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Rationale and Objectives Modern computed tomographic scanners and examination protocols often require high injection rates of iodinated contrast media (CM). The purpose of this study was to investigate the maximum injection pressures (MIPs) with different CM at different temperatures in the most common intravenous cannula (IVC) sizes. Materials and methods Three IVC sizes, 22, 20, and 18 gauge, were evaluated. All examinations were performed with a pressure-limited (300 psi) power injector. The MIPs of three different CM (Solutrast 300, Imeron 350, and Imeron 400) were measured at room temperature (20°C) and at 37°C using increasing flow rates (1–9 mL/s). The intactness of the IVCs was checked after injection. Results Heating the CM led to reductions in injection pressures (P Conclusions Heating of CM effectively reduces MIPs using power injection in common IVCs. Although the manufacturer's suggested MIP was exceeded at higher flow rates, safe CM injection seems to be possible even in small cannulas using power injection. The compilation of the obtained data is meant to serve as guidance for future decisions on parameters of the power injection of iodinated CM.

The purpose of this study is to evaluate the effect of catheter down-sizing and power injector use on the amount of contrast medium delivered during diagnostic coronary angiography (CAG). We retrospectively studied 735 patients undergoing diagnostic CAG. Patients were divided into four groups according to catheter size [4 French (Fr) or 5 Fr] and the method of contrast injection (manual or power injection). Total contrast volume, procedure time, number of catheters used and angiogram quality were analyzed. Down-sizing catheters from 5 Fr to 4 Fr reduced the amount of contrast medium in both manual injection (from 153 ± 22 to 137 ± 17 ml, −10%, p

This article describes the new technological advancements of portal systems. Implantable port devices provide intravenous access for chemotherapy administration, medication infusions, and have been approved by the Food and Drug Administration (FDA) for use in radiologic and diagnostic power injection studies. Development of the power injectable portal systems, device use, accessing and de-accessing, scope of practice, and pinch off syndrome are discussed.

Power injection variations that occur in power systems are generally nonlinear. A continuation power flow method with multiple nonlinear power injection variations is presented in this paper. To model the nature of nonlinear power injection variations, a piecewise-linear model is proposed to approximate the nonlinear model of power injections. The piecewise-linear model is studied and incorporated into continuation power flow, making it capable of handling nonlinear power injection variations. The impacts of linear as well as nonlinear load variations on the P-V curve, Q-V curve, and P-Q-V curve are numerically analyzed on test power systems. Numerical studies indicate that the direction of power injection variation can significantly affect the load margin and that the differences between uniform linear power injection directions and multiple nonlinear power injection variations can be significant. The importance of accurately modeling power injection variations on simulated power system quasi-state behaviors is stressed.

This paper introduces a complete simulation model of a direct power injection (DPI) setup, used to measure the immunity of integrated circuits to conducted continuous-wave interference. This model encompasses the whole measurement setup itself as well as the integrated circuit under test and its environment (printed circuit board, power supply). Furthermore, power losses are theoretically computed, and the most significant ones are included in the model. Therefore, the injected power level causing a malfunction of an integrated circuit, according to a given criterion, can be identified and predicted at any frequency up to 1 GHz. In addition to that, the relationship between immunity and impedance is illustrated. Simulation results obtained from the model are compared with measurement results, and these demonstrate the validity of this approach.

The unified power-flow controller (UPFC), with its unique combination of fast shunt and series compensation, offers a versatile device for the relief of transmission constraints. However, in order to realise this potential benefit, appropriate local and global power-system control strategies must first be developed. UPFC steady-state model and its implementation in normal (open-loop) power flow has been investigated by a number of investigators. This paper further develops the power-injection method based on optimal multiplier power flow for the steady-state control of UPFC for power-flow control and voltage support. The proposed power injection power-flow control can be effectively used to derive UPFC control parameters to achieve the required control objectives.

An original and reliable prototype injection setup has been developed in order to carry out accurate conducted susceptibility measurements up to 1.5 GHz. The prototype has been proposed as an alternative solution to typical injection setups such as a coupling capacitor, bias tee or cross-talk system, frequently used with the direct power injection standard IEC62132-4. Simple to build and mechanically sound, the prototype injection setup is used to merge continuous conducted electromagnetic disturbances with wanted signals by using merely a semi-rigid coaxial cable. It offers good stability on a wide frequency range. Furthermore, it is neither expensive nor complicated to build.

