Target Performance Goals Research Articles

Determination of Gain Scheduling Parameters for Loss of a Feedwater Pump Transient Mitigation Using Neural Networks

Transient mitigation for nuclear power plants is essential for safe operation. The fourth industrial revolution brings with it the potential for data-based predictive maintenance and identifying remaining time of life for degrading components. An improvement to predictive maintenance would be to address continued operation with faulty components between the time of identification and eventual replacement. The ability to perform data analysis and contemporary digital control systems allows for data-driven control system actions. A methodology is developed herein to train a neural network that can map desired system performance and current plant component capability to control system settings. Simulations of plant transients were recorded and used to train a neural network. This neural network was tested with different target performance goals. The results show that the trained neural network recommended settings that affected the control system response so as to meet the target performance goals.

Channel impeller design for centrifugal blood pump in hybrid pediatric total artificial heart: Modeling, magnet integration, and hydraulic experiments.

The purpose of this research is to address ongoing device shortfalls for pediatric patients by developing a novel pediatric hybrid total artificial heart (TAH). The valveless magnetically-levitated MCS device (Dragon Heart) has only two moving parts, integrates an axial and centrifugal blood pump into a single device, and will occupy a compact footprint within the chest for the pediatric patient population. Prior work on the Dragon Heart focused on the development of pump designs to achieve hemodynamic requirements. The impeller of these pumps was shaft-driven and thus could not be integrated for testing. The presented research leverages an existing magnetically levitated axial flow pump and focuses on centrifugal pump development. Using the axial pump diameter as a geometric constraint, a shaftless, magnetically supported centrifugal pump was designed for placement circumferentially around the axial pump domain. The new design process included the computational analysis of more than 50 potential centrifugal impeller geometries. The resulting centrifugal pump designs were prototyped and tested for levitation and no-load rotation, followed by in vitro testing using a blood analog. To meet physiologic demands, target performance goals were pressure rises exceeding 90 mm Hg for flow rates of 1-5L/min with operating speeds of less than 5000 RPM. Three puck-shaped, channel impellers for the centrifugal blood pump were selected based on achieving performance and space requirements for magnetic integration. A quasi-steady flow analysis revealed that the impeller rotational position led to a pulsatile component in the pressure generation. After prototyping, the centrifugal prototypes (3, 4, and 5 channeled designs) demonstrated levitation and no-load rotation. Hydraulic experiments established pressure generation capabilities beyond target requirements. The pressure-flow performance of the prototypes followed expected trends with a dependence on rotational speed. Pulsatile blood flow was observed without pump-speed modulation due to rotating channel passage frequency. The results are promising in the advancement of this pediatric TAH. The channeled impeller design creates pressure-flow curves that are decoupled from the flow rate, a benefit that could reduce the required controller inputs and improve treatment of hypertensive patients.

Goal Programming Framework for Prioritization of Low-Volume Road Projects Considering Network Accessibility and Stakeholders’ Preferences

One of the benefits of implementing transportation infrastructure projects is the maximization of network accessibility performance, so that system users’ mobility is optimized. However, infrastructure investment decisions rarely consider stakeholders’ preferences to network performance measures and the impact of project selection and prioritization on the network accessibility performance. This paper presents a goal programming framework that considers network accessibility performance and the total cost of road infrastructure projects or project bundles to prioritize investments, taking into account stakeholders’ preferences to the performance criteria. Results of the case study using the low-volume road (LVR) network showed that the accessibility benefits of LVR projects depend on their relative spatial location in the network, their total project cost, target performance goals, and stakeholders’ preferences to performance criteria. The study results also showed that LVR projects could maximize network accessibility even after the occurrence of network disruption events. Therefore, the proposed framework could help the decision-makers develop efficient infrastructure investment plans to mitigate natural and human-made network disruption events.

