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Purpose This paper aims to discover why such a public partnership project had been successful with a non-profit third-party alliance such as a smart city consortium (SCC) promoting smart city development. Design/methodology/approach This descriptive case study is primarily based on analysing data collected from various texts, public statements, media interviews and three semi-structured interviews with key members involved in the Covid-19 dashboard project. Findings The data and analysis reviews that both interpersonal and interorganisational trust, dedication and proactiveness of the leaders at SCC were major contributing factors to why SCC was able to partner with the Hong Kong Government in the Covid-19 dashboard in the first place and that the success was also a direct outcome of effective mass collaborative knowledge management activities. Research limitations/implications The research in leadership attributes and activities in the non-profit alliance has been few and this collaborative partnership between the alliance and the government is an example of the importance of further research in smart city leadership. Practical implications In deploying projects for mass collaboration and knowledge sharing in smart city development (which is multi-disciplinary in nature). there are still many new and evolving organisational practices and leadership matters that many business leaders and city managers can learn from. Social implications Smart city development projects involve the notion of sharing data in an open environment enabled by software and mediating tools. Successful projects such as this Hong Kong Covid-19 dashboard which serves a diverse audience can further promote the importance of an open data policy regime for the benefit of the public. Originality/value This case study covers a highly original and unique case study with the leaders at the SCC and representatives from the Hong Kong Government.

When optimising the vehicle trajectory and powertrain energy management of hybrid electric vehicles, it is important to include look-ahead information such as road conditions and other traffic. One method for doing so is dynamic programming, but the execution time of such an algorithm on a general purpose CPU is too slow for it to be useable in real time. Significant improvements in execution time can be achieved by utilising parallel computations, for example, using a Field-Programmable Gate Array (FPGA). A tool for automatically converting a vehicle model written in C++ into code that can executed on an FPGA which can be used for dynamic programming-based control is presented in this paper. A vehicle model with a mild-hybrid powertrain is used as a case study to evaluate the developed tool and the output quality and execution time of the resulting hardware.

Feature selection is an important task in data-driven control applications to identify relevant features and remove non-informative ones, for example residual selection for fault diagnosis. For multi-class data, the objective is to find a minimal set of features that can distinguish data from all different classes. A distributed feature selection algorithm is derived using convex optimization and the Alternating Direction Method of Multipliers. The distributed algorithm scales well with increasing number of classes by utilizing parallel computations. Two case studies are used to evaluate the developed feature selection algorithm: fault classification of an internal combustion engine and the MNIST data set to illustrate a larger multi-class classification problem.

By running simulation models on FPGAs, their execution speed can be significantly improved, at the cost of increased development effort. This paper describes a project to develop a tool which converts simulation models written in high level languages into fast FPGA hardware. The tool currently converts code written using custom C++ data types into Verilog. A model of a hybrid electric vehicle is used as a case study, and the resulting hardware runs significantly faster than on a general purpose CPU.

Hydrogen sulfide (H2S) represents one of the main odorant gases emitted from sewer networks. A mathematical model can be a fast and low-cost tool for estimating its emission. This study investigates two approaches to modeling H2S gas transfer at a waterfall in a discharge manhole. The first approach is based on an adaptation of oxygen models for H2S emission at a waterfall and the second consists of a new model. An experimental set-up and a statistical data analysis allowed the main factors affecting H2S emission to be studied. A new model of the emission kinetics was developed using linear regression and taking into account H2S liquid concentration, waterfall height and fluid velocity at the outlet pipe of a rising main. Its prediction interval was estimated by the residual standard deviation (15.6%) up to a rate of 2.3 g H2S·h−1. Finally, data coming from four sampling campaigns on sewer networks were used to perform simulations and compare predictions of all developed models.

Detecting changes in residuals is important for fault detection and is commonly performed by thresholding the residual using, for example, a CUSUM test. However, detecting variations in the residua ...