In this paper we examine different scalar vulnerability metrics that account for system topology and power injection profile. We pose calculable metrics related to the ratio of power disrupted along a cutset to the number of lines on a cutset. It is intended that the metrics can be used to assess the system's susceptibility to large disturbances.

This paper deals with direct power injection (DPI) simulations and it focuses on the simulation framework and post processing strategies to be performed during the design phase of automotive integrated circuits (ICs). The aim of such susceptibility simulations is to assist a designer to predict the ICs susceptibility to radio frequency interferences (RFI) during the design phase of the IC. For this purpose a complete DPI simulation model according to the standardized DPI measurement setup is introduced. Based on a simple example the methodology and several DPI simulation results are shown together with possible post processing strategies.

This paper focuses on modelling energy components within a Data Centre (DC) in a Smart City environment. This allows exploring the DC dynamics in a way that includes conditions that might be difficult or too risky to recreate in the real world, e.g. the impact of a large power injection from renewable energy sources and its influence on the DC operation. The DC components' models execution in real-time will enable Hardware in the Loop (HiL) testing of real DC equipment under fully controlled conditions.

The electromagnetic compatibility (EMC) performance of the voltage regulators is the significant factor in the EMC performance of the complete electronic system. In this paper the characterization of the voltage regulator by direct power injection (DPI) method is presented. Although, the DPI method is defined by various standards, the repeatability of the measurement can be compromised by several factors. The DPI method measurement results are presented for the L4949 voltage regulator. The repeatability of the method is assessed by various factors related to the operating point of the voltage regulator and to the measurement set-up. The obtained results are compared to the results presented by other authors.

In this paper, the failure mechanism of an embedded analog-to-digital converter (ADC) is studied and its immunity modeling with regard to electromagnetic interferences is presented. Failure causes are identified based on off-chip immunity measurements and without specific knowledge of the ADC's design. Disturbances coupling paths inside the ADC have been recognized as well as the conversion error mechanism. Then, immunity of the ADC is modeled using the ICIM-CI (Integrated Circuit Immunity Model for Conducted Immunity) black-box modeling approach. We show the interest of using the direct power injection (DPI) measurement technique for both analyzing and modeling the immunity of complex integrated circuits.

Made available in DSpace on 2016-03-02T13:04:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2015 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Elektroniczny konwerter mocy PEC używany jako interfejs rozproszonych źródeł energii został poszerzony o możliwości poprawy jakości energii. Prądowe źródło odniesienia bazuje na Teorii Zachowania Mocy CPT. In this work the functionalities of Power Electronic Converters (PEC) used as grid interface device for distributed generation sources are extended to deal with Power Quality (PQ) issues. It is proposed an alternative strategy to obtain current references based on the Conservative Power Theory (CPT). The proposed strategy contributes to the full exploitation of the PEC power capacity, allowing the PEC to act as a multifunctional device performing simultaneously selective compensation of PQ issues and power injection into the utility grid. Universidade Tecnológica Federal do Paraná (UTFPR), Campo Mourão, PR, Brasil Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Instituto de Ciência e Tecnologia de Sorocaba (ICTS), Departamento de Engenharia de Controle e Automação, Sorocaba, SP, Brasil Universidade Estadual de Campinas (UNICAMP), Faculdade de Engenharia Elétrica e de Computação (FEEC), Campinas, SP, Brasil Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Instituto de Ciência e Tecnologia de Sorocaba (ICTS), Departamento de Engenharia de Controle e Automação, Sorocaba, SP, Brasil FAPESP: 2011/15884-6 FAPESP: 2013/08545-6

The updated and new monitoring and control functionalities for distribution systems make available a huge amount of information. Indeed, not all the available information is needed to be considered; a significant simplification could be achieved by selecting and treating only the relevant information. With this aim, the concept of Load Area (LA) was recently introduced: a LA is a group of prosumers whose power injection has a similar impact on the distribution grid operating conditions. In the paper, the concept of LA is adopted to select the relevant data needed for the monitoring and control of distribution systems; a possible compact equivalent representation of the relationships between those data is proposed. The results from two test cases confirm the viability of the proposed modeling and highlight a relevant reduction in the amount of information used to describe the network.

