On the performance evaluation of lithium-ion battery systems for dynamic load functions in warship hybrid power and propulsion systems

Battery technology has developed to a juncture where high power and high energy density characteristics can be exploited for a common use battery energy storage system (ESS) for warship power systems to improve system steady state and dynamic performance. A critical review of previous research has exposed a lack of knowledge in performance assessment of battery ESS to operate as power reserve, to load level generator sets and supply laser directed energy weapons (LDEW) in a warship hybrid power and propulsion system. This research explores the performance impact of using a battery ESS in a candidate hybrid power and propulsion system. A simulation model of a lithium-ion nickel manganese cobalt based ESS was developed and validated against high rates of charge and discharge. Three system models were developed to explore the steady state, quasi-steady state and dynamic performance of the candidate power system when the battery is integrated. Three key investigations were conducted using the respective system models. The first explored the effects of ESS on the candidate power system performance when the ESS is operated as power reserve. Analysis showed that a 40% reduction in exhaust greenhouse gas (GHG) emissions was potentially achievable from the candidate warship compared to conventional operating practice. The second explored power system performance when operating the ESS operates to load level a diesel generator under quasi-steady state conditions. A 2% droop limit is suggested to mitigate against adverse quality of power supply (QPS) conditions for electrical consumers. The third investigation, and key contribution to the field of naval power systems, explored the impact of LDEW demands on the transient response of the ESS and system quality of power supply. The research findings show that the battery ESS is capable of high rates of fire for extended periods subject to state of charge operating limitations. To mitigate against adverse QPS conditions and provide operators with a realistic operating envelope to power the laser with the battery ESS, it is recommended that the power limit of the laser load should be 1.75 MW peak power

Efficient Database Generation for Data-driven Security Assessment of Power Systems

Power system security assessment methods require large datasets of operating points to train or test their performance. As historical data often contain limited number of abnormal situations, simulation data are necessary to accurately determine the security boundary. Generating such a database is an extremely demanding task, which becomes intractable even for small system sizes. This paper proposes a modular and highly scalable algorithm for computationally efficient database generation. Using convex relaxation techniques and complex network theory, we discard large infeasible regions and drastically reduce the search space. We explore the remaining space by a highly parallelizable algorithm and substantially decrease computation time. Our method accommodates numerous definitions of power system security. Here we focus on the combination of N-k security and small-signal stability. Demonstrating our algorithm on IEEE 14-bus and NESTA 162-bus systems, we show how it outperforms existing approaches requiring less than 10% of the time other methods require.Comment: Database publicly available at: https://github.com/johnnyDEDK/OPs_Nesta162Bus - Paper accepted for publication at IEEE Transactions on Power System

ИССЛЕДОВАНИЕ ВЛИЯНИЯ РЕЖИМОВ АРМЯНСКОЙ ЭНЕРГОСИСТЕМЫ НА ВЕЛИЧИНУ ТЕХНИЧЕСКИХ ПОТЕРЬ ЭНЕРГИИ В ПЕРЕДАЮЩИХ ЭЛЕКТРОСЕТЯХ

The paper analyzes an influence of operating parameters of the Armenian Power System (PS) on the value of technical power losses in the 110–220 kV transmission networks. Methods of regression and variance analyses are used in this paper. A number of calculation experiments have been carried out and such factors as power supply of the Armenian Power System, power flow between the Armenian and Iranian Power Systems, total load of the Armenian Power System, power export from the Armenian Power System to the Georgian Power System have been taken as the influencing ones. The obtained regression equations reflect the most common tendencies of the Armenian Power System behavior and allow to draw a conclusion regarding the nature of its operating parameters’ influence on the value of technical power losses in transmission networks that means to restrict the field of solution search, directed to the reduction of technical losses. Статья посвящена анализу влияния режимных параметров ЭС на величину технических потерь энергии в передающих электросетях напряжением  110–220 кВ Армении на основе методов регрессионного и дисперсионного анализа. Реализован ряд расчетных экспериментов, в ходе которых в качестве влияющих факторов приняты отпуск электроэнергии от Армянской АЭС, переток электроэнергии между ЭС Ирана и Армении, суммарная нагрузка Армянской ЭС, экспорт электроэнергии из Армянской ЭС в ЭС Грузии. Полученные регрессионные уравнения  отражают наиболее общие тенденции поведенческих свойств Армянской ЭС и позволяют сделать выводы о характере влияния ее режимных параметров на величину технических потерь энергии в передающих электросетях, а следовательно, ограничить область поиска решений, направленных на снижение технических потерь