A variable chirp rate stepped frequency linear frequency modulation waveform designed to approximate wideband non-linear radar waveforms

The non-linear frequency modulation (NLFM) waveform is one of the existing waveforms that can be used in high range resolution radar applications. However, a high sampling frequency and consequently an expensive ADC are required. To overcome this drawback while taking advantage of the features of the NLFM waveform, we suggest approximating the wideband NLFM waveform by a piecewise linear waveform and using it in a stepped frequency (SF) framework. Thus, a variable chirp rate SF-LFM waveform is proposed where SF is combined with a train of LFM pulses having different chirp rates, durations, and bandwidths. In this paper, these parameters are derived from a tangent-based NLFM waveform. At the receiver, a generalized version of the time domain (TD) algorithm is proposed to process the received echoes. Our purpose is to obtain the high range resolution profile (HRRP) whose properties are of the same magnitude orders as those obtained using a tangent-based NLFM waveform. These properties are the peak sidelobe ratio, the integrated sidelobe, and the range resolution. Toward this goal, a multi-objective optimization issue is addressed to deduce the parameters of the proposed waveform by using two types of approaches based on evolutionary algorithms. Their relevance is compared. Our analysis and simulations show that the proposed approaches attain the targeted performance goals with a smaller sampling frequency at the receiver.

Comparative Study on Power Module Architectures for Modularity and Scalability

Abstract Silicon carbide (SiC) wide bandgap power electronics are being applied in hybrid electric vehicle (HEV) and electrical vehicles (EV). The Department of Energy (DOE) has set target performance goals for 2025 to promote EV and HEV as a means of carbon emission reduction and long-term sustainability. Challenges include higher expectations on power density, performance, efficiency, thermal management, compactness, cost, and reliability. This study will benchmark state of the art silicon and SiC technologies. Power modules used in commercial traction inverters are analyzed for their within-package first-level interconnect methods, module architecture, and integration with cooling structure. A few power module package architectures from both industry-adopted standards and proposed patented technologies are compared in modularity and scalability for integration into inverters. The current trends of power module architectures and their integration into inverter are also discussed. The development of an eco-system to support the wide bandgap semiconductors-based power electronics is highlighted as an ongoing challenge.

Performance Study of the First 2-D Prototype of Vertically Integrated Pattern Recognition Associative Memory

Extremely fast pattern recognition capabilities are necessary to find and fit billions of tracks at the hardware trigger level produced every second anticipated at high-luminosity Large Hadron Collider (HL-LHC) running conditions. Associative memory (AM)-based approaches for fast pattern recognition have been proposed as a potential solution to the tracking trigger. However, at the HL-LHC, there is much less time available, and the speed performance must be improved over previous systems while maintaining a comparable number of patterns. The vertically integrated pattern recognition AM (VIPRAM) project aims to achieve the target pattern density and performance goal using 3DIC technology. The first step taken in the VIPRAM work was the development of a 2-D prototype ( protoVIPRAM00 ) in which the AM building blocks were designed to be compatible with the 3-D integration. In this article, we present the results from extensive performance studies of the protoVIPRAM00 chip in both realistic HL-LHC and extreme conditions. Results indicate that the chip operates at the design frequency of 100 MHz with perfect correctness in realistic conditions and conclude that the building blocks are ready for 3-D stacking. We also present performance boundary characterization of the chip under extreme conditions.

Development of a Non-invasive Device for Swallow Screening in Patients at Risk of Oropharyngeal Dysphagia: Results from a Prospective Exploratory Study

Oropharyngeal dysphagia is prevalent in several at-risk populations, including post-stroke patients, patients in intensive care and the elderly. Dysphagia contributes to longer hospital stays and poor outcomes, including pneumonia. Early identification of dysphagia is recommended as part of the evaluation of at-risk patients, but available bedside screening tools perform inconsistently. In this study, we developed algorithms to detect swallowing impairment using a novel accelerometer-based dysphagia detection system (DDS). A sample of 344 individuals was enrolled across seven sites in the United States. Dual-axis accelerometry signals were collected prospectively with simultaneous videofluoroscopy (VFSS) during swallows of liquid barium stimuli in thin, mildly, moderately and extremely thick consistencies. Signal processing classifiers were trained using linear discriminant analysis and 10,000 random training–test data splits. The primary objective was to develop an algorithm to detect impaired swallowing safety with thin liquids with an area under receiver operating characteristic curve (AUC) > 80% compared to the VFSS reference standard. Impaired swallowing safety was identified in 7.2% of the thin liquid boluses collected. At least one unsafe thin liquid bolus was found in 19.7% of participants, but participants did not exhibit impaired safety consistently. The DDS classifier algorithms identified participants with impaired thin liquid swallowing safety with a mean AUC of 81.5%, (sensitivity 90.4%, specificity 60.0%). Thicker consistencies were effective for reducing the frequency of penetration–aspiration. This DDS reached targeted performance goals in detecting impaired swallowing safety with thin liquids. Simultaneous measures by DDS and VFSS, as performed here, will be used for future validation studies.

