, shelfbreak front, and other local circulations on the energy-optimal paths. Results showcase the opportunities for vehicles that intelligently utilize the ocean environment to minimize energy usage, rigorously integrating ocean forecasting with optimal control of autonomous vehicles.

Automated vessel segmentation using cross-correlation and pooled covariance matrix analysis.

PubMed

Du, Jiang; Karimi, Afshin; Wu, Yijing; Korosec, Frank R; Grist, Thomas M; Mistretta, Charles A

2011-04-01

Time-resolved contrast-enhanced magnetic resonance angiography (CE-MRA) provides contrast dynamics in the vasculature and allows vessel segmentation based on temporal correlation analysis. Here we present an automated vessel segmentation algorithm including automated generation of regions of interest (ROIs), cross-correlation and pooled sample covariance matrix analysis. The dynamic images are divided into multiple equal-sized regions. In each region, ROIs for artery, vein and background are generated using an iterative thresholding algorithm based on the contrast arrival time map and contrast enhancement map. Region-specific multi-feature cross-correlation analysis and pooled covariance matrix analysis are performed to calculate the Mahalanobis distances (MDs), which are used to automatically separate arteries from veins. This segmentation algorithm is applied to a dual-phase dynamic imaging acquisition scheme where low-resolution time-resolved images are acquired during the dynamic phase followed by high-frequency data acquisition at the steady-state phase. The segmented low-resolution arterial and venous images are then combined with the high-frequency data in k-space and inverse Fourier transformed to form the final segmented arterial and venous images. Results from volunteer and patient studies demonstrate the advantages of this automated vessel segmentation and dual phase data acquisition technique. Copyright © 2011 Elsevier Inc. All rights reserved.

Modeling pre-metastatic lymphvascular niche in the mouse ear sponge assay

NASA Astrophysics Data System (ADS)

García-Caballero, Melissa; van de Velde, Maureen; Blacher, Silvia; Lambert, Vincent; Balsat, Cédric; Erpicum, Charlotte; Durré, Tania; Kridelka, Frédéric; Noel, Agnès

2017-01-01

Lymphangiogenesis, the formation of new lymphatic vessels, occurs in primary tumors and in draining lymph nodes leading to pre-metastatic niche formation. Reliable in vivo models are becoming instrumental for investigating alterations occurring in lymph nodes before tumor cell arrival. In this study, we demonstrate that B16F10 melanoma cell encapsulation in a biomaterial, and implantation in the mouse ear, prevents their rapid lymphatic spread observed when cells are directly injected in the ear. Vascular remodeling in lymph nodes was detected two weeks after sponge implantation, while their colonization by tumor cells occurred two weeks later. In this model, a huge lymphangiogenic response was induced in primary tumors and in pre-metastatic and metastatic lymph nodes. In control lymph nodes, lymphatic vessels were confined to the cortex. In contrast, an enlargement and expansion of lymphatic vessels towards paracortical and medullar areas occurred in pre-metastatic lymph nodes. We designed an original computerized-assisted quantification method to examine the lymphatic vessel structure and the spatial distribution. This new reliable and accurate model is suitable for in vivo studies of lymphangiogenesis, holds promise for unraveling the mechanisms underlying lymphatic metastases and pre-metastatic niche formation in lymph nodes, and will provide new tools for drug testing.

Evaluating the combined effects of ballast water management and trade dynamics on transfers of marine organisms by ships

PubMed Central

Carney, Katharine J.; Minton, Mark S.; Holzer, Kimberly K.; Miller, A. Whitman; McCann, Linda D.; Ruiz, Gregory M.

2017-01-01

Global trade by merchant ships is a leading mechanism for the unintentional transfer of marine organisms, including non-indigenous species, to bays and estuaries worldwide. To reduce the likelihood of new invasions, ships are increasingly being required to manage their ballast water (BW) prior to discharge in coastal waters. In the United States, most overseas arrivals have been required to manage BW discharge since 2004, primarily through ballast water exchange (BWE), which flushes out ballast tanks in the open ocean (>200 miles from shore). Studies have found BWE to generally reduce the abundance of organisms, and the amount of water exchanged has been estimated at 96–100%. Despite its widespread use, the overall effect of this management strategy on net propagule supply through time has not been explored. Here, temporal changes in zooplankton concentrations and the volume of BW discharged in Chesapeake Bay, U.S. were evaluated, comparing pre-management era and post-management era time periods. Chesapeake Bay is a large port system that receives extensive BW discharge, especially from bulk cargo vessels (bulkers) that export coal overseas. For bulkers arriving from overseas, mean zooplankton concentrations of total and coastal indicator taxa in BW did not decline between pre- (1993–2000) and post management (2012–2013) eras, when controlling for season and sampling method. Moreover, bulkers discharged 21 million tonnes (82% of total for Chesapeake Bay) of overseas BW in 2013, representing a 374% increase in volume when compared to 2005. The combination of BW discharge volume and zooplankton concentration data indicates that (a) net propagule supply by bulkers has increased since BWE began in Chesapeake Bay; and (b) changes in vessel behaviour and trade have contributed strongly to this outcome. Specifically, the coal-driven increase in BW discharge volume from 2005–2013, concurrent with the onset of BWE regulations, worked to counteract intended results from BW management. A long-term analysis of bulker arrivals (1994–2013) reveals a 20-year minimum in arrival numbers in 2000, just when the implementation of BWE began. This study underscores the need to consider shifts in trade patterns, in order to advance and evaluate effective management strategies for biological invasions. PMID:28319119

Evaluating the combined effects of ballast water management and trade dynamics on transfers of marine organisms by ships.

PubMed

Carney, Katharine J; Minton, Mark S; Holzer, Kimberly K; Miller, A Whitman; McCann, Linda D; Ruiz, Gregory M

2017-01-01

Global trade by merchant ships is a leading mechanism for the unintentional transfer of marine organisms, including non-indigenous species, to bays and estuaries worldwide. To reduce the likelihood of new invasions, ships are increasingly being required to manage their ballast water (BW) prior to discharge in coastal waters. In the United States, most overseas arrivals have been required to manage BW discharge since 2004, primarily through ballast water exchange (BWE), which flushes out ballast tanks in the open ocean (>200 miles from shore). Studies have found BWE to generally reduce the abundance of organisms, and the amount of water exchanged has been estimated at 96-100%. Despite its widespread use, the overall effect of this management strategy on net propagule supply through time has not been explored. Here, temporal changes in zooplankton concentrations and the volume of BW discharged in Chesapeake Bay, U.S. were evaluated, comparing pre-management era and post-management era time periods. Chesapeake Bay is a large port system that receives extensive BW discharge, especially from bulk cargo vessels (bulkers) that export coal overseas. For bulkers arriving from overseas, mean zooplankton concentrations of total and coastal indicator taxa in BW did not decline between pre- (1993-2000) and post management (2012-2013) eras, when controlling for season and sampling method. Moreover, bulkers discharged 21 million tonnes (82% of total for Chesapeake Bay) of overseas BW in 2013, representing a 374% increase in volume when compared to 2005. The combination of BW discharge volume and zooplankton concentration data indicates that (a) net propagule supply by bulkers has increased since BWE began in Chesapeake Bay; and (b) changes in vessel behaviour and trade have contributed strongly to this outcome. Specifically, the coal-driven increase in BW discharge volume from 2005-2013, concurrent with the onset of BWE regulations, worked to counteract intended results from BW management. A long-term analysis of bulker arrivals (1994-2013) reveals a 20-year minimum in arrival numbers in 2000, just when the implementation of BWE began. This study underscores the need to consider shifts in trade patterns, in order to advance and evaluate effective management strategies for biological invasions.

An analysis of the number of parking bays and checkout counters for a supermarket using SAS simulation studio

NASA Astrophysics Data System (ADS)

Kar, Leow Soo

2014-07-01

Two important factors that influence customer satisfaction in large supermarkets or hypermarkets are adequate parking facilities and short waiting times at the checkout counters. This paper describes the simulation analysis of a large supermarket to determine the optimal levels of these two factors. SAS Simulation Studio is used to model a large supermarket in a shopping mall with car park facility. In order to make the simulation model more realistic, a number of complexities are introduced into the model. For example, arrival patterns of customers vary with the time of the day (morning, afternoon and evening) and with the day of the week (weekdays or weekends), the transport mode of arriving customers (by car or other means), the mode of payment (cash or credit card), customer shopping pattern (leisurely, normal, exact) or choice of checkout counters (normal or express). In this study, we focus on 2 important components of the simulation model, namely the parking area, the normal and express checkout counters. The parking area is modeled using a Resource Pool block where one resource unit represents one parking bay. A customer arriving by car seizes a unit of the resource from the Pool block (parks car) and only releases it when he exits the system. Cars arriving when the Resource Pool is empty (no more parking bays) leave without entering the system. The normal and express checkouts are represented by Server blocks with appropriate service time distributions. As a case study, a supermarket in a shopping mall with a limited number of parking bays in Bangsar was chosen for this research. Empirical data on arrival patterns, arrival modes, payment modes, shopping patterns, service times of the checkout counters were collected and analyzed to validate the model. Sensitivity analysis was also performed with different simulation scenarios to identify the parameters for the optimal number the parking spaces and checkout counters.

A coronagraph for operational space weather predication

NASA Astrophysics Data System (ADS)

Middleton, Kevin F.

2017-09-01

Accurate prediction of the arrival of solar wind phenomena, in particular coronal mass ejections (CMEs), at Earth, and possibly elsewhere in the heliosphere, is becoming increasingly important given our ever-increasing reliance on technology. The potentially severe impact on human technological systems of such phenomena is termed space weather. A coronagraph is arguably the instrument that provides the earliest definitive evidence of CME eruption; from a vantage point on or near the Sun-Earth line, a coronagraph can provide near-definitive identification of an Earth-bound CME. Currently, prediction of CME arrival is critically dependent on ageing science coronagraphs whose design and operation were not optimized for space weather services. We describe the early stages of the conceptual design of SCOPE (the Solar Coronagraph for OPErations), optimized to support operational space weather services.

Linking phenological events in migratory passerines with a changing climate: 50 years in the Laurel Highlands of Pennsylvania.

PubMed

McDermott, Molly E; DeGroote, Lucas W

2017-01-01

Advanced timing of both seasonal migration and reproduction in birds has been strongly associated with a warming climate for many bird species. Phenological responses to climate linking these stages may ultimately impact fitness. We analyzed five decades of banding data from 17 migratory bird species to investigate 1) how spring arrival related to timing of breeding, 2) if the interval between arrival and breeding has changed with increasing spring temperatures, and 3) whether arrival timing or breeding timing best predicted local productivity. Four of 17 species, all mid- to long-distance migrants, hatched young earlier in years when migrants arrived earlier to the breeding grounds (~1:1 day advancement). The interval between arrival on breeding grounds and appearance of juveniles shortened with warmer spring temperatures for 12 species (1-6 days for every 1°C increase) and over time for seven species (1-8 days per decade), suggesting that some migratory passerines adapt to climate change by laying more quickly after arrival or reducing the time from laying to fledging. We found more support for the former, that the rate of reproductive advancement was higher than that for arrival in warm years. Timing of spring arrival and breeding were both poor predictors of avian productivity for most migrants analyzed. Nevertheless, we found evidence that fitness benefits may occur from shifts to earlier spring arrival for the multi-brooded Song Sparrow. Our results uniquely demonstrate that co-occurring avian species are phenologically plastic in their response to climate change on their breeding grounds. If migrants continue to show a weaker response to temperatures during migration than breeding, and the window between arrival and optimal breeding shortens further, biological constraints to plasticity may limit the ability of species to adapt successfully to future warming.

Social factors influencing hospital arrival time in acute ischemic stroke patients.

PubMed

Iosif, Christina; Papathanasiou, Mathilda; Staboulis, Eleftherios; Gouliamos, Athanasios

2012-04-01

This is a multi-center, hospital-based study aiming to estimate social factors influencing pre-hospital times of arrival in acute ischemic stroke, with a perspective of finding ways to reduce arrival time and to augment the number of patients eligible for intra-arterial thrombolysis. Acute ischemic stroke patients who presented at the emergency units of four major general public hospitals were registered. We assessed information concerning demographics, time of presentation, clinical situation, imaging, treatment, and socioeconomic factors. The sample was divided in two sub-samples, based on the time of arrival since onset of symptoms, and was statistically analyzed. During one calendar year (2005), 907 patients were registered. Among them 34.6% arrived in the first 6 h from symptom onset, 38.7% arrived between 6 and 24 h, 18.1% after 24 h and for 8.6% the time of onset was unknown. Younger age (P = 0.007), transfer with ambulatory service (Ρ = 0.002), living with a mate (Ρ = 0.004), and higher educational level (P < 0.005) were factors which correlated significantly with early arrival at the hospital. Instructing patients at high risk for stroke to live with a housemate appears beneficial for timely arrival at the hospital. The establishment of dedicated acute stroke call and transportation center should improve the percentage of early arrival. A national information campaign is needed to increase the level of awareness of the population concerning beneficial social behaviors and optimal reaction to symptoms of acute ischemic stroke.

On Revenue-Optimal Dynamic Auctions for Bidders with Interdependent Values

NASA Astrophysics Data System (ADS)

Constantin, Florin; Parkes, David C.

In a dynamic market, being able to update one's value based on information available to other bidders currently in the market can be critical to having profitable transactions. This is nicely captured by the model of interdependent values (IDV): a bidder's value can explicitly depend on the private information of other bidders. In this paper we present preliminary results about the revenue properties of dynamic auctions for IDV bidders. We adopt a computational approach to design single-item revenue-optimal dynamic auctions with known arrivals and departures but (private) signals that arrive online. In leveraging a characterization of truthful auctions, we present a mixed-integer programming formulation of the design problem. Although a discretization is imposed on bidder signals the solution is a mechanism applicable to continuous signals. The formulation size grows exponentially in the dependence of bidders' values on other bidders' signals. We highlight general properties of revenue-optimal dynamic auctions in a simple parametrized example and study the sensitivity of prices and revenue to model parameters.

Infinite capacity multi-server queue with second optional service channel

NASA Astrophysics Data System (ADS)

Ke, Jau-Chuan; Wu, Chia-Huang; Pearn, Wen Lea

2013-02-01

This paper deals with an infinite-capacity multi-server queueing system with a second optional service (SOS) channel. The inter-arrival times of arriving customers, the service times of the first essential service (FES) and the SOS channel are all exponentially distributed. A customer may leave the system after the FES channel with probability (1-θ), or at the completion of the FES may immediately require a SOS with probability θ (0 <= θ <= 1). The formulae for computing the rate matrix and stationary probabilities are derived by means of a matrix analytical approach. A cost model is developed to determine the optimal values of the number of servers and the two service rates, simultaneously, at the minimal total expected cost per unit time. Quasi-Newton method are employed to deal with the optimization problem. Under optimal operating conditions, numerical results are provided in which several system performance measures are calculated based on assumed numerical values of the system parameters.

Optimizing correlation techniques for improved earthquake location

USGS Publications Warehouse

Schaff, D.P.; Bokelmann, G.H.R.; Ellsworth, W.L.; Zanzerkia, E.; Waldhauser, F.; Beroza, G.C.

2004-01-01

Earthquake location using relative arrival time measurements can lead to dramatically reduced location errors and a view of fault-zone processes with unprecedented detail. There are two principal reasons why this approach reduces location errors. The first is that the use of differenced arrival times to solve for the vector separation of earthquakes removes from the earthquake location problem much of the error due to unmodeled velocity structure. The second reason, on which we focus in this article, is that waveform cross correlation can substantially reduce measurement error. While cross correlation has long been used to determine relative arrival times with subsample precision, we extend correlation measurements to less similar waveforms, and we introduce a general quantitative means to assess when correlation data provide an improvement over catalog phase picks. We apply the technique to local earthquake data from the Calaveras Fault in northern California. Tests for an example streak of 243 earthquakes demonstrate that relative arrival times with normalized cross correlation coefficients as low as ???70%, interevent separation distances as large as to 2 km, and magnitudes up to 3.5 as recorded on the Northern California Seismic Network are more precise than relative arrival times determined from catalog phase data. Also discussed are improvements made to the correlation technique itself. We find that for large time offsets, our implementation of time-domain cross correlation is often more robust and that it recovers more observations than the cross spectral approach. Longer time windows give better results than shorter ones. Finally, we explain how thresholds and empirical weighting functions may be derived to optimize the location procedure for any given region of interest, taking advantage of the respective strengths of diverse correlation and catalog phase data on different length scales.

Nodal Analysis Optimization Based on the Use of Virtual Current Sources: A Powerful New Pedagogical Method

ERIC Educational Resources Information Center

Chatzarakis, G. E.

2009-01-01

This paper presents a new pedagogical method for nodal analysis optimization based on the use of virtual current sources, applicable to any linear electric circuit (LEC), regardless of its complexity. The proposed method leads to straightforward solutions, mostly arrived at by inspection. Furthermore, the method is easily adapted to computer…

Improving ED efficiency to capture additional revenue.

PubMed

Mandavia, Sujal; Samaniego, Loretta

2016-06-01

An increase in the number of patients visiting emergency departments (EDs) presents an opportunity for additional revenue if hospitals take four steps to optimize resources: Streamline the patient pathway and reduce the amount of time each patient occupies a bed in the ED. Schedule staff according to the busy and light times for patient arrivals. Perform registration and triage bedside, reducing initial wait times. Create an area for patients to wait for test results so beds can be freed up for new arrivals.

Wall-to-lumen ratio of intracranial arteries measured by indocyanine green angiography

PubMed Central

Nakagawa, Daichi; Shojima, Masaaki; Yoshino, Masanori; Kin, Taichi; Imai, Hideaki; Nomura, Seiji; Saito, Toki; Nakatomi, Hirofumi; Oyama, Hiroshi; Saito, Nobuhito

2016-01-01

Background: The wall-to-lumen ratio (WLR) is an important parameter in vascular medicine because it indicates the character of vascular wall as well as the degree of stenosis. Despite the advances in medical imaging technologies, it is still difficult to measure the thin-walled normal intracranial arteries, and the reports on the WLR of normal intracranial artery are limited. It might be possible to calculate the WLR using the indocyanine green (ICG) angiography, which is used to observe intracranial vessels during microsurgery. Purpose: To evaluate the WLR of normal intracranial arteries using ICG angiography. Materials and Methods: From the three cases in which ICG angiography was recorded with a ruler during microsurgery, 20 measurement points were chosen for the analysis. The ICG was injected intravenously with a dose of 0.2 mg/kg, and the vessels were inspected at high magnification using an operating microscope equipped with near-infrared illumination system. The vessel outer diameter and the luminal diameter were measured using the images before and after the ICG arrival based on the pixel ratio method using a ruler as reference, respectively. The WLR was calculated as 0.5 × (vessel outer diameter − vessel luminal diameter). Results: The WLR (mean ± standard deviation) of normal intracranial arteries was 0.086 ± 0.022. The WLR tended to be high in small arteries. Conclusion: The WLR of normal intracranial arteries calculated using ICG angiography was consistent with the WLR reported in the previous reports based on human autopsy. PMID:27695538

Characterization of an optimized light source and comparison to pulsed dye laser for superficial and deep vessel clearance.

PubMed

Weiss, Robert A; Ross, E Victor; Tanghetti, Emil A; Vasily, David B; Childs, James J; Smirnov, Mikhail Z; Altshuler, Gregory B

2011-02-01

An arc lamp-based device providing optimized spectrum and pulse shape was characterized and compared with two pulsed dye laser (PDL) systems using a vascular phantom. Safety and effectiveness for facial telangiectasia are presented in clinical case studies. An optimized pulsed light source's (OPL) spectral and power output were characterized and compared with two 595 nm PDL devices. Purpuric threshold fluences were determined for the OPL and PDLs on Fitzpatrick type II normal skin. A vascular phantom comprising blood-filled quartz capillaries beneath porcine skin was treated by the devices at their respective purpuric threshold fluences for 3 ms pulse widths, while vessel temperatures were monitored with an infrared (IR) camera. Patients with Fitzpatrick skin types II-III received a split-face treatment with the OPL and a 595 nm PDL. The OPL provided a dual-band output spectrum from 500 to 670 nm and 850-1,200 nm, pulse widths from 3 to 100 ms, and fluences to 80 J/cm(2). The smooth output power measured during all pulse widths provides unambiguous vessel size selectivity. Percent energy in the near infra-red increased with decreasing output power from 45% to 60% and contributed 15-26% to heating of deep vessels, respectively. At purpuric threshold fluences the ratio of OPL to PDL vessel temperature rise was 1.7-2.8. OPL treatments of facial telangiectasia were well-tolerated by patients demonstrating significant improvements comparable to PDL with no downtime. Intense pulsed light (IPL) and PDL output pulse and spectral profiles are important for selective treatment of vessels in vascular lesions. The OPL's margin between purpuric threshold fluence and treatment fluence for deeper, larger vessels was greater than the corresponding margin with PDLs. The results warrant further comparison studies with IPLs and other PDLs. Copyright © 2011 Wiley-Liss, Inc.

A boosted optimal linear learner for retinal vessel segmentation

NASA Astrophysics Data System (ADS)

Poletti, E.; Grisan, E.

2014-03-01

Ocular fundus images provide important information about retinal degeneration, which may be related to acute pathologies or to early signs of systemic diseases. An automatic and quantitative assessment of vessel morphological features, such as diameters and tortuosity, can improve clinical diagnosis and evaluation of retinopathy. At variance with available methods, we propose a data-driven approach, in which the system learns a set of optimal discriminative convolution kernels (linear learner). The set is progressively built based on an ADA-boost sample weighting scheme, providing seamless integration between linear learner estimation and classification. In order to capture the vessel appearance changes at different scales, the kernels are estimated on a pyramidal decomposition of the training samples. The set is employed as a rotating bank of matched filters, whose response is used by the boosted linear classifier to provide a classification of each image pixel into the two classes of interest (vessel/background). We tested the approach fundus images available from the DRIVE dataset. We show that the segmentation performance yields an accuracy of 0.94.

A small towed beamforming array to identify vocalizing resident killer whales ( Orcinus orca) concurrent with focal behavioral observations

NASA Astrophysics Data System (ADS)

Miller, Patrick J.; Tyack, Peter L.

Investigations of communication systems benefit from concurrent observation of vocal and visible behaviors of individual animals. A device has been developed to identify individual vocalizing resident killer whales ( Orcinus orca) during focal behavioral observations. The device consists of a 2-m, 15-element hydrophone array, which is easily towed behind a small vessel, on-board multi-channel recorders, and real-time signal processing equipment. Acoustic data from the hydrophones are digitized and processed using broadband frequency-domain beamforming to yield frequency-azimuth (FRAZ) and "directo-gram" displays of arriving sounds. Based upon statistical analysis of independent portions of typical killer whale calls, the precision of the angle-of-arrival estimate ranges from ±0° to ±2.5° with a mean precision of ±1.5°. Echolocation clicks also are resolved precisely with a typical -6 dB mainlobe width of ±2.0°. Careful positioning of the array relative to the animals minimizes the effects of depth ambiguities and allows identification of individual sources in many circumstances. Several strategies for identifying vocalizing individuals are discussed and an example of a successful identification is described. Use of the array with resident killer whales did not interfere with vessel maneuverability, animal tracking, or behavioral sampling of focal individuals. This localization technique has promise for advancing the abilities of researchers to conduct unbiased behavioral and acoustic sampling of individual free-ranging cetaceans.

Scaling of angiosperm xylem structure with safety and efficiency.

PubMed

Hacke, Uwe G; Sperry, John S; Wheeler, James K; Castro, Laura

2006-06-01

We tested the hypothesis that greater cavitation resistance correlates with less total inter-vessel pit area per vessel (the pit area hypothesis) and evaluated a trade-off between cavitation safety and transport efficiency. Fourteen species of diverse growth form (vine, ring- and diffuse-porous tree, shrub) and family affinity were added to published data predominately from the Rosaceae (29 species total). Two types of vulnerability-to-cavitation curves were found. Ring-porous trees and vines showed an abrupt drop in hydraulic conductivity with increasing negative pressure, whereas hydraulic conductivity in diffuse-porous species generally decreased gradually. The ring-porous type curve was not an artifact of the centrifuge method because it was obtained also with the air-injection technique. A safety versus efficiency trade-off was evident when curves were compared across species: for a given pressure, there was a limited range of optimal vulnerability curves. The pit area hypothesis was supported by a strong relationship (r2 = 0.77) between increasing cavitation resistance and diminishing pit membrane area per vessel (A(P)). Small A(P) was associated with small vessel surface area and hence narrow vessel diameter (D) and short vessel length (L)--consistent with an increase in vessel flow resistance with cavitation resistance. This trade-off was amplified at the tissue level by an increase in xylem/vessel area ratio with cavitation resistance. Ring-porous species were more efficient than diffuse-porous species on a vessel basis but not on a xylem basis owing to higher xylem/vessel area ratios in ring-porous anatomy. Across four orders of magnitude, lumen and end-wall resistivities maintained a relatively tight proportionality with a near-optimal mean of 56% of the total vessel resistivity residing in the end-wall. This was consistent with an underlying scaling of L to D(3/2) across species. Pit flow resistance did not increase with cavitation safety, suggesting that cavitation pressure was not related to mean pit membrane porosity.

Surrogate based wind farm layout optimization using manifold mapping

NASA Astrophysics Data System (ADS)

Kaja Kamaludeen, Shaafi M.; van Zuijle, Alexander; Bijl, Hester

2016-09-01

High computational cost associated with the high fidelity wake models such as RANS or LES serves as a primary bottleneck to perform a direct high fidelity wind farm layout optimization (WFLO) using accurate CFD based wake models. Therefore, a surrogate based multi-fidelity WFLO methodology (SWFLO) is proposed. The surrogate model is built using an SBO method referred as manifold mapping (MM). As a verification, optimization of spacing between two staggered wind turbines was performed using the proposed surrogate based methodology and the performance was compared with that of direct optimization using high fidelity model. Significant reduction in computational cost was achieved using MM: a maximum computational cost reduction of 65%, while arriving at the same optima as that of direct high fidelity optimization. The similarity between the response of models, the number of mapping points and its position, highly influences the computational efficiency of the proposed method. As a proof of concept, realistic WFLO of a small 7-turbine wind farm is performed using the proposed surrogate based methodology. Two variants of Jensen wake model with different decay coefficients were used as the fine and coarse model. The proposed SWFLO method arrived at the same optima as that of the fine model with very less number of fine model simulations.

Experimental study of optimal self compacting concrete with spent foundry sand as partial replacement for M-sand using Taguchi approach

NASA Astrophysics Data System (ADS)

Nirmala, D. B.; Raviraj, S.

2016-06-01

This paper presents the application of Taguchi approach to obtain optimal mix proportion for Self Compacting Concrete (SCC) containing spent foundry sand and M-sand. Spent foundry sand is used as a partial replacement for M-sand. The SCC mix has seven control factors namely, Coarse aggregate, M-sand with Spent Foundry sand, Cement, Fly ash, Water, Super plasticizer and Viscosity modifying agent. Modified Nan Su method is used to proportion the initial SCC mix. L18 (21×37) Orthogonal Arrays (OA) with the seven control factors having 3 levels is used in Taguchi approach which resulted in 18 SCC mix proportions. All mixtures are extensively tested both in fresh and hardened states to verify whether they meet the practical and technical requirements of SCC. The quality characteristics considering "Nominal the better" situation is applied to the test results to arrive at the optimal SCC mix proportion. Test results indicate that the optimal mix satisfies the requirements of fresh and hardened properties of SCC. The study reveals the feasibility of using spent foundry sand as a partial replacement of M-sand in SCC and also that Taguchi method is a reliable tool to arrive at optimal mix proportion of SCC.

Susceptibility-weighted imaging using inter-echo-variance channel combination for improved contrast at 7 tesla.

PubMed

Hosseini, Zahra; Liu, Junmin; Solovey, Igor; Menon, Ravi S; Drangova, Maria

2017-04-01

To implement and optimize a new approach for susceptibility-weighted image (SWI) generation from multi-echo multi-channel image data and compare its performance against optimized traditional SWI pipelines. Five healthy volunteers were imaged at 7 Tesla. The inter-echo-variance (IEV) channel combination, which uses the variance of the local frequency shift at multiple echo times as a weighting factor during channel combination, was used to calculate multi-echo local phase shift maps. Linear phase masks were combined with the magnitude to generate IEV-SWI. The performance of the IEV-SWI pipeline was compared with that of two accepted SWI pipelines-channel combination followed by (i) Homodyne filtering (HPH-SWI) and (ii) unwrapping and high-pass filtering (SVD-SWI). The filtering steps of each pipeline were optimized. Contrast-to-noise ratio was used as the comparison metric. Qualitative assessment of artifact and vessel conspicuity was performed and processing time of pipelines was evaluated. The optimized IEV-SWI pipeline (σ = 7 mm) resulted in continuous vessel visibility throughout the brain. IEV-SWI had significantly higher contrast compared with HPH-SWI and SVD-SWI (P < 0.001, Friedman nonparametric test). Residual background fields and phase wraps in HPH-SWI and SVD-SWI corrupted the vessel signal and/or generated vessel-mimicking artifact. Optimized implementation of the IEV-SWI pipeline processed a six-echo 16-channel dataset in under 10 min. IEV-SWI benefits from channel-by-channel processing of phase data and results in high contrast images with an optimal balance between contrast and background noise removal, thereby presenting evidence of importance of the order in which postprocessing techniques are applied for multi-channel SWI generation. 2 J. Magn. Reson. Imaging 2017;45:1113-1124. © 2016 International Society for Magnetic Resonance in Medicine.

Optimization and guidance of flight trajectories for the national aerospace plane

NASA Technical Reports Server (NTRS)

Miele, Angelo

1990-01-01

The research on optimal trajectories for the National Aerospace Plane (NASP) performed by the Aero-Astronautics Group of Rice University from June 22, 1989 to December 31, 1990 is summarized. The aerospace plane is assumed to be controlled via the angle of attack and the power setting. The time history of the controls is optimized simultaneously with the switch times from one powerplant to another and the final time. The intent is to arrive at NASP guidance trajectories exhibiting many of the desirable characteristics of NASP optimal trajectories.

A Hamiltonian approach to the planar optimization of mid-course corrections

NASA Astrophysics Data System (ADS)

Iorfida, E.; Palmer, P. L.; Roberts, M.

2016-04-01

Lawden's primer vector theory gives a set of necessary conditions that characterize the optimality of a transfer orbit, defined accordingly to the possibility of adding mid-course corrections. In this paper a novel approach is proposed where, through a polar coordinates transformation, the primer vector components decouple. Furthermore, the case when transfer, departure and arrival orbits are coplanar is analyzed using a Hamiltonian approach. This procedure leads to approximate analytic solutions for the in-plane components of the primer vector. Moreover, the solution for the circular transfer case is proven to be the Hill's solution. The novel procedure reduces the mathematical and computational complexity of the original case study. It is shown that the primer vector is independent of the semi-major axis of the transfer orbit. The case with a fixed transfer trajectory and variable initial and final thrust impulses is studied. The acquired related optimality maps are presented and analyzed and they express the likelihood of a set of trajectories to be optimal. Furthermore, it is presented which kind of requirements have to be fulfilled by a set of departure and arrival orbits to have the same profile of primer vector.

Constrained Optimization of Average Arrival Time via a Probabilistic Approach to Transport Reliability

PubMed Central

Namazi-Rad, Mohammad-Reza; Dunbar, Michelle; Ghaderi, Hadi; Mokhtarian, Payam

2015-01-01

To achieve greater transit-time reduction and improvement in reliability of transport services, there is an increasing need to assist transport planners in understanding the value of punctuality; i.e. the potential improvements, not only to service quality and the consumer but also to the actual profitability of the service. In order for this to be achieved, it is important to understand the network-specific aspects that affect both the ability to decrease transit-time, and the associated cost-benefit of doing so. In this paper, we outline a framework for evaluating the effectiveness of proposed changes to average transit-time, so as to determine the optimal choice of average arrival time subject to desired punctuality levels whilst simultaneously minimizing operational costs. We model the service transit-time variability using a truncated probability density function, and simultaneously compare the trade-off between potential gains and increased service costs, for several commonly employed cost-benefit functions of general form. We formulate this problem as a constrained optimization problem to determine the optimal choice of average transit time, so as to increase the level of service punctuality, whilst simultaneously ensuring a minimum level of cost-benefit to the service operator. PMID:25992902

Severe limb ischemia syndrome.

PubMed

Suchý, T

1991-01-01

In the course of the study of the syndrome of severe limb ischemia (SLI) in a representative clinical material of 300 patients and a number of experimental studies, we arrived to the proposal of this optimal methodical procedure for acute vascular closures of traumatic and non-traumatic origin in the limbs: a) In every injury and sudden pain with a change of the function of the limb, it is necessary to think of the SLI syndrome and to search targetedly for it. b) In injuries connected with bleeding our first-rate task is the control of this bleeding. For a temporary arrest of the bleeding it is necessary to prefer more physiological methods sparing collateral circulation to the still most used tourniquet. For this purpose a new device for temporary hemostasis called Hemostop has proved itself, designed by the author and attested both experimentally and clinically, protected as a Czechoslovak patent. From surgical measures have acquitted themselves from this viewpoint the insertion of vascular clamp, ligature of the vessel or its temporary cannulation. c) To set the diagnosis of SLI, it usually suffices a careful anamnesis and clinical examination, advantageous is the investigation by ultrasound. The angiography because of time consumption should be used only in indicated cases. d) The time factor--"race against the time"--has to be always borne on our mind. It is necessary to achieve the recovery of blood circulation in the limb up to 6 or at the latest up to 10 hours from the onset of injury or closure. e) For shortening of the period of tissue hypoxia it is of advantage to use the temporary cannulation of injured vessels. This should be used always, whenever because of any reasons, it is not possible to execute the final reconstructive operation up to 10 hours since the injury, e. g. in polytraumatism, transport difficulties and the like. f) In isolated vascular injuries without bleeding (about 45%) and in all non-traumatic SLI the patients must be efficiently heparinized (i. v. administration, at best by infusion) to prevent the growth of the distal thrombus. g) Final vascular reconstruction should be performed only by erudited surgeons, always with thromboctomy and in protected coagulum. Optimal reconstructive performance should be chosen: for embolism the thromboembolectomy, for acute thrombosis usually the bypassing the afflicted vascular portion by the graft, in injuries appears as the optimal reconstructive measure the anastomosis end to end. At the simultaneous or isolated lesion of the stem vein, we must always try to reconstruct it.(ABSTRACT TRUNCATED AT 400 WORDS)

International piracy and armed robbery at sea : hindering maritime trade and water transportation around the world

DOT National Transportation Integrated Search

2010-04-01

Pirates prey upon targets of opportunity. Given optimal conditions (e.g., calm weather, slow cruising speed, and daylight4) relatively small, fast vessels (e.g., containerships) may be no less at risk than large, slower vessels (e.g., crude carriers)...

Flattening maps for the visualization of multibranched vessels.

PubMed

Zhu, Lei; Haker, Steven; Tannenbaum, Allen

2005-02-01

In this paper, we present two novel algorithms which produce flattened visualizations of branched physiological surfaces, such as vessels. The first approach is a conformal mapping algorithm based on the minimization of two Dirichlet functionals. From a triangulated representation of vessel surfaces, we show how the algorithm can be implemented using a finite element technique. The second method is an algorithm which adjusts the conformal mapping to produce a flattened representation of the original surface while preserving areas. This approach employs the theory of optimal mass transport. Furthermore, a new way of extracting center lines for vessel fly-throughs is provided.

Flattening Maps for the Visualization of Multibranched Vessels

PubMed Central

Zhu, Lei; Haker, Steven; Tannenbaum, Allen

2013-01-01

In this paper, we present two novel algorithms which produce flattened visualizations of branched physiological surfaces, such as vessels. The first approach is a conformal mapping algorithm based on the minimization of two Dirichlet functionals. From a triangulated representation of vessel surfaces, we show how the algorithm can be implemented using a finite element technique. The second method is an algorithm which adjusts the conformal mapping to produce a flattened representation of the original surface while preserving areas. This approach employs the theory of optimal mass transport. Furthermore, a new way of extracting center lines for vessel fly-throughs is provided. PMID:15707245

Blood flow quantification using 1D CFD parameter identification

NASA Astrophysics Data System (ADS)

Brosig, Richard; Kowarschik, Markus; Maday, Peter; Katouzian, Amin; Demirci, Stefanie; Navab, Nassir

2014-03-01

Patient-specific measurements of cerebral blood flow provide valuable diagnostic information concerning cerebrovascular diseases rather than visually driven qualitative evaluation. In this paper, we present a quantitative method to estimate blood flow parameters with high temporal resolution from digital subtraction angiography (DSA) image sequences. Using a 3D DSA dataset and a 2D+t DSA sequence, the proposed algorithm employs a 1D Computational Fluid Dynamics (CFD) model for estimation of time-dependent flow values along a cerebral vessel, combined with an additional Advection Diffusion Equation (ADE) for contrast agent propagation. The CFD system, followed by the ADE, is solved with a finite volume approximation, which ensures the conservation of mass. Instead of defining a new imaging protocol to obtain relevant data, our cost function optimizes the bolus arrival time (BAT) of the contrast agent in 2D+t DSA sequences. The visual determination of BAT is common clinical practice and can be easily derived from and be compared to values, generated by a 1D-CFD simulation. Using this strategy, we ensure that our proposed method fits best to clinical practice and does not require any changes to the medical work flow. Synthetic experiments show that the recovered flow estimates match the ground truth values with less than 12% error in the mean flow rates.

Orbital Transfer Techniques for Round-Trip Mars Missions

NASA Technical Reports Server (NTRS)

Landau, Damon

2013-01-01

The human exploration of Phobos and Deimos or the retrieval of a surface sample launched to low-Mars orbit presents a highly constrained orbital transfer problem. In general, the plane of the target orbit will not be accessible from the arrival or departure interplanetary trajectories with an (energetically optimal) tangential burn at periapsis. The orbital design is further complicated by the addition of a high-energy parking orbit for the relatively massive Deep Space Vehicle to reduce propellant expenditure, while the crew transfers to and from the target orbit in a smaller Space Exploration Vehicle. The proposed strategy shifts the arrival and departure maneuvers away from periapsis so that the apsidal line of the parking orbit lies in the plane of the target orbit, permitting highly efficient plane change maneuvers at apoapsis of the elliptical parking orbit. An apsidal shift during the arrival or departure maneuver is approximately five times as efficient as maneuvering while in Mars orbit, thus significantly reducing the propellant necessary to transfer between the arrival, target, and departure orbits.

Computed tomography angiography-fluoroscopy image fusion allows visceral vessel cannulation without angiography during fenestrated endovascular aneurysm repair.

PubMed

Schwein, Adeline; Chinnadurai, Ponraj; Behler, Greg; Lumsden, Alan B; Bismuth, Jean; Bechara, Carlos F

2018-07-01

Fenestrated endovascular aneurysm repair (FEVAR) is an evolving technique to treat juxtarenal abdominal aortic aneurysms (AAAs). Catheterization of visceral and renal vessels after the deployment of the fenestrated main body device is often challenging, usually requiring additional fluoroscopy and multiple digital subtraction angiograms. The aim of this study was to assess the clinical utility and accuracy of a computed tomography angiography (CTA)-fluoroscopy image fusion technique in guiding visceral vessel cannulation during FEVAR. Between August 2014 and September 2016, all consecutive patients who underwent FEVAR at our institution using image fusion guidance were included. Preoperative CTA images were fused with intraoperative fluoroscopy after coregistering with non-contrast-enhanced cone beam computed tomography (syngo 3D3D image fusion; Siemens Healthcare, Forchheim, Germany). The ostia of the visceral vessels were electronically marked on CTA images (syngo iGuide Toolbox) and overlaid on live fluoroscopy to guide vessel cannulation after fenestrated device deployment. Clinical utility of image fusion was evaluated by assessing the number of dedicated angiograms required for each visceral or renal vessel cannulation and the use of optimized C-arm angulation. Accuracy of image fusion was evaluated from video recordings by three raters using a binary qualitative assessment scale. A total of 26 patients (17 men; mean age, 73.8 years) underwent FEVAR during the study period for juxtarenal AAA (17), pararenal AAA (6), and thoracoabdominal aortic aneurysm (3). Video recordings of fluoroscopy from 19 cases were available for review and assessment. A total of 46 vessels were cannulated; 38 of 46 (83%) of these vessels were cannulated without angiography but based only on image fusion guidance: 9 of 11 superior mesenteric artery cannulations and 29 of 35 renal artery cannulations. Binary qualitative assessment showed that 90% (36/40) of the virtual ostia overlaid on live fluoroscopy were accurate. Optimized C-arm angulations were achieved in 35% of vessel cannulations (0/9 for superior mesenteric artery cannulation, 12/25 for renal arteries). Preoperative CTA-fluoroscopy image fusion guidance during FEVAR is a valuable and accurate tool that allows visceral and renal vessel cannulation without the need of dedicated angiograms, thus avoiding additional injection of contrast material and radiation exposure. Further refinements, such as accounting for device-induced aortic deformation and automating the image fusion workflow, will bolster this technology toward optimal routine clinical use. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Modeling the Spatial Dynamics of International Tuna Fleets

PubMed Central

2016-01-01

We developed an iterative sequential random utility model to investigate the social and environmental determinants of the spatiotemporal decision process of tuna purse-seine fishery fishing effort in the eastern Pacific Ocean. Operations of the fishing gear mark checkpoints in a continuous complex decision-making process. Individual fisher behavior is modeled by identifying diversified choices over decision-space for an entire fishing trip, which allows inclusion of prior and current vessel locations and conditions among the explanatory variables. Among these factors are vessel capacity; departure and arrival port; duration of the fishing trip; daily and cumulative distance travelled, which provides a proxy for operation costs; expected revenue; oceanographic conditions; and tons of fish on board. The model uses a two-step decision process to capture the probability of a vessel choosing a specific fishing region for the first set and the probability of switching to (or staying in) a specific region to fish before returning to its landing port. The model provides a means to anticipate the success of marine resource management, and it can be used to evaluate fleet diversity in fisher behavior, the impact of climate variability, and the stability and resilience of complex coupled human and natural systems. PMID:27537545

A Conceptual Design of a Departure Planner Decision Aid

NASA Technical Reports Server (NTRS)

Anagnostakis, Ioannis; Idris, Husni R.; Clark, John-Paul; Feron, Eric; Hansman, R. John; Odoni, Amedeo R.; Hall, William D.

2000-01-01

Terminal area Air Traffic Management handles both arriving and departing traffic. To date, research work on terminal area operations has focused primarily on the arrival flow and typically departures are taken into account only in an approximate manner. However, arrivals and departures are highly coupled processes especially in the terminal airspace, with complex interactions and sharing of the same airport resources between arrivals and departures taking place in practically every important terminal area. Therefore, the addition of automation aids for departures, possibly in co-operation with existing arrival flow automation systems, could have a profound contribution in enhancing the overall efficiency of airport operations. This paper presents the conceptual system architecture for such an automation aid, the Departure Planner (DP). This architecture can be used as a core in the development of decision-aiding systems to assist air traffic controllers in improving the performance of departure operations and optimize runway time allocation among different operations at major congested airports. The design of such systems is expected to increase the overall efficiency of terminal area operations and yield benefits for all stakeholders involved in Air Traffic Management (ATM) operations, users as well as service providers.

Real-time correction of beamforming time delay errors in abdominal ultrasound imaging

NASA Astrophysics Data System (ADS)

Rigby, K. W.

2000-04-01

The speed of sound varies with tissue type, yet commercial ultrasound imagers assume a constant sound speed. Sound speed variation in abdominal fat and muscle layers is widely believed to be largely responsible for poor contrast and resolution in some patients. The simplest model of the abdominal wall assumes that it adds a spatially varying time delay to the ultrasound wavefront. The adequacy of this model is controversial. We describe an adaptive imaging system consisting of a GE LOGIQ 700 imager connected to a multi- processor computer. Arrival time errors for each beamforming channel, estimated by correlating each channel signal with the beamsummed signal, are used to correct the imager's beamforming time delays at the acoustic frame rate. A multi- row transducer provides two-dimensional sampling of arrival time errors. We observe significant improvement in abdominal images of healthy male volunteers: increased contrast of blood vessels, increased visibility of the renal capsule, and increased brightness of the liver.