Pollution reduction technology program for turboprop engines

The reduction of CO, HC, and smoke emissions while maintaining acceptable NO(x) emissions without affecting fuel consumption, durability, maintainability, and safety was accomplished. Component combustor concept screening directed toward the demonstration of advanced combustor technology required to meet the EPA exhaust emissions standards for class P2 turboprop engines was covered. The combustion system for the Allison 501-D22A engine was used, and three combustor design concepts - reverse flow, prechamber, and staged fuel were evaluated

CF6 performance improvement

Potential CF6 engine performance improvements directed at reduced fuel consumption were identified and screened relative to airline acceptability and are reviewed. The screening process developed to provide evaluations of fuel savings and economic factors including return on investment and direct operating cost is described. In addition, assessments of development risk and production potential are made. Several promising concepts selected for full-scale development based on a ranking involving these factors are discussed

Implementing a perioperative efficiency initiative for orthopedic surgery instrumentation at an academic center: A comparative before-and-after study.

Optimizing surgical instrumentation may contribute to value-based care, particularly in commonly performed procedures. We report our experience in implementing a perioperative efficiency program in 2 types of orthopedic surgery (primary total-knee arthroplasty, TKA, and total-hip arthroplasty, THA).A comparative before-and-after study with 2 participating surgeons, each performing both THA and TKA, was conducted. Our objective was to evaluate the effect of surgical tray optimization on operating and processing time, cost, and waste associated with preparation, delivery, and staging of sterile surgical instruments. The study was designed as a prospective quality improvement initiative with pre- and postimplementation operational measures and a provider satisfaction survey.A total of 96 procedures (38 preimplementation and 58 postimplementation) were assessed using time-stamped performance endpoints. The number and weight of trays and instruments processed were reduced substantially after the optimization intervention, particularly for TKA. Setup time was reduced by 23% (6 minutes, P = .01) for TKA procedures but did not differ for THA. The number of survey respondents was small, but satisfaction was high overall among personnel involved in implementation.Optimizing instrumentation trays for orthopedic procedures yielded reduction in processing time and cost. Future research should evaluate patient outcomes and incremental/additive impact on institutional quality measures

REINVESTMENT ACTIVITY OF INDUSTRIAL ENTERPRISE – STIMULATORS AND MOTIVATORS: CASE OF UKRAINE

Basic tendencies in investment climate of Ukraine are discovered. The principal sources of investments of industrial enterprises are examined. The process of reinvestment activity of industrial enterprises and its influence on the prospects of economic growth of the country are considered. Basic stimulators and motivators which allow to accelerate the reinvestment activity of the industrial enterprises used in the global economy and recommended by international economic and financial institutions are defined and prospects of its application in Ukraine are considered.Basic tendencies in investment climate of Ukraine are discovered. The principal sources of investments of industrial enterprises are examined. The process of reinvestment activity of industrial enterprises and its influence on the prospects of economic growth of the country are considered. Basic stimulators and motivators which allow to accelerate the reinvestment activity of the industrial enterprises used in the global economy and recommended by international economic and financial institutions are defined and prospects of its application in Ukraine are considered

REINVESTMENT ACTIVITY OF INDUSTRIAL ENTERPRISE – STIMULATORS AND MOTIVATORS: CASE OF UKRAINE

Basic tendencies in investment climate of Ukraine are discovered. The principal sources of investments of industrial enterprises are examined. The process of reinvestment activity of industrial enterprises and its influence on the prospects of economic growth of the country are considered. Basic stimulators and motivators which allow to accelerate the reinvestment activity of the industrial enterprises used in the global economy and recommended by international economic and financial institutions are defined and prospects of its application in Ukraine are considered.Basic tendencies in investment climate of Ukraine are discovered. The principal sources of investments of industrial enterprises are examined. The process of reinvestment activity of industrial enterprises and its influence on the prospects of economic growth of the country are considered. Basic stimulators and motivators which allow to accelerate the reinvestment activity of the industrial enterprises used in the global economy and recommended by international economic and financial institutions are defined and prospects of its application in Ukraine are considered

General aviation piston-engine exhaust emission reduction

To support the promulgation of aircraft regulations, two airports were examined, Van Nuys and Tamiami. It was determined that the carbon monoxide (CO) emissions from piston-engine aircraft have a significant influence on the CO levels in the ambient air in and around airports, where workers and travelers would be exposed. Emissions standards were set up for control of emissions from aircraft piston engines manufactured after December 31, 1979. The standards selected were based on a technologically feasible and economically reasonable control of carbon monoxide. It was concluded that substantial CO reductions could be realized if the range of typical fuel-air ratios could be narrowed. Thus, improvements in fuel management were determined as reasonable controls