bluuebunny/crossref_metadata_2025 huggingface dataset:
On-Line Early Fault Detection of a Centrifugal Chiller Based on Data Driven Approach
Authors: Audivet Durán Cinthia , Sanjuán Marco E.
Published: November 2016

A district cooling system (DCS) is a system that distributes thermal energy through chilled water from a central source to residential, commercial, or industrial consumers, designated to air conditioning purposes. It is one of the most important part of a heating, ventilation, air conditioning and refrigeration systems (HVAC), because a DCS is composed of: Cooling towers, central chiller plant, water distribution systems and clusters of consumer buildings. This research is focused on the central chiller plant, due to it accounts for a substantial portion of the total energy consume of DCS and HVAC systems. The performance of central chiller plant is often affected by multiple faults which could be caused during installation or developed in routine operation. These non-optimal conditions and faults may cause 20–30% waste of energy consumption of HVAC&R systems. Automated fault detection and diagnosis (AFDD) tools have potential to detect an incipient fault and help to reduce undesirable conditions and energy consumption, and optimize the facility maintenance. We propose an online data driven fault detection strategy for district cooling system. The main objective is to develop an automated fault detection tool based on historical process data, which can be applied in transient operation. The proposed hybrid strategy is based on unsupervised and supervised learning techniques, and multivariate statistic techniques. Its aim is to identify the operating states of the chiller and evaluate the fault occurrence depending of its current operating state. This strategy uses the K-means clustering method, Naive Bayes classifier and Principal Component Analysis (PCA). The developed strategy was evaluated using the performance data of a 90-ton water-cooled centrifugal chiller (ASHRAE RP-1043) and also evaluated using a dynamic model of a chiller (Simscape™.) under similar conditions. The results show the advantages of novel early fault detection technique compared to Conventional PCA method in terms of sensitivity to faults occurrence and reduction of missed detection rate.
A Dynamic Model of a Single-Stage LiBr-H2O Absorption Chiller
Authors: Samutr Prangtip , Al Alili Ali
Published: November 2016

This paper presents a dynamic model of a single-stage LiBr-H2O absorption chiller. A numerical model has been developed based on mass and energy balance equations and heat transfer equations. The model is developed using MATLAB program and the system of non-linear ordinary differential equation is solved using the 4th-order Runge-Kutta method. The model is validated with experimental results from pertained literature. The results show that the maximum relative error is found when comparing the dynamic model predicted chilled water outlet temperature to experimental data, which is around 9%. The effect of the inlet hot water temperature on the hot, cooling and chilled water outlet temperatures, cooling capacity and coefficient of performance (COP) are also studied. The results show that as the hot water outlet temperature increases, the outlet temperatures of cooling and chilled water slightly change. Moreover, the cooling capacity increases and the COP slight decreases as the hot water temperature increases.
A Thermodynamic Model of a High Temperature Hybrid Compressed Air Energy Storage System for Grid Storage
Authors: Houssainy Sammy , Baghaei Lakeh Reza , Kavehpour H. Pirouz
Published: November 2016

Human activity is overloading our atmosphere with carbon dioxide and other global warming emissions. These emissions trap heat, increase the planet’s temperature, and create significant health, environmental, and climate issues. Electricity production accounts for more than one-third of U.S. global warming emissions, with the majority generated by coal-fired power plants. These plants produce approximately 25 percent of total U.S. global warming emissions. In contrast, most renewable energy sources produce little to no global warming emissions. Unfortunately, generated electricity from renewable sources rarely provides immediate response to electrical demands, as the sources of generation do not deliver a regular supply easily adjustable to consumption needs. This has led to the emergence of storage as a crucial element in the management of energy, allowing energy to be released into the grid during peak hours and meet electrical demands. Compressed air energy storage can potentially allow renewable energy sources to meet electricity demands as reliably as coal-fired power plants. Most compressed air energy storage systems run at very high pressures, which possess inherent problems such as equipment failure, high cost, and inefficiency. This research aims to illustrate the potential of compressed air energy storage systems by illustrating two different discharge configurations and outlining key variables, which have a major impact on the performance of the storage system. Storage efficiency is a key factor to making renewable sources an independent form of sustainable energy. In this paper, a comprehensive thermodynamic analysis of a compressed air energy storage system is presented. Specifically, a detailed study of the first law of thermodynamics of the entire system is presented followed by a thorough analysis of the second law of thermodynamics of the complete system. Details of both discharge and charge cycles of the storage system are presented. The first and second law based efficiencies of the system are also presented along with parametric studies, which demonstrates the effects of various thermodynamic cycle variables on the total round-trip efficiency of compressed air energy storage systems.
Thermodynamic Analysis of a Mini Hybrid Solar Driven Cooling-Desalination System
Authors: Ibrahim Nasiru I. , Al-Sulaiman Fahad A. , Rahman Saidur
Published: November 2016