A hybrid inventory management system respondingto regular demand and surge demand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammad S. Roni; Mingzhou Jin; Sandra D. Eksioglu

2014-06-01

This paper proposes a hybrid policy for a stochastic inventory system facing regular demand and surge demand. The combination of two different demand patterns can be observed in many areas, such as healthcare inventory and humanitarian supply chain management. The surge demand has a lower arrival rate but higher demand volume per arrival. The solution approach proposed in this paper incorporates the level crossing method and mixed integer programming technique to optimize the hybrid inventory policy with both regular orders and emergency orders. The level crossing method is applied to obtain the equilibrium distributions of inventory levels under a givenmore » policy. The model is further transformed into a mixed integer program to identify an optimal hybrid policy. A sensitivity analysis is conducted to investigate the impact of parameters on the optimal inventory policy and minimum cost. Numerical results clearly show the benefit of using the proposed hybrid inventory model. The model and solution approach could help healthcare providers or humanitarian logistics providers in managing their emergency supplies in responding to surge demands.« less

A Human-in-the Loop Evaluation of a Coordinated Arrival Departure Scheduling Operations for Managing Departure Delays at LaGuardia Airport

NASA Technical Reports Server (NTRS)

Lee, Paul U.; Smith, Nancy M.; Bienert, Nancy; Brasil, Connie; Buckley, Nathan; Chevalley, Eric; Homola, Jeffrey; Omar, Faisal; Parke, Bonny; Yoo, Hyo-Sang

2016-01-01

LaGuardia (LGA) departure delay was identified by the stakeholders and subject matter experts as a significant bottleneck in the New York metropolitan area. Departure delay at LGA is primarily due to dependency between LGA's arrival and departure runways: LGA departures cannot begin takeoff until arrivals have cleared the runway intersection. If one-in one-out operations are not maintained and a significant arrival-to-departure imbalance occurs, the departure backup can persist through the rest of the day. At NASA Ames Research Center, a solution called "Departure-sensitive Arrival Spacing" (DSAS) was developed to maximize the departure throughput without creating significant delays in the arrival traffic. The concept leverages a Terminal Sequencing and Spacing (TSS) operations that create and manage the arrival schedule to the runway threshold and added an interface enhancement to the traffic manager's timeline to provide the ability to manually adjust inter-arrival spacing to build precise gaps for multiple departures between arrivals. A more complete solution would include a TSS algorithm enhancement that could automatically build these multi-departure gaps. With this set of capabilities, inter-arrival spacing could be controlled for optimal departure throughput. The concept was prototyped in a human-in-the- loop (HITL) simulation environment so that operational requirements such as coordination procedures, timing and magnitude of TSS schedule adjustments, and display features for Tower, TRACON and Traffic Management Unit could be determined. A HITL simulation was conducted in August 2014 to evaluate the concept in terms of feasibility, controller workload impact, and potential benefits. Three conditions were tested, namely a Baseline condition without scheduling, TSS condition that schedules the arrivals to the runway threshold, and TSS+DSAS condition that adjusts the arrival schedule to maximize the departure throughput. The results showed that during high arrival demand period, departure throughput could be incrementally increased under TSS and TSS+DSAS conditions without compromising the arrival throughput. The concept, operational procedures, and summary results were originally published in ATM20151 but detailed results were omitted. This paper expands on the earlier paper to provide the detailed results on throughput, conformance, safety, flight time/distance, etc. that provide extra insights into the feasibility and the potential benefits on the concept.

Do Vascular Networks Branch Optimally or Randomly across Spatial Scales?

PubMed Central

Newberry, Mitchell G.; Savage, Van M.

2016-01-01

Modern models that derive allometric relationships between metabolic rate and body mass are based on the architectural design of the cardiovascular system and presume sibling vessels are symmetric in terms of radius, length, flow rate, and pressure. Here, we study the cardiovascular structure of the human head and torso and of a mouse lung based on three-dimensional images processed via our software Angicart. In contrast to modern allometric theories, we find systematic patterns of asymmetry in vascular branching, potentially explaining previously documented mismatches between predictions (power-law or concave curvature) and observed empirical data (convex curvature) for the allometric scaling of metabolic rate. To examine why these systematic asymmetries in vascular branching might arise, we construct a mathematical framework to derive predictions based on local, junction-level optimality principles that have been proposed to be favored in the course of natural selection and development. The two most commonly used principles are material-cost optimizations (construction materials or blood volume) and optimization of efficient flow via minimization of power loss. We show that material-cost optimization solutions match with distributions for asymmetric branching across the whole network but do not match well for individual junctions. Consequently, we also explore random branching that is constrained at scales that range from local (junction-level) to global (whole network). We find that material-cost optimizations are the strongest predictor of vascular branching in the human head and torso, whereas locally or intermediately constrained random branching is comparable to material-cost optimizations for the mouse lung. These differences could be attributable to developmentally-programmed local branching for larger vessels and constrained random branching for smaller vessels. PMID:27902691

MIDAS - Mission design and analysis software for the optimization of ballistic interplanetary trajectories

NASA Technical Reports Server (NTRS)

Sauer, Carl G., Jr.

1989-01-01

A patched conic trajectory optimization program MIDAS is described that was developed to investigate a wide variety of complex ballistic heliocentric transfer trajectories. MIDAS includes the capability of optimizing trajectory event times such as departure date, arrival date, and intermediate planetary flyby dates and is able to both add and delete deep space maneuvers when dictated by the optimization process. Both powered and unpowered flyby or gravity assist trajectories of intermediate bodies can be handled and capability is included to optimize trajectories having a rendezvous with an intermediate body such as for a sample return mission. Capability is included in the optimization process to constrain launch energy and launch vehicle parking orbit parameters.

Opportunities for shear energy scaling in bulk acoustic wave resonators.

PubMed

Jose, Sumy; Hueting, Raymond J E

2014-10-01

An important energy loss contribution in bulk acoustic wave resonators is formed by so-called shear waves, which are transversal waves that propagate vertically through the devices with a horizontal motion. In this work, we report for the first time scaling of the shear-confined spots, i.e., spots containing a high concentration of shear wave displacement, controlled by the frame region width at the edge of the resonator. We also demonstrate a novel methodology to arrive at an optimum frame region width for spurious mode suppression and shear wave confinement. This methodology makes use of dispersion curves obtained from finite-element method (FEM) eigenfrequency simulations for arriving at an optimum frame region width. The frame region optimization is demonstrated for solidly mounted resonators employing several shear wave optimized reflector stacks. Finally, the FEM simulation results are compared with measurements for resonators with Ta2O5/ SiO2 stacks showing suppression of the spurious modes.

Optimizing Integrated Terminal Airspace Operations Under Uncertainty

NASA Technical Reports Server (NTRS)

Bosson, Christabelle; Xue, Min; Zelinski, Shannon

2014-01-01

In the terminal airspace, integrated departures and arrivals have the potential to increase operations efficiency. Recent research has developed geneticalgorithm- based schedulers for integrated arrival and departure operations under uncertainty. This paper presents an alternate method using a machine jobshop scheduling formulation to model the integrated airspace operations. A multistage stochastic programming approach is chosen to formulate the problem and candidate solutions are obtained by solving sample average approximation problems with finite sample size. Because approximate solutions are computed, the proposed algorithm incorporates the computation of statistical bounds to estimate the optimality of the candidate solutions. A proof-ofconcept study is conducted on a baseline implementation of a simple problem considering a fleet mix of 14 aircraft evolving in a model of the Los Angeles terminal airspace. A more thorough statistical analysis is also performed to evaluate the impact of the number of scenarios considered in the sampled problem. To handle extensive sampling computations, a multithreading technique is introduced.

T2‐Weighted intracranial vessel wall imaging at 7 Tesla using a DANTE‐prepared variable flip angle turbo spin echo readout (DANTE‐SPACE)

PubMed Central

Viessmann, Olivia; Li, Linqing; Benjamin, Philip

2016-01-01

Purpose To optimize intracranial vessel wall imaging (VWI) at 7T for sharp wall depiction and high boundary contrast. Methods A variable flip angle turbo spin echo scheme (SPACE) was optimized for VWI. SPACE provides black‐blood contrast, but has less crushing effect on cerebrospinal fluid (CSF). However, a delay alternating with nutation for tailored excitation (DANTE) preparation suppresses the signal from slowly moving spins of a few mm per second. Therefore, we optimized a DANTE‐preparation module for 7T. Signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and signal ratio for vessel wall, CSF, and lumen were calculated for SPACE and DANTE‐SPACE in 11 volunteers at the middle cerebral artery (MCA). An exemplar MCA stenosis patient was scanned with DANTE‐SPACE. Results The 7T‐optimized SPACE sequence improved the vessel wall point‐spread function by 17%. The CNR between the wall and CSF was doubled (12.2 versus 5.6) for the DANTE‐SPACE scans compared with the unprepared SPACE. This increase was significant in the right hemisphere (P = 0.016), but not in the left (P = 0.090). The CNR between wall and lumen was halved, but remained at a high value (24.9 versus 56.5). Conclusion The optimized SPACE sequence improves VWI at 7T. Additional DANTE preparation increases the contrast between the wall and CSF. Increased outer boundary contrast comes at the cost of reduced inner boundary contrast. Magn Reson Med 77:655–663, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26890988

Optimal Transport Destination for Ischemic Stroke Patients With Unknown Vessel Status: Use of Prehospital Triage Scores.

PubMed

Schlemm, Eckhard; Ebinger, Martin; Nolte, Christian H; Endres, Matthias; Schlemm, Ludwig

2017-08-01

Patients with acute ischemic stroke (AIS) and large vessel occlusion may benefit from direct transportation to an endovascular capable comprehensive stroke center (mothership approach) as opposed to direct transportation to the nearest stroke unit without endovascular therapy (drip and ship approach). The optimal transport strategy for patients with AIS and unknown vessel status is uncertain. The rapid arterial occlusion evaluation scale (RACE, scores ranging from 0 to 9, with higher scores indicating higher stroke severity) correlates with the National Institutes of Health Stroke Scale and was developed to identify patients with large vessel occlusion in a prehospital setting. We evaluate how the RACE scale can help to inform prehospital triage decisions for AIS patients. In a model-based approach, we estimate probabilities of good outcome (modified Rankin Scale score of ≤2 at 3 months) as a function of severity of stroke symptoms and transport times for the mothership approach and the drip and ship approach. We use these probabilities to obtain optimal RACE cutoff scores for different transfer time settings and combinations of treatment options (time-based eligibility for secondary transfer under the drip and ship approach, time-based eligibility for thrombolysis at the comprehensive stroke center under the mothership approach). In our model, patients with AIS are more likely to benefit from direct transportation to the comprehensive stroke center if they have more severe strokes. Values of the optimal RACE cutoff scores range from 0 (mothership for all patients) to >9 (drip and ship for all patients). Shorter transfer times and longer door-to-needle and needle-to-transfer (door out) times are associated with lower optimal RACE cutoff scores. Use of RACE cutoff scores that take into account transport times to triage AIS patients to the nearest appropriate hospital may lead to improved outcomes. Further studies should examine the feasibility of translation into clinical practice. © 2017 American Heart Association, Inc.

T2-Weighted intracranial vessel wall imaging at 7 Tesla using a DANTE-prepared variable flip angle turbo spin echo readout (DANTE-SPACE).

PubMed

Viessmann, Olivia; Li, Linqing; Benjamin, Philip; Jezzard, Peter

2017-02-01

To optimize intracranial vessel wall imaging (VWI) at 7T for sharp wall depiction and high boundary contrast. A variable flip angle turbo spin echo scheme (SPACE) was optimized for VWI. SPACE provides black-blood contrast, but has less crushing effect on cerebrospinal fluid (CSF). However, a delay alternating with nutation for tailored excitation (DANTE) preparation suppresses the signal from slowly moving spins of a few mm per second. Therefore, we optimized a DANTE-preparation module for 7T. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal ratio for vessel wall, CSF, and lumen were calculated for SPACE and DANTE-SPACE in 11 volunteers at the middle cerebral artery (MCA). An exemplar MCA stenosis patient was scanned with DANTE-SPACE. The 7T-optimized SPACE sequence improved the vessel wall point-spread function by 17%. The CNR between the wall and CSF was doubled (12.2 versus 5.6) for the DANTE-SPACE scans compared with the unprepared SPACE. This increase was significant in the right hemisphere (P = 0.016), but not in the left (P = 0.090). The CNR between wall and lumen was halved, but remained at a high value (24.9 versus 56.5). The optimized SPACE sequence improves VWI at 7T. Additional DANTE preparation increases the contrast between the wall and CSF. Increased outer boundary contrast comes at the cost of reduced inner boundary contrast. Magn Reson Med 77:655-663, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

An epidemiological study of rates of illness in passengers and crew at a busy Caribbean cruise port.

PubMed

Marshall, Cathy Ann; Morris, Euclid; Unwin, Nigel

2016-04-12

The Caribbean has one of the largest cruise ship industries in the world, with close to 20 million visitors per year. The potential for communicable disease outbreaks on vessels and the transmission by ship between countries is high. Barbados has one of the busiest ports in the Caribbean. Our aim was to describe and analyse the epidemiology of illnesses experienced by passengers and crew arriving at the Bridgetown Port, Barbados between 2009 and 2013. Data on the illnesses recorded were extracted from the passenger and crew arrival registers and passenger and crew illness logs for all ships and maritime vessels arriving at Barbados' Ports and passing through its territorial waters between January 2009 and December 2013. Data were entered into an Epi Info database and most of the analysis undertaken using Epi Info Version 7. Rates per 100,000 visits were calculated, and confidence intervals on these were derived using the software Openepi. There were 1031 cases of illness from over 3 million passenger visits and 1 million crew visits during this period. The overall event rate for communicable illnesses was 15.7 (95 % CI 14.4-17.1) per 100,000 passengers, and for crew was 24.0 (21.6-26.6) per 100, 000 crew. Gastroenteritis was the predominant illness experienced by passengers and crew followed by influenza. The event rate for gastroenteritis among passengers was 13.7 (12.5-15.0) per 100,000 and 14.4 (12.6, 16.5) for crew. The event rate for non-communicable illnesses was 3.4 per 100,000 passengers with myocardial infarction being the main diagnosis. The event rate for non-communicable illnesses among crew was 2.1 per 100,000, the leading cause being injuries. The predominant illnesses reported were gastroenteritis and influenza similar to previous published reports from around the world. This study is the first of its type in the Caribbean and the data provide a baseline for future surveillance and for comparison with other countries and regions.

Buses of Cuernavaca—an agent-based model for universal random matrix behavior minimizing mutual information

NASA Astrophysics Data System (ADS)

Warchoł, Piotr

2018-06-01

The public transportation system of Cuernavaca, Mexico, exhibits random matrix theory statistics. In particular, the fluctuation of times between the arrival of buses on a given bus stop, follows the Wigner surmise for the Gaussian unitary ensemble. To model this, we propose an agent-based approach in which each bus driver tries to optimize his arrival time to the next stop with respect to an estimated arrival time of his predecessor. We choose a particular form of the associated utility function and recover the appropriate distribution in numerical experiments for a certain value of the only parameter of the model. We then investigate whether this value of the parameter is otherwise distinguished within an information theoretic approach and give numerical evidence that indeed it is associated with a minimum of averaged pairwise mutual information.

Collaborative Arrival Planning: Data Sharing and User Preference Tools

NASA Technical Reports Server (NTRS)

Zelenka, Richard E.; Edwards, Thomas A. (Technical Monitor)

1998-01-01

Air traffic growth and air carrier economic pressures have motivated efforts to increase the flexibility of the air traffic management process and change the relationship between the air traffic control service provider and the system user. One of the most visible of these efforts is the U.S. government/industry "free flight" initiative, in which the service provider concentrates on safety and cross-airline fairness, and the user on their business objectives and operating preferences, including selecting their own path and speed in real-time. In the terminal arrival phase of flight, severe restrictions and rigid control are currently placed on system users, typically without regard for individual user operational preferences. Airborne delays applied to arriving aircraft into capacity constrained airports are imposed on a first-come, first-serve basis, and thus do not allow the system user to plan for or prioritize late arrivals, or to economically optimize their arrival sequence. A central tenant of the free-flight operating paradigm is collaboration between service providers and users in reaching air traffic management decisions. Such collaboration would be particularly beneficial to an airline's "hub" operation, where off-schedule arrival aircraft are a consistent problem, as they cause serious air-port ramp difficulties, rippling airline scheduling effects, and result in large economic inefficiencies. Greater collaboration can also lead to increased airport capacity and decrease the severity of over-capacity rush periods. In the NASA Collaborative Arrival Planning (CAP) project, both independent exchange of real-time data between the service provider and system user and collaborative decision support tools are addressed. Data exchange of real-time arrival scheduling, airspace management, and air carrier fleet data between the FAA service provider and an air carrier is being conducted and evaluated. Collaborative arrival decision support tools to allow intra-airline arrival preferences are being developed and simulated. The CAP project is part of and leveraged from the NASA/FAA Center TRACON Automation System (CTAS), a fielded set of decision support tools that provide computer generated advisories for both enroute and terminal area controllers to manage and control arrival traffic more efficiently. In this paper, the NASA Collaborative Arrival Planning project is outlined and recent results detailed, including the real-time use of CTAS arrival scheduling data by a major air carrier and simulations of tactical and strategic user preference decision support tools.

The optimization air separation plants for combined cycle MHD-power plant applications

NASA Technical Reports Server (NTRS)

Juhasz, A. J.; Springmann, H.; Greenberg, R.

1980-01-01

Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD combined cycle power plants.

Cascading Delay Risk of Airline Workforce Deployments with Crew Pairing and Schedule Optimization.

PubMed

Chung, Sai Ho; Ma, Hoi Lam; Chan, Hing Kai

2017-08-01

This article concerns the assignment of buffer time between two connected flights and the number of reserve crews in crew pairing to mitigate flight disruption due to flight arrival delay. Insufficient crew members for a flight will lead to flight disruptions such as delays or cancellations. In reality, most of these disruption cases are due to arrival delays of the previous flights. To tackle this problem, many research studies have examined the assignment method based on the historical flight arrival delay data of the concerned flights. However, flight arrival delays can be triggered by numerous factors. Accordingly, this article proposes a new forecasting approach using a cascade neural network, which considers a massive amount of historical flight arrival and departure data. The approach also incorporates learning ability so that unknown relationships behind the data can be revealed. Based on the expected flight arrival delay, the buffer time can be determined and a new dynamic reserve crew strategy can then be used to determine the required number of reserve crews. Numerical experiments are carried out based on one year of flight data obtained from 112 airports around the world. The results demonstrate that by predicting the flight departure delay as the input for the prediction of the flight arrival delay, the prediction accuracy can be increased. Moreover, by using the new dynamic reserve crew strategy, the total crew cost can be reduced. This significantly benefits airlines in flight schedule stability and cost saving in the current big data era. © 2016 Society for Risk Analysis.

Prediction of the Critical Curvature for LX-17 with the Time of Arrival Data from DNS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Jin; Fried, Laurence E.; Moss, William C.

2017-01-10

We extract the detonation shock front velocity, curvature and acceleration from time of arrival data measured at grid points from direct numerical simulations of a 50mm rate-stick lit by a disk-source, with the ignition and growth reaction model and a JWL equation of state calibrated for LX-17. We compute the quasi-steady (D, κ) relation based on the extracted properties and predicted the critical curvatures of LX-17. We also proposed an explicit formula that contains the failure turning point, obtained from optimization for the (D, κ) relation of LX-17.

The cost of noise reduction for departure and arrival operations of commercial tilt rotor aircraft

NASA Technical Reports Server (NTRS)

Faulkner, H. B.; Swan, W. M.

1976-01-01

The relationship between direct operating cost (DOC) and noise annoyance due to a departure and an arrival operation was developed for commercial tilt rotor aircraft. This was accomplished by generating a series of tilt rotor aircraft designs to meet various noise goals at minimum DOC. These vehicles ranged across the spectrum of possible noise levels from completely unconstrained to the quietest vehicles that could be designed within the study ground rules. Optimization parameters were varied to find the minimum DOC. This basic variation was then extended to different aircraft sizes and technology time frames.

Validation of the Gatortail method for accurate sizing of pulmonary vessels from 3D medical images.

PubMed

O'Dell, Walter G; Gormaley, Anne K; Prida, David A

2017-12-01

Detailed characterization of changes in vessel size is crucial for the diagnosis and management of a variety of vascular diseases. Because clinical measurement of vessel size is typically dependent on the radiologist's subjective interpretation of the vessel borders, it is often prone to high inter- and intra-user variability. Automatic methods of vessel sizing have been developed for two-dimensional images but a fully three-dimensional (3D) method suitable for vessel sizing from volumetric X-ray computed tomography (CT) or magnetic resonance imaging has heretofore not been demonstrated and validated robustly. In this paper, we refined and objectively validated Gatortail, a method that creates a mathematical geometric 3D model of each branch in a vascular tree, simulates the appearance of the virtual vascular tree in a 3D CT image, and uses the similarity of the simulated image to a patient's CT scan to drive the optimization of the model parameters, including vessel size, to match that of the patient. The method was validated with a 2-dimensional virtual tree structure under deformation, and with a realistic 3D-printed vascular phantom in which the diameter of 64 branches were manually measured 3 times each. The phantom was then scanned on a conventional clinical CT imaging system and the images processed with the in-house software to automatically segment and mathematically model the vascular tree, label each branch, and perform the Gatortail optimization of branch size and trajectory. Previously proposed methods of vessel sizing using matched Gaussian filters and tubularity metrics were also tested. The Gatortail method was then demonstrated on the pulmonary arterial tree segmented from a human volunteer's CT scan. The standard deviation of the difference between the manually measured and Gatortail-based radii in the 3D physical phantom was 0.074 mm (0.087 in-plane pixel units for image voxels of dimension 0.85 × 0.85 × 1.0 mm) over the 64 branches, representing vessel diameters ranging from 1.2 to 7 mm. The linear regression fit gave a slope of 1.056 and an R 2 value of 0.989. These three metrics reflect superior agreement of the radii estimates relative to previously published results over all sizes tested. Sizing via matched Gaussian filters resulted in size underestimates of >33% over all three test vessels, while the tubularity-metric matching exhibited a sizing uncertainty of >50%. In the human chest CT data set, the vessel voxel intensity profiles with and without branch model optimization showed excellent agreement and improvement in the objective measure of image similarity. Gatortail has been demonstrated to be an automated, objective, accurate and robust method for sizing of vessels in 3D non-invasively from chest CT scans. We anticipate that Gatortail, an image-based approach to automatically compute estimates of blood vessel radii and trajectories from 3D medical images, will facilitate future quantitative evaluation of vascular response to disease and environmental insult and improve understanding of the biological mechanisms underlying vascular disease processes. © 2017 American Association of Physicists in Medicine.

Analysis of sequencing and scheduling methods for arrival traffic

NASA Technical Reports Server (NTRS)

Neuman, Frank; Erzberger, Heinz

1990-01-01

The air traffic control subsystem that performs scheduling is discussed. The function of the scheduling algorithms is to plan automatically the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several important scheduling algorithms are described and the statistical performance of the scheduling algorithms is examined. Scheduling brings order to an arrival sequence for aircraft. First-come-first-served scheduling (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the traffic, gaps will remain in the scheduled sequence of aircraft. These gaps are filled, or partially filled, by time-advancing the leading aircraft after a gap while still preserving the FCFS order. Tightly scheduled groups of aircraft remain with a mix of heavy and large aircraft. Separation requirements differ for different types of aircraft trailing each other. Advantage is taken of this fact through mild reordering of the traffic, thus shortening the groups and reducing average delays. Actual delays for different samples with the same statistical parameters vary widely, especially for heavy traffic.

Ensemble Modeling of the July 23, 2012 CME Event

NASA Astrophysics Data System (ADS)

Cash, M. D.; Biesecker, D. A.; Millward, G.; Arge, C. N.; Henney, C. J.

2013-12-01

On July 23, 2012 a large and very fast coronal mass ejection (CME) was observed by STEREO A. This CME was unusual in that the estimates of the speed of the CME ranged from 2125 km/s to 2780 km/s based on dividing the distance of STEREO A from the Sun by the transit time of the CME. Modeling of this CME event with the WSA-Enlil model has also suggested that a very fast speed is required in order to obtain the correct arrival time at 1 AU. We present a systematic study of parameter space for the July 23, 2012 CME event through an ensemble study using the WSA-Enlil model to predict the arrival time of the CME at STEREO A. We investigate how variations in the initial speed, angular width, and direction affect the predicted arrival time. We also explore how variations in the background solar wind influence CME arrival time by using varying ADAPT maps within our ensemble study. Factors involved in the fast transit time of this large CME are discussed and the optimal CME parameters are presented.

Comparison of vessel enhancement algorithms applied to time-of-flight MRA images for cerebrovascular segmentation.

PubMed

Phellan, Renzo; Forkert, Nils D

2017-11-01

Vessel enhancement algorithms are often used as a preprocessing step for vessel segmentation in medical images to improve the overall segmentation accuracy. Each algorithm uses different characteristics to enhance vessels, such that the most suitable algorithm may vary for different applications. This paper presents a comparative analysis of the accuracy gains in vessel segmentation generated by the use of nine vessel enhancement algorithms: Multiscale vesselness using the formulas described by Erdt (MSE), Frangi (MSF), and Sato (MSS), optimally oriented flux (OOF), ranking orientations responses path operator (RORPO), the regularized Perona-Malik approach (RPM), vessel enhanced diffusion (VED), hybrid diffusion with continuous switch (HDCS), and the white top hat algorithm (WTH). The filters were evaluated and compared based on time-of-flight MRA datasets and corresponding manual segmentations from 5 healthy subjects and 10 patients with an arteriovenous malformation. Additionally, five synthetic angiographic datasets with corresponding ground truth segmentation were generated with three different noise levels (low, medium, and high) and also used for comparison. The parameters for each algorithm and subsequent segmentation were optimized using leave-one-out cross evaluation. The Dice coefficient, Matthews correlation coefficient, area under the ROC curve, number of connected components, and true positives were used for comparison. The results of this study suggest that vessel enhancement algorithms do not always lead to more accurate segmentation results compared to segmenting nonenhanced images directly. Multiscale vesselness algorithms, such as MSE, MSF, and MSS proved to be robust to noise, while diffusion-based filters, such as RPM, VED, and HDCS ranked in the top of the list in scenarios with medium or no noise. Filters that assume tubular-shapes, such as MSE, MSF, MSS, OOF, RORPO, and VED show a decrease in accuracy when considering patients with an AVM, because vessels may vary from its tubular-shape in this case. Vessel enhancement algorithms can help to improve the accuracy of the segmentation of the vascular system. However, their contribution to accuracy has to be evaluated as it depends on the specific applications, and in some cases it can lead to a reduction of the overall accuracy. No specific filter was suitable for all tested scenarios. © 2017 American Association of Physicists in Medicine.

KSC-2012-3565

NASA Image and Video Library

2012-06-28

CAPE CANAVERAL, Fla. - Secured inside a transportation container, the Orion crew module arrives at the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. NASA's Michoud Assembly Facility in New Orleans built the crew module pressure vessel. The Orion production team will prepare the module for flight by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Jim Grossmann

KSC-2012-3595

NASA Image and Video Library

2012-06-29

CAPE CANAVERAL, Fla. - The Orion crew module is unwrapped after its arrival in the Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. NASA's Michoud Assembly Facility in New Orleans built the crew module pressure vessel. The Orion production team will prepare the module for flight by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Gianni Woods

KSC-2012-3567

NASA Image and Video Library

2012-06-28

CAPE CANAVERAL, Fla. - The Orion crew module, packed inside a transportation canister, arrives inside the high bay of the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. NASA's Michoud Assembly Facility in New Orleans built the crew module pressure vessel. The Orion production team will prepare the module for flight by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Jim Grossmann

Analysis of delay reducing and fuel saving sequencing and spacing algorithms for arrival traffic

NASA Technical Reports Server (NTRS)

Neuman, Frank; Erzberger, Heinz

1991-01-01

The air traffic control subsystem that performs sequencing and spacing is discussed. The function of the sequencing and spacing algorithms is to automatically plan the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several algorithms are described and their statistical performance is examined. Sequencing brings order to an arrival sequence for aircraft. First-come-first-served sequencing (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the arriving traffic, gaps will remain in the sequence of aircraft. Delays are reduced by time-advancing the leading aircraft of each group while still preserving the FCFS order. Tightly spaced groups of aircraft remain with a mix of heavy and large aircraft. Spacing requirements differ for different types of aircraft trailing each other. Traffic is reordered slightly to take advantage of this spacing criterion, thus shortening the groups and reducing average delays. For heavy traffic, delays for different traffic samples vary widely, even when the same set of statistical parameters is used to produce each sample. This report supersedes NASA TM-102795 on the same subject. It includes a new method of time-advance as well as an efficient method of sequencing and spacing for two dependent runways.

Flexible Composite-Material Pressure Vessel

NASA Technical Reports Server (NTRS)

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

Segmentation of the heart and major vascular structures in cardiovascular CT images

NASA Astrophysics Data System (ADS)

Peters, J.; Ecabert, O.; Lorenz, C.; von Berg, J.; Walker, M. J.; Ivanc, T. B.; Vembar, M.; Olszewski, M. E.; Weese, J.

2008-03-01

Segmentation of organs in medical images can be successfully performed with shape-constrained deformable models. A surface mesh is attracted to detected image boundaries by an external energy, while an internal energy keeps the mesh similar to expected shapes. Complex organs like the heart with its four chambers can be automatically segmented using a suitable shape variablility model based on piecewise affine degrees of freedom. In this paper, we extend the approach to also segment highly variable vascular structures. We introduce a dedicated framework to adapt an extended mesh model to freely bending vessels. This is achieved by subdividing each vessel into (short) tube-shaped segments ("tubelets"). These are assigned to individual similarity transformations for local orientation and scaling. Proper adaptation is achieved by progressively adapting distal vessel parts to the image only after proximal neighbor tubelets have already converged. In addition, each newly activated tubelet inherits the local orientation and scale of the preceeding one. To arrive at a joint segmentation of chambers and vasculature, we extended a previous model comprising endocardial surfaces of the four chambers, the left ventricular epicardium, and a pulmonary artery trunk. Newly added are the aorta (ascending and descending plus arch), superior and inferior vena cava, coronary sinus, and four pulmonary veins. These vessels are organized as stacks of triangulated rings. This mesh configuration is most suitable to define tubelet segments. On 36 CT data sets reconstructed at several cardiac phases from 17 patients, segmentation accuracies of 0.61-0.80mm are obtained for the cardiac chambers. For the visible parts of the newly added great vessels, surface accuracies of 0.47-1.17mm are obtained (larger errors are asscociated with faintly contrasted venous structures).

[Introduction and advantage analysis of the stepwise method for the construction of vascular trees].

PubMed

Zhang, Yan; Xie, Haiwei; Zhu, Kai

2010-08-01

A new method for constructing the model of vascular trees was proposed in this paper. By use of this method, the arterial trees in good agreement with the actual structure could be grown. In this process, all vessels in the vascular tree were divided into two groups: the conveying vessels, and the delivering branches. And different branches could be built by different ways. Firstly, the distributing rules of conveying vessels were ascertained by use of measurement data, and then the conveying vessels were constructed in accordance to the statistical rule and optimization criterion. Lastly, delivering branches were modeled by constrained constructive optimization (CCO) on the conveying vessel-trees which had already been generated. In order to compare the CCO method and stepwise method proposed here, two 3D arterial trees of human tongue were grown with their vascular tree having a special structure. Based on the corrosion casts of real arterial tree of human tongue, the data about the two trees constructed by different methods were compared and analyzed, including the averaged segment diameters at respective levels, the distribution and the diameters of the branches of first level at respective directions. The results show that the vascular tree built by stepwise method is more similar to the true arterial of human tongue when compared against the tree built by CCO method.

76 FR 184 - Notice of Buy American Waiver Under the American Recovery and Reinvestment Act of 2009

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-03

... a system that is built into a vessel's hull to reduce rolling motion when operating at sea. DATES... vessel to periodically work well beyond the Arctic waters that the hull was initially optimized for. At that time, the design of the ARRV was fairly well advanced. Besides the addition of hull length to...

Bioinspired Concepts: Unified Theory for Complex Biological and Engineering Systems

DTIC Science & Technology

2006-01-01

i.e., data flows of finite size arrive at the system randomly. For such a system , we propose a modified dual scheduling algorithm that stabilizes ...demon. We compute the efficiency of the controller over finite and infinite time intervals, and since the controller is optimal, this yields hard limits...and highly optimized tolerance. PNAS, 102, 2005. 51. G. N. Nair and R. J. Evans. Stabilizability of stochastic linear systems with finite feedback

A study on the impact of prioritising emergency department arrivals on the patient waiting time.

PubMed

Van Bockstal, Ellen; Maenhout, Broos

2018-05-03

In the past decade, the crowding of the emergency department has gained considerable attention of researchers as the number of medical service providers is typically insufficient to fulfil the demand for emergency care. In this paper, we solve the stochastic emergency department workforce planning problem and consider the planning of nurses and physicians simultaneously for a real-life case study in Belgium. We study the patient arrival pattern of the emergency department in depth and consider different patient acuity classes by disaggregating the arrival pattern. We determine the personnel staffing requirements and the design of the shifts based on the patient arrival rates per acuity class such that the resource staffing cost and the weighted patient waiting time are minimised. In order to solve this multi-objective optimisation problem, we construct a Pareto set of optimal solutions via the -constraints method. For a particular staffing composition, the proposed model minimises the patient waiting time subject to upper bounds on the staffing size using the Sample Average Approximation Method. In our computational experiments, we discern the impact of prioritising the emergency department arrivals. Triaging results in lower patient waiting times for higher priority acuity classes and to a higher waiting time for the lowest priority class, which does not require immediate care. Moreover, we perform a sensitivity analysis to verify the impact of the arrival and service pattern characteristics, the prioritisation weights between different acuity classes and the incorporated shift flexibility in the model.

Initial Investigations of Controller Tools and Procedures for Schedule-Based Arrival Operations with Mixed Flight-Deck Interval Management Equipage

NASA Technical Reports Server (NTRS)

Callantine, Todd J.; Cabrall, Christopher; Kupfer, Michael; Omar, Faisal G.; Prevot, Thomas

2012-01-01

NASA?s Air Traffic Management Demonstration-1 (ATD-1) is a multi-year effort to demonstrate high-throughput, fuel-efficient arrivals at a major U.S. airport using NASA-developed scheduling automation, controller decision-support tools, and ADS-B-enabled Flight-Deck Interval Management (FIM) avionics. First-year accomplishments include the development of a concept of operations for managing scheduled arrivals flying Optimized Profile Descents with equipped aircraft conducting FIM operations, and the integration of laboratory prototypes of the core ATD-1 technologies. Following each integration phase, a human-in-the-loop simulation was conducted to evaluate and refine controller tools, procedures, and clearance phraseology. From a ground-side perspective, the results indicate the concept is viable and the operations are safe and acceptable. Additional training is required for smooth operations that yield notable benefits, particularly in the areas of FIM operations and clearance phraseology.

Tracking sperm whales with a towed acoustic vector sensor.

PubMed

Thode, Aaron; Skinner, Jeff; Scott, Pam; Roswell, Jeremy; Straley, Janice; Folkert, Kendall

2010-11-01

Passive acoustic towed linear arrays are increasingly used to detect marine mammal sounds during mobile anthropogenic activities. However, these arrays cannot resolve between signals arriving from the port or starboard without vessel course changes or multiple cable deployments, and their performance is degraded by vessel self-noise and non-acoustic mechanical vibration. In principle acoustic vector sensors can resolve these directional ambiguities, as well as flag the presence of non-acoustic contamination, provided that the vibration-sensitive sensors can be successfully integrated into compact tow modules. Here a vector sensor module attached to the end of a 800 m towed array is used to detect and localize 1813 sperm whale "clicks" off the coast of Sitka, AK. Three methods were used to identify frequency regimes relatively free of non-acoustic noise contamination, and then the active intensity (propagating energy) of the signal was computed between 4-10 kHz along three orthogonal directions, providing unambiguous bearing estimates of two sperm whales over time. These bearing estimates are consistent with those obtained via conventional methods, but the standard deviations of the vector sensor bearing estimates are twice those of the conventionally-derived bearings. The resolved ambiguities of the bearings deduced from vessel course changes match the vector sensor predictions.

Particle swarm optimization method for small retinal vessels detection on multiresolution fundus images.

PubMed

Khomri, Bilal; Christodoulidis, Argyrios; Djerou, Leila; Babahenini, Mohamed Chaouki; Cheriet, Farida

2018-05-01

Retinal vessel segmentation plays an important role in the diagnosis of eye diseases and is considered as one of the most challenging tasks in computer-aided diagnosis (CAD) systems. The main goal of this study was to propose a method for blood-vessel segmentation that could deal with the problem of detecting vessels of varying diameters in high- and low-resolution fundus images. We proposed to use the particle swarm optimization (PSO) algorithm to improve the multiscale line detection (MSLD) method. The PSO algorithm was applied to find the best arrangement of scales in the MSLD method and to handle the problem of multiscale response recombination. The performance of the proposed method was evaluated on two low-resolution (DRIVE and STARE) and one high-resolution fundus (HRF) image datasets. The data include healthy (H) and diabetic retinopathy (DR) cases. The proposed approach improved the sensitivity rate against the MSLD by 4.7% for the DRIVE dataset and by 1.8% for the STARE dataset. For the high-resolution dataset, the proposed approach achieved 87.09% sensitivity rate, whereas the MSLD method achieves 82.58% sensitivity rate at the same specificity level. When only the smallest vessels were considered, the proposed approach improved the sensitivity rate by 11.02% and by 4.42% for the healthy and the diabetic cases, respectively. Integrating the proposed method in a comprehensive CAD system for DR screening would allow the reduction of false positives due to missed small vessels, misclassified as red lesions. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

The possibility of instability in NGATS upstream control of flow into airports

DOT National Transportation Integrated Search

2006-10-01

Representation, estimation and optimization of airport capacity has been a subject of research since the 1950s. Typically the concern has been to establish constraints on the Pareto constraint curve for various combinations of arrival and departure f...

A near-optimal low complexity sensor fusion technique for accurate indoor localization based on ultrasound time of arrival measurements from low-quality sensors

NASA Astrophysics Data System (ADS)

Mitilineos, Stelios A.; Argyreas, Nick D.; Thomopoulos, Stelios C. A.

2009-05-01

A fusion-based localization technique for location-based services in indoor environments is introduced herein, based on ultrasound time-of-arrival measurements from multiple off-the-shelf range estimating sensors which are used in a market-available localization system. In-situ field measurements results indicated that the respective off-the-shelf system was unable to estimate position in most of the cases, while the underlying sensors are of low-quality and yield highly inaccurate range and position estimates. An extensive analysis is performed and a model of the sensor-performance characteristics is established. A low-complexity but accurate sensor fusion and localization technique is then developed, which consists inof evaluating multiple sensor measurements and selecting the one that is considered most-accurate based on the underlying sensor model. Optimality, in the sense of a genie selecting the optimum sensor, is subsequently evaluated and compared to the proposed technique. The experimental results indicate that the proposed fusion method exhibits near-optimal performance and, albeit being theoretically suboptimal, it largely overcomes most flaws of the underlying single-sensor system resulting in a localization system of increased accuracy, robustness and availability.

Optimal Routing and Control of Multiple Agents Moving in a Transportation Network and Subject to an Arrival Schedule and Separation Constraints

NASA Technical Reports Server (NTRS)

Sadovsky, A. V.; Davis, D.; Isaacson, D. R.

2012-01-01

We address the problem of navigating a set of moving agents, e.g. automated guided vehicles, through a transportation network so as to bring each agent to its destination at a specified time. Each pair of agents is required to be separated by a minimal distance, generally agent-dependent, at all times. The speed range, initial position, required destination, and required time of arrival at destination for each agent are assumed provided. The movement of each agent is governed by a controlled differential equation (state equation). The problem consists in choosing for each agent a path and a control strategy so as to meet the constraints and reach the destination at the required time. This problem arises in various fields of transportation, including Air Traffic Management and train coordination, and in robotics. The main contribution of the paper is a model that allows to recast this problem as a decoupled collection of problems in classical optimal control and is easily generalized to the case when inertia cannot be neglected. Some qualitative insight into solution behavior is obtained using the Pontryagin Maximum Principle. Sample numerical solutions are computed using a numerical optimal control solver.

Prediction of Large Vessel Occlusions in Acute Stroke: National Institute of Health Stroke Scale Is Hard to Beat.

PubMed

Vanacker, Peter; Heldner, Mirjam R; Amiguet, Michael; Faouzi, Mohamed; Cras, Patrick; Ntaios, George; Arnold, Marcel; Mattle, Heinrich P; Gralla, Jan; Fischer, Urs; Michel, Patrik

2016-06-01

Endovascular treatment for acute ischemic stroke with a large vessel occlusion was recently shown to be effective. We aimed to develop a score capable of predicting large vessel occlusion eligible for endovascular treatment in the early hospital management. Retrospective, cohort study. Two tertiary, Swiss stroke centers. Consecutive acute ischemic stroke patients (1,645 patients; Acute STroke Registry and Analysis of Lausanne registry), who had CT angiography within 6 and 12 hours of symptom onset, were categorized according to the occlusion site. Demographic and clinical information was used in logistic regression analysis to derive predictors of large vessel occlusion (defined as intracranial carotid, basilar, and M1 segment of middle cerebral artery occlusions). Based on logistic regression coefficients, an integer score was created and validated internally and externally (848 patients; Bernese Stroke Registry). None. Large vessel occlusions were present in 316 patients (21%) in the derivation and 566 (28%) in the external validation cohort. Five predictors added significantly to the score: National Institute of Health Stroke Scale at admission, hemineglect, female sex, atrial fibrillation, and no history of stroke and prestroke handicap (modified Rankin Scale score, < 2). Diagnostic accuracy in internal and external validation cohorts was excellent (area under the receiver operating characteristic curve, 0.84 both). The score performed slightly better than National Institute of Health Stroke Scale alone regarding prediction error (Wilcoxon signed rank test, p < 0.001) and regarding discriminatory power in derivation and pooled cohorts (area under the receiver operating characteristic curve, 0.81 vs 0.80; DeLong test, p = 0.02). Our score accurately predicts the presence of emergent large vessel occlusions, which are eligible for endovascular treatment. However, incorporation of additional demographic and historical information available on hospital arrival provides minimal incremental predictive value compared with the National Institute of Health Stroke Scale alone.

The PulsePoint Respond mobile device application to crowdsource basic life support for patients with out-of-hospital cardiac arrest: Challenges for optimal implementation.

PubMed

Brooks, Steven C; Simmons, Graydon; Worthington, Heather; Bobrow, Bentley J; Morrison, Laurie J

2016-01-01

PulsePoint Respond is a novel mobile device application that notifies citizens within 400 m (∼ 1/4 mile) of a suspected cardiac arrest to facilitate resuscitation. Our objectives were to (1) characterize users, and (2) understand their behavior after being sent a notification. We sought to identify challenges for optimal implementation of PulsePoint-mediated bystander resuscitation. PulsePoint Respond users who sent a notification between 04/07/2012 and 06/16/2014 were invited to participate in an online survey. At the beginning of our study, PulsePoint Respond was active in more than 600 US communities. There were 1274 completed surveys (response rate 1448/6777, 21.4%). Respondents were firefighters (28%), paramedics (18%), emergency medical technicians (9%), nurses (7%), MDs (1%), other health care professionals (12%), and non-health care professionals (42%). Of those who received a PulsePoint notification, only 23% (189/813) responded to the PulsePoint notification. Of those who responded, 28% (52/187) did not arrive on scene. Of those who did arrive on scene, only 32% (44/135) found a person unconscious and not breathing normally. Of those who arrived on scene prior to emergency medical services and found a cardiac arrest victim, 79% (11/14) performed bystander cardiopulmonary resuscitation. Challenges for optimal implementation of PulsePoint Respond include technical aspects of the notifications (audio volume, precision of location information), excessive activation radii, insufficient user density in the community, and suboptimal cardiac arrest notification specificity. PulsePoint Respond has the potential to improve the community response to cardiac arrest, with 80% of responders attempting basic life support when they found a cardiac arrest victim prior to EMS. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mechanical characterization of atherosclerotic arteries using finite-element modeling: feasibility study on mock arteries.

PubMed

Pazos, Valérie; Mongrain, Rosaire; Tardif, Jean-Claude

2010-06-01

Clinical studies on lipid-lowering therapy have shown that changing the composition of lipid pools reduced significantly the risk of cardiac events associated with plaque rupture. It has been shown also that changing the composition of the lipid pool affects its mechanical properties. However, knowledge about the mechanical properties of human atherosclerotic lesions remains limited due to the difficulty of the experiments. This paper aims to assess the feasibility of characterizing a lipid pool embedded in the wall of a pressurized vessel using finite-element simulations and an optimization algorithm. Finite-element simulations of inflation experiments were used together with nonlinear least squares algorithm to estimate the material model parameters of the wall and of the inclusion. An optimal fit of the simulated experiment and the real experiment was sought with the parameter estimation algorithm. The method was first tested on a single-layer polyvinyl alcohol (PVA) cryogel stenotic vessel, and then, applied on a double-layered PVA cryogel stenotic vessel with a lipid inclusion.