Localization of unknown faults in industrial systems is a difficult task for data-driven diagnosis methods. The classification performance of many machine learning methods relies on the quality of training data. Unknown faults, for example faults not represented in training data, can be detected using, for example, anomaly classifiers. However, mapping these unknown faults to an actual location in the real system is a non-trivial problem. In model-based diagnosis, physical-based models are used to create residuals that isolate faults by mapping model equations to faulty system components. Developing sufficiently accurate physical-based models can be a time-consuming process. Hybrid modeling methods combining physical-based methods and machine learning is one solution to design data-driven residuals for fault isolation. In this work, a set of neural network-based residuals are designed by incorporating physical insights about the system behavior in the residual model structure. The residuals are trained using only fault-free data and a simulation case study shows that they can be used to perform fault isolation and localization of unknown faults in the system., Comment: 8 pages, 7 figures, If citing this paper please use: In: Proceedings of the Annual Conference of the PHM Society, Scottsdale, Arizona, USA (2019)

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Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing protocol has a poor performance in the worst case, in a sense that there is a distribution of nodes resulting in bad routing paths for that protocol, even if the nodes know their geographic positions and the geographic position of the destination of a message is known. The reason for that is that radio holes in the ad hoc network may require messages to take long detours in order to get to a destination, which are hard to find in an online fashion.

A commonly used signal for engine misfire detection is the crankshaft angular velocity measured at the flywheel. However, flywheel manufacturing errors result in vehicle-to-vehicle variations in th ...

Predicting lead-acid battery failure is important for heavy-duty trucks to avoid unplanned stops by the road. There are large amount of data from trucks in operation, however, data is not closely r ...

Routing is a challenging problem for wireless ad hoc networks, especially when the nodes are mobile and spread so widely that in most cases multiple hops are needed to route a message from one node to another. In fact, it is known that any online routing protocol has a poor performance in the worst case, in a sense that there is a distribution of nodes resulting in bad routing paths for that protocol, even if the nodes know their geographic positions and the geographic position of the destination of a message is known. The reason for that is that radio holes in the ad hoc network may require messages to take long detours in order to get to a destination, which are hard to find in an online fashion. In this short paper, we assume that the wireless ad hoc network can make limited use of long-range links provided by a global communication infrastructure like a cellular infrastructure or a satellite in order to compute an abstraction of the wireless ad hoc network that allows the messages to be sent along near-shortest paths in the ad hoc network. We present distributed algorithms that compute an abstraction of the ad hoc network in $\mathcalO left(log ^2 n\right)$ time using long-range links, which results in c -competitive routing paths between any two nodes of the ad hoc network for some constant c if the convex hulls of the radio holes do not intersect.

An important part of automotive driving assistance systems and autonomous vehicles is speed optimization and traffic flow adaptation. Vehicle sensors and wireless communication with surrounding veh ...

Most model-based diagnosis approaches reported in the literature adopt a generic architecture and approach. However, the fault hypotheses generated by these methods may differ. This is not only due to the methods, but also on the basic assumptions made by different diagnostic algorithms on fault manifestation and evolution. While comparing different diagnosis approaches, the assumptions made in each case will have a significant effect on fault diagnosability performance and must therefore also be taken into consideration. Thus, to make a fair comparison, the different approaches should be designed based on the same assumptions. This paper studies the relation between a set of commonly made assumptions and fault isolability performance in order to compare different diagnosis approaches. As a case study, five developed diagnosis systems for a wind turbine benchmark problem are evaluated to analyze the type of assumptions that are applied in the different designs.

To be able to evaluate quantitative fault diagnosability performance in model-based diagnosis is useful during the design of a diagnosis system. Different fault realizations are more or less likely ...

This paper presents a framework for distributed fault detection and isolation in dynamic systems. Our approach uses the dynamic model of each subsystem to derive a set of independent, local diagnosers. If needed, the subsystem model is extended to include measurements and model equations from its immediate neighbors to compute its diagnosis. Our approach is designed to ensure that each subsystem diagnoser provides the correct results, therefore, a local diagnosis result is equivalent to the results that would be produced by a global system diagnoser. We discuss the distribute diagnosis algorithm, and illustrate its application using a multi-tank system.