Water desalination and air conditioning consumes huge amount of energy that mostly come from fossil fuels, which produces harmful emissions detrimental to the environment. This work is concerned with the use of a new hybrid cooling and water desalination system driven by solar thermal energy. The system primarily consists of an evacuated tube solar collector, LiBr absorption chiller, and a humidification-dehumidification (HDH) unit. Seawater is used to cool the condenser and absorber of the chiller as well as the condenser of the HDH unit. The heat rejected by the absorber is used to drive the HDH unit. Thermodynamic model of the system has been formulated and simulated using engineering equation solver (EES) software. The results show that the coefficient of performance (COP) of the chiller nearly remain constant with increase in seawater temperature at the absorber inlet. The average COP of the chiller is found to be 0.76. The hybrid system efficiency increases with increase in the seawater temperature mainly due the effect of latent heat of water condensation. The rate of fresh water production increases with increase in the seawater inlet temperature. This resulted in a higher outlet temperature at the absorber exit, leading to a higher energy input to the HDH unit. Gained output ratio (GOR) increases with increase in seawater temperature. This is due to the direct proportionality of the GOR to the amount of fresh water produced. The results also revealed that increasing the flow rate of seawater causes the decrease in the fresh water production due to the corresponding decrease in the temperature of the seawater.
Considerations for the Design of a High-Temperature Particle Reoxidation Reactor for Extraction of Heat in Thermochemical Energy Storage Systems
Authors: Babiniec Sean M. , Miller James E. , Ambrosini Andrea , Stechel Ellen , Coker Eric N. , Loutzenhiser Peter G. , Ho Clifford K.
Published: November 2016

In an effort to increase thermal energy storage densities and turbine inlet temperatures in concentrating solar power (CSP) systems, focus on energy storage media has shifted from molten salts to solid particles. These solid particles are stable at temperatures far greater than that of molten salts, allowing the use of efficient high-temperature turbines in the power cycle. Furthermore, many of the solid particles under development store heat via reversible chemical reactions (thermochemical energy storage, TCES) in addition to the heat they store as sensible energy. The heat-storing reaction is often the thermal reduction of a metal oxide. If coupled to an Air-Brayton system, wherein air is used as the turbine working fluid, the subsequent extraction of both reaction and sensible heat, as well as the transfer of heat to the working fluid, can be accomplished in a direct-contact, counter-flow reoxidation reactor. However, there are several design challenges unique to such a reactor, such as maintaining requisite residence times for reactions to occur, particle conveying and mitigation of entrainment, and the balance of kinetics and heat transfer rates to achieve reactor outlet temperatures in excess of 1200 °C. In this paper, insights to addressing these challenges are offered, and design and operational tradeoffs that arise in this highly-coupled system are introduced and discussed.
Multiple Model Adaptive Estimation of a Hybrid Solid Oxide Fuel Cell Gas Turbine Power Plant Simulator
Authors: Tsai Alex , Tucker David , Emami Tooran
Published: November 2016

Operating points of a 300kW Solid Oxide Fuel Cell Gas Turbine (SOFC-GT) power plant simulator is estimated with the use of a Multiple Model Adaptive Estimation (MMAE) algorithm, aimed at improving the flexibility of controlling the system to changing operating conditions. Through a set of empirical Transfer Functions derived at two distinct operating points of a wide operating envelope, the method demonstrates the efficacy of estimating online the probability that the system behaves according to a predetermined dynamic model. By identifying which model the plant is operating under, appropriate control strategies can be switched and implemented upon changes in critical parameters of the SOFC-GT system — most notably the Load Bank (LB) disturbance and FC cathode airflow parameters. The SOFC-GT simulator allows testing of various fuel cell models under a cyber-physical configuration that incorporates a 120kW Auxiliary Power Unit, and Balance-of-Plant components in hardware, and a fuel cell model in software. The adaptation technique is beneficial to plants having a wide range of operation, as is the case for SOFC-GT systems. The practical implementation of the adaptive methodology is presented through simulation in the MATLAB/SIMULINK environment.
Numerical Study on Flame Mesoscopic-Characteristics of Oxy-Coal Mild Combustion
Authors: Liu Ruochen , An Enke , Wu Kun
Published: November 2016