Optimization of window settings for standard and advanced virtual monoenergetic imaging in abdominal dual-energy CT angiography.

PubMed

Caruso, Damiano; Parinella, Ashley H; Schoepf, U Joseph; Stroebel, Maxwell H; Mangold, Stefanie; Wichmann, Julian L; Varga-Szemes, Akos; Ball, B Devon; De Santis, Domenico; Laghi, Andrea; De Cecco, Carlo N

2017-03-01

To determine the optimal window setting for displaying virtual monoenergetic reconstructions of third generation dual-source, dual-energy CT (DECT) angiography of the abdomen. Forty-five patients were evaluated with DECT angiography (90/150 kV, 180/90 ref. mAs). Three datasets were reconstructed: standard linear blending (M_0.6), 70 keV traditional virtual monoenergetic (M70), and 40 keV advanced noise-optimized virtual monoenergetic (M40+). The best window setting (width and level, W/L) was assessed by two blinded observers and was correlated with aortic attenuation to obtain the Optimized W/L setting (O-W/L). Subjective image quality was assessed, and vessel diameters were measured to determine any possible influences between different W/L settings. Repeated measures of variance were used to evaluate comparison of W/L values, image quality, and vessel sizing between M_0.6, M70, and M40+. The Best W/L (B-W/L) for M70 and M40+ was 880/280 and 1410/450, respectively. Results from regression analysis inferred an O-W/L of 850/270 for M70 and 1350/430 for M40+. Significant differences for W and L were found between the Best and the Optimized W/L for M40+, and between M70 and M40+ for both the Best and Optimized W/L. No significant differences for vessel measurements were found using the O-W/L for M40+ compared to the standard M_0.6 (p ≥ 0.16), and significant differences were observed when using the B-W/L with M40+ compared to M_0.6 (p ≤ 0.04). In order to optimize virtual monoenergetic imaging with both traditional M70 and advanced M40+, adjusting the W/L settings is necessary. Our results suggest a W/L setting of 850/270 for M70 and 1350/430 for M40+.

Murray's Law in elastin haploinsufficient (Eln+/-) and wild-type (WT) mice.

PubMed

Sather, Bradley A; Hageman, Daniel; Wagenseil, Jessica E

2012-12-01

Using either the principle of minimum energy or constant shear stress, a relation can be derived that predicts the diameters of branching vessels at a bifurcation. This relation, known as Murray's Law, has been shown to predict vessel diameters in a variety of cardiovascular systems from adult humans to developing chicks. The goal of this study is to investigate Murray's Law in vessels from mice that are haploinsufficient for the elastin protein (Eln+/-). Elastin is one of the major proteins in the blood vessel wall and is organized in concentric rings, known as lamellae, with smooth muscle cells (SMCs) around the vessel lumen. Eln+/- mice have an increased number of lamellae, as well as smaller, thinner vessels. It is possible that due to decreased amounts of elastin available for vessel wall remodeling during development and in adulthood, Eln+/- vessels would not follow Murray's Law. We examined vessel bifurcations in six different physiologic regions, including the brain, heart, epidermis, ceocum (or cecum), testes, and intestines, in Eln+/- mice and wild-type (WT) littermates. All vessels were between 40 and 300 μm in diameter. We found that the diameters of both Eln+/- and WT vessels have an average of 13% error from the diameters predicted by Murray's Law, with no significant differences between genotypes or physiologic regions. The data suggest that vessels are optimized to follow Murray's Law, despite limitations on the proteins available for growth and remodeling of the vessel wall.

Forecasting spring from afar? Timing of migration and predictability of phenology along different migration routes of an avian herbivore.

PubMed

Kölzsch, Andrea; Bauer, Silke; de Boer, Rob; Griffin, Larry; Cabot, David; Exo, Klaus-Michael; van der Jeugd, Henk P; Nolet, Bart A

2015-01-01

Herbivorous birds are hypothesized to migrate in spring along a seasonal gradient of plant profitability towards their breeding grounds (green wave hypothesis). For Arctic breeding species in particular, following highly profitable food is important, so that they can replenish resources along the way and arrive in optimal body condition to start breeding early. We compared the timing of migratory movements of Arctic breeding geese on different flyways to examine whether flyways differed in the predictability of spring conditions at stopovers and whether this was reflected in the degree to which birds were following the green wave. Barnacle geese (Branta leucopsis) were tracked with solar GPS/ARGOS PTTs from their wintering grounds to breeding sites in Greenland (N = 7), Svalbard (N = 21) and the Barents Sea (N = 12). The numerous stopover sites of all birds were combined into a set of 16 general stopover regions. The predictability of climatic conditions along the flyways was calculated as the correlation and slope between onsets of spring at consecutive stopovers. These values differed between sites, mainly because of the presence or absence of ecological barriers. Goose arrival at stopovers was more closely tied to the local onset of spring when predictability was higher and when geese attempted breeding that year. All birds arrived at early stopovers after the onset of spring and arrived at the breeding grounds before the onset of spring, thus overtaking the green wave. This is in accordance with patterns expected for capital breeders: first, they must come into condition; at intermediate stopovers, arrival with the food quality peak is important to stay in condition, and at the breeding grounds, early arrival is favoured so that hatching of young can coincide with the peak of food quality. Our results suggest that a chain of correlations between climatic conditions at subsequent stopovers enables geese to closely track the green wave. However, the birds' precision of migratory timing seems uninfluenced by ecological barriers, indicating partly fixed migration schedules. These might become non-optimal due to climate warming and preclude accurate timing of long-distance migrants in the future. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Advanced 3D mesh manipulation in stereolithographic files and post-print processing for the manufacturing of patient-specific vascular flow phantoms

NASA Astrophysics Data System (ADS)

O'Hara, Ryan P.; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M.; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N.

2016-03-01

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms.

PubMed

O'Hara, Ryan P; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N

2016-02-27

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 - 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations.

Advanced 3D Mesh Manipulation in Stereolithographic Files and Post-Print Processing for the Manufacturing of Patient-Specific Vascular Flow Phantoms

PubMed Central

O’Hara, Ryan P.; Chand, Arpita; Vidiyala, Sowmya; Arechavala, Stacie M.; Mitsouras, Dimitrios; Rudin, Stephen; Ionita, Ciprian N.

2017-01-01

Complex vascular anatomies can cause the failure of image-guided endovascular procedures. 3D printed patient-specific vascular phantoms provide clinicians and medical device companies the ability to preemptively plan surgical treatments, test the likelihood of device success, and determine potential operative setbacks. This research aims to present advanced mesh manipulation techniques of stereolithographic (STL) files segmented from medical imaging and post-print surface optimization to match physiological vascular flow resistance. For phantom design, we developed three mesh manipulation techniques. The first method allows outlet 3D mesh manipulations to merge superfluous vessels into a single junction, decreasing the number of flow outlets and making it feasible to include smaller vessels. Next we introduced Boolean operations to eliminate the need to manually merge mesh layers and eliminate errors of mesh self-intersections that previously occurred. Finally we optimize support addition to preserve the patient anatomical geometry. For post-print surface optimization, we investigated various solutions and methods to remove support material and smooth the inner vessel surface. Solutions of chloroform, alcohol and sodium hydroxide were used to process various phantoms and hydraulic resistance was measured and compared with values reported in literature. The newly mesh manipulation methods decrease the phantom design time by 30 – 80% and allow for rapid development of accurate vascular models. We have created 3D printed vascular models with vessel diameters less than 0.5 mm. The methods presented in this work could lead to shorter design time for patient specific phantoms and better physiological simulations. PMID:28649165

Medical Problem-Solving: A Critique of the Literature.

ERIC Educational Resources Information Center

McGuire, Christine H.

1985-01-01

Prescriptive, decision-analysis of medical problem-solving has been based on decision theory that involves calculation and manipulation of complex probability and utility values to arrive at optimal decisions that will maximize patient benefits. The studies offer a methodology for improving clinical judgment. (Author/MLW)

Optimizing the admission time of outbound trucks entering a cross-dock with uniform arrival time by considering a queuing model

NASA Astrophysics Data System (ADS)

Motaghedi-Larijani, Arash; Aminnayeri, Majid

2017-03-01

Cross-docking is a supply-chain strategy that can reduce transportation and inventory costs. This study is motivated by a fruit and vegetable distribution centre in Tehran, which has cross-docks and a limited time to admit outbound trucks. In this article, outbound trucks are assumed to arrive at the cross-dock with a single outbound door with a uniform distribution (0,L). The total number of assigned trucks is constant and the loading time is fixed. A queuing model is modified for this situation and the expected waiting time of each customer is calculated. Then, a curve for the waiting time is calculated. Finally, the length of window time L is optimized to minimize the total cost, which includes the waiting time of the trucks and the admission cost of the cross-dock. Some illustrative examples of cross-docking are presented and solved using the proposed method.

The effects of invasive pests and pathogens on strategies for forest diversification.

PubMed

Macpherson, Morag F; Kleczkowski, Adam; Healey, John R; Quine, Christopher P; Hanley, Nick

2017-04-24

Diversification of the tree species composition of production forests is a frequently advocated strategy to increase resilience to pests and pathogens; however, there is a lack of a general framework to analyse the impact of economic and biological conditions on the optimal planting strategy in the presence of tree disease. To meet this need we use a novel bioeconomic model to quantitatively assess the effect of tree disease on the optimal planting proportion of two tree species. We find that diversifying the species composition can reduce the economic loss from disease even when the benefit from the resistant species is small. However, this key result is sensitive to a pathogen's characteristics (probability of arrival, time of arrival, rate of spread of infection) and the losses (damage of the disease to the susceptible species and reduced benefit of planting the resistant species). This study provides an exemplar framework which can be used to help understand the effect of a pathogen on forest management strategies.

Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization

NASA Astrophysics Data System (ADS)

Gay, H. A.; Allison, R. R.; Downie, G. H.; Mota, H. C.; Austerlitz, C.; Jenkins, T.; Sibata, C. H.

2007-06-01

A number of patients with lung cancer receive either palliative or curative high-dose-rate (HDR) endobronchial brachytherapy. Up to a third of patients treated with endobronchial HDR die from hemoptysis. Rather than accept hemoptysis as an expected potential consequence of HDR, we have calculated the radial dose distribution for an Ir-192 HDR source, rigorously examined the dose and prescription points recommended by the American Brachytherapy Society (ABS), and performed a radiobiological-based analysis. The radial dose rate of a commercially available Ir-192 source was calculated with a Monte Carlo simulation. Based on the linear quadratic model, the estimated palliative, curative and blood vessel rupture radii from the center of an Ir-192 source were obtained for the ABS recommendations and a series of customized HDR prescriptions. The estimated radius at risk for blood vessel perforation for the ABS recommendations ranges from 7 to 9 mm. An optimized prescription may in some situations reduce this radius to 4 mm. The estimated blood perforation radius is generally smaller than the palliative radius. Optimized and individualized endobronchial HDR prescriptions are currently feasible based on our current understanding of tumor and normal tissue radiobiology. Individualized prescriptions could minimize complications such as fatal hemoptysis without sacrificing efficacy. Fiducial stents, HDR catheter centering or spacers and the use of CT imaging to better assess the relationship between the catheter and blood vessels promise to be useful strategies for increasing the therapeutic index of this treatment modality. Prospective trials employing treatment optimization algorithms are needed.

Three-dimensional virtual surgery models for percutaneous coronary intervention (PCI) optimization strategies

NASA Astrophysics Data System (ADS)

Wang, Hujun; Liu, Jinghua; Zheng, Xu; Rong, Xiaohui; Zheng, Xuwei; Peng, Hongyu; Silber-Li, Zhanghua; Li, Mujun; Liu, Liyu

2015-06-01

Percutaneous coronary intervention (PCI), especially coronary stent implantation, has been shown to be an effective treatment for coronary artery disease. However, in-stent restenosis is one of the longstanding unsolvable problems following PCI. Although stents implanted inside narrowed vessels recover normal flux of blood flows, they instantaneously change the wall shear stress (WSS) distribution on the vessel surface. Improper stent implantation positions bring high possibilities of restenosis as it enlarges the low WSS regions and subsequently stimulates more epithelial cell outgrowth on vessel walls. To optimize the stent position for lowering the risk of restenosis, we successfully established a digital three-dimensional (3-D) model based on a real clinical coronary artery and analysed the optimal stenting strategies by computational simulation. Via microfabrication and 3-D printing technology, the digital model was also converted into in vitro microfluidic models with 3-D micro channels. Simultaneously, physicians placed real stents inside them; i.e., they performed “virtual surgeries”. The hydrodynamic experimental results showed that the microfluidic models highly inosculated the simulations. Therefore, our study not only demonstrated that the half-cross stenting strategy could maximally reduce restenosis risks but also indicated that 3-D printing combined with clinical image reconstruction is a promising method for future angiocardiopathy research.

Automatic Tortuosity-Based Retinopathy of Prematurity Screening System

NASA Astrophysics Data System (ADS)

Sukkaew, Lassada; Uyyanonvara, Bunyarit; Makhanov, Stanislav S.; Barman, Sarah; Pangputhipong, Pannet

Retinopathy of Prematurity (ROP) is an infant disease characterized by increased dilation and tortuosity of the retinal blood vessels. Automatic tortuosity evaluation from retinal digital images is very useful to facilitate an ophthalmologist in the ROP screening and to prevent childhood blindness. This paper proposes a method to automatically classify the image into tortuous and non-tortuous. The process imitates expert ophthalmologists' screening by searching for clearly tortuous vessel segments. First, a skeleton of the retinal blood vessels is extracted from the original infant retinal image using a series of morphological operators. Next, we propose to partition the blood vessels recursively using an adaptive linear interpolation scheme. Finally, the tortuosity is calculated based on the curvature of the resulting vessel segments. The retinal images are then classified into two classes using segments characterized by the highest tortuosity. For an optimal set of training parameters the prediction is as high as 100%.

The effect of model uncertainty on some optimal routing problems

NASA Technical Reports Server (NTRS)

Mohanty, Bibhu; Cassandras, Christos G.

1991-01-01

The effect of model uncertainties on optimal routing in a system of parallel queues is examined. The uncertainty arises in modeling the service time distribution for the customers (jobs, packets) to be served. For a Poisson arrival process and Bernoulli routing, the optimal mean system delay generally depends on the variance of this distribution. However, as the input traffic load approaches the system capacity the optimal routing assignment and corresponding mean system delay are shown to converge to a variance-invariant point. The implications of these results are examined in the context of gradient-based routing algorithms. An example of a model-independent algorithm using online gradient estimation is also included.

Design Optimization of Gas Generator Hybrid Propulsion Boosters

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Phillips, Dwight; Fink, Larry

1990-01-01

A methodology used in support of a study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specific optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates.

Testing the robustness of optimal access vessel fleet selection for operation and maintenance of offshore wind farms

DOE PAGES

Sperstad, Iver Bakken; Stålhane, Magnus; Dinwoodie, Iain; ...

2017-09-23

Optimising the operation and maintenance (O&M) and logistics strategy of offshore wind farms implies the decision problem of selecting the vessel fleet for O&M. Different strategic decision support tools can be applied to this problem, but much uncertainty remains regarding both input data and modelling assumptions. Our paper aims to investigate and ultimately reduce this uncertainty by comparing four simulation tools, one mathematical optimisation tool and one analytic spreadsheet-based tool applied to select the O&M access vessel fleet that minimizes the total O&M cost of a reference wind farm. The comparison shows that the tools generally agree on the optimalmore » vessel fleet, but only partially agree on the relative ranking of the different vessel fleets in terms of total O&M cost. The robustness of the vessel fleet selection to various input data assumptions was tested, and the ranking was found to be particularly sensitive to the vessels' limiting significant wave height for turbine access. Also the parameter with the greatest discrepancy between the tools, implies that accurate quantification and modelling of this parameter is crucial. The ranking is moderately sensitive to turbine failure rates and vessel day rates but less sensitive to electricity price and vessel transit speed.« less

Testing the robustness of optimal access vessel fleet selection for operation and maintenance of offshore wind farms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sperstad, Iver Bakken; Stålhane, Magnus; Dinwoodie, Iain

Optimising the operation and maintenance (O&M) and logistics strategy of offshore wind farms implies the decision problem of selecting the vessel fleet for O&M. Different strategic decision support tools can be applied to this problem, but much uncertainty remains regarding both input data and modelling assumptions. Our paper aims to investigate and ultimately reduce this uncertainty by comparing four simulation tools, one mathematical optimisation tool and one analytic spreadsheet-based tool applied to select the O&M access vessel fleet that minimizes the total O&M cost of a reference wind farm. The comparison shows that the tools generally agree on the optimalmore » vessel fleet, but only partially agree on the relative ranking of the different vessel fleets in terms of total O&M cost. The robustness of the vessel fleet selection to various input data assumptions was tested, and the ranking was found to be particularly sensitive to the vessels' limiting significant wave height for turbine access. Also the parameter with the greatest discrepancy between the tools, implies that accurate quantification and modelling of this parameter is crucial. The ranking is moderately sensitive to turbine failure rates and vessel day rates but less sensitive to electricity price and vessel transit speed.« less

Crossing fitness canyons by a finite population

NASA Astrophysics Data System (ADS)

Saakian, David B.; Bratus, Alexander S.; Hu, Chin-Kun

2017-06-01

We consider the Wright-Fisher model of the finite population evolution on a fitness landscape defined in the sequence space by a path of nearly neutral mutations. We study a specific structure of the fitness landscape: One of the intermediate mutations on the mutation path results in either a large fitness value (climbing up a fitness hill) or a low fitness value (crossing a fitness canyon), the rest of the mutations besides the last one are neutral, and the last sequence has much higher fitness than any intermediate sequence. We derive analytical formulas for the first arrival time of the mutant with two point mutations. For the first arrival problem for the further mutants in the case of canyon crossing, we analytically deduce how the mean first arrival time scales with the population size and fitness difference. The location of the canyon on the path of sequences has a crucial role. If the canyon is at the beginning of the path, then it significantly prolongs the first arrival time; otherwise it just slightly changes it. Furthermore, the fitness hill at the beginning of the path strongly prolongs the arrival time period; however, the hill located near the end of the path shortens it. We optimize the first arrival time by applying a nonzero selection to the intermediate sequences. We extend our results and provide a scaling for the valley crossing time via the depth of the canyon and population size in the case of a fitness canyon at the first position. Our approach is useful for understanding some complex evolution systems, e.g., the evolution of cancer.

Efficiency Benefits Using the Terminal Area Precision Scheduling and Spacing System

NASA Technical Reports Server (NTRS)

Thipphavong, Jane; Swenson, Harry N.; Lin, Paul; Seo, Anthony Y.; Bagasol, Leonard N.

2011-01-01

NASA has developed a capability for terminal area precision scheduling and spacing (TAPSS) to increase the use of fuel-efficient arrival procedures during periods of traffic congestion at a high-density airport. Sustained use of fuel-efficient procedures throughout the entire arrival phase of flight reduces overall fuel burn, greenhouse gas emissions and noise pollution. The TAPSS system is a 4D trajectory-based strategic planning and control tool that computes schedules and sequences for arrivals to facilitate optimal profile descents. This paper focuses on quantifying the efficiency benefits associated with using the TAPSS system, measured by reduction of level segments during aircraft descent and flight distance and time savings. The TAPSS system was tested in a series of human-in-the-loop simulations and compared to current procedures. Compared to the current use of the TMA system, simulation results indicate a reduction of total level segment distance by 50% and flight distance and time savings by 7% in the arrival portion of flight (200 nm from the airport). The TAPSS system resulted in aircraft maintaining continuous descent operations longer and with more precision, both achieved under heavy traffic demand levels.

TIME SHARING WITH AN EXPLICIT PRIORITY QUEUING DISCIPLINE.

DTIC Science & Technology

exponentially distributed service times and an ordered priority queue. Each new arrival buys a position in this queue by offering a non-negative bribe to the...parameters is investigated through numerical examples. Finally, to maximize the expected revenue per unit time accruing from bribes , an optimization

Optimizing airport capacity utilization in air traffic flow management subject to constraints at arrival and departure fixes

DOT National Transportation Integrated Search

1997-09-01

This paper formulates a new approach for improvement : of air traffic flow management at airports, which leads to : more efficient utilization of existing airport capacity to alleviate : the consequences of congestion. A new model is presented, : whi...

KSC-2012-3596

NASA Image and Video Library

2012-06-29

CAPE CANAVERAL, Fla. - Inside the Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida, technicians prepare a lifting ring to support the arrival of the Orion crew module. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. NASA's Michoud Assembly Facility in New Orleans built the crew module pressure vessel. The Orion production team will prepare the module for flight by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Gianni Woods

KSC-2012-3594

NASA Image and Video Library

2012-06-29

CAPE CANAVERAL, Fla. - Technicians remove a protective cover from the Orion crew module after its arrival in the Operations and Checkout Building high bay at NASA's Kennedy Space Center in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. NASA's Michoud Assembly Facility in New Orleans built the crew module pressure vessel. The Orion production team will prepare the module for flight by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Gianni Woods

An Activity-Based Non-Linear Regression Model of Sopite Syndrome and its Effects on Crew Performance in High-Speed Vessel Operations

DTIC Science & Technology

2009-03-01

80 100 120 140 -0 .6 -0 .4 -0 .2 0. 0 0. 2 0. 4 0. 6 l1 fit M irr or T ra ce r M od el Figure 26. l1fit of Mirror Tracer Model To ensure model... teachers are unfair to students is nonsense. b. Most students don’t realize the extent to which their grades are influenced by accidental happenings...understand how teachers arrive at the grades they give. b. There is a direct connection between how hard 1 study and the grades I get. 24. a. A

Model for Bi-objective emergency rescue vehicle routing optimization

NASA Astrophysics Data System (ADS)

Yang, Yuhang

2017-03-01

Vehicle routing problem is an important research topic in management science. In this paper, one vehicle can rescue multiple disaster points and two optimization objectives are rescue time and rescue effect. Rescue effect is expressed as the ratio of unloaded material to arrival time when rescue vehicles participate in rescue every time. In this paper, the corresponding emergency rescue model is established and the effectiveness of the model is verified by simulated annealing algorithm. It can provide the basis for practical decision-making.

Proceedings of the Aircraft Wake Vortices Conference Held in Washington, DC on October 29 - 31, 1991. Volume 1, Papers 1-29.

DTIC Science & Technology

1992-06-01

Large scale data collection activities began with the installation of several sensor systems at the John F. Kennedy International Airport ( JFK ) in June... airport in 1989 (Figure 2). It assists the controllers in the management of the arrival traffic by the provision of an optimized plan for the incoming...Vzf t GOAL ---- > MINIMIZE jVref -Vesti BY OPTIMIZING SENSOR PARAMETERS AND TAKING IN ACCOUNT CUMBERNESS AND ENVIRONMENTAL CONSTRAINTS AIRPORT TESTS

The Development and Application of Random Matrix Theory in Adaptive Signal Processing in the Sample Deficient Regime

DTIC Science & Technology

2014-09-01

optimal diagonal loading which minimizes the MSE. The be- havior of optimal diagonal loading when the arrival process is composed of plane waves embedded...observation vectors. The examples of the ensemble correlation matrix corresponding to the input process consisting of a single or multiple plane waves...Y ∗ij is a complex-conjugate of Yij. This result is used in order to evaluate the expectations of different quadratic forms. The Poincare -Nash

Optimized efficiency of all-electric ships by dc hybrid power systems

NASA Astrophysics Data System (ADS)

Zahedi, Bijan; Norum, Lars E.; Ludvigsen, Kristine B.

2014-06-01

Hybrid power systems with dc distribution are being considered for commercial marine vessels to comply with new stringent environmental regulations, and to achieve higher fuel economy. In this paper, detailed efficiency analysis of a shipboard dc hybrid power system is carried out. An optimization algorithm is proposed to minimize fuel consumption under various loading conditions. The studied system includes diesel engines, synchronous generator-rectifier units, a full-bridge bidirectional converter, and a Li-Ion battery bank as energy storage. In order to evaluate potential fuel saving provided by such a system, an online optimization strategy for fuel consumption is implemented. An Offshore Support Vessel (OSV) is simulated over different operating modes using the online control strategy. The resulted consumed fuel in the simulation is compared to that of a conventional ac power system, and also a dc power system without energy storage. The results show that while the dc system without energy storage provides noticeable fuel saving compared to the conventional ac system, optimal utilization of the energy storage in the dc system results in twice as much fuel saving.

Terminal Air Flow Planning

NASA Technical Reports Server (NTRS)

Denery, Dallas G.; Erzberger, Heinz; Edwards, Thomas A. (Technical Monitor)

1998-01-01

The Center TRACON Automation System (CTAS) will be the basis for air traffic planning and control in the terminal area. The system accepts arriving traffic within an extended terminal area and optimizes the flow based on current traffic and airport conditions. The operational use of CTAS will be presented together with results from current operations.

Non-Linear Optimization Applied to Angle-of-Arrival Satellite-Based Geolocation

DTIC Science & Technology

2014-06-19

Civilian Student, USAF Approved: //signed// Andrew J. Terzuoli, PhD (Chairman) //signed// Maj Marshall E. Haker , PhD (Member) //signed// Richard K...make sense. Further thanks to Dr. Haker . His enthusiasm for my research helped keep me motivated. He was also kind enough to offer an independment

The Dynamic Planner: The Sequencer, Scheduler, and Runway Allocator for Air Traffic Control Automation

NASA Technical Reports Server (NTRS)

Wong, Gregory L.; Denery, Dallas (Technical Monitor)

2000-01-01

The Dynamic Planner (DP) has been designed, implemented, and integrated into the Center-TRACON Automation System (CTAS) to assist Traffic Management Coordinators (TMCs), in real time, with the task of planning and scheduling arrival traffic approximately 35 to 200 nautical miles from the destination airport. The TMC may input to the DP a series of current and future scheduling constraints that reflect the operation and environmental conditions of the airspace. Under these constraints, the DP uses flight plans, track updates, and Estimated Time of Arrival (ETA) predictions to calculate optimal runway assignments and arrival schedules that help ensure an orderly, efficient, and conflict-free flow of traffic into the terminal area. These runway assignments and schedules can be shown directly to controllers or they can be used by other CTAS tools to generate advisories to the controllers. Additionally, the TMC and controllers may override the decisions made by the DP for tactical considerations. The DP will adapt to computations to accommodate these manual inputs.

On measurement of acoustic pulse arrival angles using a vertical array

NASA Astrophysics Data System (ADS)

Makarov, D. V.

2017-11-01

We consider a recently developed method to analyze the angular structure of pulsed acoustic fields in an underwater sound channel. The method is based on the Husimi transform that allows us to approximately link a wave field with the corresponding ray arrivals. The advantage of the method lies in the possibility of its practical realization by a vertical hydrophone array crossing only a small part of the oceanic depth. The main aim of the present work is to find the optimal parameter values of the array that ensure good angular accuracy and sufficient reliability of the algorithm to calculate the arrival angles. Broadband pulses with central frequencies of 80 and 240 Hz are considered. It is shown that an array with a length of several hundred meters allows measuring the angular spectrum with an accuracy of up to 1 degree. The angular resolution is lowered with an increase of the sound wavelength due to the fundamental limitations imposed by the uncertainty relation.

Air Traffic Management Technology Demonstration-1 Concept of Operations (ATD-1 ConOps)

NASA Technical Reports Server (NTRS)

Baxley, Brian T.; Johnson, William C.; Swenson, Harry; Robinson, John E.; Prevot, Thomas; Callantine, Todd; Scardina, John; Greene, Michael

2012-01-01

The operational goal of the ATD-1 ConOps is to enable aircraft, using their onboard FMS capabilities, to fly Optimized Profile Descents (OPDs) from cruise to the runway threshold at a high-density airport, at a high throughput rate, using primarily speed control to maintain in-trail separation and the arrival schedule. The three technologies in the ATD-1 ConOps achieve this by calculating a precise arrival schedule, using controller decision support tools to provide terminal controllers with speeds for aircraft to fly to meet times at a particular meter points, and onboard software providing flight crews with speeds for the aircraft to fly to achieve a particular spacing behind preceding aircraft.

Fully Dynamic Bin Packing

NASA Astrophysics Data System (ADS)

Ivković, Zoran; Lloyd, Errol L.

Classic bin packing seeks to pack a given set of items of possibly varying sizes into a minimum number of identical sized bins. A number of approximation algorithms have been proposed for this NP-hard problem for both the on-line and off-line cases. In this chapter we discuss fully dynamic bin packing, where items may arrive (Insert) and depart (Delete) dynamically. In accordance with standard practice for fully dynamic algorithms, it is assumed that the packing may be arbitrarily rearranged to accommodate arriving and departing items. The goal is to maintain an approximately optimal solution of provably high quality in a total amount of time comparable to that used by an off-line algorithm delivering a solution of the same quality.

Design of Semi-composite Pressure Vessel using Fuzzy and FEM

NASA Astrophysics Data System (ADS)

Sabour, Mohammad H.; Foghani, Mohammad F.

2010-04-01

The present study attempts to present a new method to design a semi-composite pressure vessel (known as hoop-wrapped composite cylinder) using fuzzy decision making and finite element method. A metal-composite vessel was designed based on ISO criteria and then the weight of the vessel was optimized for various fibers of carbon, glass and Kevlar in the cylindrical vessel. Failure criteria of von-Mises and Hoffman were respectively employed for the steel liner and the composite reinforcement to characterize the yielding/ buckling of the cylindrical pressure vessel. The fuzzy decision maker was used to estimate the thickness of the steel liner and the number of composite layers. The ratio of stresses on the composite fibers and the working pressure as well as the ratio of stresses on the composite fibers and the burst (failure) pressure were assessed. ANSYS nonlinear finite element solver was used to analyze the residual stress in the steel liner induced due to an auto-frettage process. Result of analysis verified that carbon fibers are the most suitable reinforcement to increase strength of cylinder while the weight stayed appreciably low.

3D DCE-MRA of pedal arteries in patients with diabetes mellitus

NASA Astrophysics Data System (ADS)

Zamyshevskaya, M.; Zavadovskaya, V.; Zorkaltsev, M.; Udodov, V.; Grigorev, E.

2016-02-01

Purpose was identification and evaluation of pedal vascularization in diabetic patients of using contrast MR-angiography (3D DCE-MRA). 23 diabetic feet of 23 patients (15 male, 8 female; mean age 56 ± 14.6) underwent 3D DCE-MRA (Gadobutrol 15ml) at 1.5 T. Imaging analysis included blood-flow's speed, vascular architectonic's condition and character of contrast's accumulation. Osteomyelitis was verified by surgery in 15 cases. All patients were divided in 3 groups: neuropathic, neuroischemic, ischemic forms of diabetic foot. First- pass MRA detected significant delay of contrast's arrival in ischemic group. There were no significant differences between the values of neuropathic and neuroischemic forms of diabetic foot. Pedal vessels in patients were absent. Contrast MRA revealed three types of contrast distribution in soft tissues: uniform, local increase and local absence. Osteomyelitis was associated with diffuse enhanced contrast accumulation in all cases. In summary, MRI blood vessel imaging is a promising and valuable method for examining peripheral arterial changes in diabetic foot and might be useful for treatment planning in different forms of diabetic foot.

Complete resection of hypervascularised extraventricular neurocytoma after preoperative embolisation.

PubMed

Katati, Majed; Ortiz García, Isabel; Chamorro, Clara Isabel; Horcajadas, Ángel; Hurtado, Alicia; Sánchez, Carlos; Iañez, Benjamín; Saura, Enrique; García, Ernesto; Busquier, Heriberto

2018-04-18

A 13-year-old female arrived at the Emergency Department with a two-week history of headache, and bilateral papilloedema on examination. The initial study with CT and MRI showed a large multicystic left frontal mass with calcification surrounded by peripheral oedema, subacute intralesional bleeding and association of multiple large vessels. She was initially operated on in another centre where a subacute haematoma was found, evacuating to multiple vessels and arteriolised veins. Despite the earlier neuroimaging findings, arteriovenous malformation (AVM) was suspected, so she was referred to our centre for further treatment. We performed angiography, MR angiography and MRI with advanced sequences, diagnosing a highly vascularised intra-axial tumour which was embolised. The patient was then definitively operated on, with the resulting finding of extraventricular neurocytoma (EVN). EVN are extremely rare lesions, not previously described in the literature as hypervascularised lesions, which in our case required prior angiography and embolisation for proper diagnosis and adequate management. Copyright © 2018 Sociedad Española de Neurocirugía. Publicado por Elsevier España, S.L.U. All rights reserved.

Nontraumatic Retroperitoneal Hematoma After Warfarin Administration: Fatal Case Report and Review of the Literature.

PubMed

Hosseini, Marzieh; Hosseinzadeh, Amin; Raufian, Kasra; Hedjazi, Arya

2015-12-01

Spontaneous retroperitoneal hematoma after warfarin therapy is an extremely rare event. Here, we report a 25-year-old man who was brought in to the emergency service with confusion. On arrival, the patient had hypotension, tachycardia, tachypnea, low-grade fever, and Glasgow Coma Scale score of 12. Abdominal examination revealed distention and mild tenderness in the right upper quadrant of the abdomen. The patient had a history of aortic valve replacement surgery and was on warfarin treatment at an international normalized ratio of 2.4. Our patient progressed to cardiorespiratory arrest. The resuscitation was initiated promptly. Despite all resuscitation measures, including transfusion and administration of high doses of catecholamine, the patient died of hypovolemic shock 3 hours after admission. At autopsy, the external surface of the abdominal great vessels (descending aorta and mesenteric vessels) showed scattered petechial hemorrhages without any visible site of perforation. After comprehensive exploration of the abdomen, no evidence of traumatic event was identified and the cause of internal blood loss was noted as warfarin adverse effect.

Artifacts in digital coincidence timing

DOE PAGES

Moses, W. W.; Peng, Q.

2014-10-16

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

Artifacts in digital coincidence timing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moses, W. W.; Peng, Q.

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

A two-stage approach for fully automatic segmentation of venous vascular structures in liver CT images

NASA Astrophysics Data System (ADS)

Kaftan, Jens N.; Tek, Hüseyin; Aach, Til

2009-02-01

The segmentation of the hepatic vascular tree in computed tomography (CT) images is important for many applications such as surgical planning of oncological resections and living liver donations. In surgical planning, vessel segmentation is often used as basis to support the surgeon in the decision about the location of the cut to be performed and the extent of the liver to be removed, respectively. We present a novel approach to hepatic vessel segmentation that can be divided into two stages. First, we detect and delineate the core vessel components efficiently with a high specificity. Second, smaller vessel branches are segmented by a robust vessel tracking technique based on a medialness filter response, which starts from the terminal points of the previously segmented vessels. Specifically, in the first phase major vessels are segmented using the globally optimal graphcuts algorithm in combination with foreground and background seed detection, while the computationally more demanding tracking approach needs to be applied only locally in areas of smaller vessels within the second stage. The method has been evaluated on contrast-enhanced liver CT scans from clinical routine showing promising results. In addition to the fully-automatic instance of this method, the vessel tracking technique can also be used to easily add missing branches/sub-trees to an already existing segmentation result by adding single seed-points.

Design optimization of gas generator hybrid propulsion boosters

NASA Technical Reports Server (NTRS)

Weldon, Vincent; Phillips, Dwight U.; Fink, Lawrence E.

1990-01-01

A methodology used in support of a contract study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specified optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates.

Tumor Blood Vessel Dynamics

NASA Astrophysics Data System (ADS)

Munn, Lance

2009-11-01

``Normalization'' of tumor blood vessels has shown promise to improve the efficacy of chemotherapeutics. In theory, anti-angiogenic drugs targeting endothelial VEGF signaling can improve vessel network structure and function, enhancing the transport of subsequent cytotoxic drugs to cancer cells. In practice, the effects are unpredictable, with varying levels of success. The predominant effects of anti-VEGF therapies are decreased vessel leakiness (hydraulic conductivity), decreased vessel diameters and pruning of the immature vessel network. It is thought that each of these can influence perfusion of the vessel network, inducing flow in regions that were previously sluggish or stagnant. Unfortunately, when anti-VEGF therapies affect vessel structure and function, the changes are dynamic and overlapping in time, and it has been difficult to identify a consistent and predictable normalization ``window'' during which perfusion and subsequent drug delivery is optimal. This is largely due to the non-linearity in the system, and the inability to distinguish the effects of decreased vessel leakiness from those due to network structural changes in clinical trials or animal studies. We have developed a mathematical model to calculate blood flow in complex tumor networks imaged by two-photon microscopy. The model incorporates the necessary and sufficient components for addressing the problem of normalization of tumor vasculature: i) lattice-Boltzmann calculations of the full flow field within the vasculature and within the tissue, ii) diffusion and convection of soluble species such as oxygen or drugs within vessels and the tissue domain, iii) distinct and spatially-resolved vessel hydraulic conductivities and permeabilities for each species, iv) erythrocyte particles advecting in the flow and delivering oxygen with real oxygen release kinetics, v) shear stress-mediated vascular remodeling. This model, guided by multi-parameter intravital imaging of tumor vessel structure and function, provides a tool for identifying the structural and functional determinants of tumor vessel normalization.

Uncertainty and operational considerations in mass prophylaxis workforce planning.

PubMed

Hupert, Nathaniel; Xiong, Wei; King, Kathleen; Castorena, Michelle; Hawkins, Caitlin; Wu, Cindie; Muckstadt, John A

2009-12-01

The public health response to an influenza pandemic or other large-scale health emergency may include mass prophylaxis using multiple points of dispensing (PODs) to deliver countermeasures rapidly to affected populations. Computer models created to date to determine "optimal" staffing levels at PODs typically assume stable patient demand for service. The authors investigated POD function under dynamic and uncertain operational environments. The authors constructed a Monte Carlo simulation model of mass prophylaxis (the Dynamic POD Simulator, or D-PODS) to assess the consequences of nonstationary patient arrival patterns on POD function under a variety of POD layouts and staffing plans. Compared are the performance of a standard POD layout under steady-state and variable patient arrival rates that may mimic real-life variation in patient demand. To achieve similar performance, PODs functioning under nonstationary patient arrival rates require higher staffing levels than would be predicted using the assumption of stationary arrival rates. Furthermore, PODs may develop severe bottlenecks unless staffing levels vary over time to meet changing patient arrival patterns. Efficient POD networks therefore require command and control systems capable of dynamically adjusting intra- and inter-POD staff levels to meet demand. In addition, under real-world operating conditions of heightened uncertainty, fewer large PODs will require a smaller total staff than many small PODs to achieve comparable performance. Modeling environments that capture the effects of fundamental uncertainties in public health disasters are essential for the realistic evaluation of response mechanisms and policies. D-PODS quantifies POD operational efficiency under more realistic conditions than have been modeled previously. The authors' experiments demonstrate that effective POD staffing plans must be responsive to variation and uncertainty in POD arrival patterns. These experiments highlight the need for command and control systems to be created to manage emergency response successfully.

The choosing of sleeping position in the overnight aggregation by the solitary bees Amegilla florea urens in Iriomote Island of Japan

NASA Astrophysics Data System (ADS)

Yokoi, Tomoyuki; Idogawa, Naoto; Kandori, Ikuo; Nikkeshi, Aoi; Watanabe, Mamoru

2017-04-01

In addition to the process of joining the sleeping aggregation, the choice of sleeping position is an important night-time behaviour of small diurnal insects because of the increased risk for predator attacks as well as bad weather. The aggregation behaviour of the solitary bee Amegilla florea urens was investigated to elucidate the choice of sleeping position on substrates. Male and female constructed single-sex aggregations on hanging leaves during May and June, respectively. Most individuals tended to form aggregations with other individuals while few individuals slept alone. During the aggregation forming, both the number of individuals that tried to join the aggregation and the completion time of aggregation increased with the number of sleeping individuals, whereas the success rate of joining was unaffected. The sleeping positions of subsequent arrivals on the substrates were higher than those of the first arrivals in female aggregations. Therefore, the first female to arrive tended to be located near the bottom of a hanging substrate. Dissecting sleeping females showed that they contained mature oocytes, indicating that sexually mature individuals formed aggregations. In male aggregations, however, we could not find a clear relationship between the position on substrates and the arrival sequence. We suggest that the purpose for sleeping in aggregations might be a dilution effect for nocturnal predation and that the females that finished both nesting and foraging quickly could choose the optimal positions in the aggregation when they arrived on the sleeping substrates.

Different dissecting orders of the pulmonary bronchus and vessels during right upper lobectomy are associated with surgical feasibility and postoperative recovery for lung cancer patients.

PubMed

Zhai, Hao-Ran; Yang, Xue-Ning; Nie, Qiang; Liao, Ri-Qiang; Dong, Song; Li, Wei; Jiang, Ben-Yuan; Yang, Jin-Ji; Zhou, Qing; Tu, Hai-Yan; Zhang, Xu-Chao; Wu, Yi-Long; Zhong, Wen-Zhao

2017-06-27

Right upper lobectomy (RUL) for lung cancer with different dissecting orders involves the most variable anatomical structures, but no studies have analyzed its effects on postoperative recovery. This study compared the conventional surgical approach, VAB (dissecting pulmonary vessels first, followed by the bronchus), and the alternative surgical approach, aBVA (dissecting the posterior ascending arterial branch first, followed by the bronchus and vessels) on improving surgical feasibility and postoperative recovery for lung cancer patients. According to the surgical approach, consecutive lung cancer patients undergoing RUL were grouped into aBVA and VAB cohorts. Their clinical, pathologic, and perioperative characteristics were collected to compare perioperative outcomes. Three hundred one patients were selected (109 in the aBVA cohort and 192 in the VAB cohort). The mean operation time was shorter in the aBVA cohort than in the VAB cohort (164 vs. 221 min, P < 0.001), and less blood loss occurred in the aBVA cohort (92 vs. 141 mL, P < 0.001). The rate of conversion to thoracotomy was lower in the aBVA cohort than in the VAB cohort (0% vs. 11.5%, P < 0.001). The mean duration of postoperative chest drainage was shorter in the aBVA cohort than in the VAB cohort (3.6 vs. 4.5 days, P = 0.001). The rates of postoperative complications were comparable (P = 0.629). The median overall survival was not arrived in both cohorts (P > 0.05). The median disease-free survival was comparable for all patients in the two cohorts (not arrived vs. 41.97 months) and for patients with disease recurrences (13.25 vs. 9.44 months) (both P > 0.05). The recurrence models in two cohorts were also comparable for patients with local recurrences (6.4% vs. 7.8%), distant metastases (10.1% vs. 8.3%), and both (1.8% vs. 1.6%) (all P > 0.05). Dissecting the right upper bronchus before turning over the lobe repeatedly and dissecting veins via the aBVA approach during RUL would promote surgical feasibility and achieve comparable postoperative recovery for lung cancer patients.

Techniques for Increasing the Efficiency of Automation Systems in School Library Media Centers.

ERIC Educational Resources Information Center

Caffarella, Edward P.

1996-01-01

Discusses methods of managing queues (waiting lines) to optimize the use of student computer stations in school library media centers and to make searches more efficient and effective. The three major factors in queue management are arrival interval of the patrons, service time, and number of stations. (Author/LRW)

Understanding the College First-Year Experience

ERIC Educational Resources Information Center

Kidwell, Kirk S.

2005-01-01

Each fall, thousands of high school graduates launch into the next phase of their academic careers: college. They arrive on campuses across the United States full of hope and optimism, trepidation and anxiety. All intensely feel both the eagerness to excel and the fear of failure. The author shares his experience of dealing with college first-year…

Sequential Injection Analysis for Optimization of Molecular Biology Reactions

PubMed Central

Allen, Peter B.; Ellington, Andrew D.

2011-01-01

In order to automate the optimization of complex biochemical and molecular biology reactions, we developed a Sequential Injection Analysis (SIA) device and combined this with a Design of Experiment (DOE) algorithm. This combination of hardware and software automatically explores the parameter space of the reaction and provides continuous feedback for optimizing reaction conditions. As an example, we optimized the endonuclease digest of a fluorogenic substrate, and showed that the optimized reaction conditions also applied to the digest of the substrate outside of the device, and to the digest of a plasmid. The sequential technique quickly arrived at optimized reaction conditions with less reagent use than a batch process (such as a fluid handling robot exploring multiple reaction conditions in parallel) would have. The device and method should now be amenable to much more complex molecular biology reactions whose variable spaces are correspondingly larger. PMID:21338059

Optimal execution in high-frequency trading with Bayesian learning

NASA Astrophysics Data System (ADS)

Du, Bian; Zhu, Hongliang; Zhao, Jingdong

2016-11-01

We consider optimal trading strategies in which traders submit bid and ask quotes to maximize the expected quadratic utility of total terminal wealth in a limit order book. The trader's bid and ask quotes will be changed by the Poisson arrival of market orders. Meanwhile, the trader may update his estimate of other traders' target sizes and directions by Bayesian learning. The solution of optimal execution in the limit order book is a two-step procedure. First, we model an inactive trading with no limit order in the market. The dealer simply holds dollars and shares of stocks until terminal time. Second, he calibrates his bid and ask quotes to the limit order book. The optimal solutions are given by dynamic programming and in fact they are globally optimal. We also give numerical simulation to the value function and optimal quotes at the last part of the article.