The present paper proposes an advanced approach for Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems fault detection and isolation through a model-based diagnostic algorithm. The considered algorithm is developed upon a lumped parameter model simulating a whole PEMFC system oriented towards automotive applications. This model is inspired by other models available in the literature, with further attention to stack thermal dynamics and water management. The developed model is analysed by means of Structural Analysis, to identify the correlations among involved physical variables, defined equations and a set of faults which may occur in the system (related to both auxiliary components malfunctions and stack degradation phenomena). Residual generators are designed by means of Causal Computation analysis and the maximum theoretical fault isolability, achievable with a minimal number of installed sensors, is investigated. The achieved results proved the capability of the algorithm to theoretically detect and isolate almost all faults with the only use of stack voltage and temperature sensors, with significant advantages from an industrial point of view. The effective fault isolability is proved through fault simulations at a specific fault magnitude with an advanced residual evaluation technique, to consider quantitative residual deviations from normal conditions and achieve univocal fault isolation.

Background To identify patients with pulmonary embolism (PE) without deep venous thrombosis (DVT), and to compare them with those with an identifiable source on upper (UED) and lower-extremity venous duplex scans (LED). Methods We performed a retrospective review of 2700 computed tomography angiograms of the chest between January 2008 and September 2010 and identified 230 patients with PE. We then evaluated the results of UED and LED and divided the patients into four groups based on the results of their duplex studies. We compared patients with PE and DVT with those with PE and no DVT in terms of age, gender, size and location of PE, critical illness, malignancy, and in-hospital mortality. Results We identified 152 women and 78 men (mean age, 68 years) with PE. One hundred thirty-one patients had a documented source of PE (group 1). Fifty-three patients had negative LED results, but did not undergo UED (group 2). Thirty-one patients did not undergo either LED or UED (group 3). Seven men and eight women had no documented source of PE on UED and LED (group 4). Ten of 15 patients in group 4 had a documented malignancy listed as one of their diagnoses. Because patients in groups 2 and 3 did not undergo complete duplex studies, we excluded them from our analysis. We then reviewed the discharge summaries of patients in groups 1 and 4. There was no statistically significant difference in age and gender distribution, size and location of PE, critical illness, smoking status, cardiovascular disease, trauma, and in-hospital mortality between patients in group 1 and 4. Patients in group 4 had a statistically significant increased prevalence of malignancy (67% vs. 40%, P = 0.046). Patients in group 4 also had a higher percentage of active cancer than those in group 1 (47% vs. 24%, P = 0.084), although not statistically significant. We defined active cancer as either a metastatic disease or a malignancy diagnosed shortly before or after the diagnosis of PE. Patients who were undergoing treatment for cancer at the time of diagnosis of PE were also considered to have active cancer. Conclusion We demonstrated a statistically significant increased prevalence of malignancy in patients with PE without DVT. However, pathophysiology and clinical significance are the aspects that remain to be understood after accrual of more patients and further research. Possibilities such as de novo thrombosis of pulmonary arteries, complete dislodgement of thrombi from peripheral veins, or false-negative venous duplex need to be explored.

A hybrid diagnosis system design is proposed that combines model-based and data-driven diagnosis methods for fault isolation. A set of residuals are used to detect if there is a fault in the system and a consistency-based fault isolation algorithm is used to compute all diagnosis candidates that can explain the triggered residuals. To improve fault isolation, diagnosis candidates are ranked by evaluating the residuals using a set of one-class support vector machines trained using data from different faults. The proposed diagnosis system design is evaluated using simulations of a model describing the air-flow in an internal combustion engine.

Advanced building management systems utilize future information, such as electricity spot prices, weather forecasts, and predicted electric loads and hot water consumption, to reduce the maximum electric power consumption and energy cost. A model predictive controller (MPC) is implemented for a household with one hour sample intervals, including hot water usage, charging of an electric vehicle, and domestic heating, but also an accumulator water tank to be used as an additional thermal energy storage. Both the maximum total power used in the house and the energy cost are included in the cost function to evaluate how these properties are affected by different system designs. The MPC solution is compared to the global optimal solution using dynamic programming indicating comparable performance. The robustness of the MPC is evaluated using a prediction of the future household electric consumption in the controller. Results also show that a significant part of the cost reduction is achieved for as small prediction horizons as five hours. Analysis shows that including an accumulator tank is useful for reducing the total energy cost, while reducing the peak power is mainly achieved by increasing the prediction horizon of the MPC.

When electrons are accelerated to near light-speeds through an overdense plasma by an intense laser beam, the usually opaque plasma becomes optically transparent. High-speed laser experiments provide unprecedented insight into the dynamics of this process.