This paper proposes a novel dc power flow controller for multi-terminal HVDC (MTDC) system, which can be inserted in series on transmission lines to manage dc power flow of them. Its key features include: 1) simpler circuit topology, 2) fewer components and 3) elimination of external power supply and low-frequency high-voltage-insulation isolated transformer. A three-terminal HVDC system including the dc power flow controller is studied and its operation principle and characteristics are analyzed. A simulation mode is built to test the feasibility and effectiveness of the proposed dc power flow controller with cases of power injection step down, power loss of one terminal. The results show that the proposed dc power flow controller can enhance the performance and controllability of a MTDC system.

The susceptibility to Electromagnetic Interference (EMI) of Battery Management Systems (BMSs) for Li-ion and LiPo battery packs employed in emerging electric and hybrid electric vehicles is investigated in this paper. To this purpose, a specif c test board is developed to experimentally assess the EMI susceptibility of a BMS front-end integrated circuit by direct power injection (DPI) and radiated susceptibility measurements. Experimental results are discussed highlighting different EMI-induced failure mechanisms observed during the tests.

This paper proposes different architectures for the coordinationof power injection in interconnected hybrid AC/DC gridswith Multi-TSO. The power dispatch problem is first formulatedfor the HVDC gri ...

The ACIST injection system is an automatic power injection device that allows for online control of injection rate and volume of contrast. Limited data is available whether this technology allows reducing use of contrast and fluoroscopy time. Accordingly, we compared the use of this system to manual injection among 450 consecutive patients who underwent diagnostic coronary angiography and/or angioplasty who were randomly assigned to either manual contrast injection (control; n=198) or to the ACIST system (study group; n=252). The amount of contrast, fluoroscopy and total procedural times were recorded for each patient. In the diagnostic group, the mean total amount of contrast (including wasted) was reduced by 63% when the ACIST was used compared to control (100+/-42 ml versus 163+/-56 ml; P

In conventional power systems, upstream and downstream of power were distinct. However, due to the competition, power injection and sink can appear at unexpected locations, and cost sharing for such a new power system configuration must be considered. This paper proposes a scheme for transmission expansion cost allocation among electric market participants by using Core and Nucleolus concepts of game theory, which are developed particularly for the transmission users. A solution of the n-person cooperative game is adopted to distribute the line transmission expansion cost among the players. Congestion is assumed to be the transmission constraint, and expansion of transmission line is expected to relieve transmission congestion. A case study is illustrated to demonstrate the proposed method.

Within statistical energy analysis (SEA), the coupling loss factor (CLF) is a statistical quantity defined in terms of the average behaviour of an ensemble of similar systems. Thus, the ‘effective’ CLF for a given realization may differ from the ensemble average. The effective CLF of two coupled plates with low modal density and low modal overlap fluctuates significantly compared with the ensemble average CLF. Accordingly, the CLF is the main parameter expected to determine the confidence intervals in the SEA prediction. The aim of the present paper is to quantify the variability of the effective CLF for the case of two finite rectangular plates. Extensive parameter investigations have been performed by using the dynamic stiffness method (DSM) and a ‘numerical’ power injection method (PIM) using the SEA power balance equations. The effects of frequency bandwidth and the number of modes in a band were separated by using frequency averages at a series of constant bandwidths rather than one-third octave averages, while the modal overlap is made independent of frequency by setting the damping loss factor to be inversely proportional to frequency. Finally, an improved empirical model for the variability of the CLF is derived, from these numerical results, in terms of the modal overlap factor and the number of modes in a frequency band. This model can subsequently be used to evaluate the uncertainty of the CLF of such a system.