For achieving efficient oxy-coal combustion in a MILD (Moderate or Intense Low Oxygen Dilution) state, the optimum operating conditions with high-velocity jets in a lab-scale cylindrical furnace (Φ200mm×2000mm) was determined. The mesoscopic characteristics of turbulent and flame behavior under different jet design and jet spacing were simulated and compared. The results show that L=30∼60mm(O2 side) and L=60mm(O2 center) conditions are recommended as oxy-coal MILD combustion as well as IFRF furnace condition, the flame front locates in distributed regime, the global regime was depict as 1 < l/lF < 4, 60 < ReT < 150 and 50 < Ka < 500 ; for flaming conditions, the flame front locates in small-scale turbulent regime or thin reaction zone, the global regime was depicted as 0.5 < l/lF < 4, 40 < ReT < 110 and 30 < Ka < 900 ; with high-velocity oxygen jet technology, the combustion process is in slow chemistry regime (Da << 1), governed by chemical-kinetic mechanism; large spacing (L=75mm) is not favored for co-flow burners due to poor radial mixing as well as the restriction of wall.
Theoretical Study on Chemical-Kinetic Characteristics of Oxy-Coal Mild Combustion
Authors: Liu Ruochen , An Enke , Wu Kun
Published: November 2016

The chemical-kinetic characteristics of oxy-coal MILD combustion under different initial temperature and oxygen concentration were studied numerically. Aromatic benzene was considered representative for coal molecule. A unique reaction pathway under low oxygen concentration was obtained, the activation energy and reaction rate constant of involved elementary reactions were calculated through classic transition state theory (TST). The results show that low oxygen concentration and high temperature is advantageous for thickening flame front as well as slowing down flame propagation; as oxygen concentration and temperature increase, the global activation energy increases with greater slope; the decomposition of C5H5 dominates under high oxygen concentration, while the decomposition and oxidation of C5H5 become equally important as oxygen concentration decreases, leading to a new pathway that the complexity of overall chemical reactions develops; the radical CH2CHO is easily trigged under low oxygen concentration, its decomposition reaction dominates in the unique pathway C5H5→C5H4O→c-C4H5CH2CHO→CH3 due to larger activation energy, where more CO escapes. The simulation results have theoretical referencing value, laying foundations for the further practical work.
Role of Fuel Injection Scheme in a High Intensity Combustor
Authors: Said Ahmed O. , Gupta Ashwani K.
Published: November 2016

Fuel injection at two locations in a combustor using premixed, partially pre-mixed and non-premixed schemes has been explored for improved distributed combustion. The effect of dual location fuel injection to the combustor is examined and the results compared from single fuel injection. Focus of dual and single injection scheme was on enhancing reaction zone uniformity in the combustor. A cylindrical combustor at a combustion intensity of 36MW/m3.atm and heat load of 6.25 kW was used. Three different schemes of dual location fuel injection with different proportions of fuel injected from each injector were investigated using methane as the fuel. The role of fuel distribution between the two injection ports using constant air flow rate to the combustor at room temperature was examined on reaction zone distribution and pollutants emission. Three different equivalence ratios of 0.6, 0.7 and 0.8 were examined with different fuel distributions between the two injectors to the combustor at a constant overall thermal load. The results showed lower emission with dual location fuel injection as compared to single location. Dual location fuel injection showed 48% NO reduction with 90% of the total fuel from injector 1 while only 13% reduction was achieved with 80% of the fuel injection from this location. . OH* Chemiluminescene intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream to allow longer fuel mixture preparation time prior to ignition. The longer mixing time resulted in improved mixture preparation and lower emissions. The OH* Chemiluminescene intensity distribution with fuel introduced through two injectors showed improved OH* distribution in the combustor. Improved mixture preparation enhanced reaction distribution in the combustor and lower emission.
Numerical Investigation of Novel Design of Savonius Blade Geometries for Vertical-Axis Wind Turbines
Authors: Rahman Mosfequr , Salyers Travis , Maroha Emile , Ahmed Mahbub , Salekeen Sirajus
Published: November 2016