Advancement of ion acceleration by intense laser pulses is studied with ultra-thin nanometer-thick diamond like carbon and micrometer-thick Titanium target foils. Both investigations aim at optimizing the electron density distribution which is the key for efficient laser driven ion acceleration. While recently found maximum ion energies achieved with ultra-thin foils mark record values micrometer thick foils are flexible in terms of atomic constituents. Electron recirculation is one prerequisite for the validity of a very simple model that can approximate the dependence of ion energies of nanometer-thick targets when all electrons of the irradiated target area interact coherently with the laser pulse and Coherent Acceleration of Ions by Laser pulses (CAIL) becomes dominant. Complementary experiments, an analytical model and particle in cell computer simulations show, that with regard to ultra-short laser pulses (duration ~45 fs at intensities up to 5 × 1019 W/cm2) and a micrometer-thick target foil with higher atomic number a close to linear increase of ion energies manifests in a certain range of laser intensities.

Ultrathin (o 5 nm) self-supporting diamond-like carbon (DLC) foils are prepared by filtered cathodic vacuum arc (FCVA) deposition method as targets for laser-driven ion acceleration. The thickness and the morphology of these foils are characterized by atomic force microscope (AFM) and scanning electron microscope (SEM).

In this paper we report on an experimental study of high harmonic radiation generated in nanometer-scale foil targets irradiated under normal incidence. The experiments constitute the first unambiguous observation of odd-numbered relativistic harmonics generated by the v × B component of the Lorentz force verifying a long predicted property of solid target harmonics. Simultaneously the observed harmonic spectra allow in-situ extraction of the target density in an experimental scenario which is of utmost interest for applications such as ion acceleration by the radiation pressure of an ultraintense laser.

In this paper the route towards the current optimum of laser generated ion beams by subsequently changing the important parameters such as target thickness, laser pulse contrast, angle of incidence and laser pulse polarization is sketched. Beginning with parameters of isothermal target normal sheath acceleration (TNSA), we reached the regime where the plasma expansion can be described adiabatically and results in a symmetric ion acceleration. Further we demonstrated a way to phase match the accelerating electron population with the ions, namely coherent acceleration of ions by laser pulses (CAIL), which finally lead to radiation pressure acceleration (RPA) if the laser polarization was changed from linear to circular. These findings of ion acceleration with transparent solid targets are additionally supported by analyzing the optical properties of the transmitted laser pulse (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Background The technique of long segment stenting of the superficial femoral artery (SFA) has been associated with poorer short- and long-term results. The full metal jacket (FMJ) stenting is typically described as long segment continuous stenting of a vessel segment. Initially, this technique was described in percutaneous coronary interventions. However, until recently, FMJ of the SFA has not been studied. We examined our experience with FMJ of the SFA to evaluate the outcomes and the safety of this technique. Methods Retrospective data were gathered for peripheral angioplasties and stenting for the period between January 2005 and December 2008. The cases involving FMJ stenting of the SFA were identified by angiographic findings and the operative dictations providing the stent data. Selective FMJ stenting of the SFA was performed for the residual stenosis after balloon angioplasty of the SFA because of either dissection or significant recoil. The cases with concomitant iliac artery angioplasty and/or stenting were excluded from the data set for analysis. The variables for the evaluation were primary patency rate, mortality rate, and limb salvage rate, which were stratified on the basis of the risk factors. Results A total of 63 cases involving FMJ stenting of the SFA were identified from the database of 707 patients who had peripheral endovascular interventions between January 2005 and December 2008. Average age of the patients was 70 years (range: 52-104 years, SD: 10.1 years). There were no transatlantic inter-society consensus (TASC) A lesions, 11% (7/63) of the lesions were TASC B, 68% (43/63) were TASC C, and 21% (13/63) were TASC D. The median primary patency rate was 9 months (95% CI: 5.06-12.94). The mortality rate was 4% at 6-month follow-up. The limb salvage rate was 85.7%. In all, 65% (41/63) of the patients were claudicants, whereas 23% (15/63) had intervention for some form of tissue loss (ischemic ulcer, gangrene). Associated infrapopliteal intervention was performed in 15.9% of the patients. Average creatinine level was 1.67 (range: 0.7-10.9, SD: 2.03) and 49% (31/63) of the patients had diabetes. The average 6-month patency rate was 55% (SD: 0.5). Multivariate logistic regression analysis showed that diabetes (OR: 0.33, p = 0.044, 95% CI: 0.11-0.97) and a creatinine level of ≥1.6 (OR: 0.16, p = 0.038, 95% CI: 0.03-0.9) were the independent risk factors for loss of patency in Conclusion Our experience suggests promising results for the technique of FMJ of the SFA and also that further examination of the technique is warranted.