Purpose: Are implanted central venous port catheters suitable for contrast media pressure (power) injection in computed tomography? Material and Methods: In an in vitro study 100ml of contrast medium (Ultravist 370, Schering, Berlin, Deutschland) was injected through 20 different port catheter systems using a power injector (Stellant, Medrad, Inianola, USA) with a pressure limit of 325 PSI. The injection rate was increased from 2 ml/s to 10 ml/s in increments of 2 ml/s. The maximum injection pressure and maximum injection rate were assessed. Results: An injection rate of 2 ml/s was possible in all catheter systems. Injection rates of 4 ml/s in 18 systems, 6 ml/s in 13 systems and 8 ml/s in 6 systems were achieved. With a given pressure limit of 325 PSI an injection rate of 10 ml/s was not possible in any of the port catheter systems. There were no catheter ruptures, catheter disconnections or contrast extravasations noted. Conclusion: Power injection of contrast media with a pressure limit of 325 PSI seems to be tolerated by port catheter systems. Most of the evaluated port systems allow flow rates suitable for multislice computed tomography requiring rapid contrast injection.

A 63-year-old Malay woman had a 6-French dual-lumen power-injectable peripherally inserted central catheter (PICC) inserted and subsequently underwent a contrast-enhanced computed tomography scan with intravenous contrast medium administered via the PICC. After the scan, the tip of the PICC was noted to have displaced from its original position and lodged in 1 of the small branches of the right subclavian vein. This phenomenon was then demonstrated in real time under fluoroscopy during the process of repositioning the PICC tip. Although power-injectable PICCs are designed for use with power injectors, tip displacement can and does happen. A computed tomography scout view of the chest may be necessary after each use of power injectors to confirm that the PICC tip remains in a satisfactory position.

This letter provides a comparison between the current and power injection models for angle and voltage stability analysis of power systems. Traditionally, it is believed that the current injection model is computationally more efficient. On the other hand, the power injection model requires computing the products of currents and voltages and, hence, is expected to be computationally more demanding than the current injection one. This letter compares the two approaches using a unique framework. The two formulations are compared through a dynamic 1479-bus model of the all-island Irish transmission system.

Introduction CT perfusion studies play an important role in the early detection as well as in therapy monitoring of vasospasm after subarachnoid hemorrhage. High-flow injections via central venous catheters are not recommended but may sometimes be the only possibility to obtain high-quality images. Materials and methods We retrospectively analyzed our data for CT perfusions performed with power injection of contrast material with an iodine concentration of 400 mg/ml via the distal 16G lumen of the Arrow three and five lumen central venous catheter with preset flow rates of 5 ml/s. Results 104 examinations with central venous catheters were evaluated (67 with five lumen and 37 with three lumen). No complications were observed. Mean flow rates were 4.4 ± 0.5 ml/s using the three lumen catheter and 4.6 ± 0.6 ml/s using the five lumen catheter respectively. The mean injection pressure measured by the power injector was 200.7 ± 17.5 psi for the three lumen central venous catheter and 194.5 ± 6.5 psi for the five lumen catheter, respectively. Conclusion Following a strict safety protocol there were no complications associated with power injections of contrast material containing 400 mg iodine/ml with preset flow rates up to 5 ml/s via the distal 16G lumen of the Arrow multi-lumen central venous catheter. However, since power-injections are off-label use with Arrow central venous catheters, this procedure cannot be recommended until potential safety hazards have been ruled out by the manufacturer.

We propose a novel LO power injection method developed for SIS mixers in this paper. Based on the feature of extremely small LO power requirements of SIS quantum mixing, the new method fulfills SIS pumping through a DC/IF route based built-in LO path, which is composed of an additional LO waveguide and the existing microstrip choke filter on the junction substrate. With the new method, traditional external LO diplexers(e.g., crossguide-couplers or beamsplitters) become unnecessary, resulting in a lower loss, compact, and stable receiver system. Experiments at 110- and 230 GHz bands have shown that the present method is efficient in coupling sufficient pumping power to SIS junctions from general LO sources, and the receiver sensitivities have a further improvement of about 10 K. We expect this method is also able to be applied into submillimeter wave band for SIS mixers.