A PC-PU nanoparticle/PU/decellularized scaffold composite vascular patch: Synergistically optimized overall performance promotes endothelialization.

PubMed

Zhang, Jun; Liu, Cheng; Feng, Fuling; Wang, Dawei; Lu, Shuaishuai; Wei, Guo; Mo, Hong; Qiao, Tong

2017-12-01

Composite vascular patches have gained increasingly attention due to the limited availability of autologous patches (vascular graft materials made from the blood vessels of the same recipient), the lack of growth capability of nonautologous patches (vascular graft materials made from the blood vessels of a different donor) and the disadvantages of synthetic patches. In this study, we report a highly biocompatible phosphatidylcholine-polyurethane nanoparticle/polyurethane/decellularized scaffold composite vascular patch (PCVP). It was fabricated by a facile method - cosedimentation. Its in vitro blood and cell compatibility including hemolysis, plasma recalcification time, coagulation time, platelet adhesion and cytotoxicity was evaluated. The surface modified with phosphatidylcholine-polyurethane (PC-PU) nanoparticles exhibited the improved anticoagulation activity. The in vivo performance of the PCVP was investigated in a mouse model. The nanopatterned surface that resembled the concave-convex structure of the luminal surface of native blood vessels enhanced cell attachment, proliferation, migration and differentiation. The decellularized scaffold had the mechanical property similar to that of the targeted blood vessels, which could withstand in vivo dynamic blood pressure. The overall performance of the PCVP was synergistically optimized by each layer of the multilayer design. The patched artery remained patent and the formation of endothelial tissue - endothelialization was achieved 30days after the in vivo implantation in a mouse model. Copyright © 2017 Elsevier B.V. All rights reserved.

Accelerated aortic imaging using small field of view imaging and electrocardiogram-triggered quadruple inversion recovery magnetization preparation.

PubMed

Peel, Sarah A; Hussain, Tarique; Cecelja, Marina; Abbas, Abeera; Greil, Gerald F; Chowienczyk, Philip; Spector, Tim; Smith, Alberto; Waltham, Matthew; Botnar, Rene M

2011-11-01

To accelerate and optimize black blood properties of the quadruple inversion recovery (QIR) technique for imaging the abdominal aortic wall. QIR inversion delays were optimized for different heart rates in simulations and phantom studies by minimizing the steady state magnetization of blood for T(1) = 100-1400 ms. To accelerate and improve black blood properties of aortic vessel wall imaging, the QIR prepulse was combined with zoom imaging and (a) "traditional" and (b) "trailing" electrocardiogram (ECG) triggering. Ten volunteers were imaged pre- and post-contrast administration using a conventional ECG-triggered double inversion recovery (DIR) and the two QIR implementations in combination with a zoom-TSE readout. The QIR implemented with "trailing" ECG-triggering resulted in consistently good blood suppression as the second inversion delay was timed during maximum systolic flow in the aorta. The blood signal-to-noise ratio and vessel wall to blood contrast-to-noise ratio, vessel wall sharpness, and image quality scores showed a statistically significant improvement compared with the traditional QIR implementation with and without ECG-triggering. We demonstrate that aortic vessel wall imaging can be accelerated with zoom imaging and that "trailing" ECG-triggering improves black blood properties of the aorta which is subject to motion and variable blood flow during the cardiac cycle. Copyright © 2011 Wiley Periodicals, Inc.

Research and development of a dedicated collimator for 14.2 MeV fast neutrons for imaging using a D-T generator

NASA Astrophysics Data System (ADS)

Sabo-Napadensky, I.; Weiss-Babai, R.; Gayer, A.; Vartsky, D.; Bar, D.; Mor, I.; Chacham-Zada, R.; Cohen, M.; Tamim, N.

2012-06-01

One of the main problems in neutron imaging is the scattered radiation that accompanies the direct neutrons that reach the imaging detectors and affect the image quality. We have developed a dedicated collimator for 14.2 MeV fast neutrons. The collimator optimizes the amount of scattered radiation to primary neutrons that arrive at the imaging plane. We have used different materials within the collimator in order to lower the scattered radiation that arrives at the scanned object. The image quality and the signal to noise ratios that are measured show that a mixture of BORAX (Na2B4O7ṡ10H2O) and water in the experimental beam collimator give the best results. We have used GEANT4 to simulate the collimator performance, the simulations predict the optimized material looking on the ratios of the scattered to primary neutrons that contribute in the detector. We present our experimental setup, report the results of the experimental and related simulation studies with neutrons beam generated by a 14.2 MeV D-T neutron generator.

TTSA: An Effective Scheduling Approach for Delay Bounded Tasks in Hybrid Clouds.

PubMed

Yuan, Haitao; Bi, Jing; Tan, Wei; Zhou, MengChu; Li, Bo Hu; Li, Jianqiang

2017-11-01

The economy of scale provided by cloud attracts a growing number of organizations and industrial companies to deploy their applications in cloud data centers (CDCs) and to provide services to users around the world. The uncertainty of arriving tasks makes it a big challenge for private CDC to cost-effectively schedule delay bounded tasks without exceeding their delay bounds. Unlike previous studies, this paper takes into account the cost minimization problem for private CDC in hybrid clouds, where the energy price of private CDC and execution price of public clouds both show the temporal diversity. Then, this paper proposes a temporal task scheduling algorithm (TTSA) to effectively dispatch all arriving tasks to private CDC and public clouds. In each iteration of TTSA, the cost minimization problem is modeled as a mixed integer linear program and solved by a hybrid simulated-annealing particle-swarm-optimization. The experimental results demonstrate that compared with the existing methods, the optimal or suboptimal scheduling strategy produced by TTSA can efficiently increase the throughput and reduce the cost of private CDC while meeting the delay bounds of all the tasks.

A modified generalized extremal optimization algorithm for the quay crane scheduling problem with interference constraints

NASA Astrophysics Data System (ADS)

Guo, Peng; Cheng, Wenming; Wang, Yi

2014-10-01

The quay crane scheduling problem (QCSP) determines the handling sequence of tasks at ship bays by a set of cranes assigned to a container vessel such that the vessel's service time is minimized. A number of heuristics or meta-heuristics have been proposed to obtain the near-optimal solutions to overcome the NP-hardness of the problem. In this article, the idea of generalized extremal optimization (GEO) is adapted to solve the QCSP with respect to various interference constraints. The resulting GEO is termed the modified GEO. A randomized searching method for neighbouring task-to-QC assignments to an incumbent task-to-QC assignment is developed in executing the modified GEO. In addition, a unidirectional search decoding scheme is employed to transform a task-to-QC assignment to an active quay crane schedule. The effectiveness of the developed GEO is tested on a suite of benchmark problems introduced by K.H. Kim and Y.M. Park in 2004 (European Journal of Operational Research, Vol. 156, No. 3). Compared with other well-known existing approaches, the experiment results show that the proposed modified GEO is capable of obtaining the optimal or near-optimal solution in a reasonable time, especially for large-sized problems.

CTAS: Computer intelligence for air traffic control in the terminal area

NASA Technical Reports Server (NTRS)

Erzberger, Heinz

1992-01-01

A system for the automated management and control of arrival traffic, referred to as the Center-TRACON Automation System (CTAS), has been designed by the ATC research group at NASA Ames research center. In a cooperative program, NASA and the FAA have efforts underway to install and evaluate the system at the Denver and Dallas/Ft. Worth airports. CTAS consists of three types of integrated tools that provide computer-generated intelligence for both Center and TRACON controllers to guide them in managing and controlling arrival traffic efficiently. One tool, the Traffic Management Advisor (TMA), establishes optimized landing sequences and landing times for aircraft arriving in the center airspace several hundred miles from the airport. In TRACON, TMA frequencies missed approach aircraft and unanticipated arrivals. Another tool, the Descent Advisor (DA), generates clearances for the center controllers handling at crossing times provided by TMA. In the TRACON, the final approach spacing tool (FAST) provides heading and speed clearances that produce and accurately spaced flow of aircraft on the final approach course. A data base consisting of aircraft performance models, airline preferred operational procedures and real time wind measurements contribute to the effective operation of CTAS. Extensive simulator evaluations of CTAS have demonstrated controller acceptance, delay reductions, and fuel savings.

Air Traffic Management Technology Demonstration-1 Concept of Operations (ATD-1 ConOps), Version 2.0

NASA Technical Reports Server (NTRS)

Baxley, Brian T.; Johnson, William C.; Swenson, Harry N.; Robinson, John E.; Prevot, Tom; Callantine, Todd J.; Scardina, John; Greene, Michael

2013-01-01

This document is an update to the operations and procedures envisioned for NASA s Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) integrates three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to the Final Approach Fix. These arrival streams are Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and their implantation into an operational environment. The ATD-1 goals include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage.

NASA's ATM Technology Demonstration-1: Integrated Concept of Arrival Operations

NASA Technical Reports Server (NTRS)

Baxley, Brian T.; Swenson, Harry N.; Prevot, Thomas; Callantine, Todd J.

2012-01-01

This paper describes operations and procedures envisioned for NASA s Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) demonstration will integrate three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to touchdown. It also enables aircraft to conduct Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and implantation into an operational environment. Goals of the ATD-1 demonstration include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage.

Synthesis and optimization of four bar mechanism with six design parameters

NASA Astrophysics Data System (ADS)

Jaiswal, Ankur; Jawale, H. P.

2018-04-01

Function generation is synthesis of mechanism for specific task, involves complexity for specially synthesis above five precision of coupler points. Thus pertains to large structural error. The methodology for arriving to better precision solution is to use the optimization technique. Work presented herein considers methods of optimization of structural error in closed kinematic chain with single degree of freedom, for generating functions like log(x), ex, tan(x), sin(x) with five precision points. The equation in Freudenstein-Chebyshev method is used to develop five point synthesis of mechanism. The extended formulation is proposed and results are obtained to verify existing results in literature. Optimization of structural error is carried out using least square approach. Comparative structural error analysis is presented on optimized error through least square method and extended Freudenstein-Chebyshev method.

2D Fast Vessel Visualization Using a Vessel Wall Mask Guiding Fine Vessel Detection

PubMed Central

Raptis, Sotirios; Koutsouris, Dimitris

2010-01-01

The paper addresses the fine retinal-vessel's detection issue that is faced in diagnostic applications and aims at assisting in better recognizing fine vessel anomalies in 2D. Our innovation relies in separating key visual features vessels exhibit in order to make the diagnosis of eventual retinopathologies easier to detect. This allows focusing on vessel segments which present fine changes detectable at different sampling scales. We advocate that these changes can be addressed as subsequent stages of the same vessel detection procedure. We first carry out an initial estimate of the basic vessel-wall's network, define the main wall-body, and then try to approach the ridges and branches of the vasculature's using fine detection. Fine vessel screening looks into local structural inconsistencies in vessels properties, into noise, or into not expected intensity variations observed inside pre-known vessel-body areas. The vessels are first modelled sufficiently but not precisely by their walls with a tubular model-structure that is the result of an initial segmentation. This provides a chart of likely Vessel Wall Pixels (VWPs) yielding a form of a likelihood vessel map mainly based on gradient filter's intensity and spatial arrangement parameters (e.g., linear consistency). Specific vessel parameters (centerline, width, location, fall-away rate, main orientation) are post-computed by convolving the image with a set of pre-tuned spatial filters called Matched Filters (MFs). These are easily computed as Gaussian-like 2D forms that use a limited range sub-optimal parameters adjusted to the dominant vessel characteristics obtained by Spatial Grey Level Difference statistics limiting the range of search into vessel widths of 16, 32, and 64 pixels. Sparse pixels are effectively eliminated by applying a limited range Hough Transform (HT) or region growing. Major benefits are limiting the range of parameters, reducing the search-space for post-convolution to only masked regions, representing almost 2% of the 2D volume, good speed versus accuracy/time trade-off. Results show the potentials of our approach in terms of time for detection ROC analysis and accuracy of vessel pixel (VP) detection. PMID:20706682

Segmentation of hepatic artery in multi-phase liver CT using directional dilation and connectivity analysis

NASA Astrophysics Data System (ADS)

Wang, Lei; Schnurr, Alena-Kathrin; Zidowitz, Stephan; Georgii, Joachim; Zhao, Yue; Razavi, Mohammad; Schwier, Michael; Hahn, Horst K.; Hansen, Christian

2016-03-01

Segmentation of hepatic arteries in multi-phase computed tomography (CT) images is indispensable in liver surgery planning. During image acquisition, the hepatic artery is enhanced by the injection of contrast agent. The enhanced signals are often not stably acquired due to non-optimal contrast timing. Other vascular structure, such as hepatic vein or portal vein, can be enhanced as well in the arterial phase, which can adversely affect the segmentation results. Furthermore, the arteries might suffer from partial volume effects due to their small diameter. To overcome these difficulties, we propose a framework for robust hepatic artery segmentation requiring a minimal amount of user interaction. First, an efficient multi-scale Hessian-based vesselness filter is applied on the artery phase CT image, aiming to enhance vessel structures with specified diameter range. Second, the vesselness response is processed using a Bayesian classifier to identify the most probable vessel structures. Considering the vesselness filter normally performs not ideally on the vessel bifurcations or the segments corrupted by noise, two vessel-reconnection techniques are proposed. The first technique uses a directional morphological operator to dilate vessel segments along their centerline directions, attempting to fill the gap between broken vascular segments. The second technique analyzes the connectivity of vessel segments and reconnects disconnected segments and branches. Finally, a 3D vessel tree is reconstructed. The algorithm has been evaluated using 18 CT images of the liver. To quantitatively measure the similarities between segmented and reference vessel trees, the skeleton coverage and mean symmetric distance are calculated to quantify the agreement between reference and segmented vessel skeletons, resulting in an average of 0:55+/-0:27 and 12:7+/-7:9 mm (mean standard deviation), respectively.

Halophila stipulacea: survival under adverse conditions.

NASA Astrophysics Data System (ADS)

Morton, C. R., Jr.; Primack, A. G.; Wyllie-Echeverria, S.

2016-02-01

Halophila stipulacea is an invasive seagrass species originally native to the Indian Ocean. It invaded the Mediterranean Sea shortly after the opening of the Suez Canal, and has recently been found in the Caribbean. It has been suggested that it arrived in the Mediterranean attached to small pleasure craft, fishing craft, or small cargo vessels. This research examines the feasibility of these methods of transport and the possibility that arrived transported by ocean currents. To investigate potential transport vectors, we collected rooted samples of H. stipulacae from Brewers Bay on the island of Saint Thomas, USVI, and exposed them to conditions that would be experienced under each alternative method of transport. The health of the samples was monitored using a FLOURPEN FP 100 portable fluorometer. Rhizomes, and associated leaf pairs declined rapidly when exposed to air, submersed in freshwater, or kept damp in a towel soaked in seawater, but survived for more than 5 weeks when left floating in a bucket submersed in a seawater tank. Water temperature ranged between 27C and 30C during the experiment. This suggests that it might be possible for H. stipulacae to cross the Atlantic aided by currents.

Separation-Compliant, Optimal Routing and Control of Scheduled Arrivals in a Terminal Airspace

NASA Technical Reports Server (NTRS)

Sadovsky, Alexander V.; Davis, Damek; Isaacson, Douglas R.

2013-01-01

We address the problem of navigating a set (fleet) of aircraft in an aerial route network so as to bring each aircraft to its destination at a specified time and with minimal distance separation assured between all aircraft at all times. The speed range, initial position, required destination, and required time of arrival at destination for each aircraft are assumed provided. Each aircraft's movement is governed by a controlled differential equation (state equation). The problem consists in choosing for each aircraft a path in the route network and a control strategy so as to meet the constraints and reach the destination at the required time. The main contribution of the paper is a model that allows to recast this problem as a decoupled collection of problems in classical optimal control and is easily generalized to the case when inertia cannot be neglected. Some qualitative insight into solution behavior is obtained using the Pontryagin Maximum Principle. Sample numerical solutions are computed using a numerical optimal control solver. The proposed model is first step toward increasing the fidelity of continuous time control models of air traffic in a terminal airspace. The Pontryagin Maximum Principle implies the polygonal shape of those portions of the state trajectories away from those states in which one or more aircraft pair are at minimal separation. The model also confirms the intuition that, the narrower the allowed speed ranges of the aircraft, the smaller the space of optimal solutions, and that an instance of the optimal control problem may not have a solution at all (i.e., no control strategy that meets the separation requirement and other constraints).

Risk-Based, Hypothesis-Driven Framework for Hydrological Field Campaigns with Case Studies

NASA Astrophysics Data System (ADS)

Harken, B.; Rubin, Y.

2014-12-01

There are several stages in any hydrological modeling campaign, including: formulation and analysis of a priori information, data acquisition through field campaigns, inverse modeling, and prediction of some environmental performance metric (EPM). The EPM being predicted could be, for example, contaminant concentration or plume travel time. These predictions often have significant bearing on a decision that must be made. Examples include: how to allocate limited remediation resources between contaminated groundwater sites or where to place a waste repository site. Answering such questions depends on predictions of EPMs using forward models as well as levels of uncertainty related to these predictions. Uncertainty in EPM predictions stems from uncertainty in model parameters, which can be reduced by measurements taken in field campaigns. The costly nature of field measurements motivates a rational basis for determining a measurement strategy that is optimal with respect to the uncertainty in the EPM prediction. The tool of hypothesis testing allows this uncertainty to be quantified by computing the significance of the test resulting from a proposed field campaign. The significance of the test gives a rational basis for determining the optimality of a proposed field campaign. This hypothesis testing framework is demonstrated and discussed using various synthetic case studies. This study involves contaminated aquifers where a decision must be made based on prediction of when a contaminant will arrive at a specified location. The EPM, in this case contaminant travel time, is cast into the hypothesis testing framework. The null hypothesis states that the contaminant plume will arrive at the specified location before a critical amount of time passes, and the alternative hypothesis states that the plume will arrive after the critical time passes. The optimality of different field campaigns is assessed by computing the significance of the test resulting from each one. Evaluating the level of significance caused by a field campaign involves steps including likelihood-based inverse modeling and semi-analytical conditional particle tracking.

Multiparametric estimation of brain hemodynamics with MR fingerprinting ASL.

PubMed

Su, Pan; Mao, Deng; Liu, Peiying; Li, Yang; Pinho, Marco C; Welch, Babu G; Lu, Hanzhang

2017-11-01

Assessment of brain hemodynamics without exogenous contrast agents is of increasing importance in clinical applications. This study aims to develop an MR perfusion technique that can provide noncontrast and multiparametric estimation of hemodynamic markers. We devised an arterial spin labeling (ASL) method based on the principle of MR fingerprinting (MRF), referred to as MRF-ASL. By taking advantage of the rich information contained in MRF sequence, up to seven hemodynamic parameters can be estimated concomitantly. Feasibility demonstration, flip angle optimization, comparison with Look-Locker ASL, reproducibility test, sensitivity to hypercapnia challenge, and initial clinical application in an intracranial steno-occlusive process, Moyamoya disease, were performed to evaluate this technique. Magnetic resonance fingerprinting ASL provided estimation of up to seven parameters, including B1+, tissue T 1 , cerebral blood flow (CBF), tissue bolus arrival time (BAT), pass-through arterial BAT, pass-through blood volume, and pass-through blood travel time. Coefficients of variation of the estimated parameters ranged from 0.2 to 9.6%. Hypercapnia resulted in an increase in CBF by 57.7%, and a decrease in BAT by 13.7 and 24.8% in tissue and vessels, respectively. Patients with Moyamoya disease showed diminished CBF and lengthened BAT that could not be detected with regular ASL. Magnetic resonance fingerprinting ASL is a promising technique for noncontrast, multiparametric perfusion assessment. Magn Reson Med 78:1812-1823, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

NextGen Operations in a Simulated NY Area Airspace

NASA Technical Reports Server (NTRS)

Smith, Nancy M.; Parke, Bonny; Lee, Paul; Homola, Jeff; Brasil, Connie; Buckley, Nathan; Cabrall, Chris; Chevalley, Eric; Lin, Cindy; Morey, Susan;

Interstellar Sweat Equity

NASA Astrophysics Data System (ADS)

Cohen, M. H.; Becker, R. E.; O'Donnell, D. J.; Brody, A. R.

So, you have just launched aboard the Starship, headed to an exoplanet light years from Earth. You will spend the rest of your natural life on this journey in the expectation and hope that your grandchildren will arrive safely, land, and build a new settlement. You will need to govern the community onboard the Starship. This system of governance must meet unique requirements for participation, representation, and decision-making. On a spaceship that can fly and operate by itself, what will the crewmembers do for their generations in transit? Certainly, they will train and train again to practice the skills they will need upon arrival at a new world. However, this vicarious practice neither suffices to prepare the future pioneers for their destiny at a new star nor will it provide them with the satisfaction in their own work. To hone the crewmembers' inventive and technical skills, to challenge and prepare them for pioneering, the crew would build and expand the interstellar ship in transit. This transstellar ``sweat equity'' gives a stake in the enterprise to all the people, providing meaningful and useful activity to the new generations of crewmembers. They build all the new segments of the vessel from raw materials - including atmosphere - stored on board. Construction of new pressure shell modules would be one option, but they also reconstruct or fill-in existing pressurized volumes. The crew makes new life support system components and develops new agricultural modules in anticipation of their future needs. Upon arrival at the new star or planet, the crew shall apply these robustly developed skills and self-sufficient spirit to their new home.

Diagnosis and Treatment of Traumatic Cerebrovascular Injury: Pitfalls in the Management of Neurotrauma.

PubMed

Kobata, Hitoshi

2017-08-15

Traumatic cerebrovascular injury (TCVI) is an uncommon clinical entity in traumatic brain injury (TBI), yet it may cause devastating brain injury with high morbidity and mortality. Early recognition and prioritized strategic treatment are of paramount importance. A total of 1966 TBI patients admitted between 1999 and 2015 in our tertiary critical care center were reviewed. Screening of TCVI was based on the Guidelines for the Management of Severe Head Injury in Japan. TCVI was confirmed in 33 (1.7%) patients; 29 blunt and 4 penetrating injuries. The primary location of the injury included 16 cervical, 6 craniofacial, and 11 intracranial lesions. On arrival, 15 patients presented with hemorrhage, 5 of these arrived in shock status with massive hemorrhage. Ten presented with ischemic symptoms. Sixteen patients underwent surgical or endovascular intervention, 13 of whom required immediate treatment upon arrival. Surgical procedures included clipping or trapping for traumatic aneurysms, superficial temporal artery - middle cerebral artery bypass, carotid endarterectomy, and direct suture of the injured vessels. Endovascular intervention was undertaken in 7 patients; embolization with Gelfoam (Pharmacia and Upjohn Company, Kalamazoo, MI, USA) or coil for 6 hemorrhagic lesions and stent placement for 1 lesion causing ischemia. Patients' outcome assessed by the Glasgow Outcome Scale at 3 months were good recovery in 8, moderate disability in 3, severe disability in 9, persistent vegetative state in 1, and death in 12, respectively. In order to rescue potentially salvageable TCVI patients, neurosurgeons in charge should be aware of TCVI and master basic skills of cerebrovascular surgical and endovascular procedures to utilize in an emergency setting.

Method for accurate sizing of pulmonary vessels from 3D medical images

NASA Astrophysics Data System (ADS)

O'Dell, Walter G.

2015-03-01

Detailed characterization of vascular anatomy, in particular the quantification of changes in the distribution of vessel sizes and of vascular pruning, is essential for the diagnosis and management of a variety of pulmonary vascular diseases and for the care of cancer survivors who have received radiation to the thorax. Clinical estimates of vessel radii are typically based on setting a pixel intensity threshold and counting how many "On" pixels are present across the vessel cross-section. A more objective approach introduced recently involves fitting the image with a library of spherical Gaussian filters and utilizing the size of the best matching filter as the estimate of vessel diameter. However, both these approaches have significant accuracy limitations including mis-match between a Gaussian intensity distribution and that of real vessels. Here we introduce and demonstrate a novel approach for accurate vessel sizing using 3D appearance models of a tubular structure along a curvilinear trajectory in 3D space. The vessel branch trajectories are represented with cubic Hermite splines and the tubular branch surfaces represented as a finite element surface mesh. An iterative parameter adjustment scheme is employed to optimally match the appearance models to a patient's chest X-ray computed tomography (CT) scan to generate estimates for branch radii and trajectories with subpixel resolution. The method is demonstrated on pulmonary vasculature in an adult human CT scan, and on 2D simulated test cases.

A simplified, low power system for effective vessel sealing

NASA Astrophysics Data System (ADS)

Lyle, Allison B.; Kennedy, Jenifer S.; Schmaltz, Dale F.; Kennedy, Aaron S.

2015-03-01

The first bipolar vessel sealing system was developed nearly 15 years ago and has since become standard of care in surgery. These systems make use of radio frequency current that is delivered between bipolar graspers to permanently seal arteries, veins and tissue bundles. Conventional vessel sealing generators are based off traditional electrosurgery generator architecture and deliver high power (150-300 Watts) and high current using complex control and sense algorithms to adjust the output for vessel sealing applications. In recent years, a need for small-scale surgical vessel sealers has developed as surgeons strive to further reduce their footprint on patients. There are many technical challenges associated with miniaturization of vessel sealing devices including maintaining electrical isolation while delivering high current in a saline environment. Research into creating a small, 3mm diameter vessel sealer revealed that a highly simplified generator system could be used to achieve excellent results and subsequently a low power vessel sealing system was developed. This system delivers 25 Watts constant power while limiting voltage (<= Vrms) and current (<= Amps) until an impedance endpoint is achieved, eliminating the use of complicated control and sensing software. The result is optimized tissue effect, where high seal strength is maintained (> 360mmHg), but seal times (1.7 +/- 0.7s versus 4.1 +/- 0.7s), thermal spread (<1mm vs <=2mm) and total energy delivery are reduced, when compared to an existing high power system.

Optimized Baking of the DIII-D Vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

P.M. Anderson; A.G. Kellman

The DIII-D tokamak vacuum vessel baking system is used to heat the vessel walls and internal hardware to an average temperature of 350 C to allow rapid conditioning of the vacuum surfaces. The system combines inductive heating and a circulating hot air system to provide rapid heating with temperature uniformity required by stress considerations. In recent years, the time to reach 350 C had increased from 9 hrs to 14 hrs. To understand and remedy this sluggish heating rate, an evaluation of the baking system was recently performed. The evaluation indicated that the mass of additional in-vessel hardware (50% increasemore » in mass) was primarily responsible. This paper reports on this analysis and the results of the addition of an electric air heater and procedural changes that have been implemented. Preliminary results indicate that the time to 350 C has been decreased to 4.5 hours and the temperature uniformity has improved.« less

Optimal occlusion uniformly partitions red blood cells fluxes within a microvascular network

PubMed Central

Tu, Shenyinying; Liu, Yu-Hsiu; Savage, Van M.; Hsiai, Tzung K.; Roper, Marcus

2017-01-01

In animals, gas exchange between blood and tissues occurs in narrow vessels, whose diameter is comparable to that of a red blood cell. Red blood cells must deform to squeeze through these narrow vessels, transiently blocking or occluding the vessels they pass through. Although the dynamics of vessel occlusion have been studied extensively, it remains an open question why microvessels need to be so narrow. We study occlusive dynamics within a model microvascular network: the embryonic zebrafish trunk. We show that pressure feedbacks created when red blood cells enter the finest vessels of the trunk act together to uniformly partition red blood cells through the microvasculature. Using mathematical models as well as direct observation, we show that these occlusive feedbacks are tuned throughout the trunk network to prevent the vessels closest to the heart from short-circuiting the network. Thus occlusion is linked with another open question of microvascular function: how are red blood cells delivered at the same rate to each micro-vessel? Our analysis shows that tuning of occlusive feedbacks increase the total dissipation within the network by a factor of 11, showing that uniformity of flows rather than minimization of transport costs may be prioritized by the microvascular network. PMID:29244812

Optimization research of railway passenger transfer scheme based on ant colony algorithm

NASA Astrophysics Data System (ADS)

Ni, Xiang

2018-05-01

The optimization research of railway passenger transfer scheme can provide strong support for railway passenger transport system, and its essence is path search. This paper realized the calculation of passenger transfer scheme for high speed railway when giving the time and stations of departure and arrival. The specific method that used were generating a passenger transfer service network of high-speed railway, establishing optimization model and searching by Ant Colony Algorithm. Finally, making analysis on the scheme from LanZhouxi to BeiJingXi which were based on high-speed railway network of China in 2017. The results showed that the transfer network and model had relatively high practical value and operation efficiency.

Perspective: Stochastic magnetic devices for cognitive computing

NASA Astrophysics Data System (ADS)

Roy, Kaushik; Sengupta, Abhronil; Shim, Yong

2018-06-01

Stochastic switching of nanomagnets can potentially enable probabilistic cognitive hardware consisting of noisy neural and synaptic components. Furthermore, computational paradigms inspired from the Ising computing model require stochasticity for achieving near-optimality in solutions to various types of combinatorial optimization problems such as the Graph Coloring Problem or the Travelling Salesman Problem. Achieving optimal solutions in such problems are computationally exhaustive and requires natural annealing to arrive at the near-optimal solutions. Stochastic switching of devices also finds use in applications involving Deep Belief Networks and Bayesian Inference. In this article, we provide a multi-disciplinary perspective across the stack of devices, circuits, and algorithms to illustrate how the stochastic switching dynamics of spintronic devices in the presence of thermal noise can provide a direct mapping to the computational units of such probabilistic intelligent systems.

An approach of traffic signal control based on NLRSQP algorithm

NASA Astrophysics Data System (ADS)

Zou, Yuan-Yang; Hu, Yu

2017-11-01

This paper presents a linear program model with linear complementarity constraints (LPLCC) to solve traffic signal optimization problem. The objective function of the model is to obtain the minimization of total queue length with weight factors at the end of each cycle. Then, a combination algorithm based on the nonlinear least regression and sequence quadratic program (NLRSQP) is proposed, by which the local optimal solution can be obtained. Furthermore, four numerical experiments are proposed to study how to set the initial solution of the algorithm that can get a better local optimal solution more quickly. In particular, the results of numerical experiments show that: The model is effective for different arrival rates and weight factors; and the lower bound of the initial solution is, the better optimal solution can be obtained.

Navy LPD-17 Amphibious Ship Procurement: Background, Issues, and Options for Congress

DTIC Science & Technology

2010-08-02

and Options for Congress 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e . TASK NUMBER 5f...has been required, disrupting the optimal construction sequence and application of lessons learned for follow-on vessels in these programs... NGSS ) ability to recover in the aftermath of Hurricane Katrina, particularly in regard to construction of LPD 17 Class vessels.” • “I am equally

Navy LPD-17 Amphibious Ship Procurement: Background, Issues, and Options for Congress

DTIC Science & Technology

2010-07-07

and Options for Congress 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e . TASK NUMBER 5f...has been required, disrupting the optimal construction sequence and application of lessons learned for follow-on vessels in these programs... NGSS ) ability to recover in the aftermath of Hurricane Katrina, particularly in regard to construction of LPD 17 Class vessels.” • “I am equally

Navy LPD-17 Amphibious Ship Procurement: Background, Issues, and Options for Congress

DTIC Science & Technology

2010-10-04

Issues, and Options for Congress 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e . TASK NUMBER 5f...rework has been required, disrupting the optimal construction sequence and application of lessons learned for follow-on vessels in these programs...Systems’ ( NGSS ) ability to recover in the aftermath of Hurricane Katrina, particularly in regard to construction of LPD 17 Class vessels.” • “I am

Optimizing integrated airport surface and terminal airspace operations under uncertainty

NASA Astrophysics Data System (ADS)

Bosson, Christabelle S.

In airports and surrounding terminal airspaces, the integration of surface, arrival and departure scheduling and routing have the potential to improve the operations efficiency. Moreover, because both the airport surface and the terminal airspace are often altered by random perturbations, the consideration of uncertainty in flight schedules is crucial to improve the design of robust flight schedules. Previous research mainly focused on independently solving arrival scheduling problems, departure scheduling problems and surface management scheduling problems and most of the developed models are deterministic. This dissertation presents an alternate method to model the integrated operations by using a machine job-shop scheduling formulation. A multistage stochastic programming approach is chosen to formulate the problem in the presence of uncertainty and candidate solutions are obtained by solving sample average approximation problems with finite sample size. The developed mixed-integer-linear-programming algorithm-based scheduler is capable of computing optimal aircraft schedules and routings that reflect the integration of air and ground operations. The assembled methodology is applied to a Los Angeles case study. To show the benefits of integrated operations over First-Come-First-Served, a preliminary proof-of-concept is conducted for a set of fourteen aircraft evolving under deterministic conditions in a model of the Los Angeles International Airport surface and surrounding terminal areas. Using historical data, a representative 30-minute traffic schedule and aircraft mix scenario is constructed. The results of the Los Angeles application show that the integration of air and ground operations and the use of a time-based separation strategy enable both significant surface and air time savings. The solution computed by the optimization provides a more efficient routing and scheduling than the First-Come-First-Served solution. Additionally, a data driven analysis is performed for the Los Angeles environment and probabilistic distributions of pertinent uncertainty sources are obtained. A sensitivity analysis is then carried out to assess the methodology performance and find optimal sampling parameters. Finally, simulations of increasing traffic density in the presence of uncertainty are conducted first for integrated arrivals and departures, then for integrated surface and air operations. To compare the optimization results and show the benefits of integrated operations, two aircraft separation methods are implemented that offer different routing options. The simulations of integrated air operations and the simulations of integrated air and surface operations demonstrate that significant traveling time savings, both total and individual surface and air times, can be obtained when more direct routes are allowed to be traveled even in the presence of uncertainty. The resulting routings induce however extra take off delay for departing flights. As a consequence, some flights cannot meet their initial assigned runway slot which engenders runway position shifting when comparing resulting runway sequences computed under both deterministic and stochastic conditions. The optimization is able to compute an optimal runway schedule that represents an optimal balance between total schedule delays and total travel times.

Mapping of an ultrasonic bath for ultrasound assisted extraction of mangiferin from Mangifera indica leaves.

PubMed

Kulkarni, Vrushali M; Rathod, Virendra K

2014-03-01

The present work deals with the mapping of an ultrasonic bath for the maximum extraction of mangiferin from Mangifera indica leaves. I3(-) liberation experiments (chemical transformations) and extraction (physical transformations) were carried out at different locations in an ultrasonic bath and compared. The experimental findings indicated a similar trend in variation in an ultrasonic bath by both these methods. Various parameters such as position and depth of vessel in an ultrasonic bath, diameter and shape of a vessel, frequency and input power which affect the extraction yield have been studied in detail. Maximum yield of mangiferin obtained was approximately 31 mg/g at optimized parameters: distance of 2.54 cm above the bottom of the bath, 7 cm diameter of vessel, flat bottom vessel, 6.35 cm liquid height, 122 W input power and 25 kHz frequency. The present work indicates that the position and depth of vessel in an ultrasonic bath, diameter and shape of a vessel, frequency and input power have significant effect on the extraction yield. This work can be used as a base for all ultrasonic baths to obtain maximum efficiency for ultrasound assisted extraction. Copyright © 2013 Elsevier B.V. All rights reserved.

Surgical stent planning: simulation parameter study for models based on DICOM standards.

PubMed

Scherer, S; Treichel, T; Ritter, N; Triebel, G; Drossel, W G; Burgert, O

2011-05-01

Endovascular Aneurysm Repair (EVAR) can be facilitated by a realistic simulation model of stent-vessel-interaction. Therefore, numerical feasibility and integrability in the clinical environment was evaluated. The finite element method was used to determine necessary simulation parameters for stent-vessel-interaction in EVAR. Input variables and result data of the simulation model were examined for their standardization using DICOM supplements. The study identified four essential parameters for the stent-vessel simulation: blood pressure, intima constitution, plaque occurrence and the material properties of vessel and plaque. Output quantities such as radial force of the stent and contact pressure between stent/vessel can help the surgeon to evaluate implant fixation and sealing. The model geometry can be saved with DICOM "Surface Segmentation" objects and the upcoming "Implant Templates" supplement. Simulation results can be stored using the "Structured Report". A standards-based general simulation model for optimizing stent-graft selection may be feasible. At present, there are limitations due to specification of individual vessel material parameters and for simulating the proximal fixation of stent-grafts with hooks. Simulation data with clinical relevance for documentation and presentation can be stored using existing or new DICOM extensions.

Blood vessel damage correlated with irradiance for in vivo vascular targeted photodynamic therapy

NASA Astrophysics Data System (ADS)

Zhang, Jinde; Tan, Zou; Niu, Xiangyu; Lin, Linsheng; Lin, Huiyun; Li, Buhong

2016-10-01

Vascular targeted photodynamic therapy (V-PDT) has been widely utilized for the prevention or treatment of vascular-related diseases, including age-related macular degeneration, port-wine stains and prostate cancer. In order to quantitative assessment the blood vessel damage during V-PDT, nude mice were implanted with Titanium dorsal skin window chambers for in vivo V-PDT studies. For treatments, various irradiances including 50, 75, 100 and 200 mW/cm2 provided by a 532 nm semiconductor laser were performed with the same total light dose of 30 J/cm2 after the mice were intravenously injection of Rose Bengal for 25 mg/Kg body weight. Laser speckle imaging and microscope were used to monitor blood flow dynamics and vessel constriction during and after V-PDT, respectively. The V-PDT induced vessel damages between different groups were compared. The results show that significant difference in blood vessel damage was found between the lower irradiances (50, 75 and 100 mW/cm2) and higher irradiance (200 mW/cm2), and the blood vessel damage induced by V-PDT is positively correlated with irradiance. This study implies that the optimization of irradiance is required for enhancing V-PDT therapeutic efficiency.

Conception et analyse d'un systeme d'optimisation de plans de vol pour les avions

NASA Astrophysics Data System (ADS)

Maazoun, Wissem

The main objective of this thesis is to develop an optimization method for the preparation of flight plans for aircrafts. The flight plan minimizes all costs associated with the flight. We determine an optimal path for an airplane from a departure airport to a destination airport. The optimal path minimizes the sum of all costs, i.e. the cost of fuel added to the cost of time (wages, rental of the aircraft, arrival delays, etc.). The optimal trajectory is obtained by considering all possible trajectories on a 3D graph (longitude, latitude and altitude) where the altitude levels are separated by 2,000 feet, and by applying a shortest path algorithm. The main task was to accurately compute fuel consumption on each edge of the graph, making sure that each arc has a minimal cost and is covered in a realistic way from the point of view of control, i.e. in accordance with the rules of navigation. To compute the cost of an arc, we take into account weather conditions (temperature, pressure, wind components, etc.). The optimization of each arc is done via the evaluation of an optimum speed that takes all costs into account. Each arc of the graph typically includes several sub-phases of the flight, e.g. altitude change, speed change, and constant speed and altitude. In the initial climb and the final descent phases, the costs are determined by considering altitude changes at constant CAS (Calibrated Air Speed) or constant Mach number. CAS and Mach number are adjusted to minimize cost. The aerodynamic model used is the one proposed by Eurocontrol, which uses the BADA (Base of Aircraft Data) tables. This model is based on the total energy equation that determines the instantaneous fuel consumption. Calculations on each arc are done by solving a system of differential equations that systematically takes all costs into account. To compute the cost of an arc, we must know the time to go through it, which is generally unknown. To have well-posed boundary conditions, we use the horizontal displacement as the independent variable of the system of differential equations. We consider the velocity components of the wind in a 3D system of coordinates to compute the instantaneous ground speed of the aircraft. To consider the cost of time, we use the cost index. The cost of an arc depends on the aircraft mass at the beginning of this arc, and this mass depends on the path. As we consider all possible paths, the cost of an arc must be computed for each trajectory to which it belongs. For a long-distance flight, the number of arcs to be considered in the graph is large and therefore the cost of an arc is typically computed many times. Our algorithm computes the costs of one million arcs in seconds while having a high accuracy. The determination of the optimal trajectory can therefore be done in a short time. To get the optimal path, the mass of the aircraft at the departure point must also be optimal. It is therefore necessary to know the optimal amount of fuel for the journey. The aircraft mass is known only at the arrival point. This mass is the mass of the aircraft including passengers, cargo and reserve fuel mass. The optimal path is determined by calculating backwards, i.e. from the arrival point to the departure point. For the determination of the optimal trajectory, we use an elliptical grid that has focal points at the departure and arrival points. The use of this grid is essential for the construction of a direct and acyclic graph. We use the Bellman-Ford algorithm on a DAG to determine the shortest path. This algorithm is easy to implement and results in short computation times. Our algorithm computes an optimal trajectory with an optimal cost for each arc. Altitude changes are done optimally with respect to the mass of the aircraft and the cost of time. Our algorithm gives the mass, speed, altitude and total cost at any point of the trajectory as well as the optimal profiles of climb and descent. A prototype has been implemented in C. We made simulations of all types of possible arcs and of several complete trajectories to illustrate the behaviour of the algorithm.

Re-Thinking Pedagogy for Middle School Students with Little, No or Severely Interrupted Schooling

ERIC Educational Resources Information Center

Dooley, Karen

2009-01-01

The arrival of substantial cohorts of English language learners from Africa with little, no or severely interrupted schooling is requiring new pedagogic responses from teachers in Australia and other Western countries of refugee re-settlement. If the students are to have optimal educational and life chances, it is crucial for them to acquire…

Parameterizing Phrase Based Statistical Machine Translation Models: An Analytic Study

ERIC Educational Resources Information Center

Cer, Daniel

2011-01-01

The goal of this dissertation is to determine the best way to train a statistical machine translation system. I first develop a state-of-the-art machine translation system called Phrasal and then use it to examine a wide variety of potential learning algorithms and optimization criteria and arrive at two very surprising results. First, despite the…

NREL Tests Energy Storage System to Fill Renewable Gaps | News | NREL

Science.gov Websites

Tests Energy Storage System to Fill Renewable Gaps NREL Tests Energy Storage System to Fill -megawatt energy storage system from Renewable Energy Systems (RES) Americas will assist research that aims to optimize the grid for wind and solar plants. The system arrived at NREL's National Wind Technology

Solid State Research.

DTIC Science & Technology

1995-08-15

contact formation. 16 The surface morphology was examined using Nomarski contrast microscopy. The alloy composi- tion of AlGaAs layers was...tunnel. For this purpose, a previously reported FEA fabrication process [2] based on laser- interferometric lithography is being optimized to produce...allows angle of arrival to be determined using only compressed pulse amplitudes. The alternative is an interferometric antenna coupled to a

A two-stage stochastic optimization model for scheduling electric vehicle charging loads to relieve distribution-system constraints

DOE PAGES

Wu, Fei; Sioshansi, Ramteen

2017-05-25

Electric vehicles (EVs) hold promise to improve the energy efficiency and environmental impacts of transportation. However, widespread EV use can impose significant stress on electricity-distribution systems due to their added charging loads. This paper proposes a centralized EV charging-control model, which schedules the charging of EVs that have flexibility. This flexibility stems from EVs that are parked at the charging station for a longer duration of time than is needed to fully recharge the battery. The model is formulated as a two-stage stochastic optimization problem. The model captures the use of distributed energy resources and uncertainties around EV arrival timesmore » and charging demands upon arrival, non-EV loads on the distribution system, energy prices, and availability of energy from the distributed energy resources. We use a Monte Carlo-based sample-average approximation technique and an L-shaped method to solve the resulting optimization problem efficiently. We also apply a sequential sampling technique to dynamically determine the optimal size of the randomly sampled scenario tree to give a solution with a desired quality at minimal computational cost. Here, we demonstrate the use of our model on a Central-Ohio-based case study. We show the benefits of the model in reducing charging costs, negative impacts on the distribution system, and unserved EV-charging demand compared to simpler heuristics. Lastly, we also conduct sensitivity analyses, to show how the model performs and the resulting costs and load profiles when the design of the station or EV-usage parameters are changed.« less

Optimal 3D culture of primary articular chondrocytes for use in the rotating wall vessel bioreactor.