Introduction La technique de stenting long d’un segment de l’artere femorale superficielle (AFS) a ete associee a des resultats mediocres a court et long termes. Le full metal jacket (FMJ) stenting est typiquement decrit comme le stenting continu d’un long segment vasculaire. Au debut, cette technique a ete decrite dans les interventions coronaires percutanees. Cependant, jusqu’a recemment, le FMJ de l’AFS n’a pas ete etudie. Nous avons examine notre experience de FMJ de l’AFS afin d’evaluer les resultats et la surete de cette technique. Methodes Les donnees retrospectives etaient recueillies concernant les angioplasties peripheriques avec stenting sur la periode de janvier 2005 a decembre 2008. Les cas impliquant un stenting en FMJ de l’AFS etaient identifies par les resultats angiographiques et les comptes-rendus operatoires fournissant les donnees du stent. Le stenting selectif en FMJ de l’AFS etait realise pour une stenose residuelle apres angioplastie au ballon de l’AFS en raison d’une dissection ou d’un recoil significatif. Les cas d’angioplastie concomitante et/ou stenting de l’artere iliaque etaient exclus des donnees analysees. Les criteres d’evaluation etaient les taux primaires de permeabilite, taux de mortalite, et taux de sauvetage de membre, qui etaient stratifiees sur la base des facteurs de risque. Resultats Un total de 63 cas impliquant un stenting en FMJ de l’AFS ont ete identifies dans la base de donnees de 707 patients qui avaient eu des interventions endovasculaires peripheriques entre janvier 2005 et decembre 2008. L’âge moyen des patients etait de 70 ans (extremes : 52-104 ans, ecart-type : 10,1 ans). Il n’y avait aucune lesion TASC A, 11% (7/63) des lesions etaient TASC B, 68% (43/63) etaient TASC C, et 21% (13/63) etaient TASC D. Le taux primaire median de permeabilite etait de 9 mois (IC a 95% : 5,06-12,94). Le taux de mortalite etait de 4% au cours du suivi de six mois. Le taux de sauvetage de membre etait de 85,7%. En tout, 65% (41/63) des patients etaient des claudicants, tandis que 23% (15/63) ont eu une intervention pour un trouble trophique (ulcere, gangrene ischemique). Une intervention sous poplitee associee a ete effectuee dans 15,9% des patients. Le niveau moyen de creatininemie etait de 1,67 (extremes : 0,7-10,9, ecart-type : 2,03) et 49% (31/63) des patients etaient diabetiques. Le taux moyen a six mois de permeabilite etait de 55% (ecart-type : 0,5). L’analyse de regression logistique multivariee montrait que le diabete (OR : 0,33, p = 0,044, IC a 95% : 0,11-0,97) et un niveau de creatininemie ≥ 1,6 (OR : 0,16, p = 0,038, ic a 95% : 0,03-0,9) etaient des facteurs de risque independants de thrombose Conclusion Notre experience suggere des resultats prometteurs de la technique de FMJ de l’AFS, et d’autres etudes sur cette technique sont justifiees.

e19010Background: All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) have revolutionized the treatment of acute promyelocytic leukemia (APML). Anthracycline is added at induction for high ri...

e18929Background: There exists significant variation in lung cancer treatment depending on physician, payer and stage of disease without significant difference in survival or QoL (Quality of Life)....

The greenhouses of solar drying for urban residual sludge represent an economic alternative to the classic thermal dryers. The aim of this study is the modelling with a two-scale approach of the process Solia ™ . A three-dimensional modelling with the software Ansys ® /Fluent ® allows to visualize internal aeraulics and exchanges, and so to underline influent parameters on the process effiency. The systemic zero-dimensional model is developed on Matlab ® /Simulink ® software. It takes into account the previous exchanges and allows a higher physical simulation time, at a day or season scale.