Phasor Measurement Units (PMUs) are being employed in power system to achieve better monitoring and control of power grid. Due to their high cost, PMUs are placed at some strategic locations. However, while upgrading a power system monitoring structure, engineers may face problem of no communication facility at a bus. PMUs need a sound communication structure so that it can perform time-synchronized measurements by communicating with the GPS Satellites. This paper presents an optimal placement algorithm of Phasor Measurement Units (PMU) placement approach in a system where communication facility is limited. IEEE 14 bus system was selected and existing optimal PMU placement algorithms are modified considering the presence of power flow and power injection measurements.

Re-supplying loads on outage through cross-connect from adjacent feeders in a distribution system may cause voltage drop and hence require load shedding. However, the surplus PV generated in some of the LV feeders can prevent load shedding, and improve reliability. In order to measure these effects, this paper proposes the application of Direct Load Flow method[1] in reliability evaluation of distribution systems with PV units. As part of this study, seasonal impacts on load consumption together with surplus PV output power injection to higher voltage networks are also considered. New indices are proposed to measure yearly expected energy export, from LV to MV and from MV to higher voltage network.

Dispersed photovoltaic generation integrated in the low voltage distribution grids leads their operation towards an active approach. In that context, new methodologies are needed in order to identify and to accurately quantify the impact of this massive renewable penetration on the grid operation. For this purpose, the authors of this study have developed in a previous analysis a probabilistic load flow tool directly based on the use of smart meters data. The goal of this tool was to quantify probabilities of overvoltage in radial low voltage grids with increased photovoltaic penetrations. However, the drawback of this approach was the too long (15 minutes) sampling time step of smart meters that did not allow the consideration of fast fluctuations of photovoltaic generation. In the present paper, an original adaptation of the existing tool is therefore presented, which enables the consideration of short temporary photovoltaic power fluctuations. Thanks to this new development, it is shown that a more accurate estimation of overvoltage situations, due to photovoltaic generation, is permitted.

The latest development of Convertible Static Compensators (CSC) drives the importance of the Flexible AC Transmission System controllers to higher levels because of their controllable nature and effective power flow management of multi-line systems. To realize the effect of CSC on a given power system Interline Power Flow Controller (IPFC) is considered and Power Injection Model (PIM) for the same device is proposed in this paper. The comfort in mathematical modeling and the incorporation procedure in Newton-Raphson load flow with PIM increase its importance. In this paper, proper location to install device using contingency analysis is discussed. Numerical results without and with IPFC for the variation of device control parameters is presented. The obtained results show the performance of the proposed IPFC model.

tool to detect significant renal artery stenosis? Purpose: To evaluate the diagnostic value of multidetector CT angiography (MDCTA) of the renal arteries. Methods: 27 patients underwent MDCTA of the renal arteries. Scan parameters were: collimation 4 × 1 mm, pitch 1.5, effective slice thickness 1.25 mm, reconstruction increment 0.8mm, circulation time measurement, power injection of 80 ml iomeprol 400, flow 4 ml/sec. Independent reading on laser film was done by two radiologists using edited maximum intensity projections, multiplanar reconstructions and source images. Standard of reference was a 3D-FLASH MR angiography (1.5 T, 3.9/1.2, 10° 0.2 mmol GdDTPA/kg bw) in 10 and intraarterial angiography in 17 patients. Results: Analysing 63 arteries, sensitivity, specificity, positive predictive value and negative predictive value in terms of detection of moderate and high grade renal artery stenosis (n = 10) were 90, 98, 90 and 98% for reader A, and 90% each for reader B, respectively (κ = 0.91 interobserver agreement). 1/11 acessory renal arteries was missed by both angiography and MDCTA. Image quality was graded as excellent or good in 26/27 of cases by both readers. Conclusion: MDCTA proved to be a highly accurate tool in the detection of therapeutically relevant renal artery stenosis.