PubMed

Mellor, Liliana F; Baker, Travis L; Brown, Raquel J; Catlin, Lindsey W; Oxford, Julia Thom

2014-08-01

Reliable culturing methods for primary articular chondrocytes are essential to study the effects of loading and unloading on joint tissue at the cellular level. Due to the limited proliferation capacity of primary chondrocytes and their tendency to dedifferentiate in conventional culture conditions, long-term culturing conditions of primary chondrocytes can be challenging. The goal of this study was to develop a suspension culturing technique that not only would retain the cellular morphology, but also maintain the gene expression characteristics of primary articular chondrocytes. Three-dimensional culturing methods were compared and optimized for primary articular chondrocytes in the rotating wall vessel bioreactor, which changes the mechanical culture conditions to provide a form of suspension culture optimized for low shear and turbulence. We performed gene expression analysis and morphological characterization of cells cultured in alginate beads, Cytopore-2 microcarriers, primary monolayer culture, and passaged monolayer cultures using reverse transcription-PCR and laser scanning confocal microscopy. Primary chondrocytes grown on Cytopore-2 microcarriers maintained the phenotypical morphology and gene expression pattern observed in primary bovine articular chondrocytes, and retained these characteristics for up to 9 d. Our results provide a novel and alternative culturing technique for primary chondrocytes suitable for studies that require suspension such as those using the rotating wall vessel bioreactor. In addition, we provide an alternative culturing technique for primary chondrocytes that can impact future mechanistic studies of osteoarthritis progression, treatments for cartilage damage and repair, and cartilage tissue engineering.

An automated method for accurate vessel segmentation.

PubMed

Yang, Xin; Liu, Chaoyue; Le Minh, Hung; Wang, Zhiwei; Chien, Aichi; Cheng, Kwang-Ting Tim

2017-05-07

Vessel segmentation is a critical task for various medical applications, such as diagnosis assistance of diabetic retinopathy, quantification of cerebral aneurysm's growth, and guiding surgery in neurosurgical procedures. Despite technology advances in image segmentation, existing methods still suffer from low accuracy for vessel segmentation in the two challenging while common scenarios in clinical usage: (1) regions with a low signal-to-noise-ratio (SNR), and (2) at vessel boundaries disturbed by adjacent non-vessel pixels. In this paper, we present an automated system which can achieve highly accurate vessel segmentation for both 2D and 3D images even under these challenging scenarios. Three key contributions achieved by our system are: (1) a progressive contrast enhancement method to adaptively enhance contrast of challenging pixels that were otherwise indistinguishable, (2) a boundary refinement method to effectively improve segmentation accuracy at vessel borders based on Canny edge detection, and (3) a content-aware region-of-interests (ROI) adjustment method to automatically determine the locations and sizes of ROIs which contain ambiguous pixels and demand further verification. Extensive evaluation of our method is conducted on both 2D and 3D datasets. On a public 2D retinal dataset (named DRIVE (Staal 2004 IEEE Trans. Med. Imaging 23 501-9)) and our 2D clinical cerebral dataset, our approach achieves superior performance to the state-of-the-art methods including a vesselness based method (Frangi 1998 Int. Conf. on Medical Image Computing and Computer-Assisted Intervention) and an optimally oriented flux (OOF) based method (Law and Chung 2008 European Conf. on Computer Vision). An evaluation on 11 clinical 3D CTA cerebral datasets shows that our method can achieve 94% average accuracy with respect to the manual segmentation reference, which is 23% to 33% better than the five baseline methods (Yushkevich 2006 Neuroimage 31 1116-28; Law and Chung 2008 European Conf. on Computer Vision; Law and Chung 2009 IEEE Trans. Image Process. 18 596-612; Wang 2015 J. Neurosci. Methods 241 30-6) with manually optimized parameters. Our system has also been applied clinically for cerebral aneurysm development analysis. Experimental results on 10 patients' data, with two 3D CT scans per patient, show that our system's automatic diagnosis outcomes are consistent with clinicians' manual measurements.

An automated method for accurate vessel segmentation

NASA Astrophysics Data System (ADS)

Yang, Xin; Liu, Chaoyue; Le Minh, Hung; Wang, Zhiwei; Chien, Aichi; (Tim Cheng, Kwang-Ting

2017-05-01

Vessel segmentation is a critical task for various medical applications, such as diagnosis assistance of diabetic retinopathy, quantification of cerebral aneurysm’s growth, and guiding surgery in neurosurgical procedures. Despite technology advances in image segmentation, existing methods still suffer from low accuracy for vessel segmentation in the two challenging while common scenarios in clinical usage: (1) regions with a low signal-to-noise-ratio (SNR), and (2) at vessel boundaries disturbed by adjacent non-vessel pixels. In this paper, we present an automated system which can achieve highly accurate vessel segmentation for both 2D and 3D images even under these challenging scenarios. Three key contributions achieved by our system are: (1) a progressive contrast enhancement method to adaptively enhance contrast of challenging pixels that were otherwise indistinguishable, (2) a boundary refinement method to effectively improve segmentation accuracy at vessel borders based on Canny edge detection, and (3) a content-aware region-of-interests (ROI) adjustment method to automatically determine the locations and sizes of ROIs which contain ambiguous pixels and demand further verification. Extensive evaluation of our method is conducted on both 2D and 3D datasets. On a public 2D retinal dataset (named DRIVE (Staal 2004 IEEE Trans. Med. Imaging 23 501-9)) and our 2D clinical cerebral dataset, our approach achieves superior performance to the state-of-the-art methods including a vesselness based method (Frangi 1998 Int. Conf. on Medical Image Computing and Computer-Assisted Intervention) and an optimally oriented flux (OOF) based method (Law and Chung 2008 European Conf. on Computer Vision). An evaluation on 11 clinical 3D CTA cerebral datasets shows that our method can achieve 94% average accuracy with respect to the manual segmentation reference, which is 23% to 33% better than the five baseline methods (Yushkevich 2006 Neuroimage 31 1116-28; Law and Chung 2008 European Conf. on Computer Vision; Law and Chung 2009 IEEE Trans. Image Process. 18 596-612; Wang 2015 J. Neurosci. Methods 241 30-6) with manually optimized parameters. Our system has also been applied clinically for cerebral aneurysm development analysis. Experimental results on 10 patients’ data, with two 3D CT scans per patient, show that our system’s automatic diagnosis outcomes are consistent with clinicians’ manual measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasser, M.N.; Schultze Kool, L.J.; Roos, A. de

Our goal was to assess the value of MRA for detecting stenoses in the celiac (CA) and superior mesenteric (SMA) arteries in patients suspected of having chronic mesenteric ischemia, using an optimized systolically gated 3D phase contrast technique. In an initial study in 24 patients who underwent conventional angiography of the abdominal vessels for different clinical indications, a 3D phase contrast MRA technique (3D-PCA) was evaluated and optimized to image the CAs and SMAs. Subsequently, a prospective study was performed to assess the value of systolically gated 3D-PCA in evaluation of the mesenteric arteries in 10 patients with signs andmore » symptoms of chronic mesenteric ischemia. Intraarterial digital subtraction angiography and surgical findings were used as the reference standard. In the initial study, systolic gating appeared to be essential in imaging the SMA on 3D-PCA. In 10 patients suspected of mesenteric ischemia, systolically gated 3D-PCA identified significant proximal disease in the two mesenteric vessels in 4 patients. These patients underwent successful reconstruction of their stenotic vessels. Cardiac-gated MRA may become a useful tool in selection of patients suspected of having mesenteric ischemia who may benefit from surgery. 16 refs., 6 figs., 4 tabs.« less

Fatal poisoning and other health hazards connected with industrial fishing

PubMed Central

Dalgaard, J. B.; Dencker, F.; Fallentin, B.; Hansen, P.; Kaempe, B.; Steensberg, J.; Wilhardt, P.

1972-01-01

Dalgaard, J. B., Dencker, F., Fallentin, B., Hansen, P., Kaempe, B., Steensberg, J., and Wilhardt, P. (1972).Brit. J. industr. Med.,29, 307-316. Fatal poisoning and other health hazards connected with industrial fishing. The literature about death and health problems related to work with fish for industrial use is reviewed. Three fatal cases and several instances of unconsciousness or cases of fainting are reported. An investigation was carried out into the composition of the air in the holds and forecastles of Danish industrial-fishing cutters on their arrival at port. The laboratory procedures are described, and the results are reported. In several instances the low concentrations of oxygen and/or high concentrations of carbon dioxide and hydrogen sulphide found were considered to be hazardous to life. The fatalities and sudden loss of consciousness in the reported cases are ascribed to these changes, hypoxia and hypercapnia being the most important causes. The risk of poisoning seems to be greatest during the landing of trash-fish and in fish-meal plants. Persons under the influence of alcohol may, for one reason or another, be particularly susceptible. The most important preventive measure is improvement of the quality of the raw material which would also reduce the nuisance from smell. Two safety belts with ropes should be provided in the vessels and close to the pits in the fish-meal plants. Fishermen should leave the vessel after arrival in port and not return until after unloading has been completed. During unloading and in the factories, effective mechanical ventilation is essential. Apparatus to monitor the concentrations of oxygen, carbon dioxide, hydrogen sulphide, and ammonia should be available in the fishing ports, and cases of accident, including mere `faintings', should be subjected to prompt medical and technical investigation. From the occupational medical aspect, fishermen are in a less satisfactory situation than workers on shore. An occupational health service, including pre-employment and periodic examinations of personnel and working conditions, is recommended. Images PMID:5044602

On the optimal use of a slow server in two-stage queueing systems

NASA Astrophysics Data System (ADS)

Papachristos, Ioannis; Pandelis, Dimitrios G.

2017-07-01

We consider two-stage tandem queueing systems with a dedicated server in each queue and a slower flexible server that can attend both queues. We assume Poisson arrivals and exponential service times, and linear holding costs for jobs present in the system. We study the optimal dynamic assignment of servers to jobs assuming that two servers cannot collaborate to work on the same job and preemptions are not allowed. We formulate the problem as a Markov decision process and derive properties of the optimal allocation for the dedicated (fast) servers. Specifically, we show that the one downstream should not idle, and the same is true for the one upstream when holding costs are larger there. The optimal allocation of the slow server is investigated through extensive numerical experiments that lead to conjectures on the structure of the optimal policy.

Application of Combined Two-Dimensional and Three-Dimensional Transvaginal Contrast Enhanced Ultrasound in the Diagnosis of Endometrial Carcinoma

PubMed Central

Zhou, Hui-li; Xiang, Hong; Duan, Li; Shahai, Gulinaer; Liu, Hui; Li, Xiang-hong; Mou, Rui-xue

2015-01-01

Objective. The goal of this study was to explore the clinical value of combining two-dimensional (2D) and three-dimensional (3D) transvaginal contrast-enhanced ultrasounds (CEUS) in diagnosis of endometrial carcinoma (EC). Methods. In this prospective diagnostic study, transvaginal 2D and 3D CEUS were performed on 68 patients with suspected EC, and the results of the obtained 2D-CEUS and 3D-CEUS images were compared with the gold standard for statistical analysis. Results. 2D-CEUS benign endometrial lesions showed the normal uterine perfusion phase while EC cases showed early arrival and early washout of the contrast agent and nonuniform enhancement. The 3D-CEUS images differed in central blood vessel manifestation, blood vessel shape, and vascular pattern between benign and malignant endometrial lesions (P < 0.05). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of transvaginal 2D-CEUS and 2D-CEUS combined with 3D-CEUS for diagnosis of benign and malignant endometrial lesions were 76.9%, 73.8%, 64.5%, 83.8%, and 75.0% and 84.6%, 83.3%, 75.9%, 89.7%, and 83.8%, respectively. Conclusion. 3D-CEUS is a useful supplement to 2D-CEUS and can clearly reveal the angioarchitecture spatial relationships between vessels and depth of myometrial invasion in EC. The combined use of 2D and 3D-CEUS can offer direct, accurate, and comprehensive diagnosis of early EC. PMID:26090396

Doppler velocity measurements from large and small arteries of mice

PubMed Central

Reddy, Anilkumar K.; Madala, Sridhar; Entman, Mark L.; Michael, Lloyd H.; Taffet, George E.

2011-01-01

With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans. PMID:21572013

Transport of the Harmful Bloom Alga Aureococcus anophagefferens by Oceangoing Ships and Coastal Boats

PubMed Central

Doblin, Martina A.; Popels, Linda C.; Coyne, Kathryn J.; Hutchins, David A.; Cary, S. Craig; Dobbs, Fred C.

2004-01-01

It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species Aureococcus anophagefferens (brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of Aureococcus (>22 ppt) and the low salinity of the residual ballast water (∼2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute Aureococcus. During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were sampled. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well sample. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of Aureococcus. PMID:15528511

The IceCube Neutrino Observatory, the Pierre Auger Observatory and the Telescope Array: Joint Contribution to the 34th International Cosmic Ray Conference (ICRC 2015)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aartsen, M.G.; et al.

2015-11-06

We have conducted three searches for correlations between ultra-high energy cosmic rays detected by the Telescope Array and the Pierre Auger Observatory, and high-energy neutrino candidate events from IceCube. Two cross-correlation analyses with UHECRs are done: one with 39 cascades from the IceCube `high-energy starting events' sample and the other with 16 high-energy `track events'. The angular separation between the arrival directions of neutrinos and UHECRs is scanned over. The same events are also used in a separate search using a maximum likelihood approach, after the neutrino arrival directions are stacked. To estimate the significance we assume UHECR magnetic deflections to be inversely proportional to their energy, with valuesmore » $$3^\\circ$$, $$6^\\circ$$ and $$9^\\circ$$ at 100 EeV to allow for the uncertainties on the magnetic field strength and UHECR charge. A similar analysis is performed on stacked UHECR arrival directions and the IceCube sample of through-going muon track events which were optimized for neutrino point-source searches.« less

Research and Development of Automated Eddy Current Testing for Composite Overwrapped Pressure Vessels

NASA Technical Reports Server (NTRS)

Carver, Kyle L.; Saulsberry, Regor L.; Nichols, Charles T.; Spencer, Paul R.; Lucero, Ralph E.

2012-01-01

Eddy current testing (ET) was used to scan bare metallic liners used in the fabrication of composite overwrapped pressure vessels (COPVs) for flaws which could result in premature failure of the vessel. The main goal of the project was to make improvements in the areas of scan signal to noise ratio, sensitivity of flaw detection, and estimation of flaw dimensions. Scan settings were optimized resulting in an increased signal to noise ratio. Previously undiscovered flaw indications were observed and investigated. Threshold criteria were determined for the system software's flaw report and estimation of flaw dimensions were brought to an acceptable level of accuracy. Computer algorithms were written to import data for filtering and a numerical derivative filtering algorithm was evaluated.

Longitudinal gradient coil optimization in the presence of transient eddy currents.

PubMed

Trakic, A; Liu, F; Lopez, H Sanchez; Wang, H; Crozier, S

2007-06-01

The switching of magnetic field gradient coils in magnetic resonance imaging (MRI) inevitably induces transient eddy currents in conducting system components, such as the cryostat vessel. These secondary currents degrade the spatial and temporal performance of the gradient coils, and compensation methods are commonly employed to correct for these distortions. This theoretical study shows that by incorporating the eddy currents into the coil optimization process, it is possible to modify a gradient coil design so that the fields created by the coil and the eddy currents combine together to generate a spatially homogeneous gradient that follows the input pulse. Shielded and unshielded longitudinal gradient coils are used to exemplify this novel approach. To assist in the evaluation of transient eddy currents induced within a realistic cryostat vessel, a low-frequency finite-difference time-domain (FDTD) method using the total-field scattered-field (TFSF) scheme was performed. The simulations demonstrate the effectiveness of the proposed method for optimizing longitudinal gradient fields while taking into account the spatial and temporal behavior of the eddy currents.

Hybrid Wound Filaments for Greater Resistance to Impacts

NASA Technical Reports Server (NTRS)

DeLay, Thomas K.; Patterson, James E.; Olson, Michael A.

2008-01-01

A hybrid material containing wound filaments made of a hybrid of high-strength carbon fibers and poly(phenylene benzobisoxazole) [PBO] fibers is discussed. This hybrid material is chosen in an effort to increase the ability of the pressure vessel to resist damage by low-speed impacts (e.g., dropping of tools on the vessel or bumping of the vessel against hard objects during installation and use) without significantly increasing the weight of the vessel. While the basic concept of hybridizing fibers in filament-wound structures is not new, the use of hybridization to increase resistance to impacts is an innovation, and can be expected to be of interest in the composite-pressure-vessel industry. The precise types and the proportions of the high-strength carbon fibers and the PBO fibers in the hybrid are chosen, along with the filament-winding pattern, to maximize the advantageous effects and minimize the disadvantageous effects of each material. In particular, one seeks to (1) take advantage of the ability of the carbon fibers to resist stress rupture while minimizing their contribution to vulnerability of the vessel to impact damage and (2) take advantage of the toughness of the PBO fibers while minimizing their contribution to vulnerability of the vessel to stress rupture. Experiments on prototype vessels fabricated according to this concept have shown promising results. At the time of reporting the information for this article, research toward understanding and optimizing the performances of PBO fibers so as to minimize their contribution to vulnerability of the pressure vessel to stress rupture had yet to be performed.

Brain vascular image enhancement based on gradient adjust with split Bregman

NASA Astrophysics Data System (ADS)

Liang, Xiao; Dong, Di; Hui, Hui; Zhang, Liwen; Fang, Mengjie; Tian, Jie

2016-04-01

Light Sheet Microscopy is a high-resolution fluorescence microscopic technique which enables to observe the mouse brain vascular network clearly with immunostaining. However, micro-vessels are stained with few fluorescence antibodies and their signals are much weaker than large vessels, which make micro-vessels unclear in LSM images. In this work, we developed a vascular image enhancement method to enhance micro-vessel details which should be useful for vessel statistics analysis. Since gradient describes the edge information of the vessel, the main idea of our method is to increase the gradient values of the enhanced image to improve the micro-vessels contrast. Our method contained two steps: 1) calculate the gradient image of LSM image, and then amplify high gradient values of the original image to enhance the vessel edge and suppress low gradient values to remove noises. Then we formulated a new L1-norm regularization optimization problem to find an image with the expected gradient while keeping the main structure information of the original image. 2) The split Bregman iteration method was used to deal with the L1-norm regularization problem and generate the final enhanced image. The main advantage of the split Bregman method is that it has both fast convergence and low memory cost. In order to verify the effectiveness of our method, we applied our method to a series of mouse brain vascular images acquired from a commercial LSM system in our lab. The experimental results showed that our method could greatly enhance micro-vessel edges which were unclear in the original images.

The research of a solution on locating optimally a station for seismic disasters rescue in a city

NASA Astrophysics Data System (ADS)

Yao, Qing-Lin

1995-02-01

When the stations for seismic disasters rescue in future or the similars are designed on a network of communication line, the general absolute center of a graph needs to be solved to reduce the requirements in the number of stations and running parameters and to establish an optimal station in a sense distribution of the rescue arrival time by the way of locating optimally the stations. The existing solution on this problem was proposed by Edward (1978) in which, however, there is serious deviation. In this article, the work of Edward (1978) is developed in both formula and figure, more correct solution is proposed and proved. Then the result from the newer solution is contrasted with that from the older one in a instance about locating optimally the station for seismic disasters rescue.

Numerical Parameter Optimization of the Ignition and Growth Model for HMX Based Plastic Bonded Explosives

NASA Astrophysics Data System (ADS)

Gambino, James; Tarver, Craig; Springer, H. Keo; White, Bradley; Fried, Laurence

2017-06-01

We present a novel method for optimizing parameters of the Ignition and Growth reactive flow (I&G) model for high explosives. The I&G model can yield accurate predictions of experimental observations. However, calibrating the model is a time-consuming task especially with multiple experiments. In this study, we couple the differential evolution global optimization algorithm to simulations of shock initiation experiments in the multi-physics code ALE3D. We develop parameter sets for HMX based explosives LX-07 and LX-10. The optimization finds the I&G model parameters that globally minimize the difference between calculated and experimental shock time of arrival at embedded pressure gauges. This work was performed under the auspices of the U.S. DOE by LLNL under contract DE-AC52-07NA27344. LLNS, LLC LLNL-ABS- 724898.

Storage capacity: how big should it be

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malina, M.A.

1980-01-28

A mathematical model was developed for determining the economically optimal storage capacity of a given material or product at a manufacturing plant. The optimum was defined as a trade-off between the inventory-holding costs and the cost of customer-service failures caused by insufficient stocks for a peak-demand period. The order-arrival, production, storage, and shipment process was simulated by Monte Carlo techniques to calculate the probability of order delays for various lengths of time as a function of storage capacity. Example calculations for the storage of a bulk liquid chemical in tanks showed that the conclusions arrived at, via this model, aremore » comparatively insensitive to errors made in estimating the capital cost of storage or the risk of losing an order because of a late delivery.« less

Arterial tree tracking from anatomical landmarks in magnetic resonance angiography scans

NASA Astrophysics Data System (ADS)

O'Neil, Alison; Beveridge, Erin; Houston, Graeme; McCormick, Lynne; Poole, Ian

2014-03-01

This paper reports on arterial tree tracking in fourteen Contrast Enhanced MRA volumetric scans, given the positions of a predefined set of vascular landmarks, by using the A* algorithm to find the optimal path for each vessel based on voxel intensity and a learnt vascular probability atlas. The algorithm is intended for use in conjunction with an automatic landmark detection step, to enable fully automatic arterial tree tracking. The scan is filtered to give two further images using the top-hat transform with 4mm and 8mm cubic structuring elements. Vessels are then tracked independently on the scan in which the vessel of interest is best enhanced, as determined from knowledge of typical vessel diameter and surrounding structures. A vascular probability atlas modelling expected vessel location and orientation is constructed by non-rigidly registering the training scans to the test scan using a 3D thin plate spline to match landmark correspondences, and employing kernel density estimation with the ground truth center line points to form a probability density distribution. Threshold estimation by histogram analysis is used to segment background from vessel intensities. The A* algorithm is run using a linear cost function constructed from the threshold and the vascular atlas prior. Tracking results are presented for all major arteries excluding those in the upper limbs. An improvement was observed when tracking was informed by contextual information, with particular benefit for peripheral vessels.

Examining P-Wave Arrivals of Low-Frequency Earthquakes for Evidence of Attenuation and its Effects on Moment-Duration Scaling

NASA Astrophysics Data System (ADS)

Gerzina, J.; Rubin, A. M.

2017-12-01

Bostock et. al. (2015) found that low-frequency earthquake (LFE) duration is nearly independent of moment, a result that is surprising enough to warrant investigating whether it might be an artifact of attenuation. Bostock et. al. (2017) found that bulk crustal attenuation could not be the culprit, but suggested that near-source attenuation might cause pronounced depletion of high frequency S-waves. Despite their lower signal-to noise ratio, looking at the P-waves might be enlightening because they aren't expected to attenuate as much as S-waves in the high Vp/Vs region near the tremor source. We have examined P-wave arrivals of LFEs that occurred during episodic tremor in the Cascadia subduction zone with the goal of refining the relationship between LFE magnitude and duration.Bostock et. al's duration measurements were made on stacked templates rather than individual arrivals. Because members of Bostock's LFE families vary in location, and therefore in P-S delay time, aligning the stacks primarily on the S arrival may artificially widen the P pulse. To circumvent this, we used cross-station cross correlations on Bostock's detections to identify and stack events with similar locations and therefore similar P-S delay times, until P arrivals became visible. We then stacked these stacks based on cross-correlating the optimal P component in a small window surrounding the P arrival. Although this procedure narrowed both the P and S pulse widths, it did not dramatically narrow P in relation to S, nor did we observe different P pulse widths for small and large events.We also compared the frequency spectra of small windows around the expected P and S arrivals for each amplitude bin. Although there is more high-frequency content in P-waves than S-waves, we have not yet been able to resolve a difference in P-wave corner frequency for different event sizes. Thus our preliminary results support the notion that LFEs are intrinsically low frequency.

A Sequential Linear Quadratic Approach for Constrained Nonlinear Optimal Control with Adaptive Time Discretization and Application to Higher Elevation Mars Landing Problem

NASA Astrophysics Data System (ADS)

Sandhu, Amit

A sequential quadratic programming method is proposed for solving nonlinear optimal control problems subject to general path constraints including mixed state-control and state only constraints. The proposed algorithm further develops on the approach proposed in [1] with objective to eliminate the use of a high number of time intervals for arriving at an optimal solution. This is done by introducing an adaptive time discretization to allow formation of a desirable control profile without utilizing a lot of intervals. The use of fewer time intervals reduces the computation time considerably. This algorithm is further used in this thesis to solve a trajectory planning problem for higher elevation Mars landing.

Two-phase framework for near-optimal multi-target Lambert rendezvous

NASA Astrophysics Data System (ADS)

Bang, Jun; Ahn, Jaemyung

2018-03-01

This paper proposes a two-phase framework to obtain a near-optimal solution of multi-target Lambert rendezvous problem. The objective of the problem is to determine the minimum-cost rendezvous sequence and trajectories to visit a given set of targets within a maximum mission duration. The first phase solves a series of single-target rendezvous problems for all departure-arrival object pairs to generate the elementary solutions, which provides candidate rendezvous trajectories. The second phase formulates a variant of traveling salesman problem (TSP) using the elementary solutions prepared in the first phase and determines the final rendezvous sequence and trajectories of the multi-target rendezvous problem. The validity of the proposed optimization framework is demonstrated through an asteroid exploration case study.

Study of flutter related computational procedures for minimum weight structural sizing of advanced aircraft

NASA Technical Reports Server (NTRS)

Oconnell, R. F.; Hassig, H. J.; Radovcich, N. A.

1976-01-01

Results of a study of the development of flutter modules applicable to automated structural design of advanced aircraft configurations, such as a supersonic transport, are presented. Automated structural design is restricted to automated sizing of the elements of a given structural model. It includes a flutter optimization procedure; i.e., a procedure for arriving at a structure with minimum mass for satisfying flutter constraints. Methods of solving the flutter equation and computing the generalized aerodynamic force coefficients in the repetitive analysis environment of a flutter optimization procedure are studied, and recommended approaches are presented. Five approaches to flutter optimization are explained in detail and compared. An approach to flutter optimization incorporating some of the methods discussed is presented. Problems related to flutter optimization in a realistic design environment are discussed and an integrated approach to the entire flutter task is presented. Recommendations for further investigations are made. Results of numerical evaluations, applying the five methods of flutter optimization to the same design task, are presented.

Vertical Compliance Trends in KBOS OPD Arrival Redesign

NASA Technical Reports Server (NTRS)

Stewart, Michael Jeffrey; Matthews, Bryan L.; Feary, Michael S.

2016-01-01

This report is a high-level summary of vertical compliance trends and overall rates of Area Navigation Optimized Profile Descent (RNAV OPD) utilization for Boston Logan International Airport. Specifically, we investigated trends from three RNAV OPDs and the subsequent redesigned iterations of those procedures: OOSHN3 to OOSHN4, ROBUC1 to ROBUC2, and QUABN3 to JFUND1.

Minute by Minute: School Strategies for Optimizing Time. Case Studies of Promising Practices

ERIC Educational Resources Information Center

Corwin, Elise; Dunn, Lillian; Warco, Amanda; Lauria, Verna; Mulgrew-Daretany, Kathleen; Anzalone, Lisa

2014-01-01

In the last decade, there have been significant increases in the New York City high school graduation rates. Nevertheless, far too many students are graduating high school without the knowledge and skills they will need for college and career, and far too many continue to require remediation once they arrive at college. A central priority of the…

Multimedia Network Design Study

DTIC Science & Technology

1989-09-30

manipulation and analysis of the equations involved, thereby providing the application of the great range of powerful mathematical optimization...be treated by this analysis. First, all arrivals to the network have the Poisson distribution, and separate traffic classes may have separate qrrival...different for open and closed networks, so these two situations will be treated separately in the following subsections. 2.3.1 The Computational Process in

Research Of Airborne Precision Spacing to Improve Airport Arrival Operations

NASA Technical Reports Server (NTRS)

Barmore, Bryan E.; Baxley, Brian T.; Murdoch, Jennifer L.

2011-01-01

In September 2004, the European Organization for the Safety of Air Navigation (EUROCONTROL) and the United States Federal Aviation Administration (FAA) signed a Memorandum of Cooperation to mutually develop, modify, test, and evaluate systems, procedures, facilities, and devices to meet the need for safe and efficient air navigation and air traffic control in the future. In the United States and Europe, these efforts are defined within the architectures of the Next Generation Air Transportation System (NextGen) Program and Single European Sky Air Traffic Management Research (SESAR) Program respectively. Both programs have identified Airborne Spacing as a critical component, with Automatic Dependent Surveillance Broadcast (ADS-B) as a key enabler. Increased interest in reducing airport community noise and the escalating cost of aviation fuel has led to the use of Continuous Descent Arrival (CDA) procedures to reduce noise, emissions, and fuel usage compared to current procedures. To provide these operational enhancements, arrival flight paths into terminal areas are planned around continuous vertical descents that are closer to an optimum trajectory than those in use today. The profiles are designed to be near-idle descents from cruise altitude to the Final Approach Fix (FAF) and are typically without any level segments. By staying higher and faster than conventional arrivals, CDAs also save flight time for the aircraft operator. The drawback is that the variation of optimized trajectories for different types and weights of aircraft requires the Air Traffic Controller to provide more airspace around an aircraft on a CDA than on a conventional arrival procedure. This additional space decreases the throughput rate of the destination airport. Airborne self-spacing concepts have been developed to increase the throughput at high-demand airports by managing the inter-arrival spacing to be more precise and consistent using on-board guidance. It has been proposed that the additional space needed around an aircraft performing a CDA could be reduced or eliminated when using airborne spacing techniques.

Impact of lean six sigma process improvement methodology on cardiac catheterization laboratory efficiency.

PubMed

Agarwal, Shikhar; Gallo, Justin J; Parashar, Akhil; Agarwal, Kanika K; Ellis, Stephen G; Khot, Umesh N; Spooner, Robin; Murat Tuzcu, Emin; Kapadia, Samir R

2016-03-01

Operational inefficiencies are ubiquitous in several healthcare processes. To improve the operational efficiency of our catheterization laboratory (Cath Lab), we implemented a lean six sigma process improvement initiative, starting in June 2010. We aimed to study the impact of lean six sigma implementation on improving the efficiency and the patient throughput in our Cath Lab. All elective and urgent cardiac catheterization procedures including diagnostic coronary angiography, percutaneous coronary interventions, structural interventions and peripheral interventions performed between June 2009 and December 2012 were included in the study. Performance metrics utilized for analysis included turn-time, physician downtime, on-time patient arrival, on-time physician arrival, on-time start and manual sheath-pulls inside the Cath Lab. After implementation of lean six sigma in the Cath Lab, we observed a significant improvement in turn-time, physician downtime, on-time patient arrival, on-time physician arrival, on-time start as well as sheath-pulls inside the Cath Lab. The percentage of cases with optimal turn-time increased from 43.6% in 2009 to 56.6% in 2012 (p-trend<0.001). Similarly, the percentage of cases with an aggregate on-time start increased from 41.7% in 2009 to 62.8% in 2012 (p-trend<0.001). In addition, the percentage of manual sheath-pulls performed in the Cath Lab decreased from 60.7% in 2009 to 22.7% in 2012 (p-trend<0.001). The current longitudinal study illustrates the impact of successful implementation of a well-known process improvement initiative, lean six sigma, on improving and sustaining efficiency of our Cath Lab operation. After the successful implementation of this continuous quality improvement initiative, there was a significant improvement in the selected performance metrics namely turn-time, physician downtime, on-time patient arrival, on-time physician arrival, on-time start as well as sheath-pulls inside the Cath Lab. Copyright © 2016 Elsevier Inc. All rights reserved.

Gastrointestinal illness on passenger cruise ships, 1975-1978.

PubMed Central

Dannenberg, A L; Yashuk, J C; Feldman, R A

1982-01-01

Following investigations in 1972-1973 of outbreaks of enteric disease on cruise ships using American ports, a surveillance system was established which required that 24 hours before arrival in port, each ship report the number of persons with diarrheal illness seen by the ship's physician during the cruise. The reported data were found to be reliable; they established a baseline incidence for diarrhea on cruise ships. A significantly high portion of enteric disease outbreaks occurred on vessels that did not pass routine annual or semiannual sanitation inspections. The cruise ship sanitation program, developed with the cooperation of the cruise ship industry and the Centers for Disease Control, appears to have been successful in reducing the overall rate of cruise ship associated outbreaks of enteric illness. PMID:7065338

KSC-2012-3612

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, center, talks to the media in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the arrival in Florida of NASA's first space-bound Orion capsule, behind him. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3625

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – Dan Dumbacher, NASA deputy associate administrator for Exploration Systems Development, addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3621

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA astronaut Ricky Arnold addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3639

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director Robert Cabana addresses the audience assembled in Kennedy's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3630

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3629

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Deputy Administrator Lori Garver addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3613

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, left, and NASA Deputy Director Lori Garver discuss NASA's first space-bound Orion capsule in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3620

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director Robert Cabana addresses the audience assembled in Kennedy's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3638

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director Robert Cabana addresses the audience assembled in Kennedy's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3627

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Deputy Administrator Lori Garver addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3628

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Deputy Administrator Lori Garver addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3606

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, left, and NASA Kennedy Space Center Director Robert Cabana inspect NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3631

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3626

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Kennedy Space Center Director Robert Cabana addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3622

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Deputy Administrator Lori Garver addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3640

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – Mark Geyer, Orion program manager, addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3632

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – Orion Program Manager Mark Geyer addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

Sealing scientific probes against deep space and the Venusian environment A tough job

NASA Technical Reports Server (NTRS)

Pokras, J.; Reinert, R. P.; Switz, R. J.

1978-01-01

The Pioneer Venus mission evolved from studies conducted during the late 1960s and early 1970s. It was found that a need existed for low cost orbiters and landers to explore the planet. The considered mission was to be accomplished with six separate vehicles arriving at Venus nearly simultaneously in mid-December 1978. The probes are designed to survive entry and descent into the atmosphere. A description is presented of the approaches used to maintain sealing integrity for the large and small probes under the constraints imposed by the harsh Venusian environment. Attention is given to probe vehicle configuration, pressure vessel sealing requirements, material and configuration considerations, permanent seals, separable seals, development problems, and aspects of seal testing.

Uncluttered Single-Image Visualization of Vascular Structures using GPU and Integer Programming

PubMed Central

Won, Joong-Ho; Jeon, Yongkweon; Rosenberg, Jarrett; Yoon, Sungroh; Rubin, Geoffrey D.; Napel, Sandy

2013-01-01

Direct projection of three-dimensional branching structures, such as networks of cables, blood vessels, or neurons onto a 2D image creates the illusion of intersecting structural parts and creates challenges for understanding and communication. We present a method for visualizing such structures, and demonstrate its utility in visualizing the abdominal aorta and its branches, whose tomographic images might be obtained by computed tomography or magnetic resonance angiography, in a single two-dimensional stylistic image, without overlaps among branches. The visualization method, termed uncluttered single-image visualization (USIV), involves optimization of geometry. This paper proposes a novel optimization technique that utilizes an interesting connection of the optimization problem regarding USIV to the protein structure prediction problem. Adopting the integer linear programming-based formulation for the protein structure prediction problem, we tested the proposed technique using 30 visualizations produced from five patient scans with representative anatomical variants in the abdominal aortic vessel tree. The novel technique can exploit commodity-level parallelism, enabling use of general-purpose graphics processing unit (GPGPU) technology that yields a significant speedup. Comparison of the results with the other optimization technique previously reported elsewhere suggests that, in most aspects, the quality of the visualization is comparable to that of the previous one, with a significant gain in the computation time of the algorithm. PMID:22291148

Optimization of waste combinations during in-vessel composting of agricultural waste.

PubMed

Varma, V Sudharsan; Kalamdhad, Ajay S; Kumar, Bimlesh

2017-01-01

In-vessel composting of agricultural waste is a well-described approach for stabilization of compost within a short time period. Although composting studies have shown the different combinations of waste materials for producing good quality compost, studies of the particular ratio of the waste materials in the mix are still limited. In the present study, composting was conducted with a combination of vegetable waste, cow dung, sawdust and dry leaves using a 550 L rotary drum composter. Application of a radial basis functional neural network was used to simulate the composting process. The model utilizes physico-chemical parameters with different waste materials as input variables and three output variables: volatile solids, soluble biochemical oxygen demand and carbon dioxide evolution. For the selected model, the coefficient of determination reached the high value of 0.997. The complicated interaction of agricultural waste components during composting makes it a nonlinear problem so it is difficult to find the optimal waste combinations for producing quality compost. Optimization of a trained radial basis functional model has yielded the optimal proportion as 62 kg, 17 kg and 9 kg for vegetable waste, cow dung and sawdust, respectively. The results showed that the predictive radial basis functional model described for drum composting of agricultural waste was well suited for organic matter degradation and can be successfully applied.

Requirements analysis and preliminary design of a robotic assistant for reconstructive microsurgery.

PubMed

Vanthournhout, L; Herman, B; Duisit, J; Château, F; Szewczyk, J; Lengelé, B; Raucent, B

2015-08-01

Microanastomosis is a microsurgical gesture that involves suturing two very small blood vessels together. This gesture is used in many operations such as avulsed member auto-grafting, pediatric surgery, reconstructive surgery - including breast reconstruction by free flap. When vessels have diameters smaller than one millimeter, hand tremors make movements difficult to control. This paper introduces our preliminary steps towards robotic assistance for helping surgeons to perform microanastomosis in optimal conditions, in order to increase gesture quality and reliability even on smaller diameters. A general needs assessment and an experimental motion analysis were performed to define the requirements of the robot. Geometric parameters of the kinematic structure were then optimized to fulfill specific objectives. A prototype of the robot is currently being designed and built in order to providing a sufficient increase in accuracy without prolonging the duration of the procedure.

Optimization of Energy Consumption and Mass Transfer Parameters in a Surface Aeration Vessel.

PubMed

Mohammadpour, A; AkhavanBehabadi, M A; Ebrahimzadeh, M; Raisee, M; MajdiNasab, A R; Nosrati, M; Mousavi, S M

2016-04-01

This paper reports tests on a lab-scale surface aeration vessel was equipped with a Rushton turbine to examine its performance in terms of standard aeration efficiency (SAE), mixing time, and void fraction characteristics. These characteristics were investigated by tests using variations of rotor speed, impeller immersion depth, and water level. Results showed that variation of impeller immersion depth had a greater effect on the SAE compared to variation of water level. Moreover, the SAE increased with rotor speeds up to about 150 to 200 rpm and then decreased. In addition, void fraction improved by impeller immersion depth and rotor speed enhancement; however, mixing time and power number were reduced as rotor speed increased. According to the response surface methodology statistical optimizations, optimum values for rotor speed, impeller immersion depth, and water level were 168.90 rpm, 25 mm, and 30 cm, respectively, to achieve the maximum value of SAE.

Imaging the Vessel Wall in Major Peripheral Arteries using Susceptibility Weighted Imaging

PubMed Central

Yang, Qi; Liu, Jiantao; Barnes, Samuel R.S.; Wu, Zhen; Li, Kuncheng; Neelavalli, Jaladhar; Hu, Jiani; Haacke, E. Mark

2009-01-01

Purpose To demonstrate a novel contrast mechanism for imaging the vessel wall and vessel wall calcification using susceptibility weighted imaging (SWI). Materials and Methods 18 subjects were imaged with multi-detector computed tomography (MDCT) and high resolution SWI at 3T. The SWI imaging parameters were optimized to allow for the best visualization of the femoral artery lumen and the arterial wall in magnitude and phase images, respectively. SWI filtered phase data were used to evaluate the diamagnetic susceptibility of vessel wall and of putative vessel wall calcification. Imaging was performed using TE = 15.6 ms (in-phase for fat); TR = 25 ms, FA = 10°, BW = 80 Hz/pixel, resolution = 0.5mm ×0.5mm in-plane and 1.0mm through-plane, an acquisition matrix of 512 × 384 × 64 (for read, phase and slice-select directions) and a total scan time of 8 minutes. Results Nineteen calcifications were identified in CT and SWI and they correlated well in both size and position. The contrast-to-noise ratio between the blood signal in the lumen of the artery and arterial wall was 11.7:1 and 7.4:1 in magnitude and in phase images, respectively. Conclusion SWI provides a novel means to visualize vessel wall and recognize the presence of calcification. PMID:19629989

Nonrigid registration of 3D longitudinal optical coherence tomography volumes with choroidal neovascularization

NASA Astrophysics Data System (ADS)

Wei, Qiangding; Shi, Fei; Zhu, Weifang; Xiang, Dehui; Chen, Haoyu; Chen, Xinjian

2017-02-01

In this paper, we propose a 3D registration method for retinal optical coherence tomography (OCT) volumes. The proposed method consists of five main steps: First, a projection image of the 3D OCT scan is created. Second, the vessel enhancement filter is applied on the projection image to detect vessel shadow. Third, landmark points are extracted based on both vessel positions and layer information. Fourth, the coherent point drift method is used to align retinal OCT volumes. Finally, a nonrigid B-spline-based registration method is applied to find the optimal transform to match the data. We applied this registration method on 15 3D OCT scans of patients with Choroidal Neovascularization (CNV). The Dice coefficients (DSC) between layers are greatly improved after applying the nonrigid registration.

Factors associated with epinephrine administration for anaphylaxis in children before arrival to the emergency department.

PubMed

Robinson, Melissa; Greenhawt, Matthew; Stukus, David R

2017-08-01

Epinephrine is the first-line treatment for anaphylaxis but may be underused by patients and medical personnel. To evaluate factors associated with anaphylaxis management before arrival at the emergency department (ED) or urgent care center (UCC). We performed a retrospective review of electronic medical records for all patients aged 0 to 25 years presenting with anaphylaxis to the ED or UCC at a pediatric academic referral center during 2009 to 2013. A total of 408 patients (mean age, 7.25 years; 62% male) were included for analysis. Only 148 patients (36.3%) received epinephrine before arrival at the ED or UCC. Reactions occurring at home (n = 36/114) were less likely to be treated with epinephrine compared with reactions occurring at school (n = 30/49) (odds ratio [OR], 0.29; 95% confidence interval [CI], 0.15-0.59). The odds of receiving epinephrine before arrival at the ED or UCC were significantly lower with a 2-organ system (OR, 0.50; 95% CI, 0.30-0.85) or 3-organ system (OR, 0.41; 95% CI, 0.21-0.81) presentation compared with 1-organ system involvement. Foods (342 [83.8%]) were the most commonly reported provoking trigger. Patients who did not receive epinephrine before arrival at the ED or UCC were significantly less likely to be discharged to home (OR, 0.56; 95% CI, 0.37-0.86; P = .01). This study identifies factors associated with prehospital management of anaphylaxis for children, which highlight that epinephrine administration may be occurring with considerable delay. Increased awareness and education of caregivers, patients, and medical professionals are necessary to provide optimal management. Copyright © 2017 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Potential for an Arctic-breeding migratory bird to adjust spring migration phenology to Arctic amplification.

PubMed

Lameris, Thomas K; Scholten, Ilse; Bauer, Silke; Cobben, Marleen M P; Ens, Bruno J; Nolet, Bart A

2017-10-01

Arctic amplification, the accelerated climate warming in the polar regions, is causing a more rapid advancement of the onset of spring in the Arctic than in temperate regions. Consequently, the arrival of many migratory birds in the Arctic is thought to become increasingly mismatched with the onset of local spring, consequently reducing individual fitness and potentially even population levels. We used a dynamic state variable model to study whether Arctic long-distance migrants can advance their migratory schedules under climate warming scenarios which include Arctic amplification, and whether such an advancement is constrained by fuel accumulation or the ability to anticipate climatic changes. Our model predicts that barnacle geese Branta leucopsis suffer from considerably reduced reproductive success with increasing Arctic amplification through mistimed arrival, when they cannot anticipate a more rapid progress of Arctic spring from their wintering grounds. When geese are able to anticipate a more rapid progress of Arctic spring, they are predicted to advance their spring arrival under Arctic amplification up to 44 days without any reproductive costs in terms of optimal condition or timing of breeding. Negative effects of mistimed arrival on reproduction are predicted to be somewhat mitigated by increasing summer length under warming in the Arctic, as late arriving geese can still breed successfully. We conclude that adaptation to Arctic amplification may rather be constrained by the (un)predictability of changes in the Arctic spring than by the time available for fuel accumulation. Social migrants like geese tend to have a high behavioural plasticity regarding stopover site choice and migration schedule, giving them the potential to adapt to future climate changes on their flyway. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Engineering of arteries in vitro

PubMed Central

Huang, Angela H.; Niklason, Laura E.