Device-Enhanced MEC: Multi-Access Edge Computing (MEC) Aided by End Device Computation and Caching: A Survey

Multi-access edge computing (MEC) has recently been proposed to aid mobile end devices in providing compute- and data-intensive services with low latency. Growing service demands by the end devices may overwhelm MEC installations, while cost constraints limit the increases of the installed MEC computing and data storage capacities. At the same time, the ever increasing computation capabilities and storage capacities of mobile end devices are valuable resources that can be utilized to enhance the MEC. This article comprehensively surveys the topic area of device-enhanced MEC, i.e., mechanisms that jointly utilize the resources of the community of end devices and the installed MEC to provide services to end devices. We classify the device-enhanced MEC mechanisms into mechanisms for computation offloading and mechanisms for caching. We further subclassify the offloading and caching mechanisms according to the targeted performance goals, which include throughput maximization, latency minimization, energy conservation, utility maximization, and enhanced security. We identify the main limitations of the existing device-enhanced MEC mechanisms and outline future research directions.

Ten factors to consider when developing usability scenarios and tasks for health information technology

The quality of usability testing is highly dependent upon the associated usability scenarios. To promote usability testing as part of electronic health record (EHR) certification, the Office of the National Coordinator (ONC) for Health Information Technology requires that vendors test specific capabilities of EHRs with clinical end-users and report their usability testing process – including the test scenarios used – along with the results. The ONC outlines basic expectations for usability testing, but there is little guidance in usability texts or scientific literature on how to develop usability scenarios for healthcare applications. The objective of this article is to outline key factors to consider when developing usability scenarios and tasks to evaluate computer-interface based health information technologies. To achieve this goal, we draw upon a decade of our experience conducting usability tests with a variety of healthcare applications and a wide range of end-users, to include healthcare professionals as well as patients. We discuss 10 key factors that influence scenario development: objectives of usability testing; roles of end-user(s); target performance goals; evaluation time constraints; clinical focus; fidelity; scenario-related bias and confounders; embedded probes; minimize risks to end-users; and healthcare related outcome measures. For each factor, we present an illustrative example. This article is intended to aid usability researchers and practitioners in their efforts to advance health information technologies. The article provides broad guidance on usability scenario development and can be applied to a wide range of clinical information systems and applications.

Perioperative Outcomes From the Prospective Multicenter Least Invasive Fast-Track EVAR (LIFE) Registry

Purpose: To determine the feasibility, perioperative resource utilization, and safety of a fast-track endovascular aneurysm repair (EVAR) protocol in well-selected patients. Methods: Between October 2014 and May 2016, the LIFE (Least Invasive Fast-track EVAR) registry ( ClinicalTrials.gov identifier NCT02224794) enrolled 250 patients (mean age 73±8 years; 208 men) in a fast-track EVAR protocol comprised of bilateral percutaneous access using the 14-F Ovation stent-graft, no general anesthesia, no intensive care unit (ICU) admission, and next-day discharge. The primary endpoint was major adverse events (MAE) through 30 days. The target performance goal for the MAE endpoint was 10.4%. Results: Vascular access, stent-graft delivery, and stent-graft deployment success were 100%. A total of 216 (86%) patients completed all elements of the fast-track EVAR protocol. Completion of individual elements was 98% for general anesthesia avoidance, 97% for bilateral percutaneous access, 96% for ICU avoidance, and 92% for next-day discharge. Perioperative outcomes included mean procedure time of 88 minutes, median blood loss of 50 mL, early oral nutrition (median 6 hours), early mobilization (median 8 hours), and short hospitalization (median 26 hours). Fast-track EVAR completers had shorter procedure time (p<0.001), less blood loss (p=0.04), faster return to oral nutrition (p<0.001) and ambulation (p<0.01), and shorter hospital stay (p<0.001). With 241 (96%) of the 250 patients returning for the 30-day follow-up, the MAE incidence was 0.4% (90% CI 0.1% to 1.8%), significantly less than the 10.4% performance goal (p<0.001). No aneurysm rupture, conversion to surgery, or aneurysm-related secondary procedure was reported. There were no type III endoleaks and 1 (0.4%) type I endoleak. Iliac limb occlusion was identified in 2 (0.8%) patients. The 30-day hospital readmission rate was 1.6% overall. Conclusion: A fast-track EVAR protocol was feasible in well-selected patients and resulted in efficient perioperative resource utilization with excellent safety and effectiveness.