Purpose The purpose of this work was to determine the tolerance of silicone peripherally inserted central catheters (PICCs) of different sizes and lengths to power injection of contrast materials at flow rates suitable for CT studies. Method Fifty silicone PICCs in three single-lumen sizes (3 to 5F) and two double-lumen sizes (6 and 7F) were cut to two lengths (35 and 45 cm), and a uniform volume of 74% ioversol was injected into each at increasing rates of flow by a power injector. The flow rate, volume, and peak pressure were recorded for each injection. Results The respective tolerated flows for the 35 and 45 cm PICCs were 0.65 ml/s at 125 psi and 0.56 ml/s at 125 psi for the 3F catheters, 1.58 ml/s at 150 psi and 1.04 ml/s at 150 psi for the 4F catheters, 4.20 ml/s at 200 psi and 3.02 ml/s at 170 psi for the 5F catheters, 1.50 ml/s at 145 psi and 0.88 ml/s at 150 psi for the 6F catheters, and 9.52 ml/s at 350 psi and 8.78 ml/s at 330 psi for the 7F catheters. Conclusion The 3F catheters were unsuitable for power injection for CT studies because they could not accommodate adequate flow rates. The 4F single-lumen and 6F double-lumen catheters withstood flow rates that were marginally adequate for CT studies. The 5F single-lumen and 7F double-lumen PICCs tolerated peak flows and pressures well within the range necessary to allow power injection of contrast materials for CT studies. For each size of PICC, the 35 cm length withstood higher flow rates than the 45 cm length before failure.

Load-flow control with multifunctional FACTS devices can maintain the reliable system operation in the event of additionally demanded power transits. For a systematic transit control, the aptitude of possible FACTS locations is assessed by a sensitivity analysis based on the generation shift distribution factors (GSDF) and the power injection model (PIM). Finally a computer-aided identification of favorable FACTS locations in extended transit scenarios is presented.

This paper presents an application of the ICIM-CI model to the prediction of the susceptibility of ICs (Integrated Circuits) to environmental disturbances in avionic boards. The method is illustrated by the obsolescence study of three commercial operational amplifiers (Op-Amps) showing quasi-identical electrical characteristics and pin-to-pin compatibility, through the comparison of their respective conducted immunities. The model is developed in VHDL-AMS language, and the simulation results are validated through comparison with Direct Power Injection measurements.

This paper presents an optimal multiplier based Newton-Raphson power flow algorithm for reliably and efficiently handling power systems with embedded flexible AC transmission systems (FACTS) devices such as unified power flow controllers (UPFCs). A power injection transformation of a two voltage source UPFC model is derived in rectangular form. After detailed analyses of issues in implementation of UPFCs in power flow programmes by various power flow algorithms, the optimal multiplier power flow method for ill-conditioned systems is adopted. The proposed UPFC model and power flow algorithm have been programmed and vigorously tested in a number of systems. The results on the IEEE 30-bus test system and a 306-bus practical system are reported and compared with conventional user defined model type programmes, which clearly illustrate the effectiveness of the proposed algorithm.

OBJECTIVE. Our objective is to review our safety experience with hand injection of central venous catheters for administration of IV contrast material for CT in children.CONCLUSION. Administration of IV contrast material by means of hand injection led to damage of four central venous catheters during a 6-year period at our institution (0.3% of central venous catheters hand injected during that time). In addition to the growing evidence of the safety of power injection of IV contrast material in central venous catheters, the potential danger of hand injection of central venous catheters should be considered when policies are made concerning the delivery of IV contrast material via central venous catheters.

This letter shows the existence of multiple equilibria that arise from the use of the state model of the unified power flow controller (UPFC). These multiple equilibria can arise from a common power injection model for the same terminal conditions of shunt bus voltage and series active and reactive power injections. The multiple equilibria result in two or more sets of eigenvalues, some of which may indicate an unstable operating condition. Therefore, the use of the UPFC power injection model must be used with caution to ensure stable operation of the UPFC.

The objective of this communication is to present a method of determining coupling loss factors by the power injection method which is easy to compute, accurate and which is not affected by the strength of the coupling between subsystems. The method of determining coupling loss factors presented here assumes the possibility of accurately determining the power injected to subsystems