2014-01-01

This review will focus on two elements that are essential for functional arterial regeneration in vitro: the mechanical environment and the bioreactors used for tissue growth. The importance of the mechanical environment to embryological development, vascular functionality, and vascular graft regeneration will be discussed. Bioreactors generate mechanical stimuli to simulate the biomechanical environment of the arterial system. This system has been used to reconstruct arterial grafts with appropriate mechanical strength for implantation by controlling the chemical and mechanical environments in which the grafts are grown. Bioreactors are powerful tools to study the effect of mechanical stimuli on extracellular matrix (ECM) architecture and the mechanical properties of engineered vessels. Hence biomimetic systems enable us to optimize chemo-biomechanical culture conditions to regenerate engineered vessels with physiological properties similar to those of native arterial vessels. In addition, this review will introduce and examine various approaches and techniques that have been used to engineer biologically-based vascular grafts, including collagen-based grafts, fibrin-gel grafts, cell sheet engineering, biodegradable polymers, and decellularization of native vessels. PMID:24399290

Benefits Assessment for Single-Airport Tactical Runway Configuration Management Tool (TRCM)

NASA Technical Reports Server (NTRS)

Oseguera-Lohr, Rosa; Phojanamonogkolkij, Nipa; Lohr, Gary W.

2015-01-01

The System-Oriented Runway Management (SORM) concept was developed as part of the Airspace Systems Program (ASP) Concepts and Technology Development (CTD) Project, and is composed of two basic capabilities: Runway Configuration Management (RCM), and Combined Arrival/Departure Runway Scheduling (CADRS). RCM is the process of designating active runways, monitoring the active runway configuration for suitability given existing factors, and predicting future configuration changes; CADRS is the process of distributing arrivals and departures across active runways based on local airport and National Airspace System (NAS) goals. The central component in the SORM concept is a tool for taking into account all the various factors and producing a recommendation for what would be the optimal runway configuration, runway use strategy, and aircraft sequence, considering as many of the relevant factors required in making this type of decision, and user preferences, if feasible. Three separate tools were initially envisioned for this research area, corresponding to the time scale in which they would operate: Strategic RCM (SRCM), with a planning horizon on the order of several hours, Tactical RCM (TRCM), with a planning horizon on the order of 90 minutes, and CADRS, with a planning horizon on the order of 15-30 minutes[1]. Algorithm development was initiated in all three of these areas, but the most fully developed to date is the TRCM algorithm. Earlier studies took a high-level approach to benefits, estimating aggregate benefits across most of the major airports in the National Airspace Systems (NAS), for both RCM and CADRS [2]. Other studies estimated the benefit of RCM and CADRS using various methods of re-sequencing arrivals to reduce delays3,4, or better balancing of arrival fixes5,6. Additional studies looked at different methods for performing the optimization involved in selecting the best Runway Configuration Plan (RCP) to use7-10. Most of these previous studies were high-level or generic in nature (not focusing on specific airports), and benefits were aggregated for the entire NAS, with relatively low fidelity simulation of SORM functions and aircraft trajectories. For SORM research, a more detailed benefits assessment of RCM and CADRS for specific airports or metroplexes is needed.

Artifacts in Digital Coincidence Timing

PubMed Central

Moses, W. W.; Peng, Q.

2014-01-01

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator. All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e., the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the “optimal” method. The purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization. PMID:25321885

Optimal dynamic voltage scaling for wireless sensor nodes with real-time constraints

NASA Astrophysics Data System (ADS)

Cassandras, Christos G.; Zhuang, Shixin

2005-11-01

Sensors are increasingly embedded in manufacturing systems and wirelessly networked to monitor and manage operations ranging from process and inventory control to tracking equipment and even post-manufacturing product monitoring. In building such sensor networks, a critical issue is the limited and hard to replenish energy in the devices involved. Dynamic voltage scaling is a technique that controls the operating voltage of a processor to provide desired performance while conserving energy and prolonging the overall network's lifetime. We consider such power-limited devices processing time-critical tasks which are non-preemptive, aperiodic and have uncertain arrival times. We treat voltage scaling as a dynamic optimization problem whose objective is to minimize energy consumption subject to hard or soft real-time execution constraints. In the case of hard constraints, we build on prior work (which engages a voltage scaling controller at task completion times) by developing an intra-task controller that acts at all arrival times of incoming tasks. We show that this optimization problem can be decomposed into two simpler ones whose solution leads to an algorithm that does not actually require solving any nonlinear programming problems. In the case of soft constraints, this decomposition must be partly relaxed, but it still leads to a scalable (linear in the number of tasks) algorithm. Simulation results are provided to illustrate performance improvements in systems with intra-task controllers compared to uncontrolled systems or those using inter-task control.

Factors Affecting Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Tidewater Glacier Inlets in Alaska: Can Tourism Vessels and Seals Coexist?

PubMed Central

2015-01-01

Large numbers of harbor seals (Phoca vitulina) use habitat in tidewater glaciers in Alaska for pupping, breeding, and molting. Glacial fjords are also popular tourist destinations; however, visitation by numerous vessels can result in disturbance of seals during critical life-history phases. We explored factors affecting haul-out behavior of harbor seals at a glacial site frequented by tourism vessels. In 2008-10, we deployed VHF transmitters on 107 seals in Endicott Arm, Alaska. We remotely monitored presence and haul-out behavior of tagged seals and documented vessel presence with time-lapse cameras. We evaluated the influence of environmental and physical factors on the probability of being hauled out, duration of haul-out bouts, and as factors associated with the start and end of a haulout. Location, season, hour, and interactions of location by year, season, hour, and sex significantly influenced haul-out probability, as did ice, weather, and vessels. Seals were more likely to be hauled out with greater ice availability during the middle of the day, and less likely to be hauled out if vessels were present. Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability. Haul-out duration was longest in association with starting on incoming tides, clear skies, no precipitation, occurring in the middle of the day, and ending in the late afternoon or evening. End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout. Probability of being hauled out was highest in June, during pupping season. Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00. PMID:26017404

Temperature-dependent modulation of regional lymphatic contraction frequency and flow.

PubMed

Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela; Moriondo, Andrea

2017-11-01

Lymph drainage and propulsion are sustained by an extrinsic mechanism, based on mechanical forces acting from the surrounding tissues against the wall of lymphatic vessels, and by an intrinsic mechanism attributable to active spontaneous contractions of the lymphatic vessel muscle. Despite being heterogeneous, the mechanisms underlying the generation of spontaneous contractions share a common biochemical nature and are thus modulated by temperature. In this study, we challenged excised tissues from rat diaphragm and hindpaw, endowed with spontaneously contracting lymphatic vessels, to temperatures from 24°C (hindpaw) or 33°C (diaphragmatic vessels) to 40°C while measuring lymphatic contraction frequency ( f c ) and amplitude. Both vessel populations displayed a sigmoidal relationship between f c and temperature, each centered around the average temperature of surrounding tissue (36.7 diaphragmatic and 32.1 hindpaw lymphatics). Although the slope factor of the sigmoidal fit to the f c change of hindpaw vessels was 2.3°C·cycles -1 ·min -1 , a value within the normal range displayed by simple biochemical reactions, the slope factor of the diaphragmatic lymphatics was 0.62°C·cycles -1 ·min -1 , suggesting the added involvement of temperature-sensing mechanisms. Lymph flow calculated as a function of temperature confirmed the relationship observed on f c data alone and showed that none of the two lymphatic vessel populations would be able to adapt to the optimal working temperature of the other tissue district. This poses a novel question whether lymphatic vessels might not adapt their function to accommodate the change if exposed to a surrounding temperature, which is different from their normal condition. NEW & NOTEWORTHY This study demonstrates to what extent lymphatic vessel intrinsic contractility and lymph flow are modulated by temperature and that this modulation is dependent on the body district that the vessels belong to, suggesting a possible functional misbehavior should lymphatic vessels be exposed to a chronically different temperature. Copyright © 2017 the American Physiological Society.

Factors Affecting Haul-Out Behavior of Harbor Seals (Phoca vitulina) in Tidewater Glacier Inlets in Alaska: Can Tourism Vessels and Seals Coexist?

PubMed

Blundell, Gail M; Pendleton, Grey W

2015-01-01

Large numbers of harbor seals (Phoca vitulina) use habitat in tidewater glaciers in Alaska for pupping, breeding, and molting. Glacial fjords are also popular tourist destinations; however, visitation by numerous vessels can result in disturbance of seals during critical life-history phases. We explored factors affecting haul-out behavior of harbor seals at a glacial site frequented by tourism vessels. In 2008-10, we deployed VHF transmitters on 107 seals in Endicott Arm, Alaska. We remotely monitored presence and haul-out behavior of tagged seals and documented vessel presence with time-lapse cameras. We evaluated the influence of environmental and physical factors on the probability of being hauled out, duration of haul-out bouts, and as factors associated with the start and end of a haulout. Location, season, hour, and interactions of location by year, season, hour, and sex significantly influenced haul-out probability, as did ice, weather, and vessels. Seals were more likely to be hauled out with greater ice availability during the middle of the day, and less likely to be hauled out if vessels were present. Cruise ships had the strongest negative effect; however, most vessel types negatively affected haul-out probability. Haul-out duration was longest in association with starting on incoming tides, clear skies, no precipitation, occurring in the middle of the day, and ending in the late afternoon or evening. End of haulouts was associated with increasing cloud cover, low ice availability, and vessel presence; large-sized tourism vessels or all-vessel-types combined were significant predictors of ending a haul-out bout. Probability of being hauled out was highest in June, during pupping season. Potential disturbances of harbor seals could be reduced, enabling longer resting times for seals and fewer interruptions for nursing pups, if vessels focused the majority of visits to glacial habitat to before or after the hours of 08:00-17:00 or, less optimally, 09:00-16:00.

In vivo laser assisted end-to-end anastomosis with ICG-infused chitosan patches

NASA Astrophysics Data System (ADS)

Rossi, Francesca; Matteini, Paolo; Esposito, Giuseppe; Scerrati, Alba; Albanese, Alessio; Puca, Alfredo; Maira, Giulio; Rossi, Giacomo; Pini, Roberto

2011-07-01

Laser assisted vascular repair is a new optimized technique based on the use of ICG-infused chitosan patch to close a vessel wound, with or even without few supporting single stitches. We present an in vivo experimental study on an innovative end-to-end laser assisted vascular anastomotic (LAVA) technique, performed with the application of ICGinfused chitosan patches. The photostability and the mechanical properties of ICG-infused chitosan films were preliminary measured. The in vivo study was performed in 10 New Zealand rabbits. After anesthesia, a 3-cm segment of the right common carotid artery was exposed, thus clamped proximally and distally. The artery was then interrupted by means of a full thickness cut. Three single microsutures were used to approximate the two vessel edges. The ICG-infused chitosan patch was rolled all over the anastomotic site and welded by the use of a diode laser emitting at 810 nm and equipped with a 300 μm diameter optical fiber. Welding was obtained by delivering single laser spots to induce local patch/tissue adhesion. The result was an immediate closure of the anastomosis, with no bleeding at clamps release. Thus animals underwent different follow-up periods, in order to evaluate the welded vessels over time. At follow-up examinations, all the anastomoses were patent and no bleeding signs were documented. Samples of welded vessels underwent histological examinations. Results showed that this technique offer several advantages over conventional suturing methods: simplification of the surgical procedure, shortening of the operative time, better re-endothelization and optimal vascular healing process.

Classification of large-scale fundus image data sets: a cloud-computing framework.

PubMed

Roychowdhury, Sohini

2016-08-01

Large medical image data sets with high dimensionality require substantial amount of computation time for data creation and data processing. This paper presents a novel generalized method that finds optimal image-based feature sets that reduce computational time complexity while maximizing overall classification accuracy for detection of diabetic retinopathy (DR). First, region-based and pixel-based features are extracted from fundus images for classification of DR lesions and vessel-like structures. Next, feature ranking strategies are used to distinguish the optimal classification feature sets. DR lesion and vessel classification accuracies are computed using the boosted decision tree and decision forest classifiers in the Microsoft Azure Machine Learning Studio platform, respectively. For images from the DIARETDB1 data set, 40 of its highest-ranked features are used to classify four DR lesion types with an average classification accuracy of 90.1% in 792 seconds. Also, for classification of red lesion regions and hemorrhages from microaneurysms, accuracies of 85% and 72% are observed, respectively. For images from STARE data set, 40 high-ranked features can classify minor blood vessels with an accuracy of 83.5% in 326 seconds. Such cloud-based fundus image analysis systems can significantly enhance the borderline classification performances in automated screening systems.

Angiographic analysis for phantom simulations of endovascular aneurysm treatments with a new fully retrievable asymmetric flow diverter.

PubMed

Yoganand, Aradhana; Wood, Rachel P; Jimenez, Carlos; Siddiqui, Adnan; Snyder, Kenneth; Nagesh, S V Setlur; Bednarek, D R; Rudin, S; Baier, Robert; Ionita, Ciprian N

2015-02-21

Digital Subtraction Angiography (DSA) is the main diagnostic tool for intracranial aneurysms (IA) flow-diverter (FD) assisted treatment. Based on qualitative contrast flow evaluation, interventionists decide on subsequent steps. We developed a novel fully Retrievable Asymmetric Flow-Diverter (RAFD) which allows controlled deployment, repositioning and detachment achieve optimal flow diversion. The device has a small low porosity or solid region which is placed such that it would achieve maximum aneurysmal in-jet flow deflection with minimum impairment to adjacent vessels. We tested the new RAFD using a flow-loop with an idealized and a patient specific IA phantom in carotid-relevant physiological conditions. We positioned the deflection region at three locations: distally, center and proximally to the aneurysm orifice and analyzed aneurysm dome flow using DSA derived maps for mean transit time (MTT) and bolus arrival times (BAT). Comparison between treated and untreated (control) maps quantified the RAFD positioning effect. Average MTT, related to contrast presence in the aneurysm dome increased, indicating flow decoupling between the aneurysm and parent artery. Maximum effect was observed in the center and proximal position (~75%) of aneurysm models depending on their geometry. BAT maps, correlated well with inflow jet direction and magnitude. Reduction and jet dispersion as high as about 50% was observed for various treatments. We demonstrated the use of DSA data to guide the placement of the RAFD and showed that optimum flow diversion within the aneurysm dome is feasible. This could lead to more effective and a safer IA treatment using FDs.

Angiographic analysis for phantom simulations of endovascular aneurysm treatments with a new fully retrievable asymmetric flow diverter

NASA Astrophysics Data System (ADS)

Yoganand, Aradhana; Wood, Rachel P.; Jimenez, Carlos; Siddiqui, Adnan; Snyder, Kenneth; Setlur Nagesh, S. V.; Bednarek, D. R.; Rudin, S.; Baier, Robert; Ionita, Ciprian N.

2015-03-01

Digital Subtraction Angiography (DSA) is the main diagnostic tool for intracranial aneurysms (IA) flow-diverter (FD) assisted treatment. Based on qualitative contrast flow evaluation, interventionists decide on subsequent steps. We developed a novel fully Retrievable Asymmetric Flow-Diverter (RAFD) which allows controlled deployment, repositioning and detachment achieve optimal flow diversion. The device has a small low porosity or solid region which is placed such that it would achieve maximum aneurysmal in-jet flow deflection with minimum impairment to adjacent vessels. We tested the new RAFD using a flow-loop with an idealized and a patient specific IA phantom in carotid-relevant physiological conditions. We positioned the deflection region at three locations: distally, center and proximally to the aneurysm orifice and analyzed aneurysm dome flow using DSA derived maps for mean transit time (MTT) and bolus arrival times (BAT). Comparison between treated and untreated (control) maps quantified the RAFD positioning effect. Average MTT, related to contrast presence in the aneurysm dome increased, indicating flow decoupling between the aneurysm and parent artery. Maximum effect was observed in the center and proximal position (~75%) of aneurysm models depending on their geometry. BAT maps, correlated well with inflow jet direction and magnitude. Reduction and jet dispersion as high as about 50% was observed for various treatments. We demonstrated the use of DSA data to guide the placement of the RAFD and showed that optimum flow diversion within the aneurysm dome is feasible. This could lead to more effective and a safer IA treatment using FDs.

A strain energy filter for 3D vessel enhancement with application to pulmonary CT images.

PubMed

Xiao, Changyan; Staring, Marius; Shamonin, Denis; Reiber, Johan H C; Stolk, Jan; Stoel, Berend C

2011-02-01

The traditional Hessian-related vessel filters often suffer from detecting complex structures like bifurcations due to an over-simplified cylindrical model. To solve this problem, we present a shape-tuned strain energy density function to measure vessel likelihood in 3D medical images. This method is initially inspired by established stress-strain principles in mechanics. By considering the Hessian matrix as a stress tensor, the three invariants from orthogonal tensor decomposition are used independently or combined to formulate distinctive functions for vascular shape discrimination, brightness contrast and structure strength measuring. Moreover, a mathematical description of Hessian eigenvalues for general vessel shapes is obtained, based on an intensity continuity assumption, and a relative Hessian strength term is presented to ensure the dominance of second-order derivatives as well as suppress undesired step-edges. Finally, we adopt the multi-scale scheme to find an optimal solution through scale space. The proposed method is validated in experiments with a digital phantom and non-contrast-enhanced pulmonary CT data. It is shown that our model performed more effectively in enhancing vessel bifurcations and preserving details, compared to three existing filters. Copyright © 2010 Elsevier B.V. All rights reserved.

The pathophysiology of chronic thromboembolic pulmonary hypertension.

PubMed

Simonneau, Gérald; Torbicki, Adam; Dorfmüller, Peter; Kim, Nick

2017-03-31

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, progressive pulmonary vascular disease that is usually a consequence of prior acute pulmonary embolism. CTEPH usually begins with persistent obstruction of large and/or middle-sized pulmonary arteries by organised thrombi. Failure of thrombi to resolve may be related to abnormal fibrinolysis or underlying haematological or autoimmune disorders. It is now known that small-vessel abnormalities also contribute to haemodynamic compromise, functional impairment and disease progression in CTEPH. Small-vessel disease can occur in obstructed areas, possibly triggered by unresolved thrombotic material, and downstream from occlusions, possibly because of excessive collateral blood supply from high-pressure bronchial and systemic arteries. The molecular processes underlying small-vessel disease are not completely understood and further research is needed in this area. The degree of small-vessel disease has a substantial impact on the severity of CTEPH and postsurgical outcomes. Interventional and medical treatment of CTEPH should aim to restore normal flow distribution within the pulmonary vasculature, unload the right ventricle and prevent or treat small-vessel disease. It requires early, reliable identification of patients with CTEPH and use of optimal treatment modalities in expert centres. Copyright ©ERS 2017.

Kinetics of Supercritical Water Oxidation

DTIC Science & Technology

1995-12-31

milestone and Sandia Technical Report. A much-needed report describing in detail the operation of the Supercritical Fluids Reactor (SFR) was also...years. In addition, the literature research required to arrive at this optimal design will be used to improve the performance of the Supercritical Fluids ...the Supercritical Fluids Reactor (SFR)" (Sandia National Laboratories Report SAND-8203, Livermore, CA, 1995). R. R. Steeper, "Methane and Methanol

Time-Zone-Pattern Satellite Broadcasting Antenna

NASA Technical Reports Server (NTRS)

Galindo, Victor; Rahmat-Samii, Yahya; Imbriale, William A.; Cohen, Herb; Cagnon, Ronald R.

1988-01-01

Direct-broadcast satellite antenna designs provide contoured beams to match four time zones in 48 contiguous states and spot beams for Alaska, Hawaii, and Puerto Rico presented in 29-page report. Includes descriptions of procedures used to arrive at optimized designs. Arrangements, amplitudes, and phases of antenna feeds presented in tables. Gain contours shown graphically. Additional tables of performance data given for cities in service area of Eastern satellite.

Optimization of the two-sample rank Neyman-Pearson detector

NASA Astrophysics Data System (ADS)

Akimov, P. S.; Barashkov, V. M.

1984-10-01

The development of optimal algorithms concerned with rank considerations in the case of finite sample sizes involves considerable mathematical difficulties. The present investigation provides results related to the design and the analysis of an optimal rank detector based on a utilization of the Neyman-Pearson criteria. The detection of a signal in the presence of background noise is considered, taking into account n observations (readings) x1, x2, ... xn in the experimental communications channel. The computation of the value of the rank of an observation is calculated on the basis of relations between x and the variable y, representing interference. Attention is given to conditions in the absence of a signal, the probability of the detection of an arriving signal, details regarding the utilization of the Neyman-Pearson criteria, the scheme of an optimal rank, multichannel, incoherent detector, and an analysis of the detector.

Topology optimization for nonlinear dynamic problems: Considerations for automotive crashworthiness

NASA Astrophysics Data System (ADS)

Kaushik, Anshul; Ramani, Anand

2014-04-01

Crashworthiness of automotive structures is most often engineered after an optimal topology has been arrived at using other design considerations. This study is an attempt to incorporate crashworthiness requirements upfront in the topology synthesis process using a mathematically consistent framework. It proposes the use of equivalent linear systems from the nonlinear dynamic simulation in conjunction with a discrete-material topology optimizer. Velocity and acceleration constraints are consistently incorporated in the optimization set-up. Issues specific to crash problems due to the explicit solution methodology employed, nature of the boundary conditions imposed on the structure, etc. are discussed and possible resolutions are proposed. A demonstration of the methodology on two-dimensional problems that address some of the structural requirements and the types of loading typical of frontal and side impact is provided in order to show that this methodology has the potential for topology synthesis incorporating crashworthiness requirements.

Optimal pricing policies for services with consideration of facility maintenance costs

NASA Astrophysics Data System (ADS)

Yeh, Ruey Huei; Lin, Yi-Fang

2012-06-01

For survival and success, pricing is an essential issue for service firms. This article deals with the pricing strategies for services with substantial facility maintenance costs. For this purpose, a mathematical framework that incorporates service demand and facility deterioration is proposed to address the problem. The facility and customers constitute a service system driven by Poisson arrivals and exponential service times. A service demand with increasing price elasticity and a facility lifetime with strictly increasing failure rate are also adopted in modelling. By examining the bidirectional relationship between customer demand and facility deterioration in the profit model, the pricing policies of the service are investigated. Then analytical conditions of customer demand and facility lifetime are derived to achieve a unique optimal pricing policy. The comparative statics properties of the optimal policy are also explored. Finally, numerical examples are presented to illustrate the effects of parameter variations on the optimal pricing policy.

Programmable Differential Delay Circuit With Fine Delay Adjustment

DOEpatents

DeRyckere, John F.; Jenkins, Philip Nord; Cornett, Frank Nolan

2002-07-09

Circuitry that provides additional delay to early arriving signals such that all data signals arrive at a receiving latch with same path delay. The delay of a forwarded clock reference is also controlled such that the capturing clock edge will be optimally positioned near quadrature (depending on latch setup/hold requirements). The circuitry continuously adapts to data and clock path delay changes and digital filtering of phase measurements reduce errors brought on by jittering data edges. The circuitry utilizes only the minimum amount of delay necessary to achieve objective thereby limiting any unintended jitter. Particularly, this programmable differential delay circuit with fine delay adjustment is designed to allow the skew between ASICS to be minimized. This includes skew between data bits, between data bits and clocks as well as minimizing the overall skew in a channel between ASICS.

3D first-arrival traveltime tomography with modified total variation regularization

NASA Astrophysics Data System (ADS)

Jiang, Wenbin; Zhang, Jie

2018-02-01

Three-dimensional (3D) seismic surveys have become a major tool in the exploration and exploitation of hydrocarbons. 3D seismic first-arrival traveltime tomography is a robust method for near-surface velocity estimation. A common approach for stabilizing the ill-posed inverse problem is to apply Tikhonov regularization to the inversion. However, the Tikhonov regularization method recovers smooth local structures while blurring the sharp features in the model solution. We present a 3D first-arrival traveltime tomography method with modified total variation (MTV) regularization to preserve sharp velocity contrasts and improve the accuracy of velocity inversion. To solve the minimization problem of the new traveltime tomography method, we decouple the original optimization problem into two following subproblems: a standard traveltime tomography problem with the traditional Tikhonov regularization and a L2 total variation problem. We apply the conjugate gradient method and split-Bregman iterative method to solve these two subproblems, respectively. Our synthetic examples show that the new method produces higher resolution models than the conventional traveltime tomography with Tikhonov regularization. We apply the technique to field data. The stacking section shows significant improvements with static corrections from the MTV traveltime tomography.

Investigation, Modeling, and Analysis of Integrated Metroplex Arrival and Departure Coordination Concepts

NASA Technical Reports Server (NTRS)

Clarke, John-Paul B.; Brooks, James; McClain, Evan; Paladhi, Anwesha Roy; Li, Leihong; Schleicher, David; Saraf, Aditya; Timar, Sebastian; Crisp, Don; Bertino, Jason;

Method and apparatus for optimizing determination of the originating depth of borehole cuttings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mc Auley, J.A.; Eppler, S.G.

1987-11-24

This patent describes a method for determining the arrival at the surface of an identifiable material from a predetermined drilling depth independent of pump stroke rate and intermittent operations during the utilization of at least a drill bit, a positive displacement mud pump and drilling mud during the drilling of a well. The method comprises the steps of: adding identifiable material to the drilling mud as the drilling mud is being pumped downwardly into the well; initiate count of the pump strokes of the positive displacement mud pump as the previous step occurs; observe arrival of the identifiable material atmore » the surface of the earth as the drilling mud exits from the well; observe the accumulated count of the pump strokes of the positive displacement mud pump which occur between step one and step three; subtract, from the accumulated count of the previous step, the number of pump strokes of the positive displacement mud pump required to pump the identifiable material down to the drill bit to establish a number of lag strokes; and utilize the number obtained in the previous step to identify the arrival of drill cuttings from a predetermined depth.« less

Bioresorbable scaffolds for percutaneous coronary interventions

PubMed Central

Gogas, Bill D.

2014-01-01

Innovations in drug-eluting stents (DES) have substantially reduced rates of in-segment restenosis and early stent thrombosis, improving clinical outcomes following percutaneous coronary interventions (PCI). However a fixed metallic implant in a vessel wall with restored patency and residual disease remains a precipitating factor for sustained local inflammation, in-stent neo-atherosclerosis and impaired vasomotor function increasing the risk for late complications attributed to late or very late stent thrombosis and late target lesion revascularization (TLR) (late catch-up). The quest for optimal coronary stenting continues by further innovations in stent design and by using biocompatible materials other than cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding, local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics have been recently developed. These devices have been utilized in selected clinical applications so far providing preliminary evidence of safety showing comparable performance with current generation drug-eluting stents (DES). Herein we provide a comprehensive overview of the current status of these technologies, we elaborate on the potential benefits of transient coronary scaffolds over permanent stents in the context of vascular reparation therapy, and we further focus on the evolving challenges these devices have to overcome to compete with current generation DES. Condensed Abstract:: The quest for optimizing percutaneous coronary interventions continues by iterative innovations in device materials beyond cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding; local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics were recently developed. These devices have been utilized in selected clinical applications providing preliminary evidence of safety showing comparable intermediate term clinical outcomes with current generation drug-eluting stents. PMID:25780795

Application of MSCTA combined with VRT in the operation of cervical dumbbell tumors

PubMed Central

Wang, Wan; Lin, Jia; Knosp, Engelbert; Zhao, Yuanzheng; Xiu, Dianhui; Guo, Yongchuan

2015-01-01

Cervical dumbbell tumor poses great difficulties for neurosurgical treatment and incurs remarkable local recurrence rate as the formidable problem for neurosurgery. However, as the routine preoperative evaluation scheme, MRI and CT failed to reveal the mutual three-dimensional relationships between tumor and adjacent structures. Here, we report the clinical application of MSCTA and VRT in three-dimensional reconstruction of cervical dumbbell tumors. From January 2012 to July 2014, 24 patients diagnosed with cervical dumbbell tumor were retrospectively analyzed. All patients enrolled were indicated for preoperative MSCTA/VRT image reconstruction to explore the three-dimensional stereoscopic anatomical relationships among neuroma, spinal cord and vertebral artery to achieve optimal surgical approach from multiple configurations and surgical practice. Three-dimensional mutual anatomical relationships among tumor, adjacent vessels and vertebrae were vividly reconstructed by MSCTA/VRT in all patients in accordance with intraoperative findings. Multiple configurations for optimal surgical approach contribute to total resection of tumor, minimal damage to vessels and nerves, and maximal maintenance of cervical spine stability. Preoperative MSCTA/VRT contributes to reconstruction of three-dimensional stereoscopic anatomical relationships between cervical dumbbell tumor and adjacent structures for optimal surgical approach by multiple configurations and reduction of intraoperative damages and postoperative complications. PMID:26550385

Application of MSCTA combined with VRT in the operation of cervical dumbbell tumors.

PubMed

Wang, Wan; Lin, Jia; Knosp, Engelbert; Zhao, Yuanzheng; Xiu, Dianhui; Guo, Yongchuan

2015-01-01

Cervical dumbbell tumor poses great difficulties for neurosurgical treatment and incurs remarkable local recurrence rate as the formidable problem for neurosurgery. However, as the routine preoperative evaluation scheme, MRI and CT failed to reveal the mutual three-dimensional relationships between tumor and adjacent structures. Here, we report the clinical application of MSCTA and VRT in three-dimensional reconstruction of cervical dumbbell tumors. From January 2012 to July 2014, 24 patients diagnosed with cervical dumbbell tumor were retrospectively analyzed. All patients enrolled were indicated for preoperative MSCTA/VRT image reconstruction to explore the three-dimensional stereoscopic anatomical relationships among neuroma, spinal cord and vertebral artery to achieve optimal surgical approach from multiple configurations and surgical practice. Three-dimensional mutual anatomical relationships among tumor, adjacent vessels and vertebrae were vividly reconstructed by MSCTA/VRT in all patients in accordance with intraoperative findings. Multiple configurations for optimal surgical approach contribute to total resection of tumor, minimal damage to vessels and nerves, and maximal maintenance of cervical spine stability. Preoperative MSCTA/VRT contributes to reconstruction of three-dimensional stereoscopic anatomical relationships between cervical dumbbell tumor and adjacent structures for optimal surgical approach by multiple configurations and reduction of intraoperative damages and postoperative complications.

Segmentation of arterial vessel wall motion to sub-pixel resolution using M-mode ultrasound.

PubMed

Fancourt, Craig; Azer, Karim; Ramcharan, Sharmilee L; Bunzel, Michelle; Cambell, Barry R; Sachs, Jeffrey R; Walker, Matthew

2008-01-01

We describe a method for segmenting arterial vessel wall motion to sub-pixel resolution, using the returns from M-mode ultrasound. The technique involves measuring the spatial offset between all pairs of scans from their cross-correlation, converting the spatial offsets to relative wall motion through a global optimization, and finally translating from relative to absolute wall motion by interpolation over the M-mode image. The resulting detailed wall distension waveform has the potential to enhance existing vascular biomarkers, such as strain and compliance, as well as enable new ones.

A Computational Approach to Model Vascular Adaptation During Chronic Hemodialysis: Shape Optimization as a Substitute for Growth Modeling

NASA Astrophysics Data System (ADS)

Mahmoudzadeh Akherat, S. M. Javid; Boghosian, Michael; Cassel, Kevin; Hammes, Mary

2015-11-01

End-stage-renal disease patients depend on successful long-term hemodialysis via vascular access, commonly facilitated via a Brachiocephalic Fistula (BCF). The primary cause of BCF failure is Cephalic Arch Stenosis (CAS). It is believed that low Wall Shear Stress (WSS) regions, which occur because of the high flow rates through the natural bend in the cephalic vein, create hemodynamic circumstances that trigger the onset and development of Intimal Hyperplasia (IH) and subsequent CAS. IH is hypothesized to be a natural effort to reshape the vessel, aiming to bring the WSS values back to a physiologically acceptable range. We seek to explore the correlation between regions of low WSS and subsequent IH and CAS in patient-specific geometries. By utilizing a shape optimization framework, a method is proposed to predict cardiovascular adaptation that could potentially be an alternative to vascular growth and remodeling. Based on an objective functional that seeks to alter the vessel shape in such a way as to readjust the WSS to be within the normal physiological range, CFD and shape optimization are then coupled to investigate whether the optimal shape evolution is correlated with actual patient-specific geometries thereafter. Supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (R01 DK90769).

KSC-2012-3623

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, NASA Kennedy Space Center Director Robert Cabana, NASA Deputy Administrator Lori Garver and U.S. Senator Bill Nelson participate in an event in Kennedy's Operations and Checkout Building high bay marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3633

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – David Beaman, NASA Space Launch System spacecraft and payload integration manager, addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3636

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA astronaut Rex Walheim talks to Michael Leinbach, director of Human Spaceflight Operations for United Launch Alliance, in Kennedy Space Center's Operations and Checkout Building high bay during an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3624

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, NASA Kennedy Space Center Director Robert Cabana, NASA Deputy Administrator Lori Garver and U.S. Senator Bill Nelson participate in an event in Kennedy's Operations and Checkout Building high bay marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3641

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, U.S. Senator Bill Nelson, NASA project engineer Trent Smith and NASA astronaut Nicole Stott share a moment of levity in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3635

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – John Karas, vice president and general manager of Human Spaceflight for Lockheed Martin Space Systems, addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3604

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson checks out NASA's first space-bound Orion capsule at NASA's Kennedy Space Center in Florida. Nelson and the spacecraft are in Kennedy's Operations and Checkout Building high bay for an event marking its arrival at Kennedy. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3607

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, U.S. Senator Bill Nelson, NASA Kennedy Space Center Director Robert Cabana and NASA Deputy Director Lori Garver discuss NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3615

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, Kennedy Space Center Director Robert Cabana and U.S. Senator Bill Nelson pose for a portrait in front of NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3642

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, U.S. Senator Bill Nelson and NASA astronaut Nicole Stott pose for a portrait in front of NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3634

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – Pepper Phillips, program manager for NASA's Ground Systems Development and Operations, addresses the audience assembled in Kennedy Space Center's Operations and Checkout Building high bay for an event marking the arrival of NASA's first space-bound Orion capsule in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

Kuwait oil spill studied

NASA Astrophysics Data System (ADS)

Bush, Susan

1992-02-01

More than a year after the Persian Gulf War, scientists are still trying to assess the environmental impact of the estimated 6-8 million barrels of oil that were dumped into the gulf and to understand the environmental processes that take place in such a disturbance. Many atmospheric studies were done in the months immediately following the war, but oceanographic studies have been slower in getting started.The National Oceanic and Atmospheric Administration is currently spearheading a major oceanographic study being undertaken in the Persian Gulf by the research vessel Mt. Mitchell. The ship left its home port of Norfolk, Va., in mid-January and arrived in Muscat, Oman, on February 16 to begin a 100-day oceanographic and environmental survey. The six-leg cruise will feature physical oceanography, near-shore, and marine life studies.

Actinide Isotope Ratios Measured by Resonance Ionization Mass Spectrometry: Optimization of Ionization Schemes and Demonstration Using Nuclear Fallout

DTIC Science & Technology

2017-12-01

Massive particles arrive later than lighter particles. The uncertainty in the time of the ions formation and the distance travelled results in the...response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and...9 2. The Time -Dependent Schrödinger Equation ............................12 3. Stimulated Excitation to Bound States

Optimization and Calculation of Probability Performances of Processes of Storage and Processing of Refrigerator Containerized Cargoes

NASA Astrophysics Data System (ADS)

Nyrkov, A. P.; Sokolov, S. S.; Chernyi, S. G.; Shnurenko, A. A.; Pavlova, L. A.

2016-08-01

In the work the queueing system of the disconnected multi-channel type to which irregular, uniform or not uniform flows of requests with a unlimited latency period arrive is considered. The system is considered on an example of the container terminal having conditional-functional sections with a definite mark-to-space ratio on which the irregular inhomogeneous traffic flow with resultant intensity acts.

The role of chemistry in the energy challenge.

PubMed

Schlögl, Robert

2010-02-22

Chemistry with its key targets of providing materials and processes for conversion of matter is at the center stage of the energy challenge. Most energy conversion systems work on (bio)chemical energy carriers and require for their use suitable process and material solutions. The enormous scale of their application demands optimization beyond the incremental improvement of empirical discoveries. Knowledge-based systematic approaches are mandatory to arrive at scalable and sustainable solutions. Chemistry for energy, "ENERCHEM" contributes in many ways already today to the use of fossil energy carriers. Optimization of these processes exemplified by catalysis for fuels and chemicals production or by solid-state lightning can contribute in the near future substantially to the dual challenge of energy use and climate protection being in fact two sides of the same challenge. The paper focuses on the even greater role that ENERCHEM will have to play in the era of renewable energy systems where the storage of solar energy in chemical carries and batteries is a key requirement. A multidisciplinary and diversified approach is suggested to arrive at a stable and sustainable system of energy conversion processes. The timescales for transformation of the present energy scenario will be decades and the resources will be of global economic dimensions. ENERCHEM will have to provide the reliable basis for such technologies based on deep functional understanding.

Curved planar reformation and optimal path tracing (CROP) method for false positive reduction in computer-aided detection of pulmonary embolism in CTPA

NASA Astrophysics Data System (ADS)

Zhou, Chuan; Chan, Heang-Ping; Guo, Yanhui; Wei, Jun; Chughtai, Aamer; Hadjiiski, Lubomir M.; Sundaram, Baskaran; Patel, Smita; Kuriakose, Jean W.; Kazerooni, Ella A.

2013-03-01

The curved planar reformation (CPR) method re-samples the vascular structures along the vessel centerline to generate longitudinal cross-section views. The CPR technique has been commonly used in coronary CTA workstation to facilitate radiologists' visual assessment of coronary diseases, but has not yet been used for pulmonary vessel analysis in CTPA due to the complicated tree structures and the vast network of pulmonary vasculature. In this study, a new curved planar reformation and optimal path tracing (CROP) method was developed to facilitate feature extraction and false positive (FP) reduction and improve our PE detection system. PE candidates are first identified in the segmented pulmonary vessels at prescreening. Based on Dijkstra's algorithm, the optimal path (OP) is traced from the pulmonary trunk bifurcation point to each PE candidate. The traced vessel is then straightened and a reformatted volume is generated using CPR. Eleven new features that characterize the intensity, gradient, and topology are extracted from the PE candidate in the CPR volume and combined with the previously developed 9 features to form a new feature space for FP classification. With IRB approval, CTPA of 59 PE cases were retrospectively collected from our patient files (UM set) and 69 PE cases from the PIOPED II data set with access permission. 595 and 800 PEs were manually marked by experienced radiologists as reference standard for the UM and PIOPED set, respectively. At a test sensitivity of 80%, the average FP rate was improved from 18.9 to 11.9 FPs/case with the new method for the PIOPED set when the UM set was used for training. The FP rate was improved from 22.6 to 14.2 FPs/case for the UM set when the PIOPED set was used for training. The improvement in the free response receiver operating characteristic (FROC) curves was statistically significant (p<0.05) by JAFROC analysis, indicating that the new features extracted from the CROP method are useful for FP reduction.

Imaging diagnostics in ovarian cancer: magnetic resonance imaging and a scoring system guiding choice of primary treatment.

PubMed

Kasper, Sigrid M; Dueholm, Margit; Marinovskij, Edvard; Blaakær, Jan

2017-03-01

To analyze the ability of magnetic resonance imaging (MRI) and systematic evaluation at surgery to predict optimal cytoreduction in primary advanced ovarian cancer and to develop a preoperative scoring system for cancer staging. Preoperative MRI and standard laparotomy were performed in 99 women with either ovarian or primary peritoneal cancer. Using univariate and multivariate logistic regression analysis of a systematic description of the tumor in nine abdominal compartments obtained by MRI and during surgery plus clinical parameters, a scoring system was designed that predicted non-optimal cytoreduction. Non-optimal cytoreduction at operation was predicted by the following: (A) presence of comorbidities group 3 or 4 (ASA); (B) tumor presence in multiple numbers of different compartments, and (C) numbers of specified sites of organ involvement. The score includes: number of compartments involved (1-9 points), >1 subdiaphragmal location with presence of tumor (1 point); deep organ involvement of liver (1 point), porta hepatis (1 point), spleen (1 point), mesentery/vessel (1 point), cecum/ileocecal (1 point), rectum/vessels (1 point): ASA groups 3 and 4 (2 points). Use of the scoring system based on operative findings gave an area under the curve (AUC) of 91% (85-98%) for patients in whom optimal cytoreduction could not be achieved. The score AUC obtained by MRI was 84% (76-92%), and 43% of non-optimal cytoreduction patients were identified, with only 8% of potentially operable patients being falsely evaluated as suitable for non-optimal cytoreduction at the most optimal cut-off value. Tumor in individual locations did not predict operability. This systematic scoring system based on operative findings and MRI may predict non-optimal cytoreduction. MRI is able to assess ovarian cancer with peritoneal carcinomatosis with satisfactory concordance with laparotomic findings. This scoring system could be useful as a clinical guideline and should be evaluated and developed further in larger studies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Value of C-Arm Cone Beam Computed Tomography Image Fusion in Maximizing the Versatility of Endovascular Robotics.

PubMed

Chinnadurai, Ponraj; Duran, Cassidy; Al-Jabbari, Odeaa; Abu Saleh, Walid K; Lumsden, Alan; Bismuth, Jean

2016-01-01

To report our initial experience and highlight the value of using intraoperative C-arm cone beam computed tomography (CT; DynaCT(®)) image fusion guidance along with steerable robotic endovascular catheter navigation to optimize vessel cannulation. Between May 2013 and January 2015, all patients who underwent endovascular procedures using DynaCT image fusion technique along with Hansen Magellan vascular robotic catheter were included in this study. As a part of preoperative planning, relevant vessel landmarks were electronically marked in contrast-enhanced multi-slice computed tomography images and stored. At the beginning of procedure, an intraoperative noncontrast C-arm cone beam CT (syngo DynaCT(®), Siemens Medical Solutions USA Inc.) was acquired in the hybrid suite. Preoperative images were then coregistered to intraoperative DynaCT images using aortic wall calcifications and bone landmarks. Stored landmarks were then overlaid on 2-dimensional (2D) live fluoroscopic images as virtual markers that are updated in real-time with C-arm, table movements and image zoom. Vascular access and robotic catheter (Magellan(®), Hansen Medical) was setup per standard. Vessel cannulation was performed based on electronic virtual markers on live fluoroscopy using robotic catheter. The impact of 3-dimensional (3D) image fusion guidance on robotic vessel cannulation was evaluated retrospectively, by assessing quantitative parameters like number of angiograms acquired before vessel cannulation and qualitative parameters like accuracy of vessel ostium and centerline markers. All 17 vessels were cannulated successfully in 14 patients' attempted using robotic catheter and image fusion guidance. Median vessel diameter at origin was 5.4 mm (range, 2.3-13 mm), whereas 12 of 17 (70.6%) vessels had either calcified and/or stenosed origin from parent vessel. Nine of 17 vessels (52.9 %) were cannulated without any contrast injection. Median number of angiograms required before cannulation was 0 (range, 0-2). On qualitative assessment, 14 of 15 vessels (93.3%) had grade = 1 accuracy (guidewire inside virtual ostial marker). Fourteen of 14 vessels had grade = 1 accuracy (virtual centerlines that matched with the actual vessel trajectory during cannulation). In this small series, the experience of using DynaCT image fusion guidance together with a steerable endovascular robotic catheter indicates that such image fusion strategies can enhance intraoperative 2D fluoroscopy by bringing preoperative 3D information about vascular stenosis and/or calcification, angulation, and take off from main vessel thereby facilitating ultimate vessel cannulation. Copyright © 2016 Elsevier Inc. All rights reserved.

Investigation of temporal vascular effects induced by focused ultrasound treatment with speckle-variance optical coherence tomography

PubMed Central

Tsai, Meng-Tsan; Chang, Feng-Yu; Lee, Cheng-Kuang; Gong, Cihun-Siyong Alex; Lin, Yu-Xiang; Lee, Jiann-Der; Yang, Chih-Hsun; Liu, Hao-Li

2014-01-01

Focused ultrasound (FUS) can be used to locally and temporally enhance vascular permeability, improving the efficiency of drug delivery from the blood vessels into the surrounding tissue. However, it is difficult to evaluate in real time the effect induced by FUS and to noninvasively observe the permeability enhancement. In this study, speckle-variance optical coherence tomography (SVOCT) was implemented for the investigation of temporal effects on vessels induced by FUS treatment. With OCT scanning, the dynamic change in vessels during FUS exposure can be observed and studied. Moreover, the vascular effects induced by FUS treatment with and without the presence of microbubbles were investigated and quantitatively compared. Additionally, 2D and 3D speckle-variance images were used for quantitative observation of blood leakage from vessels due to the permeability enhancement caused by FUS, which could be an indicator that can be used to determine the influence of FUS power exposure. In conclusion, SVOCT can be a useful tool for monitoring FUS treatment in real time, facilitating the dynamic observation of temporal effects and helping to determine the optimal FUS power. PMID:25071945

Measurement of stray EC radiation on W7-AS

NASA Astrophysics Data System (ADS)

Gandini, F.; Hirsch, M.; Cirant, S.; Erckmann, V.; Granucci, G.; Kasparek, W.; Laqua, H. P.; Muzzini, V.; Nowak, S.; Radau, S.