With the increasing demand for clean, renewable energy sources, vertical-axis wind turbine (VAWT) research has gained considerable interest. The technology is primarily used for small-scale power applications in environments with unsteady wind conditions, such as urban locations. For this type of turbine the most important features are self-starting characteristics and energy conversion efficiency. For the Savonius type rotor, performance is increased by reducing drag losses on the advancing blades. The present study addresses the numerical verification of the performance of new designs for drag-driven VAWTs.

Two new models were created using SolidWorks along with a standard Savonius model consisting of semicircular blades for benchmarking. All models were designed with the same swept area for comparison. 3D numerical simulation was completed using ANSYS FLUENT. Static conditions were first solved with a moving reference frame (MRF). The results from the MRF simulations were then used to initialize the transient solvers using sliding mesh models (SMM). 3D pressure distributions on the moving blades for each model were analyzed. From inputs of wind and rotational speed, torque values and coefficients of moment were reported. Each model was tested over a range of tip-speed ratios, and power coefficients were calculated. Results were compared to a standard Savonius VAWT, and increased maximum power coefficient was achieved with the new blade geometries.
Analysis of a Renewable Energy Based System Using Nanofluids for Power Generation
Authors: Alashkar Adnan , Gadalla Mohamed
Published: November 2016

In this present paper, a performance analysis of an Integrated Solar Rankine Cycle (ISRC) is provided. The ISRC consists of a nanofluid-based Parabolic Trough Solar Collector (PTSC), and a Thermal Energy Storage System (TES) integrated with a Rankine Cycle. The effect of dispersing Copper (Cu) nanoparticles in a conventional heating fluid (Syltherm 800) on the output performance and cost of the ISRC is studied for different volume fractions, and for two modes of operation. The first mode assumes no storage, while the second assumes a storage system with a storage period of 7 hours. For the second mode of operation, the charging and discharging cycles are explained. The results show that the presence of the nanoparticles causes an increase in the overall energy produced by the ISRC for both modes of operation, and also causes a decrease in the Levelized Cost of Electricity (LEC), and an increase in the net savings of the ISRC. When comparing the two modes of operation it is established that the existence of a storage system leads to a higher power generation, and a lower LEC; however the efficiency of the cycle drops. It is seen that the maximum increase in the annual energy output of the ISRC caused by the addition of the nanoparticles is around 3.5%, while the maximum increase in the net savings is around 12.8%.
Application of Ramberg-Osgood Plasticity to Determine Cyclic Hardening Parameters
Authors: Bouchenot Thomas , Felemban Bassem , Mejia Cristian , Gordon Ali P.
Published: November 2016

Critical components of modern turbomachinery are frequently subjected to a myriad of service conditions that include diverse mechanical loads at elevated temperatures. The cost, applicability, and accuracy of either numerical or analytical component-level simulations are largely dependent on the material model chosen for the application. A non-interaction (NI) model derived from individual elastic, plastic, and creep components is developed in this study. The candidate material under examination for this application is 2.25Cr-1Mo, a low-alloy ferritic steel commonly used in chemical processing, nuclear reactors, pressure vessels, and power generation. Data acquired from literature over a range of temperatures up to 650°C are used to calibrate the creep and plastic components described using constitutive models generally native to general-purpose FEA. Traditional methods invoked to generate coefficients for advanced constitutive models such as non-linear kinematic hardening employ numerical fittings of hysteresis data, which result in values that are neither repeatable nor display reasonable temperature-dependence. By extrapolating simplifications commonly used for reduced-order model approximations, an extension utilizing only the cyclic Ramberg-Osgood coefficients has been developed to identify these parameters. Unit cell simulations are conducted to verify the accuracy of the approach. Results are compared with isothermal and non-isothermal literature data.
Gas Turbine Common Issues, Failure Investigations, Root Cause Analyses, and Preventative Actions
Authors: Garner Stephen , Ibrahim Zuhair
Published: November 2016