Our objective was to determine the level and timing of peak hepatic enhancement in children using power injection of contrast media, helical CT, and computer-automated scan technology.Forty-nine abdominal CT studies were performed using computer-automated scan technology. Patients were divided into four groups on the basis of body weight and contrast dose (group 1A,or = 20 kg and 2 ml/kg; group 1B,or = 20 kg and 3 ml/kg; group 2, 21-40 kg and 2 ml/kg; group 3,40 kg andor = 2 ml/kg). Contrast injection rates were based on body weight (groups 1A and 1B, 1 ml/sec; group 2, 1.5 ml/sec; and group 3, 2 ml/sec). The peak hepatic enhancement level in Hounsfield units and the time to reach peak enhancement were determined for each patient.The mean peak hepatic enhancement and time to peak enhancement after completion of contrast injection were group 1A, 45 H and 11 sec; group 1B, 62 H and 3 sec; group 2, 52 H and 12 sec; and group 3, 45 H and 10 sec.The level and timing of peak hepatic enhancement in pediatric patients can be obtained using computer-automated scan technology. These data may then be used to optimize hepatic enhancement when obtaining helical abdominal CT scans of pediatric patients.

PURPOSE To study the tolerance of peripherally inserted central catheters (PICCs) of varying sizes and materials to power injection of radiographic contrast agents. MATERIALS AND METHODS Eight different models of silicone and five different models of polyurethane single-lumen PICCs were injected with increasing rates of iothalamate 60% with use of a power injector. Tolerated and bursting rates and pressures were recorded. RESULTS There was a wide range of tolerated rates and pressures, depending on the inner and outer diameters of the catheters and on the catheter material. Silicone PICCs tolerated rates between 0.4 and 7.0 mL/sec and polyurethane PICCs tolerated rates between 0.6 and 10.2 mL/sec, depending on the specific catheter. The 5 Fr silicone PICCs and the 4 Fr and 5Fr polyurethane PICCs tested all tolerated rates greater than 4 mL/sec. Silicone catheters tolerated pressures between 107 and 184 psi, and polyurethane catheters tolerated pressures between l60 and 314 psi. CONCLUSIONS Larger single-lumen silicone and polyurethane PICCs may be suitable for power injection of contrast agents.

To determine in-line pressures generated in small-bore central venous catheters during power injection of computed tomographic (CT) contrast media.Five 3.0-7.0-F central venous catheters for pediatric patients were tested at full and half lengths in vitro. In-line pressures were measured during power injection of three contrast media. Rates of injection were increased in steps from 0.1 to 5.0 mL/sec or until a peak pressure of 100 psi (700 kPa) was achieved. The maximum tolerated flow rate was determined with reference to the manufacturer's suggested operating pressure limit for each catheter.At full length, the maximum tolerated flow rates were as follows: 2-3 mL/sec for the large lumen and 1-1.4 mL/sec for the small lumen of the 7.0-F double-lumen catheter; 0.2-0.4 and 0.8-1.2 mL/sec for the 3.0- and 4.0-F peripherally inserted central catheters, respectively; 0.7-1.2 mL/sec for the 6.6-F catheter; and only 0.2 mL/sec for the 4.2-F catheter, which ruptured during testing at higher flow rates.Flow rates were documented at which certain small-bore central venous catheters should tolerate power injection of CT contrast media with peak pressures remaining below the manufacturer's recommended operating pressure limits. These data may serve as a guide for clinical use.

Rationale and Objectives. A videodensitometric technique that allows measurement of absolute cross-sectional area of any complex lesion was compared with an intravascular ultrasound (US) technique. Methods. Stenotic devices (10–15 mm long) with cross sections of different shapes were placed in the distal aortas of five anesthetized pigs (weight, 40–50 kg). The stenotic devices were imaged by using an intravascular US probe after power injection of contrast material. Results. A comparison of actual areas and measured cross-sectional areas of the stenotic devices showed that videodensitometry and intravascular US produced better results than edge-detection techniques for both unsubtracted and temporal subtraction images. Conclusion. These data suggest that the videodensitometric technique can be used to measure absolute cross-sectional areas of arteries with different shapes.

To optimize findings at dynamic gadolinium-enhanced hepatic magnetic resonance imaging in the hepatic arterial phase, a timing examination was performed after injection of a 0.5-mL timing bolus of gadopentetate dimeglumine. In the experimental group (n = 28), power injection was used and the imaging delay was determined in each patient on the basis of the results of the timing examination. In the control group (n = 28), hand injection and a fixed 20-second imaging delay were used. Arterial-phase examinations (defined as relative liver enhancement of not more than 30% of peak parenchymal enhancement) were successful in 26 (93%) experimental group patients and in 17 (61%) control group patients.