2001-10-01

In the framework of a collaboration between IFP-CNR Milano, IPP Garching/Greifswald and IPF Stuttgart, a set of four millimeterwave probes has been installed in W7-AS stellarator at selected positions of the inner vessel wall. Their purpose is to observe RF stray radiation during operation in presence of strong level of Electron Cyclotron (EC) waves, used for plasma start-up, heating and current drive. The aim of these measurements is to benchmark two complementary theoretical models for the distribution of the stray radiation in the vessel. From these codes, quantitative predictions are expected for the spatial distribution of the RF wall load and the RF-impact on in-vessel components in large future devices such as W7-X and, possibly, ITER. This input is important to optimize the wall armour and select rf-compatible in-vessel materials. We present first measurements from different heating and startup scenarios, with up to 800 kW of injected power at 140 GHz and different launching geometries. An analysis of measurements performed on FTU using a previous version of sniffer probe is also presented.

A study on the structural characteristics and shape of outfitting equipment support in 300K DWT crude oil tanker

NASA Astrophysics Data System (ADS)

Jeong, K.; Jeong, H.; Ji, M.; Kim, J.; Park, J.; Chung, H.

2015-09-01

With the increase in the size and speed of recently built vessels, the output and speed (rpm) of propulsion or generation engines have continuously increased, and the high-output, highspeed engine has become a major cause of excessive vessel noise and vibration. Accordingly, resonance occurs in the equipment and other outfitting equipment installed in a vessel, and thus, periodic requests for correction are received from ship owners or officers. In this study, to resolve this problem, supports that stably fix the outfitting equipment installed in the engine room of a very large crude oil tanker and provide protection from physical or external shock were classified into seven types for three kinds of widely used standard shapes, and an optimized shape was developed and suggested by analyzing the structural characteristics of the shapes of the supports (the maximum bending moment, maximum bending stress, and maximum deformation) using DNV NATICUS HULL 3D BEAM, a structural analysis program, so that it could be used for the outfitting design of a vessel.

Thermal model for optimization of vascular laser tissue soldering.

PubMed

Bogni, Serge; Stumpp, Oliver; Reinert, Michael; Frenz, Martin

2010-06-01

Laser tissue soldering (LTS) is a promising technique for tissue fusion based on a heat-denaturation process of proteins. Thermal damage of the fused tissue during the laser procedure has always been an important and challenging problem. Particularly in LTS of arterial blood vessels strong heating of the endothelium should be avoided to minimize the risk of thrombosis. A precise knowledge of the temperature distribution within the vessel wall during laser irradiation is inevitable. The authors developed a finite element model (FEM) to simulate the temperature distribution within blood vessels during LTS. Temperature measurements were used to verify and calibrate the model. Different parameters such as laser power, solder absorption coefficient, thickness of the solder layer, cooling of the vessel and continuous vs. pulsed energy deposition were tested to elucidate their impact on the temperature distribution within the soldering joint in order to reduce the amount of further animal experiments. A pulsed irradiation with high laser power and high absorbing solder yields the best results. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The importance of matched poloidal spectra to error field correction in DIII-D

DOE PAGES

Paz-Soldan, Carlos; Lanctot, Matthew J.; Logan, Nikolas C.; ...

2014-07-09

Optimal error field correction (EFC) is thought to be achieved when coupling to the least-stable "dominant" mode of the plasma is nulled at each toroidal mode number ( n). The limit of this picture is tested in the DIII-D tokamak by applying superpositions of in- and ex-vessel coil set n = 1 fields calculated to be fully orthogonal to the n = 1 dominant mode. In co-rotating H-mode and low-density Ohmic scenarios the plasma is found to be respectively 7x and 20x less sensitive to the orthogonal field as compared to the in-vessel coil set field. For the scenarios investigated,more » any geometry of EFC coil can thus recover a strong majority of the detrimental effect introduced by the n = 1 error field. Furthermore, despite low sensitivity to the orthogonal field, its optimization in H-mode is shown to be consistent with minimizing the neoclassical toroidal viscosity torque and not the higher-order n = 1 mode coupling.« less

Guidelines for Developing Spacecraft Structural Requirements: A Thermal and Environmental Perspective

NASA Technical Reports Server (NTRS)

Holladay, Jon; Day, Greg; Gill, Larry

2004-01-01

Spacecraft are typically designed with a primary focus on weight in order to meet launch vehicle performance parameters. However, for pressurized and/or man-rated spacecraft, it is also necessary to have an understanding of the vehicle operating environments to properly size the pressure vessel. Proper sizing of the pressure vessel requires an understanding of the space vehicle's life cycle and compares the physical design optimization (weight and launch "cost") to downstream operational complexity and total life cycle cost. This paper will provide an overview of some major environmental design drivers and provide examples for calculating the optimal design pressure versus a selected set of design parameters related to thermal and environmental perspectives. In addition, this paper will provide a generic set of cracking pressures for both positive and negative pressure relief valves that encompasses worst case environmental effects for a variety of launch / landing sites. Finally, several examples are included to highlight pressure relief set points and vehicle weight impacts for a selected set of orbital missions.

Estimated incident cost savings in shipping due to inspections.

PubMed

Knapp, Sabine; Bijwaard, Govert; Heij, Christiaan

2011-07-01

The effectiveness of safety inspections of ships has been analysed from various angles, but until now, relatively little attention has been given to translate risk reduction into incident cost savings. This paper provides a monetary quantification of the cost savings that can be attributed to port state control inspections and industry vetting inspections. The dataset consists of more than half a million ship arrivals between 2002 and 2007 and contains inspections of port state authorities in the USA and Australia and of three industry vetting regimes. The effect of inspections in reducing the risk of total loss accidents is estimated by means of duration models, in terms of the gained probability of survival. The monetary benefit of port state control inspections is estimated to range, on average, from about 70 to 190 thousand dollars, with median values ranging from about 20 to 45 thousand dollars. Industry inspections have even higher benefits, especially for tankers. The savings are in general higher for older and larger vessels, and also for vessels with undefined flag and unknown classification society. As inspection costs are relatively low in comparison to potential cost savings, the results underline the importance of determining ships with relatively high risk of total loss. Copyright © 2011 Elsevier Ltd. All rights reserved.

Supply-side invasion ecology: characterizing propagule pressure in coastal ecosystems

PubMed Central

Verling, Emma; Ruiz, Gregory M; Smith, L. David; Galil, Bella; Miller, A. Whitman; Murphy, Kathleen R

2005-01-01

The observed rates and deleterious impacts of biological invasions have caused significant alarm in recent years, driving efforts to reduce the risk (establishment) of new introductions. Characterizing the supply of propagules is key to understanding invasion risk and developing effective management strategies. In coastal ecosystems, ships' ballast water is an important transfer mechanism (vector) for marine and freshwater species. Commercial ships exhibit a high degree of variation in ballast water operations that affect both the quantity and quality of propagule supply, and thereby invasion risk. The per-ship inoculation size from ballast water depends upon both the volume discharged and the organism density. Moreover, propagule quality will vary among source regions (ports) and voyage routes, due to differences in species composition and transport conditions, respectively. We show that significant differences exist in (i) the frequency and volume of ballast water discharge among vessel types, (ii) the frequency of vessel types and routes (source regions) among recipient ports, and (iii) the transit success (survivorship) of zooplankton in ballast tanks among voyage routes. Thus, propagule supply is not a simple function of total ship arrivals. For ships, as well as other vectors, variation in propagule quantity and quality must be explicitly considered to estimate invasion risk and advance predictive ability. PMID:16024389

Microsurgical Repair of Ruptured Aneurysms Associated with Moyamoya-Pattern Collateral Vessels of the Middle Cerebral Artery: A Report of Two Cases.

PubMed

Lang, Min; Moore, Nina Z; Witek, Alex M; Kshettry, Varun R; Bain, Mark D

2017-09-01

Patients with Moyamoya or other intracranial steno-occlusive disease are at risk for developing aneurysms associated with flow through collateral vessels. Because these lesions are rare, the optimal management remains unclear. Here, we describe 2 cases of microsurgical repair of ruptured collateral vessel aneurysms associated with middle cerebral artery (MCA) occlusion. The first patient was a 61-year-old man who presented with right frontal and intraventricular hemorrhage. Angiography revealed chronic right M1 occlusion and a 3-mm spherical lenticulostriate aneurysm. The frontal lobe hematoma was evacuated to reveal the aneurysm, which was safely cauterized and resected by coagulating and dividing the lenticulostriate parent vessel. The procedure was carried out with neuronavigation guidance and intraoperative neuromonitoring. The patient was discharged with no neurologic deficits. The second patient was a 53-year-old woman who presented with subarachnoid and intracerebral hemorrhage. Computed tomography angiogram showed a 2-mm saccular MCA aneurysm. Emergency left decompressive hemicraniectomy and hematoma evacuation were performed. The aneurysm, arising from a small collateral type vessel, was safely clipped without complications. Postoperative angiography revealed absence of the superior MCA trunk with a dense network of collateral vessels at the site of the clipped aneurysm. The patient recovered well and was ambulating independently 6 months postoperatively. No rebleeding occurred in the 2 patients. Our experience suggests that patients with MCA occlusion can harbor associated aneurysms related to flow through collateral vessels and can present with hemorrhage. Microsurgical repair of these aneurysms can be performed safely to prevent rebleeding. Copyright © 2017 Elsevier Inc. All rights reserved.

Interplanetary Mission Design Handbook: Earth-to-Mars Mission Opportunities 2026 to 2045

NASA Technical Reports Server (NTRS)

Burke, Laura M.; Falck, Robert D.; McGuire, Melissa L.

2010-01-01

The purpose of this Mission Design Handbook is to provide trajectory designers and mission planners with graphical information about Earth to Mars ballistic trajectory opportunities for the years of 2026 through 2045. The plots, displayed on a departure date/arrival date mission space, show departure energy, right ascension and declination of the launch asymptote, and target planet hyperbolic arrival excess speed, V(sub infinity), for each launch opportunity. Provided in this study are two sets of contour plots for each launch opportunity. The first set of plots shows Earth to Mars ballistic trajectories without the addition of any deep space maneuvers. The second set of plots shows Earth to Mars transfer trajectories with the addition of deep space maneuvers, which further optimize the determined trajectories. The accompanying texts explains the trajectory characteristics, transfers using deep space maneuvers, mission assumptions and a summary of the minimum departure energy for each opportunity.

A deep learning-based reconstruction of cosmic ray-induced air showers

NASA Astrophysics Data System (ADS)

Erdmann, M.; Glombitza, J.; Walz, D.

2018-01-01

We describe a method of reconstructing air showers induced by cosmic rays using deep learning techniques. We simulate an observatory consisting of ground-based particle detectors with fixed locations on a regular grid. The detector's responses to traversing shower particles are signal amplitudes as a function of time, which provide information on transverse and longitudinal shower properties. In order to take advantage of convolutional network techniques specialized in local pattern recognition, we convert all information to the image-like grid of the detectors. In this way, multiple features, such as arrival times of the first particles and optimized characterizations of time traces, are processed by the network. The reconstruction quality of the cosmic ray arrival direction turns out to be competitive with an analytic reconstruction algorithm. The reconstructed shower direction, energy and shower depth show the expected improvement in resolution for higher cosmic ray energy.

Kalman Filters for Time Delay of Arrival-Based Source Localization

NASA Astrophysics Data System (ADS)

Klee, Ulrich; Gehrig, Tobias; McDonough, John

2006-12-01

In this work, we propose an algorithm for acoustic source localization based on time delay of arrival (TDOA) estimation. In earlier work by other authors, an initial closed-form approximation was first used to estimate the true position of the speaker followed by a Kalman filtering stage to smooth the time series of estimates. In the proposed algorithm, this closed-form approximation is eliminated by employing a Kalman filter to directly update the speaker's position estimate based on the observed TDOAs. In particular, the TDOAs comprise the observation associated with an extended Kalman filter whose state corresponds to the speaker's position. We tested our algorithm on a data set consisting of seminars held by actual speakers. Our experiments revealed that the proposed algorithm provides source localization accuracy superior to the standard spherical and linear intersection techniques. Moreover, the proposed algorithm, although relying on an iterative optimization scheme, proved efficient enough for real-time operation.

A Concept for Airborne Precision Spacing for Dependent Parallel Approaches

NASA Technical Reports Server (NTRS)

Barmore, Bryan E.; Baxley, Brian T.; Abbott, Terence S.; Capron, William R.; Smith, Colin L.; Shay, Richard F.; Hubbs, Clay

2012-01-01

The Airborne Precision Spacing concept of operations has been previously developed to support the precise delivery of aircraft landing successively on the same runway. The high-precision and consistent delivery of inter-aircraft spacing allows for increased runway throughput and the use of energy-efficient arrivals routes such as Continuous Descent Arrivals and Optimized Profile Descents. This paper describes an extension to the Airborne Precision Spacing concept to enable dependent parallel approach operations where the spacing aircraft must manage their in-trail spacing from a leading aircraft on approach to the same runway and spacing from an aircraft on approach to a parallel runway. Functionality for supporting automation is discussed as well as procedures for pilots and controllers. An analysis is performed to identify the required information and a new ADS-B report is proposed to support these information needs. Finally, several scenarios are described in detail.

Modeling and Simulation of Bus Dispatching Policy for Timed Transfers on Signalized Networks

NASA Astrophysics Data System (ADS)

Cho, Hsun-Jung; Lin, Guey-Shii

2007-12-01

The major work of this study is to formulate the system cost functions and to integrate the bus dispatching policy with signal control. The integrated model mainly includes the flow dispersion model for links, signal control model for nodes, and dispatching control model for transfer terminals. All such models are inter-related for transfer operations in one-center transit network. The integrated model that combines dispatching policies with flexible signal control modes can be applied to assess the effectiveness of transfer operations. It is found that, if bus arrival information is reliable, an early dispatching decision made at the mean bus arrival times is preferable. The costs for coordinated operations with slack times are relatively low at the optimal common headway when applying adaptive route control. Based on such findings, a threshold function of bus headway for justifying an adaptive signal route control under various time values of auto drivers is developed.

Effect of injection rate on contrast-enhanced MR angiography image quality: Modulation transfer function analysis.

PubMed

Clark, Toshimasa J; Wilson, Gregory J; Maki, Jeffrey H

2017-07-01

Contrast-enhanced (CE)-MRA optimization involves interactions of sequence duration, bolus timing, contrast recirculation, and both R 1 relaxivity and R2*-related reduction of signal. Prior data suggest superior image quality with slower gadolinium injection rates than typically used. A computer-based model of CE-MRA was developed, with contrast injection, physiologic, and image acquisition parameters varied over a wide gamut. Gadolinium concentration was derived using Verhoeven's model with recirculation, R 1 and R2* calculated at each time point, and modulation transfer curves used to determine injection rates, resulting in optimal resolution and image contrast for renal and carotid artery CE-MRA. Validation was via a vessel stenosis phantom and example patients who underwent carotid CE-MRA with low effective injection rates. Optimal resolution for renal and carotid CE-MRA is achieved with injection rates between 0.5 to 0.9 mL/s and 0.2 to 0.3 mL/s, respectively, dependent on contrast volume. Optimal image contrast requires slightly faster injection rates. Expected signal-to-noise ratio varies with both contrast volume and cardiac output. Simulated vessel phantom and clinical carotid CE-MRA exams at an effective contrast injection rate of 0.4 to 0.5 mL/s demonstrate increased resolution. Optimal image resolution is achieved at intuitively low, effective injection rates (0.2-0.9 mL/s, dependent on imaging parameters and contrast injection volume). Magn Reson Med 78:357-369, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Increased Vessel Depiction of the Carotid Bifurcation with a Specialized 16-Channel Phased Array Coil at 3T

PubMed Central

Tate, Quinn; Kim, Seong-Eun; Treiman, Gerald; Parker, Dennis L.; Hadley, J. Rock

2012-01-01

The purpose of this work was to design and construct a multi-channel receive-only RF coil for 3 Tesla magnetic resonance imaging of the human carotid artery and bifurcation with optimized signal to noise ratio in the carotid vessels along the full extent of the neck. A neck phantom designed to match the anatomy of a subject with a neck representing the body habitus often seen in subjects with carotid arterial disease, was constructed. Sixteen circular coil elements were arranged on a semi-rigid fiberglass former that closely fit the shape of the phantom, resulting in a 16-channel bilateral phased array coil. Comparisons were made between this coil and a typical 4-channel carotid coil in a study of 10 carotid vessels in 5 healthy volunteers. The 16-channel carotid coil showed a 73% average improvement in signal to noise ratio (SNR) at the carotid bifurcation. This coil also maintained an SNR greater than the peak SNR of the 4-channel coil over a vessel length of 10 cm. The resulting increase in SNR improved vessel depiction of the carotid arteries over an extended field of view, and demonstrated better image quality for higher parallel imaging reduction factors compared to the 4-channel coil. PMID:22777692

Major vessel involvement in Behçet disease.

PubMed

Calamia, Kenneth T; Schirmer, Michael; Melikoglu, Melike

2005-01-01

Large vessel vasculitis occurs in a subgroup of patients with Behçet disease at high risk for disease-related morbidity and mortality. Recognition of patients at risk, early detection of vasculitis, and the need for aggressive treatment are essential for optimal care of these patients. The authors review the clinical spectrum and management of large vessel problems in Behçet disease, highlighting contributions over the past year. Vasculo-Behçet patients are at risk for multiple vessel-related complications including thromboses, stenoses, occlusions, and aneurysms. A number of factors may contribute to thrombosis in individual cases, but the primary reason for clot seems to reside in the inflammatory process in the arterial wall, still incompletely understood. An appreciation for the challenges in the perioperative period requires the joint efforts of physicians and surgeons, and fuels the study of alternate, less invasive procedures for Behçet patients. Because of earlier recognition, aggressive medical treatment, and novel surgical procedures, the morbidity and mortality of large vessel vasculitis in Behçet disease are beginning to change. In the absence of controlled treatment studies, reports of clinical experience remain an important source of information for clinicians. Identification of patients at risk for vascular complications remains a priority.

Phase-sensitive dual-inversion recovery for accelerated carotid vessel wall imaging.

PubMed

Bonanno, Gabriele; Brotman, David; Stuber, Matthias

2015-03-01

Dual-inversion recovery (DIR) is widely used for magnetic resonance vessel wall imaging. However, optimal contrast may be difficult to obtain and is subject to RR variability. Furthermore, DIR imaging is time-inefficient and multislice acquisitions may lead to prolonged scanning times. Therefore, an extension of phase-sensitive (PS) DIR is proposed for carotid vessel wall imaging. The statistical distribution of the phase signal after DIR is probed to segment carotid lumens and suppress their residual blood signal. The proposed PS-DIR technique was characterized over a broad range of inversion times. Multislice imaging was then implemented by interleaving the acquisition of 3 slices after DIR. Quantitative evaluation was then performed in healthy adult subjects and compared with conventional DIR imaging. Single-slice PS-DIR provided effective blood-signal suppression over a wide range of inversion times, enhancing wall-lumen contrast and vessel wall conspicuity for carotid arteries. Multislice PS-DIR imaging with effective blood-signal suppression is enabled. A variant of the PS-DIR method has successfully been implemented and tested for carotid vessel wall imaging. This technique removes timing constraints related to inversion recovery, enhances wall-lumen contrast, and enables a 3-fold increase in volumetric coverage at no extra cost in scanning time.

Least squares QR-based decomposition provides an efficient way of computing optimal regularization parameter in photoacoustic tomography.

PubMed

Shaw, Calvin B; Prakash, Jaya; Pramanik, Manojit; Yalavarthy, Phaneendra K

2013-08-01

A computationally efficient approach that computes the optimal regularization parameter for the Tikhonov-minimization scheme is developed for photoacoustic imaging. This approach is based on the least squares-QR decomposition which is a well-known dimensionality reduction technique for a large system of equations. It is shown that the proposed framework is effective in terms of quantitative and qualitative reconstructions of initial pressure distribution enabled via finding an optimal regularization parameter. The computational efficiency and performance of the proposed method are shown using a test case of numerical blood vessel phantom, where the initial pressure is exactly known for quantitative comparison.

Alien species pathways to the Galapagos Islands, Ecuador.

PubMed

Toral-Granda, M Verónica; Causton, Charlotte E; Jäger, Heinke; Trueman, Mandy; Izurieta, Juan Carlos; Araujo, Eddy; Cruz, Marilyn; Zander, Kerstin K; Izurieta, Arturo; Garnett, Stephen T

2017-01-01

Alien species, one of the biggest threats to natural ecosystems worldwide, are of particular concern for oceanic archipelagos such as Galápagos. To enable more effective management of alien species, we reviewed, collated and analysed all available records of alien species for Galápagos. We also assembled a comprehensive dataset on pathways to and among the Galápagos Islands, including tourist and resident numbers, tourist vessels, their itineraries and visitation sites, aircraft capacity and occupancy, air and sea cargo and biosecurity interceptions. So far, 1,579 alien terrestrial and marine species have been introduced to Galápagos by humans. Of these, 1,476 have become established. Almost half of these were intentional introductions, mostly of plants. Most unintentional introductions arrived on plants and plant associated material, followed by transport vehicles, and commodities (in particular fruit and vegetables). The number, frequency and geographic origin of pathways for the arrival and dispersal of alien species to and within Galápagos have increased over time, tracking closely the increase in human population (residents and tourists) on the islands. Intentional introductions of alien species should decline as biosecurity is strengthened but there is a danger that unintentional introductions will increase further as tourism on Galápagos expands. This unique world heritage site will only retain its biodiversity values if the pathways for invasion are managed effectively.

Recommendations for representative ballast water sampling

NASA Astrophysics Data System (ADS)

Gollasch, Stephan; David, Matej

2017-05-01

Until now, the purpose of ballast water sampling studies was predominantly limited to general scientific interest to determine the variety of species arriving in ballast water in a recipient port. Knowing the variety of species arriving in ballast water also contributes to the assessment of relative species introduction vector importance. Further, some sampling campaigns addressed awareness raising or the determination of organism numbers per water volume to evaluate the species introduction risk by analysing the propagule pressure of species. A new aspect of ballast water sampling, which this contribution addresses, is compliance monitoring and enforcement of ballast water management standards as set by, e.g., the IMO Ballast Water Management Convention. To achieve this, sampling methods which result in representative ballast water samples are essential. We recommend such methods based on practical tests conducted on two commercial vessels also considering results from our previous studies. The results show that different sampling approaches influence the results regarding viable organism concentrations in ballast water samples. It was observed that the sampling duration (i.e., length of the sampling process), timing (i.e., in which point in time of the discharge the sample is taken), the number of samples and the sampled water quantity are the main factors influencing the concentrations of viable organisms in a ballast water sample. Based on our findings we provide recommendations for representative ballast water sampling.

Alien species pathways to the Galapagos Islands, Ecuador

PubMed Central

Trueman, Mandy; Izurieta, Juan Carlos; Araujo, Eddy; Cruz, Marilyn; Zander, Kerstin K.; Izurieta, Arturo

2017-01-01

Alien species, one of the biggest threats to natural ecosystems worldwide, are of particular concern for oceanic archipelagos such as Galápagos. To enable more effective management of alien species, we reviewed, collated and analysed all available records of alien species for Galápagos. We also assembled a comprehensive dataset on pathways to and among the Galápagos Islands, including tourist and resident numbers, tourist vessels, their itineraries and visitation sites, aircraft capacity and occupancy, air and sea cargo and biosecurity interceptions. So far, 1,579 alien terrestrial and marine species have been introduced to Galápagos by humans. Of these, 1,476 have become established. Almost half of these were intentional introductions, mostly of plants. Most unintentional introductions arrived on plants and plant associated material, followed by transport vehicles, and commodities (in particular fruit and vegetables). The number, frequency and geographic origin of pathways for the arrival and dispersal of alien species to and within Galápagos have increased over time, tracking closely the increase in human population (residents and tourists) on the islands. Intentional introductions of alien species should decline as biosecurity is strengthened but there is a danger that unintentional introductions will increase further as tourism on Galápagos expands. This unique world heritage site will only retain its biodiversity values if the pathways for invasion are managed effectively. PMID:28902860

Stochastic optimal control as non-equilibrium statistical mechanics: calculus of variations over density and current

NASA Astrophysics Data System (ADS)

Chernyak, Vladimir Y.; Chertkov, Michael; Bierkens, Joris; Kappen, Hilbert J.

2014-01-01

In stochastic optimal control (SOC) one minimizes the average cost-to-go, that consists of the cost-of-control (amount of efforts), cost-of-space (where one wants the system to be) and the target cost (where one wants the system to arrive), for a system participating in forced and controlled Langevin dynamics. We extend the SOC problem by introducing an additional cost-of-dynamics, characterized by a vector potential. We propose derivation of the generalized gauge-invariant Hamilton-Jacobi-Bellman equation as a variation over density and current, suggest hydrodynamic interpretation and discuss examples, e.g., ergodic control of a particle-within-a-circle, illustrating non-equilibrium space-time complexity.

Video-assisted thoracic surgery for left upper lobectomy for complex lesions: how to extend the indication with optimal safety?

PubMed

Bayard, Nathanaël Frank; Barnett, Stephen Arthur; Rinieri, Philippe; Melki, Jean; Peillon, Christophe; Baste, Jean Marc

2016-08-01

The feasibility of extending the VATS approach to locally advanced NSCLC has been described with good clinical outcome. These complex resections are still technically challenging and patient safety must remain the highest priority. In this article, we describe our routine VATS approach for left upper lobectomy in proximal, locally advanced lesions. Both surgical and anaesthesiology teams are trained during simulation sessions to respond rapidly in case of urgent thoracotomy. Encircling arterial and venous vessels allow control of inadvertent bleeding during difficult dissection. Also, whenever needed the double vessel control technique is a time saver waiting for conversion to thoracotomy.

Solving bi-level optimization problems in engineering design using kriging models

NASA Astrophysics Data System (ADS)

Xia, Yi; Liu, Xiaojie; Du, Gang

2018-05-01

Stackelberg game-theoretic approaches are applied extensively in engineering design to handle distributed collaboration decisions. Bi-level genetic algorithms (BLGAs) and response surfaces have been used to solve the corresponding bi-level programming models. However, the computational costs for BLGAs often increase rapidly with the complexity of lower-level programs, and optimal solution functions sometimes cannot be approximated by response surfaces. This article proposes a new method, namely the optimal solution function approximation by kriging model (OSFAKM), in which kriging models are used to approximate the optimal solution functions. A detailed example demonstrates that OSFAKM can obtain better solutions than BLGAs and response surface-based methods, and at the same time reduce the workload of computation remarkably. Five benchmark problems and a case study of the optimal design of a thin-walled pressure vessel are also presented to illustrate the feasibility and potential of the proposed method for bi-level optimization in engineering design.

Monitoring Churn in Wireless Networks

NASA Astrophysics Data System (ADS)

Holzer, Stephan; Pignolet, Yvonne Anne; Smula, Jasmin; Wattenhofer, Roger

Wireless networks often experience a significant amount of churn, the arrival and departure of nodes. In this paper we propose a distributed algorithm for single-hop networks that detects churn and is resilient to a worst-case adversary. The nodes of the network are notified about changes quickly, in asymptotically optimal time up to an additive logarithmic overhead. We establish a trade-off between saving energy and minimizing the delay until notification for single- and multi-channel networks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doug Blankenship

PDFs of seismic reflection profiles 101,110, 111 local to the West Flank FORGE site. 45 line kilometers of seismic reflection data are processed data collected in 2001 through the use of vibroseis trucks. The initial analysis and interpretation of these data was performed by Unruh et al. (2001). Optim processed these data by inverting the P-wave first arrivals to create a 2-D velocity structure. Kirchhoff images were then created for each line using velocity tomograms (Unruh et al., 2001).

Analysis of intra-aortic balloon pump model with ovine myocardial infarction.

PubMed

Abdolrazaghi, Mona; Navidbakhsh, Mahdi; Hassani, Kamran; Rabbani, Shahram; Ahmadi, Hossein

2009-12-01

In this study, we have tried to model the effects of intra-aortic balloon pump (IABP) on myocardial infarction (MI) using the standardized data of MI in sheep which was obtained by ligation of the left anterior descending coronary artery. Mathematical model of whole cardiovascular system was presented in accordance to the arterial tree. The lumped parameter model was primarily obtained for a rigid vessel regarding the vessel diameter. In this study, the proper lumped model of every vessel was obtained by incorporating the rigid vessel lumped model into the capacitance as a compliance of the vessel. Intra-aortic balloon pump was modeled with the hemodynamic parameters of the aorta. It was assumed that balloon pump inflates at the beginning of the diastole and deflates near the beginning of the next systole. During balloon pumping, the vessel diameter variation function counter pulsates sinusoidally with the same period of the cardiac cycle. End systolic pressure and end diastolic pressure decreases along with hemodynamic flow optimized through systemic arteries due to balloon pumping in diastole. It has been shown that the blood flow in subclavian artery increases as well. Moreover, the cardiac work keeps low, which prone to lower oxygen consumption. The results of modeling are in good agreement with IABP documentation. The presented model is a useful tool for studying of the cardiovascular system pathology and the presented modeling data are in good agreement with the experimental ones.

HIFU procedures at moderate intensities--effect of large blood vessels.

PubMed

Hariharan, P; Myers, M R; Banerjee, R K

2007-06-21

A three-dimensional computational model is presented for studying the efficacy of high-intensity focused ultrasound (HIFU) procedures targeted near large blood vessels. The analysis applies to procedures performed at intensities below the threshold for cavitation, boiling and highly nonlinear propagation, but high enough to increase tissue temperature a few degrees per second. The model is based upon the linearized KZK equation and the bioheat equation in tissue. In the blood vessel the momentum and energy equations are satisfied. The model is first validated in a tissue phantom, to verify the absence of bubble formation and nonlinear effects. Temperature rise and lesion-volume calculations are then shown for different beam locations and orientations relative to a large vessel. Both single and multiple ablations are considered. Results show that when the vessel is located within about a beam width (few mm) of the ultrasound beam, significant reduction in lesion volume is observed due to blood flow. However, for gaps larger than a beam width, blood flow has no major effect on the lesion formation. Under the clinically representative conditions considered, the lesion volume is reduced about 40% (relative to the no-flow case) when the beam is parallel to the blood vessel, compared to about 20% for a perpendicular orientation. Procedures involving multiple ablation sites are affected less by blood flow than single ablations. The model also suggests that optimally focused transducers can generate lesions that are significantly larger (>2 times) than the ones produced by highly focused beams.

HIFU procedures at moderate intensities—effect of large blood vessels

NASA Astrophysics Data System (ADS)

Hariharan, P.; Myers, M. R.; Banerjee, R. K.

2007-07-01

A three-dimensional computational model is presented for studying the efficacy of high-intensity focused ultrasound (HIFU) procedures targeted near large blood vessels. The analysis applies to procedures performed at intensities below the threshold for cavitation, boiling and highly nonlinear propagation, but high enough to increase tissue temperature a few degrees per second. The model is based upon the linearized KZK equation and the bioheat equation in tissue. In the blood vessel the momentum and energy equations are satisfied. The model is first validated in a tissue phantom, to verify the absence of bubble formation and nonlinear effects. Temperature rise and lesion-volume calculations are then shown for different beam locations and orientations relative to a large vessel. Both single and multiple ablations are considered. Results show that when the vessel is located within about a beam width (few mm) of the ultrasound beam, significant reduction in lesion volume is observed due to blood flow. However, for gaps larger than a beam width, blood flow has no major effect on the lesion formation. Under the clinically representative conditions considered, the lesion volume is reduced about 40% (relative to the no-flow case) when the beam is parallel to the blood vessel, compared to about 20% for a perpendicular orientation. Procedures involving multiple ablation sites are affected less by blood flow than single ablations. The model also suggests that optimally focused transducers can generate lesions that are significantly larger (>2 times) than the ones produced by highly focused beams.

Registration Methods for IVUS: Transversal and Longitudinal Transducer Motion Compensation.

PubMed

Talou, Gonzalo D Maso; Blanco, Pablo J; Larrabide, Ignacio; Bezerra, Cristiano Guedes; Lemos, Pedro A; Feijoo, Raul A

2017-04-01

Intravascular ultrasound (IVUS) is a fundamental imaging technique for atherosclerotic plaque assessment, interventionist guidance, and, ultimately, as a tissue characterization tool. The studies acquired by this technique present the spatial description of the vessel during the cardiac cycle. However, the study frames are not properly sorted. As gating methods deal with the cardiac phase classification of the frames, the gated studies lack motion compensation between vessel and catheter. In this study, we develop registration strategies to arrange the vessel data into its rightful spatial sequence. Registration is performed by compensating longitudinal and transversal relative motion between vessel and catheter. Transversal motion is identified through maximum likelihood estimator optimization, while longitudinal motion is estimated by a neighborhood similarity estimator among the study frames. A strongly coupled implementation is proposed to compensate for both motion components at once. Loosely coupled implementations (DLT and DTL) decouple the registration process, resulting in more computationally efficient algorithms in detriment of the size of the set of candidate solutions. The DTL outperforms DLT and coupled implementations in terms of accuracy by a factor of 1.9 and 1.4, respectively. Sensitivity analysis shows that perivascular tissue must be considered to obtain the best registration outcome. Evidences suggest that the method is able to measure axial strain along the vessel wall. The proposed registration sorts the IVUS frames for spatial location, which is crucial for a correct interpretation of the vessel wall kinematics along the cardiac phases.

Multi-modal magnetic resonance imaging and histology of vascular function in xenografts using macromolecular contrast agent hyperbranched polyglycerol (HPG-GdF).

PubMed

Baker, Jennifer H E; McPhee, Kelly C; Moosvi, Firas; Saatchi, Katayoun; Häfeli, Urs O; Minchinton, Andrew I; Reinsberg, Stefan A

2016-01-01

Macromolecular gadolinium (Gd)-based contrast agents are in development as blood pool markers for MRI. HPG-GdF is a 583 kDa hyperbranched polyglycerol doubly tagged with Gd and Alexa 647 nm dye, making it both MR and histologically visible. In this study we examined the location of HPG-GdF in whole-tumor xenograft sections matched to in vivo DCE-MR images of both HPG-GdF and Gadovist. Despite its large size, we have shown that HPG-GdF extravasates from some tumor vessels and accumulates over time, but does not distribute beyond a few cell diameters from vessels. Fractional plasma volume (fPV) and apparent permeability-surface area product (aPS) parameters were derived from the MR concentration-time curves of HPG-GdF. Non-viable necrotic tumor tissue was excluded from the analysis by applying a novel bolus arrival time (BAT) algorithm to all voxels. aPS derived from HPG-GdF was the only MR parameter to identify a difference in vascular function between HCT116 and HT29 colorectal tumors. This study is the first to relate low and high molecular weight contrast agents with matched whole-tumor histological sections. These detailed comparisons identified tumor regions that appear distinct from each other using the HPG-GdF biomarkers related to perfusion and vessel leakiness, while Gadovist-imaged parameter measures in the same regions were unable to detect variation in vascular function. We have established HPG-GdF as a biocompatible multi-modal high molecular weight contrast agent with application for examining vascular function in both MR and histological modalities. Copyright © 2015 John Wiley & Sons, Ltd.

Host plant volatiles serve to increase the response of male European grape berry moths, Eupoecilia ambiguella, to their sex pheromone.

PubMed

Schmidt-Büsser, Daniela; von Arx, Martin; Guerin, Patrick M

2009-09-01

The European grape berry moth is an important pest in vineyards. Males respond to the female-produced sex pheromone released from a piezo nebulizer in a dose-dependent manner in a wind tunnel: <50% arrive at the source at 5-50 pg/min (underdosed), 80% arrive at 100 pg/min to 10 ng/min (optimal) and <20% arrive at 100 ng/min (overdosed). Males responding to overdosed pheromone show in flight arrestment at 80 cm from the source. Host plant chemostimuli for Eupoecilia ambiguella increase the responses of males to underdosed and overdosed pheromone. (Z)-3-hexen-1-ol, (+)-terpinen-4-ol, (E)-beta-caryophyllene and methyl salicylate released with the underdosed pheromone cause a significant increase in male E. ambiguella flying to the source. Time-event analysis indicates a positive correlation between faster activation and probability of source contact by the responding males. The four host plant compounds added to the overdosed pheromone permitted males to take off faster and with a higher probability of flying to the source. This suggests that perception of host plant products with the sex pheromone facilitates male E. ambiguella to locate females on host plants, lending credence to the hypothesis that plant products can signal rendezvous sites suitable for mating.

Experiment Description and Results for Arrival Operations Using Interval Management with Spacing to Parallel Dependent Runways (IMSPiDR)

NASA Technical Reports Server (NTRS)

Baxley, Brian T.; Murdoch, Jennifer L.; Swieringa, Kurt A.; Barmore, Bryan E.; Capron, William R.; Hubbs, Clay E.; Shay, Richard F.; Abbott, Terence S.

2013-01-01

The predicted increase in the number of commercial aircraft operations creates a need for improved operational efficiency. Two areas believed to offer increases in aircraft efficiency are optimized profile descents and dependent parallel runway operations. Using Flight deck Interval Management (FIM) software and procedures during these operations, flight crews can achieve by the runway threshold an interval assigned by air traffic control (ATC) behind the preceding aircraft that maximizes runway throughput while minimizing additional fuel consumption and pilot workload. This document describes an experiment where 24 pilots flew arrivals into the Dallas Fort-Worth terminal environment using one of three simulators at NASA?s Langley Research Center. Results indicate that pilots delivered their aircraft to the runway threshold within +/- 3.5 seconds of their assigned time interval, and reported low workload levels. In general, pilots found the FIM concept, procedures, speeds, and interface acceptable. Analysis of the time error and FIM speed changes as a function of arrival stream position suggest the spacing algorithm generates stable behavior while in the presence of continuous (wind) or impulse (offset) error. Concerns reported included multiple speed changes within a short time period, and an airspeed increase followed shortly by an airspeed decrease.

Is patient size important in dose determination and optimization in cardiology?

NASA Astrophysics Data System (ADS)

Reay, J.; Chapple, C. L.; Kotre, C. J.

2003-12-01

Patient dose determination and optimization have become more topical in recent years with the implementation of the Medical Exposures Directive into national legislation, the Ionising Radiation (Medical Exposure) Regulations. This legislation incorporates a requirement for new equipment to provide a means of displaying a measure of patient exposure and introduces the concept of diagnostic reference levels. It is normally assumed that patient dose is governed largely by patient size; however, in cardiology, where procedures are often very complex, the significance of patient size is less well understood. This study considers over 9000 cardiology procedures, undertaken throughout the north of England, and investigates the relationship between patient size and dose. It uses simple linear regression to calculate both correlation coefficients and significance levels for data sorted by both room and individual clinician for the four most common examinations, left ventrical and/or coronary angiography, single vessel stent insertion and single vessel angioplasty. This paper concludes that the correlation between patient size and dose is weak for the procedures considered. It also illustrates the use of an existing method for removing the effect of patient size from dose survey data. This allows typical doses and, therefore, reference levels to be defined for the purposes of dose optimization.

Estimating linear-nonlinear models using Rényi divergences

PubMed Central

Kouh, Minjoon; Sharpee, Tatyana O.

2009-01-01

This paper compares a family of methods for characterizing neural feature selectivity using natural stimuli in the framework of the linear-nonlinear model. In this model, the spike probability depends in a nonlinear way on a small number of stimulus dimensions. The relevant stimulus dimensions can be found by optimizing a Rényi divergence that quantifies a change in the stimulus distribution associated with the arrival of single spikes. Generally, good reconstructions can be obtained based on optimization of Rényi divergence of any order, even in the limit of small numbers of spikes. However, the smallest error is obtained when the Rényi divergence of order 1 is optimized. This type of optimization is equivalent to information maximization, and is shown to saturate the Cramér-Rao bound describing the smallest error allowed for any unbiased method. We also discuss conditions under which information maximization provides a convenient way to perform maximum likelihood estimation of linear-nonlinear models from neural data. PMID:19568981

Estimating linear-nonlinear models using Renyi divergences.

PubMed

Kouh, Minjoon; Sharpee, Tatyana O

2009-01-01

This article compares a family of methods for characterizing neural feature selectivity using natural stimuli in the framework of the linear-nonlinear model. In this model, the spike probability depends in a nonlinear way on a small number of stimulus dimensions. The relevant stimulus dimensions can be found by optimizing a Rényi divergence that quantifies a change in the stimulus distribution associated with the arrival of single spikes. Generally, good reconstructions can be obtained based on optimization of Rényi divergence of any order, even in the limit of small numbers of spikes. However, the smallest error is obtained when the Rényi divergence of order 1 is optimized. This type of optimization is equivalent to information maximization, and is shown to saturate the Cramer-Rao bound describing the smallest error allowed for any unbiased method. We also discuss conditions under which information maximization provides a convenient way to perform maximum likelihood estimation of linear-nonlinear models from neural data.

Variable porosity of the pipeline embolization device in straight and curved vessels: a guide for optimal deployment strategy.

PubMed

Shapiro, M; Raz, E; Becske, T; Nelson, P K

2014-04-01

Low-porosity endoluminal devices for the treatment of intracranial aneurysms, also known as flow diverters, have been in experimental and clinical use for close to 10 years. Despite rigorous evidence of their safety and efficacy in well-controlled trials, a number of key factors concerning their use remain poorly defined. Among these, none has received more attention to date than the debate on how many devices are optimally required to achieve a safe, effective, and economical outcome. Additional, related questions concern device sizing relative to the parent artery and optimal method of deployment of the devices. While some or all of these issues may be ultimately answered on an empiric basis via subgroup analysis of growing treatment cohorts, we believe that careful in vitro examination of relevant device properties can also help guide its in vivo use. We conducted a number of benchtop experiments to investigate the varied porosity of Pipeline Embolization Devices deployed in a simulated range of parent vessel diameters and applied these results toward conceptualizing optimal treatment strategies of fusiform and wide-neck aneurysms. The results of our studies confirm a predictable parabolic variability in device porosity based on the respective comparative sizes of the device and recipient artery, as well as device curvature. Even modest oversizing leads to a significant increase in porosity. The experiments demonstrate various deleterious effects of device oversizing relative to the parent artery and provide strategies for addressing size mismatches when they are unavoidable.

Automated Power-Distribution System

NASA Technical Reports Server (NTRS)

Ashworth, Barry; Riedesel, Joel; Myers, Chris; Miller, William; Jones, Ellen F.; Freeman, Kenneth; Walsh, Richard; Walls, Bryan K.; Weeks, David J.; Bechtel, Robert T.

1992-01-01

Autonomous power-distribution system includes power-control equipment and automation equipment. System automatically schedules connection of power to loads and reconfigures itself when it detects fault. Potential terrestrial applications include optimization of consumption of power in homes, power supplies for autonomous land vehicles and vessels, and power supplies for automated industrial processes.

Design modification for the modular helium reactor for higher temperature operation and reliability studies for nuclear hydrogen production processes

NASA Astrophysics Data System (ADS)

Reza, S. M. Mohsin

Design options have been evaluated for the Modular Helium Reactor (MHR) for higher temperature operation. An alternative configuration for the MHR coolant inlet flow path is developed to reduce the peak vessel temperature (PVT). The coolant inlet path is shifted from the annular path between reactor core barrel and vessel wall through the permanent side reflector (PSR). The number and dimensions of coolant holes are varied to optimize the pressure drop, the inlet velocity, and the percentage of graphite removed from the PSR to create this inlet path. With the removal of ˜10% of the graphite from PSR the PVT is reduced from 541°C to 421°C. A new design for the graphite block core has been evaluated and optimized to reduce the inlet coolant temperature with the aim of further reduction of PVT. The dimensions and number of fuel rods and coolant holes, and the triangular pitch have been changed and optimized. Different packing fractions for the new core design have been used to conserve the number of fuel particles. Thermal properties for the fuel elements are calculated and incorporated into these analyses. The inlet temperature, mass flow and bypass flow are optimized to limit the peak fuel temperature (PFT) within an acceptable range. Using both of these modifications together, the PVT is reduced to ˜350°C while keeping the outlet temperature at 950°C and maintaining the PFT within acceptable limits. The vessel and fuel temperatures during low pressure conduction cooldown and high pressure conduction cooldown transients are found to be well below the design limits. The reliability and availability studies for coupled nuclear hydrogen production processes based on the sulfur iodine thermochemical process and high temperature electrolysis process have been accomplished. The fault tree models for both these processes are developed. Using information obtained on system configuration, component failure probability, component repair time and system operating modes and conditions, the system reliability and availability are assessed. Required redundancies are made to improve system reliability and to optimize the plant design for economic performance. The failure rates and outage factors of both processes are found to be well below the maximum acceptable range.