Assessing the need for an update of a probabilistic seismic hazard analysis using a SSHAC Level 1 study and the Seismic Hazard Periodic Reevaluation Methodology

A key decision for nuclear facilities is evaluating the need for an update of an existing seismic hazard analysis in light of new data and information that has become available since the time that analysis was completed. We introduce the newly developed risk-informed Seismic Hazard Periodic Reevaluation Methodology (referred to as the SHPRM) and present how a Senior Seismic Hazard Analysis Committee (SSHAC) Level 1 probabilistic seismic hazard analysis (PSHA) was performed in an implementation of this new methodology. The SHPRM offers a defensible and documented approach that considers both the changes in seismic hazard and engineering-based risk information of an existing nuclear facility to assess the need for an update of an existing PSHA. The SHPRM has seven evaluation criteria that are employed at specific analysis, decision, and comparison points in a graded approach, based on the nuclear facility's seismic design category. The SHPRM is implemented using a SSHAC Level 1 study performed for the Idaho National Laboratory, USA. The implementation focuses on the SHPRM evaluation criteria that are based directly on the seismic hazard, and the inputs to these criteria are derived from the SSHAC Level 1 PHSA. To illustrate outcomes of the SHPRM that do not lead to the need for an update and those that do, the example implementations of the SHPRM are performed for nuclear facilities that have target performance goals expressed as the mean annual frequency of unacceptable performance at 1×10−4, 4×10−5 and 1×10−5.

Literature Review of Advancements in Adaptive Ramp Metering

Over a period spanning more than 30 years, several ramp metering algorithms have been developed to improve the operation of freeways. Many of these algorithms were deployed in several regions of the world, and field evaluations have shown their significance to improve traffic conditions on freeways and ramps. Previous reviews of ramp metering algorithms focused more on the research outcomes and evaluations of traditional metering algorithms developed in the early stage of ramp metering research. The purpose of this paper is to cover the more recent developments in ramp metering in relation to the traditional metering strategies. Several local and coordinated ramp metering algorithms were reviewed. In summary, Asservissement Linéaire d’Entrée Autoroutière (ALINEA) was found to be the most widely deployed local ramp metering strategy. The algorithm is simple and implementation costs less than other strategies. It also guarantees the targeted performance goals provided that the on-ramp has sufficient storage. Several extensions were proposed in the literature to fine-tune its performance. Among the coordinated metering strategies, zone based metering is simple to implement and easy to re-configure. System-wide adaptive ramp metering (SWARM) algorithm is more sensitive to calibrate for accurate prediction of traffic states. Heuristic ramp-metering coordination (HERO) algorithm can be useful if both local and coordinated control are desired particularly if the local control is using ALINEA. Fuzzy logic based algorithms are gaining popularity because of the simplicity and the fast re-configuration capability. Advanced real time metering system (ARMS) seems theoretically promising because of its proactive nature to prevent congestion; however, its performance is highly dependent upon accurate predictions. Finally, some guidelines were proposed for future research to develop new proposals and to extend the existing algorithms for guaranteed performance solutions.

Fast-track endovascular aneurysm repair: rationale and design of the multicenter Least Invasive Fast-Track EVAR (LIFE) registry.

BackgroundConsiderable technological advancements have recently been made with endovascular stent grafts for the treatment of abdominal aortic aneurysm (AAA). However, there is opportunity to further improve the efficiency of endovascular aneurysm repair (EVAR), which may yield better patient outcomes and lower perioperative treatment costs.Methods/DesignThe Least Invasive Fast-Track EVAR (LIFE) registry was developed to determine the clinical utility and cost effectiveness of the Ovation® Prime stent graft when used under least invasive conditions using a defined fast-track protocol. The LIFE study is a prospective multicenter post-market registry of the ultra-low profile (14F) Ovation Prime stent graft when used in the treatment of patients with AAA using a fast-track protocol, consisting of appropriate patient selection, bilateral percutaneous access, avoidance of general anesthesia and intensive care unit admission, and next-day discharge. The primary endpoint of the study is the proportion of subjects that experience a major adverse event within 30 days of the initial procedure. Primary endpoint data will be compared to a target performance goal. A total of 250 subjects will be enrolled at up to 40 sites in the United States. The first subject in this study was enrolled in October 2014 and enrollment is anticipated to continue through mid-2016.DiscussionThe recent development of ultra low-profile stent grafts enables EVAR using least invasive methods. A structured fast-track EVAR protocol may yield clinical and cost benefits versus standard EVAR.Trial registrationClinicalTrials.gov Identifier: NCT02224794