Model-based diagnosis compares observations from a system with predictions using a mathematical model to detect and isolate faulty components. Analyzing which faults that can be detected and isolat ...

A model-based misfire detection algorithm is proposed. The algorithm is able to detect misfires and identify the failing cylinder during different conditions, such as cylinder-to-cylinder variations, cold starts, and different engine behavior in different operating points. Also, a method is proposed for automatic tuning of the algorithm based on training data. The misfire detection algorithm is evaluated using data from several vehicles on the road and the results show that a low misclassification rate is achieved even during difficult conditions. (C) 2014 Elsevier Ltd. All rights reserved. Funding Agencies|Volvo Car Corporation; Swedish Research Council within the Linnaeus Center CADICS

Local changes in the topology of electricity grids can cause overloads far away from the disturbance, making the prediction of the robustness against changes in the topology - for example caused by power outages or grid extensions - a challenging task. The impact of single-line additions on the long-range response of DC electricity grids has recently been studied. By solving the real part of the static AC load flow equations, we conduct a similar investigation for AC grids. In a regular 2D grid graph with cyclic boundary conditions, we find a power law decay for the change of power flow as a function of distance to the disturbance over a wide range of distances. The power exponent increases and saturates for large system sizes. By applying the same analysis to the German transmission grid topology, we show that also in real-world topologies a long-ranged response can be found., Comment: 12 pages, 16 figures, submitted to PRE

A number of residual generation methods have been developed for robust model-based fault detection and isolation (FDI). There have also been a number of offline (i.e., design-time) methods that focus on optimizing FDI performance (e.g., trading off detection performance versus cost). However, design-time algorithms are not tuned to optimize performance for different operating regions of system behavior. To do this, would need to define online measures of sensitivity and robustness, and use them to select the best residual set online as system behavior transitions between operating regions. In this paper we develop a quantitative measure of residual performance, called the detectability ratio that applies to additive and multiplicative uncertainties when determining the best residual set in different operating regions. We discuss this methodology and demonstrate its effectiveness using a case study.

Diagnostic for investigating and distinguishing different laser ion acceleration mechanisms has been developed and successfully tested. An ion separation wide angle spectrometer can simultaneously investigate three important aspects of the laser plasma interaction: (1) acquire angularly resolved energy spectra for two ion species, (2) obtain ion energy spectra for multiple species, separated according to their charge to mass ratio, along selected axes, and (3) collect laser radiation reflected from and transmitted through the target and propagating in the same direction as the ion beam. Thus, the presented diagnostic constitutes a highly adaptable tool for accurately studying novel acceleration mechanisms in terms of their angular energy distribution, conversion efficiency, and plasma density evolution.

Background To examine the effect of office-based duplex-guided balloon-assisted maturation (DG-BAM) on arteriovenous fistula (AVF), we retrospectively analyzed our experience. Methods Over the past 10 months, we performed 185 DG-BAMs (range, 1–8 procedures; mean, 3.7) in 45 patients (29 male, 16 female; mean age, 68.2 ± 12.8 years) with 31 radial–cephalic, 7 brachial–cephalic, and 7 brachial–basilic AVFs. Balloon sizes (3–10 mm) were chosen based on duplex measurements (1–2 mm larger than minimal vein diameter). Forearm AVFs were dilated to 8 mm, and arm AVFs were dilated to 10 mm. Results All cases but one (99.5%) were successfully dilated. This exception was a large AVF rupture that required surgical repair. AVFs failed to mature in seven of the remaining 44 patients (16%) despite DG-BAM because of proximal vein stenoses (PVS). Four patients had cephalic arch stenoses, and three had proximal subclavian vein stenoses. Arm AVFs were more commonly associated with PVS (6 of 14 patients, 43%) as compared with the ones placed in the forearm (1 of 30 patients, 3.3%), with a P value of 0.0024. All these seven AVFs subsequently matured after successful balloon angioplasty of the venous outflow. Conclusions These data suggest that office-based DG-BAM of AVFs is feasible, safe, and averts nephrotoxic contrast and radiation. PVS appear to be the most common cause of failure for AVFs subjected to BAM. Because arm AVFs are at increased risk of PVS, we suggest that a careful duplex evaluation of the outflow be performed in these cases and in all AVFs that fail to mature.