KSC-2012-3609

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, center, takes questions from the media in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the arrival in Florida of NASA's first space-bound Orion capsule. NASA Deputy Director Lori Garver and Kennedy Space Center Director Robert Cabana talk nearby. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3617

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, Kennedy Space Center Director Robert Cabana, Orion Program Manager Mark Geyer, U.S. Senator Bill Nelson and NASA Deputy Director Lori Garver pose for a portrait in front of NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3614

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, Orion Program Manager Mark Geyer, U.S. Senator Bill Nelson and NASA Deputy Director Lori Garver pose for a portrait in front of NASA's first space-bound Orion capsule in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3608

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, center, takes questions from the media in Kennedy Space Center's Operations and Checkout Building high bay following an event marking the arrival in Florida of NASA's first space-bound Orion capsule. NASA Deputy Director Lori Garver and Kennedy Space Center Director Robert Cabana talk nearby. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3616

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – From left, Kennedy Space Center Director Robert Cabana, U.S. Senator Bill Nelson and NASA Deputy Director Lori Garver pose for a portrait in front of NASA's first space-bound Orion capsule in Kennedy's Operations and Checkout Building high bay following an event marking the spacecraft's arrival in Florida. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3603

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – NASA Deputy Director Lori Garver, left, visits NASA's Kennedy Space Center in Florida to participate in an event marking the arrival of NASA's first space-bound Orion capsule at Kennedy. With Garver in Kennedy's Operations and Checkout Building high bay are, from left, U.S. Senator Bill Nelson and Trent Smith, NASA project engineer. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

KSC-2012-3605

NASA Image and Video Library

2012-07-02

CAPE CANAVERAL, Fla. – U.S. Senator Bill Nelson, left, checks out NASA's first space-bound Orion capsule at NASA's Kennedy Space Center in Florida. With Nelson in Kennedy's Operations and Checkout Building high bay for an event marking the spacecraft's arrival at Kennedy are NASA Deputy Director Lori Garver and Kennedy Director Robert Cabana. Slated for Exploration Flight Test-1, an uncrewed mission planned for 2014, the capsule will travel farther into space than any human spacecraft has gone in more than 40 years. The capsule was shipped to Kennedy from NASA's Michoud Assembly Facility in New Orleans where the crew module pressure vessel was built. The Orion production team will prepare the module for flight at Kennedy by installing heat-shielding thermal protection systems, avionics and other subsystems. For more information, visit http://www.nasa.gov/orion. Photo credit: NASA/Kim Shiflett

Runway Operations Planning: A Two-Stage Solution Methodology

NASA Technical Reports Server (NTRS)

Anagnostakis, Ioannis; Clarke, John-Paul

2003-01-01

The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. Thus, Runway Operations Planning (ROP) is a critical component of airport operations planning in general and surface operations planning in particular. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, may be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. Generating optimal runway operations plans was approached in with a 'one-stage' optimization routine that considered all the desired objectives and constraints, and the characteristics of each aircraft (weight class, destination, Air Traffic Control (ATC) constraints) at the same time. Since, however, at any given point in time, there is less uncertainty in the predicted demand for departure resources in terms of weight class than in terms of specific aircraft, the ROP problem can be parsed into two stages. In the context of the Departure Planner (OP) research project, this paper introduces Runway Operations Planning (ROP) as part of the wider Surface Operations Optimization (SOO) and describes a proposed 'two stage' heuristic algorithm for solving the Runway Operations Planning (ROP) problem. Focus is specifically given on including runway crossings in the planning process of runway operations. In the first stage, sequences of departure class slots and runwy crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the departure class slots are populated with specific flights from the pool of available aircraft, by solving an integer program. Preliminary results from the algorithm implementation on real-world traffic data are included.

Contrast based band selection for optimized weathered oil detection in hyperspectral images

NASA Astrophysics Data System (ADS)

Levaux, Florian; Bostater, Charles R., Jr.; Neyt, Xavier

2012-09-01

Hyperspectral imagery offers unique benefits for detection of land and water features due to the information contained in reflectance signatures such as the bi-directional reflectance distribution function or BRDF. The reflectance signature directly shows the relative absorption and backscattering features of targets. These features can be very useful in shoreline monitoring or surveillance applications, for example to detect weathered oil. In real-time detection applications, processing of hyperspectral data can be an important tool and Optimal band selection is thus important in real time applications in order to select the essential bands using the absorption and backscatter information. In the present paper, band selection is based upon the optimization of target detection using contrast algorithms. The common definition of the contrast (using only one band out of all possible combinations available within a hyperspectral image) is generalized in order to consider all the possible combinations of wavelength dependent contrasts using hyperspectral images. The inflection (defined here as an approximation of the second derivative) is also used in order to enhance the variations in the reflectance spectra as well as in the contrast spectrua in order to assist in optimal band selection. The results of the selection in term of target detection (false alarms and missed detection) are also compared with a previous method to perform feature detection, namely the matched filter. In this paper, imagery is acquired using a pushbroom hyperspectral sensor mounted at the bow of a small vessel. The sensor is mechanically rotated using an optical rotation stage. This opto-mechanical scanning system produces hyperspectral images with pixel sizes on the order of mm to cm scales, depending upon the distance between the sensor and the shoreline being monitored. The motion of the platform during the acquisition induces distortions in the collected HSI imagery. It is therefore necessary to apply a motion correction to the imagery. In this paper, imagery is corrected for the pitching motion of a vessel, which causes most of the deformation when the vessel is anchored at 2 points (bow and stern) during the acquisition of the hyperspectral imagry.

The fully actuated traffic control problem solved by global optimization and complementarity

NASA Astrophysics Data System (ADS)

Ribeiro, Isabel M.; de Lurdes de Oliveira Simões, Maria

2016-02-01

Global optimization and complementarity are used to determine the signal timing for fully actuated traffic control, regarding effective green and red times on each cycle. The average values of these parameters can be used to estimate the control delay of vehicles. In this article, a two-phase queuing system for a signalized intersection is outlined, based on the principle of minimization of the total waiting time for the vehicles. The underlying model results in a linear program with linear complementarity constraints, solved by a sequential complementarity algorithm. Departure rates of vehicles during green and yellow periods were treated as deterministic, while arrival rates of vehicles were assumed to follow a Poisson distribution. Several traffic scenarios were created and solved. The numerical results reveal that it is possible to use global optimization and complementarity over a reasonable number of cycles and determine with efficiency effective green and red times for a signalized intersection.

STEPS: a grid search methodology for optimized peptide identification filtering of MS/MS database search results.

PubMed

Piehowski, Paul D; Petyuk, Vladislav A; Sandoval, John D; Burnum, Kristin E; Kiebel, Gary R; Monroe, Matthew E; Anderson, Gordon A; Camp, David G; Smith, Richard D

2013-03-01

For bottom-up proteomics, there are wide variety of database-searching algorithms in use for matching peptide sequences to tandem MS spectra. Likewise, there are numerous strategies being employed to produce a confident list of peptide identifications from the different search algorithm outputs. Here we introduce a grid-search approach for determining optimal database filtering criteria in shotgun proteomics data analyses that is easily adaptable to any search. Systematic Trial and Error Parameter Selection--referred to as STEPS--utilizes user-defined parameter ranges to test a wide array of parameter combinations to arrive at an optimal "parameter set" for data filtering, thus maximizing confident identifications. The benefits of this approach in terms of numbers of true-positive identifications are demonstrated using datasets derived from immunoaffinity-depleted blood serum and a bacterial cell lysate, two common proteomics sample types. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Risk assessment in man and mouse.

PubMed

Balci, Fuat; Freestone, David; Gallistel, Charles R

2009-02-17

Human and mouse subjects tried to anticipate at which of 2 locations a reward would appear. On a randomly scheduled fraction of the trials, it appeared with a short latency at one location; on the complementary fraction, it appeared after a longer latency at the other location. Subjects of both species accurately assessed the exogenous uncertainty (the probability of a short versus a long trial) and the endogenous uncertainty (from the scalar variability in their estimates of an elapsed duration) to compute the optimal target latency for a switch from the short- to the long-latency location. The optimal latency was arrived at so rapidly that there was no reliably discernible improvement over trials. Under these nonverbal conditions, humans and mice accurately assess risks and behave nearly optimally. That this capacity is well-developed in the mouse opens up the possibility of a genetic approach to the neurobiological mechanisms underlying risk assessment.

Risk assessment in man and mouse

PubMed Central

Balci, Fuat; Freestone, David; Gallistel, Charles R.

2009-01-01

Human and mouse subjects tried to anticipate at which of 2 locations a reward would appear. On a randomly scheduled fraction of the trials, it appeared with a short latency at one location; on the complementary fraction, it appeared after a longer latency at the other location. Subjects of both species accurately assessed the exogenous uncertainty (the probability of a short versus a long trial) and the endogenous uncertainty (from the scalar variability in their estimates of an elapsed duration) to compute the optimal target latency for a switch from the short- to the long-latency location. The optimal latency was arrived at so rapidly that there was no reliably discernible improvement over trials. Under these nonverbal conditions, humans and mice accurately assess risks and behave nearly optimally. That this capacity is well-developed in the mouse opens up the possibility of a genetic approach to the neurobiological mechanisms underlying risk assessment. PMID:19188592

Optimizing the Long-Term Operating Plan of Railway Marshalling Station for Capacity Utilization Analysis

PubMed Central

Zhou, Wenliang; Yang, Xia; Deng, Lianbo

2014-01-01

Not only is the operating plan the basis of organizing marshalling station's operation, but it is also used to analyze in detail the capacity utilization of each facility in marshalling station. In this paper, a long-term operating plan is optimized mainly for capacity utilization analysis. Firstly, a model is developed to minimize railcars' average staying time with the constraints of minimum time intervals, marshalling track capacity, and so forth. Secondly, an algorithm is designed to solve this model based on genetic algorithm (GA) and simulation method. It divides the plan of whole planning horizon into many subplans, and optimizes them with GA one by one in order to obtain a satisfactory plan with less computing time. Finally, some numeric examples are constructed to analyze (1) the convergence of the algorithm, (2) the effect of some algorithm parameters, and (3) the influence of arrival train flow on the algorithm. PMID:25525614

Eligibility and Predictors for Acute Revascularization Procedures in a Stroke Center.

PubMed

Vanacker, Peter; Lambrou, Dimitris; Eskandari, Ashraf; Mosimann, Pascal J; Maghraoui, Ali; Michel, Patrik

2016-07-01

Endovascular treatment (EVT) is a new standard of care for selected, large vessel occlusive strokes. We aimed to determine frequency of potentially eligible patients for intravenous thrombolysis (IVT) and EVT in comprehensive stroke centers. In addition, predictors of EVT eligibility were derived. Patients from a stroke center-based registry (2003-2014), admitted within 24 hours of last proof of usual health, were selected if they had all data to determine IVT and EVT eligibility according to American Heart Association/American Stroke Association (AHA/ASA) guidelines (class I-IIa recommendations). Moreover, less restrictive criteria adapted from randomized controlled trials and clinical practice were tested. Maximum onset-to-door time windows for IVT eligibility were 3.5 hours (allowing door-to-needle delay of ≤60 minutes) and 4.5 hours for EVT eligibility (door-to-groin delay ≤90 minutes). Demographic and clinical information were used in logistic regression analysis to derive variables associated with EVT eligibility. A total of 2704 patients with acute ischemic stroke were included, of which 26.8% were transfers. Of all patients with stroke arriving at our comprehensive stroke center, a total proportion of 12.4% patients was eligible for IVT. Frequency of EVT eligibility differed between AHA/ASA guidelines and less restrictive approach: 2.9% versus 4.9%, respectively, of all patients with acute ischemic stroke and 10.5% versus 17.7%, respectively, of all patients arriving within <6 hours. Predictors for AHA-EVT eligibility were younger, shorter onset-to-admission delays, higher National Institutes of Health Stroke Scale (NIHSS), decreased vigilance, hemineglect, absent cerebellar signs, atrial fibrillation, smoking, and decreasing glucose levels (area under the curve=0.86). Of patients arriving within 6 hours at a comprehensive stroke center, 10.5% are EVT eligible according to AHA/ASA criteria, 17.7% according to criteria resembling randomized controlled trials, and twice as many patients are IVT eligible (36.2%). © 2016 American Heart Association, Inc.

Numerical optimization of three-dimensional coils for NSTX-U

DOE PAGES

Lazerson, S. A.; Park, J. -K.; Logan, N.; ...

2015-09-03

A tool for the calculation of optimal three-dimensional (3D) perturbative magnetic fields in tokamaks has been developed. The IPECOPT code builds upon the stellarator optimization code STELLOPT to allow for optimization of linear ideal magnetohydrodynamic perturbed equilibrium (IPEC). This tool has been applied to NSTX-U equilibria, addressing which fields are the most effective at driving NTV torques. The NTV torque calculation is performed by the PENT code. Optimization of the normal field spectrum shows that fields with n = 1 character can drive a large core torque. It is also shown that fields with n = 3 features are capablemore » of driving edge torque and some core torque. Coil current optimization (using the planned in-vessel and existing RWM coils) on NSTX-U suggest the planned coils set is adequate for core and edge torque control. In conclusion, comparison between error field correction experiments on DIII-D and the optimizer show good agreement.« less

Common Bolted Joint Analysis Tool

NASA Technical Reports Server (NTRS)

Imtiaz, Kauser

2011-01-01

Common Bolted Joint Analysis Tool (comBAT) is an Excel/VB-based bolted joint analysis/optimization program that lays out a systematic foundation for an inexperienced or seasoned analyst to determine fastener size, material, and assembly torque for a given design. Analysts are able to perform numerous what-if scenarios within minutes to arrive at an optimal solution. The program evaluates input design parameters, performs joint assembly checks, and steps through numerous calculations to arrive at several key margins of safety for each member in a joint. It also checks for joint gapping, provides fatigue calculations, and generates joint diagrams for a visual reference. Optimum fastener size and material, as well as correct torque, can then be provided. Analysis methodology, equations, and guidelines are provided throughout the solution sequence so that this program does not become a "black box:" for the analyst. There are built-in databases that reduce the legwork required by the analyst. Each step is clearly identified and results are provided in number format, as well as color-coded spelled-out words to draw user attention. The three key features of the software are robust technical content, innovative and user friendly I/O, and a large database. The program addresses every aspect of bolted joint analysis and proves to be an instructional tool at the same time. It saves analysis time, has intelligent messaging features, and catches operator errors in real time.

Design and simulation of a descent controller for strategic four-dimensional aircraft navigation. M.S. Thesis

NASA Technical Reports Server (NTRS)

Lax, F. M.

1975-01-01

A time-controlled navigation system applicable to the descent phase of flight for airline transport aircraft was developed and simulated. The design incorporates the linear discrete-time sampled-data version of the linearized continuous-time system describing the aircraft's aerodynamics. Using optimal linear quadratic control techniques, an optimal deterministic control regulator which is implementable on an airborne computer is designed. The navigation controller assists the pilot in complying with assigned times of arrival along a four-dimensional flight path in the presence of wind disturbances. The strategic air traffic control concept is also described, followed by the design of a strategic control descent path. A strategy for determining possible times of arrival at specified waypoints along the descent path and for generating the corresponding route-time profiles that are within the performance capabilities of the aircraft is presented. Using a mathematical model of the Boeing 707-320B aircraft along with a Boeing 707 cockpit simulator interfaced with an Adage AGT-30 digital computer, a real-time simulation of the complete aircraft aerodynamics was achieved. The strategic four-dimensional navigation controller for longitudinal dynamics was tested on the nonlinear aircraft model in the presence of 15, 30, and 45 knot head-winds. The results indicate that the controller preserved the desired accuracy and precision of a time-controlled aircraft navigation system.

Optimizing a Drone Network to Deliver Automated External Defibrillators.

PubMed

Boutilier, Justin J; Brooks, Steven C; Janmohamed, Alyf; Byers, Adam; Buick, Jason E; Zhan, Cathy; Schoellig, Angela P; Cheskes, Sheldon; Morrison, Laurie J; Chan, Timothy C Y

2017-06-20

Public access defibrillation programs can improve survival after out-of-hospital cardiac arrest, but automated external defibrillators (AEDs) are rarely available for bystander use at the scene. Drones are an emerging technology that can deliver an AED to the scene of an out-of-hospital cardiac arrest for bystander use. We hypothesize that a drone network designed with the aid of a mathematical model combining both optimization and queuing can reduce the time to AED arrival. We applied our model to 53 702 out-of-hospital cardiac arrests that occurred in the 8 regions of the Toronto Regional RescuNET between January 1, 2006, and December 31, 2014. Our primary analysis quantified the drone network size required to deliver an AED 1, 2, or 3 minutes faster than historical median 911 response times for each region independently. A secondary analysis quantified the reduction in drone resources required if RescuNET was treated as a large coordinated region. The region-specific analysis determined that 81 bases and 100 drones would be required to deliver an AED ahead of median 911 response times by 3 minutes. In the most urban region, the 90th percentile of the AED arrival time was reduced by 6 minutes and 43 seconds relative to historical 911 response times in the region. In the most rural region, the 90th percentile was reduced by 10 minutes and 34 seconds. A single coordinated drone network across all regions required 39.5% fewer bases and 30.0% fewer drones to achieve similar AED delivery times. An optimized drone network designed with the aid of a novel mathematical model can substantially reduce the AED delivery time to an out-of-hospital cardiac arrest event. © 2017 American Heart Association, Inc.

Mathematical model of marine diesel engine simulator for a new methodology of self propulsion tests

NASA Astrophysics Data System (ADS)

Izzuddin, Nur; Sunarsih, Priyanto, Agoes

2015-05-01

As a vessel operates in the open seas, a marine diesel engine simulator whose engine rotation is controlled to transmit through propeller shaft is a new methodology for the self propulsion tests to track the fuel saving in a real time. Considering the circumstance, this paper presents the real time of marine diesel engine simulator system to track the real performance of a ship through a computer-simulated model. A mathematical model of marine diesel engine and the propeller are used in the simulation to estimate fuel rate, engine rotating speed, thrust and torque of the propeller thus achieve the target vessel's speed. The input and output are a real time control system of fuel saving rate and propeller rotating speed representing the marine diesel engine characteristics. The self-propulsion tests in calm waters were conducted using a vessel model to validate the marine diesel engine simulator. The simulator then was used to evaluate the fuel saving by employing a new mathematical model of turbochargers for the marine diesel engine simulator. The control system developed will be beneficial for users as to analyze different condition of vessel's speed to obtain better characteristics and hence optimize the fuel saving rate.

Adaptable setups for magnetic drug targeting in human muscular arteries: Design and implementation

NASA Astrophysics Data System (ADS)

Hajiaghajani, Amirhossein; Hashemi, Soheil; Abdolali, Ali

2017-09-01

Magnetic drug targeting has been used to steer magnetic therapeutic agents and has received much attention for capillaries and human brain arteries. In this paper, we focus on noninvasive targeting of nanoparticles in muscular arteries, in where the vessel diameter and blood flow are much challengingly higher than brain capillaries. We aim to design a low intensity magnetic field which avoids potential side effects on blood cells while steers particles with high targeting rate. The setup design procedure is considerably flexible to be used in a wide variety of large vessels. Using particle tracing, a new method is proposed to connect the geometry of the vessel under the action of targeting to the required magnetic force. Specifications of the coil which is placed outside the body are derived based on this required force. Mutual effects of coil dimensions on the produced magnetic force are elaborated and summarized in a design flowchart to be used for arbitrary muscular vessel sizes. The performance of the optimized coil is validated by in vitro experiments and it is shown that particles are steered with the average efficiency of 80.2% for various conditions.

Design, Analysis and R&D of the EAST In-Vessel Components

NASA Astrophysics Data System (ADS)

Yao, Damao; Bao, Liman; Li, Jiangang; Song, Yuntao; Chen, Wenge; Du, Shijun; Hu, Qingsheng; Wei, Jing; Xie, Han; Liu, Xufeng; Cao, Lei; Zhou, Zibo; Chen, Junling; Mao, Xinqiao; Wang, Shengming; Zhu, Ning; Weng, Peide; Wan, Yuanxi

2008-06-01

In-vessel components are important parts of the EAST superconducting tokamak. They include the plasma facing components, passive plates, cryo-pumps, in-vessel coils, etc. The structural design, analysis and related R&D have been completed. The divertor is designed in an up-down symmetric configuration to accommodate both double null and single null plasma operation. Passive plates are used for plasma movement control. In-vessel coils are used for the active control of plasma vertical movements. Each cryo-pump can provide an approximately 45 m3/s pumping rate at a pressure of 10-1 Pa for particle exhaust. Analysis shows that, when a plasma current of 1 MA disrupts in 3 ms, the EM loads caused by the eddy current and the halo current in a vertical displacement event (VDE) will not generate an unacceptable stress on the divertor structure. The bolted divertor thermal structure with an active cooling system can sustain a load of 2 MW/m2 up to a 60 s operation if the plasma facing surface temperature is limited to 1500 °C. Thermal testing and structural optimization testing were conducted to demonstrate the analysis results.

[Imaging anatomy of cranial nerves].

PubMed

Hermier, M; Leal, P R L; Salaris, S F; Froment, J-C; Sindou, M

2009-04-01

Knowledge of the anatomy of the cranial nerves is mandatory for optimal radiological exploration and interpretation of the images in normal and pathological conditions. CT is the method of choice for the study of the skull base and its foramina. MRI explores the cranial nerves and their vascular relationships precisely. Because of their small size, it is essential to obtain images with high spatial resolution. The MRI sequences optimize contrast between nerves and surrounding structures (cerebrospinal fluid, fat, bone structures and vessels). This chapter discusses the radiological anatomy of the cranial nerves.

[Optimization of the parameters of microcirculatory structural adaptation model based on improved quantum-behaved particle swarm optimization algorithm].

PubMed

Pan, Qing; Yao, Jialiang; Wang, Ruofan; Cao, Ping; Ning, Gangmin; Fang, Luping

2017-08-01

The vessels in the microcirculation keep adjusting their structure to meet the functional requirements of the different tissues. A previously developed theoretical model can reproduce the process of vascular structural adaptation to help the study of the microcirculatory physiology. However, until now, such model lacks the appropriate methods for its parameter settings with subsequent limitation of further applications. This study proposed an improved quantum-behaved particle swarm optimization (QPSO) algorithm for setting the parameter values in this model. The optimization was performed on a real mesenteric microvascular network of rat. The results showed that the improved QPSO was superior to the standard particle swarm optimization, the standard QPSO and the previously reported Downhill algorithm. We conclude that the improved QPSO leads to a better agreement between mathematical simulation and animal experiment, rendering the model more reliable in future physiological studies.

Catastrophic antiphospholipid syndrome (Ronald Asherson syndrome) and obstetric pathology.

PubMed

Makatsariya, Alexander D; Khizroeva, Jamilya; Bitsadze, Viktoriya O

2018-05-24

Catastrophic antiphospholipid syndrome (CAPS) is an uncommon, often fatal, variant of the antiphospholipid syndrome (APS) that results in a widespread coagulopathy and high titres of antiphospholipid antibodies (aPL) and affects predominantly small vessels supplying organs with the development of multiorgan failure. It remains unclear why some patients develop the typical clinical picture of APS (thrombosis of large vessels), whereas others show the development of progressive microthrombosis, which the authors called "thrombotic storm" and multiple organ failure, that is, CAPS. Since 2001-2016, we discovered 17 patients with CAPS development. CAPS is life-threatening condition, but optimal treatment for CAPS is not developed yet and the mortality rate is as high as 30%-40%.

Optimal Shape of a Gamma-ray Collimator: single vs double knife edge

NASA Astrophysics Data System (ADS)

Metz, Albert; Hogenbirk, Alfred

2017-09-01

Gamma-ray collimators in nuclear waste scanners are used for selecting a narrow vertical segment in activity measurements of waste vessels. The system that is used by NRG uses tapered slit collimators of both the single and double knife edge type. The properties of these collimators were investigated by means of Monte Carlo simulations. We found that single knife edge collimators are highly preferable for a conservative estimate of the activity of the waste vessels. These collimators show much less dependence on the angle of incidence of the radiation than double knife edge collimators. This conclusion also applies to cylindrical collimators of the single knife edge type, that are generally used in medical imaging spectroscopy.

Air Medical Evacuations From the German North Sea Wind Farm Bard Offshore 1: Traumatic Injuries, Acute Diseases, and Rescue Process Times (2011-2013).

PubMed

Dethleff, Dirk; Weinrich, Nils; Kowald, Birgitt; Hory, Dorothea; Franz, Rüdiger; Nielsen, Maja Verena; Seide, Klaus; Jürgens, Christian; Stuhr, Markus

2016-01-01

Our purpose was 2-fold: 1) to show emergency-related traumatic injury and acute disease patterns and 2) to evaluate air rescue process times in a remotely located German offshore wind farm. Optimally, this will support methodologies to reduce offshore help time (time from the incoming emergency call until offshore arrival of the helicopter). The type and severity of traumatic injuries and acute diseases were retrospectively analyzed for 39 air medevacs from August 2011 to December 2013, and the process times of air rescue missions were evaluated in detail. Forty-nine percent of the medevacs were related to traumatic injuries, whereas 41% were associated with acute diseases and 10% remained unclear. Cardiovascular and gastrointestinal disorders accounted for 90% of internal medical cases. About 69% of the trauma was related to contusions, lacerations, and cuts. The main body regions injured were limbs (∼59%) and head (∼32%). The total rescue time until arrival at the destination facility averaged 175.3 minutes (standard deviation = 54.4 minutes). The mean helicopter offshore arrival time was 106.9 minutes (standard deviation = 57.4 minutes) after the incoming emergency call. In 64% of the medevacs, the helicopter arrived on scene within a help time of 90 minutes. A reduction of help time (≤ 60 minutes) for time-critical severe trauma and acute diseases may be anticipated through rapid and focused medical and logistic decision-making processes by the onshore dispatch center combined with professional, qualified, and well-trained flight and rescue personnel. Copyright © 2016 Air Medical Journal Associates. Published by Elsevier Inc. All rights reserved.

Use of Gabor filters and deep networks in the segmentation of retinal vessel morphology

NASA Astrophysics Data System (ADS)

Leopold, Henry A.; Orchard, Jeff; Zelek, John; Lakshminarayanan, Vasudevan

2017-02-01

The segmentation of retinal morphology has numerous applications in assessing ophthalmologic and cardiovascular disease pathologies. The early detection of many such conditions is often the most effective method for reducing patient risk. Computer aided segmentation of the vasculature has proven to be a challenge, mainly due to inconsistencies such as noise, variations in hue and brightness that can greatly reduce the quality of fundus images. Accurate fundus and/or retinal vessel maps give rise to longitudinal studies able to utilize multimodal image registration and disease/condition status measurements, as well as applications in surgery preparation and biometrics. This paper further investigates the use of a Convolutional Neural Network as a multi-channel classifier of retinal vessels using the Digital Retinal Images for Vessel Extraction database, a standardized set of fundus images used to gauge the effectiveness of classification algorithms. The CNN has a feed-forward architecture and varies from other published architectures in its combination of: max-pooling, zero-padding, ReLU layers, batch normalization, two dense layers and finally a Softmax activation function. Notably, the use of Adam to optimize training the CNN on retinal fundus images has not been found in prior review. This work builds on prior work of the authors, exploring the use of Gabor filters to boost the accuracy of the system to 0.9478 during post processing. The mean of a series of Gabor filters with varying frequencies and sigma values are applied to the output of the network and used to determine whether a pixel represents a vessel or non-vessel.

Enhanced delineation of degradation in aortic walls through OCT

NASA Astrophysics Data System (ADS)

Real, Eusebio; Val-Bernal, José Fernando; Revuelta, José M.; Pontón, Alejandro; Calvo Díez, Marta; Mayorga, Marta; López-Higuera, José M.; Conde, Olga M.

2015-03-01

Degradation of the wall of human ascending thoracic aorta has been assessed through Optical Coherence Tomography (OCT). OCT images of the media layer of the aortic wall exhibit micro-structure degradation in case of diseased aortas from aneurysmal vessels or in aortas prone to aortic dissections. The degeneration in vessel walls appears as low-reflectivity areas due to the invasive appearance of acidic polysaccharides and mucopolysaccharides within a typical ordered microstructure of parallel lamellae of smooth muscle cells, elastin and collagen fibers. An OCT indicator of wall degradation can be generated upon the spatial quantification of the extension of degraded areas in a similar way as conventional histopathology. This proposed OCT marker offers a real-time clinical insight of the vessel status to help cardiovascular surgeons in vessel repair interventions. However, the delineation of degraded areas on the B-scan image from OCT is sometimes difficult due to presence of speckle noise, variable SNR conditions on the measurement process, etc. Degraded areas could be outlined by basic thresholding techniques taking advantage of disorders evidences in B-scan images, but this delineation is not always optimum and requires complex additional processing stages. This work proposes an optimized delineation of degraded spots in vessel walls, robust to noisy environments, based on the analysis of the second order variation of image intensity of backreflection to determine the type of local structure. Results improve the delineation of wall anomalies providing a deeper physiological perception of the vessel wall conditions. Achievements could be also transferred to other clinical scenarios: carotid arteries, aorto-iliac or ilio-femoral sections, intracranial, etc.

SeeCoast: persistent surveillance and automated scene understanding for ports and coastal areas

NASA Astrophysics Data System (ADS)

Rhodes, Bradley J.; Bomberger, Neil A.; Freyman, Todd M.; Kreamer, William; Kirschner, Linda; L'Italien, Adam C.; Mungovan, Wendy; Stauffer, Chris; Stolzar, Lauren; Waxman, Allen M.; Seibert, Michael

2007-04-01

SeeCoast is a prototype US Coast Guard port and coastal area surveillance system that aims to reduce operator workload while maintaining optimal domain awareness by shifting their focus from having to detect events to being able to analyze and act upon the knowledge derived from automatically detected anomalous activities. The automated scene understanding capability provided by the baseline SeeCoast system (as currently installed at the Joint Harbor Operations Center at Hampton Roads, VA) results from the integration of several components. Machine vision technology processes the real-time video streams provided by USCG cameras to generate vessel track and classification (based on vessel length) information. A multi-INT fusion component generates a single, coherent track picture by combining information available from the video processor with that from surface surveillance radars and AIS reports. Based on this track picture, vessel activity is analyzed by SeeCoast to detect user-defined unsafe, illegal, and threatening vessel activities using a rule-based pattern recognizer and to detect anomalous vessel activities on the basis of automatically learned behavior normalcy models. Operators can optionally guide the learning system in the form of examples and counter-examples of activities of interest, and refine the performance of the learning system by confirming alerts or indicating examples of false alarms. The fused track picture also provides a basis for automated control and tasking of cameras to detect vessels in motion. Real-time visualization combining the products of all SeeCoast components in a common operating picture is provided by a thin web-based client.

Distributed Method to Optimal Profile Descent

NASA Astrophysics Data System (ADS)

Kim, Geun I.

Current ground automation tools for Optimal Profile Descent (OPD) procedures utilize path stretching and speed profile change to maintain proper merging and spacing requirements at high traffic terminal area. However, low predictability of aircraft's vertical profile and path deviation during decent add uncertainty to computing estimated time of arrival, a key information that enables the ground control center to manage airspace traffic effectively. This paper uses an OPD procedure that is based on a constant flight path angle to increase the predictability of the vertical profile and defines an OPD optimization problem that uses both path stretching and speed profile change while largely maintaining the original OPD procedure. This problem minimizes the cumulative cost of performing OPD procedures for a group of aircraft by assigning a time cost function to each aircraft and a separation cost function to a pair of aircraft. The OPD optimization problem is then solved in a decentralized manner using dual decomposition techniques under inter-aircraft ADS-B mechanism. This method divides the optimization problem into more manageable sub-problems which are then distributed to the group of aircraft. Each aircraft solves its assigned sub-problem and communicate the solutions to other aircraft in an iterative process until an optimal solution is achieved thus decentralizing the computation of the optimization problem.

A parallel competitive Particle Swarm Optimization for non-linear first arrival traveltime tomography and uncertainty quantification

NASA Astrophysics Data System (ADS)

Luu, Keurfon; Noble, Mark; Gesret, Alexandrine; Belayouni, Nidhal; Roux, Pierre-François

2018-04-01

Seismic traveltime tomography is an optimization problem that requires large computational efforts. Therefore, linearized techniques are commonly used for their low computational cost. These local optimization methods are likely to get trapped in a local minimum as they critically depend on the initial model. On the other hand, global optimization methods based on MCMC are insensitive to the initial model but turn out to be computationally expensive. Particle Swarm Optimization (PSO) is a rather new global optimization approach with few tuning parameters that has shown excellent convergence rates and is straightforwardly parallelizable, allowing a good distribution of the workload. However, while it can traverse several local minima of the evaluated misfit function, classical implementation of PSO can get trapped in local minima at later iterations as particles inertia dim. We propose a Competitive PSO (CPSO) to help particles to escape from local minima with a simple implementation that improves swarm's diversity. The model space can be sampled by running the optimizer multiple times and by keeping all the models explored by the swarms in the different runs. A traveltime tomography algorithm based on CPSO is successfully applied on a real 3D data set in the context of induced seismicity.

Development of a realistic, dynamic digital brain phantom for CT perfusion validation

NASA Astrophysics Data System (ADS)

Divel, Sarah E.; Segars, W. Paul; Christensen, Soren; Wintermark, Max; Lansberg, Maarten G.; Pelc, Norbert J.

2016-03-01

Physicians rely on CT Perfusion (CTP) images and quantitative image data, including cerebral blood flow, cerebral blood volume, and bolus arrival delay, to diagnose and treat stroke patients. However, the quantification of these metrics may vary depending on the computational method used. Therefore, we have developed a dynamic and realistic digital brain phantom upon which CTP scans can be simulated based on a set of ground truth scenarios. Building upon the previously developed 4D extended cardiac-torso (XCAT) phantom containing a highly detailed brain model, this work consisted of expanding the intricate vasculature by semi-automatically segmenting existing MRA data and fitting nonuniform rational B-spline surfaces to the new vessels. Using time attenuation curves input by the user as reference, the contrast enhancement in the vessels changes dynamically. At each time point, the iodine concentration in the arteries and veins is calculated from the curves and the material composition of the blood changes to reflect the expected values. CatSim, a CT system simulator, generates simulated data sets of this dynamic digital phantom which can be further analyzed to validate CTP studies and post-processing methods. The development of this dynamic and realistic digital phantom provides a valuable resource with which current uncertainties and controversies surrounding the quantitative computations generated from CTP data can be examined and resolved.

Robust automatic control system of vessel descent-rise device for plant with distributed parameters “cable – towed underwater vehicle”

NASA Astrophysics Data System (ADS)

Chupina, K. V.; Kataev, E. V.; Khannanov, A. M.; Korshunov, V. N.; Sennikov, I. A.

2018-05-01

The paper is devoted to a problem of synthesis of the robust control system for a distributed parameters plant. The vessel descent-rise device has a heave compensation function for stabilization of the towed underwater vehicle on a set depth. A sea state code, parameters of the underwater vehicle and cable vary during underwater operations, the vessel heave is a stochastic process. It means that the plant and external disturbances have uncertainty. That is why it is necessary to use the robust theory for synthesis of an automatic control system, but without use of traditional methods of optimization, because this cable has distributed parameters. The offered technique has allowed one to design an effective control system for stabilization of immersion depth of the towed underwater vehicle for various degrees of sea roughness and to provide its robustness to deviations of parameters of the vehicle and cable’s length.

Automation process for morphometric analysis of volumetric CT data from pulmonary vasculature in rats.

PubMed

Shingrani, Rahul; Krenz, Gary; Molthen, Robert

2010-01-01

With advances in medical imaging scanners, it has become commonplace to generate large multidimensional datasets. These datasets require tools for a rapid, thorough analysis. To address this need, we have developed an automated algorithm for morphometric analysis incorporating A Visualization Workshop computational and image processing libraries for three-dimensional segmentation, vascular tree generation and structural hierarchical ordering with a two-stage numeric optimization procedure for estimating vessel diameters. We combine this new technique with our mathematical models of pulmonary vascular morphology to quantify structural and functional attributes of lung arterial trees. Our physiological studies require repeated measurements of vascular structure to determine differences in vessel biomechanical properties between animal models of pulmonary disease. Automation provides many advantages including significantly improved speed and minimized operator interaction and biasing. The results are validated by comparison with previously published rat pulmonary arterial micro-CT data analysis techniques, in which vessels were manually mapped and measured using intense operator intervention. Published by Elsevier Ireland Ltd.

Automated detection of neovascularization for proliferative diabetic retinopathy screening.

PubMed

Roychowdhury, Sohini; Koozekanani, Dara D; Parhi, Keshab K

2016-08-01

Neovascularization is the primary manifestation of proliferative diabetic retinopathy (PDR) that can lead to acquired blindness. This paper presents a novel method that classifies neovascularizations in the 1-optic disc (OD) diameter region (NVD) and elsewhere (NVE) separately to achieve low false positive rates of neovascularization classification. First, the OD region and blood vessels are extracted. Next, the major blood vessel segments in the 1-OD diameter region are classified for NVD, and minor blood vessel segments elsewhere are classified for NVE. For NVD and NVE classifications, optimal region-based feature sets of 10 and 6 features, respectively, are used. The proposed method achieves classification sensitivity, specificity and accuracy for NVD and NVE of 74%, 98.2%, 87.6%, and 61%, 97.5%, 92.1%, respectively. Also, the proposed method achieves 86.4% sensitivity and 76% specificity for screening images with PDR from public and local data sets. Thus, the proposed NVD and NVE detection methods can play a key role in automated screening and prioritization of patients with diabetic retinopathy.

Angioarchitecture of the bovine tunica albuginea vascular complex--a corrosive and histological study.

PubMed

Polguj, Michał; Sopiński, Marek; Jędrzejewski, Kazimierz; Bolanowski, Wojciech; Topol, Mirosław

2011-10-01

Histological and corrosive studies of 75 bovine testes were focused on the vascular complex of the tunica albuginea. Thanks to used MultiScanBase v.14.02 software arterial and venous vessels and also vascular anastomoses were analyzed preciously. The studies revealed the superficial layer containing vessels of smaller diameter and reduced wall structure and the deeper layer with wider, winding vessels and complete wall structure. The branches of the testicular artery and intra-tunical veins formed a vascular complex of the tunica albuginea. The intra-tunical veins were divided into two types. Type I veins ran parallel, drained intra-parenchymal veins and formed the origin of pampiniform plexus. Type II veins drained into type I intra-tunical veins. Indirect anastomoses among intra-tunical veins and arteries and venovenous connections were observed. The results of the study could contribute fuller description of the regulatory mechanism for testicular blood supply and optimization of the testicular biopsy to minimize bleeding risk. Copyright © 2010 Elsevier Ltd. All rights reserved.

Microcatheter Shaping for Intracranial Aneurysm Coiling Using the 3-Dimensional Printing Rapid Prototyping Technology: Preliminary Result in the First 10 Consecutive Cases.

PubMed

Namba, Katsunari; Higaki, Ayuho; Kaneko, Naoki; Mashiko, Toshihiro; Nemoto, Shigeru; Watanabe, Eiju

2015-07-01

An optimal microcatheter is necessary for successful coiling of an intracranial aneurysm. The optimal shape may be predetermined before the endovascular surgery via the use of a 3-dimensional (3D) printing rapid prototyping technology. We report a preliminary series of intracranial aneurysms treated with a microcatheter shape determined by the patient's anatomy and configuration of the aneurysm, which was fabricated with a 3D printer aneurysm model. A solid aneurysm model was fabricated with a 3D printer based on the data acquired from the 3D rotational angiogram. A hollow aneurysm model with an identical vessel and aneurysm lumen to the actual anatomy was constructed with use of the solid model as a mold. With use of the solid model, a microcatheter shaping mandrel was formed to identically line the 3D curvature of the parent vessel and the long axis of the aneurysm. With use of the mandrel, a test microcatheter was shaped and validated for the accuracy with the hollow model. All the planning processes were undertaken at least 1 day before treatment. The preshaped mandrel was then applied in the endovascular procedure. Ten consecutive intracranial aneurysms were coiled with the pre-planned shape of the microcatheter and evaluated for the clinical and anatomical outcomes and microcatheter accuracy and stability. All of pre-planned microcatheters matched the vessel and aneurysm anatomy. Seven required no microguidewire assistance in catheterizing the aneurysm whereas 3 required guiding of a microguidewire. All of the microcatheters accurately aligned the long axis of the aneurysm. The pre-planned microcatheter shapes demonstrated stability in all except in 1 large aneurysm case. When a 3D printing rapid type prototyping technology is used, a patient-specific and optimal microcatheter shape may be determined preoperatively. Copyright © 2015 Elsevier Inc. All rights reserved.

Provision of servo-controlled cooling during neonatal transport.

PubMed

Johnston, Ewen D; Becher, Julie-Clare; Mitchell, Anne P; Stenson, Benjamin J

2012-09-01

Therapeutic hypothermia is a time critical intervention for infants who have experienced a hypoxic-ischaemic event. Previously reported methods of cooling during transport do not demonstrate the same stability achieved in the neonatal unit. The authors developed a system which allowed provision of servo-controlled cooling throughout transport, and present their first year's experience. Retrospective review of routinely collected patient data. 14 out-born infants were referred for cooling during a 12-month period. Nine infants were managed with the servo-controlled system during transport. Cooling was commenced in all infants before 6 h of life. Median time from team arrival to the infant having a temperature in the target range (33-34°C) was 45 min. Median temperature during transfer was 33.5°C (range 33-34°C). Temperature on arrival at the cooling centre ranged from 33.4°C to 33.8°C. Servo-controlled cooling during transport is feasible and provides an optimal level of thermal control.

Filtering for networked control systems with single/multiple measurement packets subject to multiple-step measurement delays and multiple packet dropouts

NASA Astrophysics Data System (ADS)

Moayedi, Maryam; Foo, Yung Kuan; Chai Soh, Yeng

2011-03-01

The minimum-variance filtering problem in networked control systems, where both random measurement transmission delays and packet dropouts may occur, is investigated in this article. Instead of following the many existing results that solve the problem by using probabilistic approaches based on the probabilities of the uncertainties occurring between the sensor and the filter, we propose a non-probabilistic approach by time-stamping the measurement packets. Both single-measurement and multiple measurement packets are studied. We also consider the case of burst arrivals, where more than one packet may arrive between the receiver's previous and current sampling times; the scenario where the control input is non-zero and subject to delays and packet dropouts is examined as well. It is shown that, in such a situation, the optimal state estimate would generally be dependent on the possible control input. Simulations are presented to demonstrate the performance of the various proposed filters.

Cuff-less blood pressure measurement using pulse arrival time and a Kalman filter

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Chen, Xianxiang; Fang, Zhen; Xue, Yongjiao; Zhan, Qingyuan; Yang, Ting; Xia, Shanhong

2017-02-01

The present study designs an algorithm to increase the accuracy of continuous blood pressure (BP) estimation. Pulse arrival time (PAT) has been widely used for continuous BP estimation. However, because of motion artifact and physiological activities, PAT-based methods are often troubled with low BP estimation accuracy. This paper used a signal quality modified Kalman filter to track blood pressure changes. A Kalman filter guarantees that BP estimation value is optimal in the sense of minimizing the mean square error. We propose a joint signal quality indice to adjust the measurement noise covariance, pushing the Kalman filter to weigh more heavily on measurements from cleaner data. Twenty 2 h physiological data segments selected from the MIMIC II database were used to evaluate the performance. Compared with straightforward use of the PAT-based linear regression model, the proposed model achieved higher measurement accuracy. Due to low computation complexity, the proposed algorithm can be easily transplanted into wearable sensor devices.

Hazardous materials accidents: initial scene assessment and patient care.

PubMed

Leonard, R B

1993-06-01

Hazardous materials, i.e., chemicals that are toxic, corrosive, flammable, or explosive, are a ubiquitous aspect of modern life. They are manufactured throughout the United States, shipped by truck, train, barge, and pipeline, and stored at a wide variety of locations, including factories, military bases, and warehouses. Accidents involving hazardous materials present an added dimension of danger to emergency personnel arriving first at the scene, and have the potential to produce chemically contaminated patients who require special medical treatment. Personnel arriving first at the scene must understand how to evaluate the scene for fast and safe mitigation without endangering themselves. Chemically contaminated patients require prompt treatment, which, for optimal outcome, must begin at the scene. Although frequently the identification of the hazardous materials involved is not known initially, emergency personnel may safely provide medical care to the victims by understanding and following the principles of hazardous materials accidents and the pathophysiology of chemical injuries as presented in this paper.