The increasing penetration of Distributed Generation (DG) in distribution electrical systems may cause alteration of voltage profiles on the lines. Traditionally, distribution networks with radial configuration are designed as a passive top-down architecture where voltage regulation is mainly performed by an On-Load Tap Changer (OLTC) transformer located at the Primary Substation. Therefore it becomes rather difficult to compensate lines radiating out from the same bus-bar where some of these are subject to overvoltages due to the power injection by DGs connected whereas others are subject to voltage drops due to the presence of passive loads only. A first step in regulation and managing the voltage levels, in order to be consistent with the contingent needs of the network, may be a decentralized local control strategy performed by the DG units, however better results will be obtained with a coordinated OLTC intervention. In this paper an OLTC control strategy, based on only few remote measurements, is proposed. This procedure allows the tap changer controller to infer the state of network node voltages and to act accordingly. The performance of the proposed control method is demonstrated through simulations on a realistic MV distribution network.

In this paper, method to identify strong nodes in a transmission grid is shown. The method can be used to identify transmission system investment needs and can serve as filter for transmission system investment optimization. Based on an optimal power flow calculation, the maximum power injection capability of buses is calculated. In this context AC OPF and DC OPF methods are compared in terms of accuracy, convergence and computational effort. To take uncertainties in generation and load into account, the Gaussian Component Combination Method (GCCM) is used, which is compared to Monte Carlo Simulation (MCS). The importance of considering security aspects while determining strong nodes is depicted using N-1 analysis. Additionally, the effect of power flow controlling devices on the maximum power injection capability of investigated grid nodes is shown, in particular with phase shifting transformers and HVDC links.

In order to build an accurate impedance model, we provide a parameter determination method by using an artificial intelligence algorithm—acceleration particle swarm optimization (APSO). Comparing with the impedance model that is provided by IC-EMC 2.5, our impedance result is more close to the measurement result. The parameter determination of impedance model is validated by applying to the direct power injection (DPI) coupling path model.

Low frequency inter-area oscillations have been identified as a significant problem in utility systems due to the potential for system damage and the resulting restrictions on power transmission over select lines. Previous research has identified real power injection by energy storage based damping control nodes as a promising approach to mitigate inter-area oscillations. In this paper, a candidate energy storage system based on UltraCapacitor technology is evaluated for damping control applications in the Western Electric Coordinating Council (WECC), and an analytical method for ensuring proper stability margins is also presented for inclusion in a future supervisory control algorithm. Dynamic simulations of the WECC were performed to validate the expected system performance. Finally, the Nyquist stability criteria was employed to derive safe operating regions in the gain, time delay space for a simple two-area system to provide guaranteed margins of stability.

Objective : Our goal was to optimize the efficiency of contrast material (CM) application in routine examinations of the neck by the use of spiral CT and slow power injection. Materials and Methods : Dynamic studies were performed in 14 patients to establish a set protocol for spiral CT examinations of the neck. Prospectively, 100 patients were examined either by use of the spiral technique with 100 ml CM (30 g iodine) injected in two phases or in conventional CT with 150 ml CM (45 g iodine). Vascular and parenchymal enhancement was evaluated at three distinct levels of the neck. Results : Despite the reduced CM volume in spiral CT, vascular enhancement was significantly higher at all three levels. Parenchymal enhancement was comparable in both groups. CM exploitation in vascular opacification (ratio of mean enhancement to applied CM volume) was 0.87 in spiral CT compared with 0.43 in conventional CT. Conclusion : Spiral CT significantly increases the efficiency of CM application and is well suited for routine examinations of the neck.

This letter presents a problem of calculating load flow in distribution feeders via the conventional three-phase backward/forward sweep method when voltage regulators in the bidirectional mode are experiencing reverse flow due to power injection from distributed generation downstream the regulators. It also presents a simple but effectively modification in the algorithm of that method to overcome the problem. A modified version of the IEEE 34 buses distribution test feeder will be used to demonstrate the problem and the proposed algorithm solution.