A novel method for characterising the full spectrum of deuteron ions emitted by laser driven multi-species ion sources is discussed. The procedure is based on using differential filtering over the detector of a Thompson parabola ion spectrometer, which enables discrimination of deuterium ions from heavier ion species with the same charge-to-mass ratio (such as C6+, O8+, etc.). Commonly used Fuji Image plates were used as detectors in the spectrometer, whose absolute response to deuterium ions over a wide range of energies was calibrated by using slotted CR-39 nuclear track detectors. A typical deuterium ion spectrum diagnosed in a recent experimental campaign is presented., 7 pages, 7 figures

Here we present experimental results on laser-driven ion accel- eration from relativistically transparent, overdense plasmas in the break-out afterburner (BOA) regime. Experiments were preformed at the Trident ultra-high contrast laser facility at Los Alamos National Laboratory, and at the Texas Petawatt laser facility, located in the University of Texas at Austin. It is shown that when the target becomes relativistically transparent to the laser, an epoch of dramatic acceleration of ions occurs that lasts until the electron density in the expanding target reduces to the critical density in the non-relativistic limit. For given laser parameters, the optimal target thickness yielding the highest maximum ion energy is one in which this time window for ion acceleration overlaps with the intensity peak of the laser pulse. A simple analytic model of relativistically induced transparency is presented for plasma expansion at the

In underwater imaging, refraction changes the geometry of image formation, causing the perspective camera model to be invalid. Hence, a systematic model error occurs when computing 3D models using the perspective camera model. This paper deals with the problem of computing dense depth maps of underwater scenes with explicit incorporation of refraction of light at the underwater housing. It is assumed that extrinsic, intrinsic, and housing parameters have been calibrated for all cameras. Due to the refractive camera’s characteristics it is not possible to directly apply epipolar geometry or rectification to images because the single-view-point model and, consequently, homographies are invalid. Additionally, the projection of 3D points into the camera cannot be computed efficiently, but requires solving a 12 th degree polynomial. Therefore, the method proposed is an adapted plane sweep algorithm that is based on the idea of back-projecting rays for each pixel and view onto the 3D-hypothesis planes using the GPU. This allows to efficiently warp all images onto the plane, where they can be compared. Consequently, projections of 3D points and homographies are not utilized.

Fourth-order cross-correlation of the laser pulse is obtained from the spectral interferogram produced from the laser pulse and a self-created reference pulse. High dynamic range contrast measurement (60 dB) is demonstrated by measuring an imposed pre-pulse.

Neutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers sufficient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to produce a forward peaked neutron flux with a record yield, on the order of ${10}^{10}\text{ }\text{ }\mathrm{n}/\mathrm{sr}$. We present results comparing the two acceleration mechanisms and the first short pulse laser generated neutron radiograph.

In the last few years several multi-view display systems appeared increasing in size and the number of views that can be displayed. The increasing number of views allow for more realistic content with a high level of detail and complex lighting. For highest quality the images of synthetic scenes are usually ray traced. For large displays that are able to resolve a large amount of different views the number of viewing rays is enormous and it would take several month to render the content via ray tracing. One solution is to render only a few images and interpolate the remaining images with an image based rendering approach. This work introduces an algorithm that selects the best viewpoints for an image based rendering algorithm on the basis of given criteria. Special care is taken to cover occlusions and account for the dimension and angular resolution of multi-view displays.