El trilema de la política monetaria en Colombia no se cumple

&lt;p align="justify"&gt;El artículo hace una presentación de la política monetaria y cambiaria en Colombia durante la última década con énfasis en el posible cumplimiento del trilema monetario, el cual establece que la principal implicación de la política monetaria es determinar una tasa de cambio deseable para lograr los propósitos del comercio internacional; una tasa de interés apetecible para incentivar la actividad productiva, y una mayor movilidad de capitales compatible con el funcionamiento de la meta inflación objetivo. De otra parte, se verificará la imposibilidad del trilema considerando la paridad descubierta de las tasas de interés en un ambiente macroeconómico caracterizado por una tasa de cam- bio flexible, pero revaluada, una baja tasa de interés doméstica y una incertidumbre del mercado financiero internacional, lo cual se ha reflejado en un aumento de los saldos de la cuenta de capital y financiera, especialmente los pasivos, y en un mayor déficit de la cuenta corriente.&lt;/p&gt;

Application of the performance-goal based approach for establishing the SSE site specific response spectrum for new nuclear power plants in South Africa

Nuclear installation license holders in South Africa have become increasingly interested in the performance-goal based approach defined in the American Society of Civil Engineering Standard ASCE/SEI 43-05 for establishing the safe shutdown earthquake (SSE) site specific design response spectrum (SSRS) for new nuclear power plants. This approach has been adopted by the U.S. Nuclear Regulatory Commission (NRC) and has now been followed at more than 20 sites in that country. Quantitative performance goals are required when establishing seismic design basis parameters using the performance-goal based approach. However, the quantitative performance goals recommended in ASCE/SEI 43-05 were established based on country-specific operating experience and seismic probabilistic risk assessment (SPRA) applications conducted for existing plants designed and operated to meet specific safety criteria, set by a specific regulatory body. Whilst ASCE/SEI 43-05 provides enough flexibility for the selection of other user-specified quantitative performance goals, there is no guidance on how quantitative performance goals should be established in the absence of extensive operational experience accompanied by data derived from rigorous SPRA applications. This paper presents two practical approaches that can be used to provide a technical basis and to demonstrate the derivation of quantitative values of target performance goals when no data related to past and present operational experience exist to justify technical specifications.

Objective evaluation of a laparoscopic surgical skill program for residents and senior surgeons.

Laparoscopic surgery adapts poorly to apprenticeship models for general surgical training. Standardized skill acquisition and validation programs, targeted performance goals, and a supervised, enforced, skill-based curriculum that readily can be shared between trainee and instructor must replace the observation and incremental skill-acquisition model used in an open surgical environment. The Yale Laparoscopic Skills and Suturing Program was used to develop a data bank for objective evaluation of dexterity and suturing skills for laparoscopic surgical training. The current study compares trainee and senior surgeon performance in this standardized training program. To compare objectively evaluated laparoscopic surgical skills and suturing capability of senior surgeons and of residents after they have completed the same standardized training regimen. Two hundred ninety-one trained surgeons performed 8730 standardized laparoscopic dexterity drills and 2910 intracorporeal suturing exercises in the Yale Laparoscopic Skills and Suturing Program. Their performance was supervised by an instructor who recorded performance and timing of the tasks in a 2 1/2-day program. Ninety-nine residents performed the same drills and exercises the same number of times and followed the same technique for intracorporeal suturing. Percentile graphs were prepared for each type of drill and suturing exercise to allow comparison of levels of achievement among different training groups. The performance of the residents was the same as that of trained surgeons for the rope pass drill and the suturing exercise. Residents in comparison with trained surgeons performed the triangle transfer drill faster and the new cup drop drill and old cup drop drill more slowly. There was no significant difference in performance between male and female residents. Basic skills relevant to laparoscopic performance can be acquired with a high level of competence in a brief course unrelated to prior surgical experience, sex, or age.