Background Venous outflow obstruction may play a role in patients with chronic venous stasis symptoms who fail to improve despite conventional modalities of treatment that focus on the reflux component of the disease with little attention to the possibility of an obstructive component. The introduction of minimally invasive venous stenting using venography and intravenous ultrasonography (IVUS) provides the ability to treat the “obstructive” component of the disease. Methods We undertook a retrospective review of 56 limbs in 53 patients with chronic venous stasis symptoms. Initial transcutaneous Doppler ultrasonographic evaluation of the inferior vena cava, iliac, femoral, greater saphenous, and perforator veins was performed looking for any evidence of deep venous thrombosis, superficial venous thrombosis, perforator veins, and reflux (location and degree). Afterword, the patients were managed in the conventional fashion (leg elevation, compression, and great saphenous vein (GSV) and perforator ablation, if present) for a period of 3 months. If ulcer healing was not noted, iliac-femoral venography and IVUS were undertaken. A significant stenosis was defined as a 50% reduction in vein cross-sectional area as measured by IVUS. 1,2,3 Stenotic lesions were managed with stenting followed by balloon angioplasty. Patients were followed up for ulcer healing or improvement of stasis symptoms. Results Of the 56 limbs, 10 (17.8%) had postthrombotic changes, 7 (12.5%) had incompetent perforators, and 27 (48.2%) had an incompetent superficial venous system. In the stented group ( n = 29), 3 limbs had perforator ablation alone, 13 limbs had GSV ablation alone, and 1 limb had both perforator and GSV ablation. In the unstented group ( n = 27), 10 limbs had GSV ablation alone, and 3 limbs had both perforator and GSV ablation. The overall incidence of deep reflux was 51.8%; 17 of 29 limbs (58.6%) in the stented group had evidence of deep reflux, and 12 of 27 limbs (44.4%) in the unstented group had deep reflux. All venograms except one (98.2%) were performed under local anesthesia with sedation. The procedure was performed in an ambulatory setting in 69.6% (39 of 56) of the limbs. CEAP clinical severity class distribution was as follows: C2, 4%; C3, 16%; C4, 18%; C5, 5%; C6, 57%. Over half of the limbs (29 of 56) were found to have stenotic lesions and required stenting. Eight patients (11 limbs) did not return for ulcer healing assessment. The majority (19 of 29) of limbs in the stented group had a CEAP of 6. Among the patients with CEAP 6 who returned for follow-up ( n = 26), 7 had no evidence of stenosis and required no stenting. Only one of those (14.3%) healed his ulcers after 3 months (average follow-up of 4.8 months). The remainder 19 limbs were found to have stenotic lesions and underwent stenting. The ulcers healed in 11 of those (58%) over a period of 1 week to 8 months (average of 5 months), with average follow-up of 3.6 months ( p = 0.08). The cumulative primary and secondary patency rates were 93.1% (27 of 29) and 100% (29 of 29), respectively. Two stent thromboses occurred within 4 weeks of the initial procedure. Both occurred in patients with postthrombotic obstruction. One patient developed a superficial femoral artery pseudoaneurysm. Conclusion Over half of our patients with open ulcers had stenotic lesions. The ulcers healed in 58% of the stented limbs. That indicates that outflow obstruction may play a significant role in patients with chronic venous stasis symptoms, especially those with open ulcers who failed to respond to other treatment modalities. The procedure itself is relatively safe and simple and can be performed on an ambulatory basis.

Recently a new display type has emerged that is able to display 50,000 views offering a full parallax autostereoscopic view of static scenes. With the advancement in the manufacturing technology, multi-view displays come with more and more views of dynamic content, closing the gap to this high quality full parallax display. The established method of content generation for synthetic stereo images is to render both views. To ensure a high quality these images are often ray traced. With the increasing number of views, rendering of all views is not feasible for multi-view displays. Therefore methods are required that can render the large amount of different views required by those displays efficiently. In the following a complete solution is presented that describes how all views for a full parallax display can be rendered from a small set of input images and their associated depth images with an image-based rendering algorithm. An acceleration of the rendering of two orders of magnitude is achieved by different parallelization techniques and the use of efficient data structures. Moreover, the problem of finding the best-next-view for an image-based rendering algorithm is addressed and a solution is presented that ranks possible viewpoints based on their suitability for an image-based rendering algorithm.

Relevant to laser based electron/ion accelerations, a single shot second harmonic generation frequency resolved optical gating (FROG) system has been developed to characterize laser pulses (80 J, ∼600 fs) incident on and transmitted through nanofoil targets, employing relay imaging, spatial filter, and partially coated glass substrates to reduce spatial nonuniformity and B-integral. The device can be completely aligned without using a pulsed laser source. Variations of incident pulse shape were measured from durations of 613 fs (nearly symmetric shape) to 571 fs (asymmetric shape with pre- or postpulse). The FROG measurements are consistent with independent spectral and autocorrelation measurements.