Gas turbines are a type of internal combustion engine and are used in a wide range of services powering aircraft of all types, as well as driving mechanical equipment such as pumps, compressors in the petrochemical industry, and generators in the electric utility industry. Similar to the reciprocating internal combustion engine in an automobile, energy (mechanical or electrical) is generated by the burning of a hydrocarbon fuel (i.e., jet fuel, diesel or natural gas). The core of a gas turbine engine is comprised of three main sections: the compressor section, the combustor section, and the turbine section. To ensure that a gas turbine operates safely, reliably, and with optimum performance, all gas turbines are provided with a control system designed either by the OEM or according to the OEM’s specification. The OEM-provided control systems will typically include complex and integrated subsystems such as (but not limited to): a graphic user interface, an engine management system (EMS or ECS), a safety related system (SRS), and a package control system (PCS) that may interface with a facilities’ existing computerized control systems. Any failure of the mechanical systems, electro-mechanical systems, or logic based control systems of a gas turbine can result in forced outage.

A forced outage of a gas turbine, whether in a mechanical service, such as pipelines, or in either a simple cycle or combined cycle power generation installation results in a reduction of system availability and therefore a loss in revenue. The significant capital investment in a gas turbine system necessitates a high degree of reliability and system availability while reducing forced outages. A power plant can minimize occurrences of forced outages and optimize recovery of capacity by effectively combining proactive and reactive solutions.

This paper will discuss both proactive and reactive programs as well as their implementation in order to answer the key questions that often surround an outage: How is outage time minimized while increasing reliability and system availability? What went wrong and who or what is responsible? How soon can the unit or the plant get back online? And what operational or maintenance considerations are needed to prevent a similar recurrence.

Proactive approaches to be discussed include process hazard analyses (PHA) such as hazard and operability studies (HAZOP), hazard identification (HAZID), layer-of-protection analyses (LOPA), what-if analyses, and quantitative risk assessments (QRA) in addition to failure mode and effects analysis (FMEA); and failure mode, effects and criticality analysis (FMECA). Reactive approaches to be discussed include various root cause analysis (RCA) and failure analysis (FA) techniques and methodologies such as fault-tree analysis. Case studies and some lessons learned will also be presented to illustrate the methods.
Assessment of Power Consumption of an Electrodynamic Dust Shield to Clean Solar Panels
Authors: Chesnutt Jennifer K. W. , Guo Bing , Wu Chang-Yu
Published: November 2016

Substantial time and money have been directed toward photovoltaic solar power. However, mitigation of dust on solar panels has been largely neglected. The objective of this research was to determine the performance and power consumption of an electrodynamic dust shield (EDS) to clean solar panels as a function of dust particle size. We utilized a discrete element method to computationally simulate the transport, collision, and electrodynamic interactions of particles subjected to electrodynamic waves generated by an EDS. The EDS consisted of electrodes embedded within a dielectric material. 1250 monodisperse particles with diameters of 30–50 μm were simulated. In the absence of particle-particle interactions, an increase in diameter increased particle transport distance due to increased particle charge. However, inclusion of particle-particle collisions produced interactions such that an intermediate diameter yielded the smallest transport distance. Average power required to lift a particle off the surface was smallest with the smallest particle; however, power requirement decreased with diameter with a constant loading of particles on the EDS. Calculated from our simulation data, power consumption per unit area of an experimental EDS agreed with previous experimental studies. Our study elucidated important aspects of EDS operation and power consumption to mitigate dust on solar panels.
Indirect Combustion Technology With Renewable Non-Edible Transesterified Oil Feedstock
Authors: Soloiu Valentin , Moncada Jose , Naes Tyler , Muiños Martin , Harp Spencer
Published: November 2016

This investigation focused on the combustion and performance of an indirect injection (IDI) diesel engine powered by a non-edible biodiesel blend, Brassica Carinata. This oilseed has become an attractive non-edible feedstock for biodiesel in the United States, given potential agronomical advantages. A small bore, single cylinder IDI engine was run at 2000 rpm and 5.5 bar indicated mean effective pressure (IMEP) using ultra-low sulfur diesel #2 (ULSD#2) and compared with C50, a 50% Carinata biodiesel-ULSD#2 blend (by mass). The apparent heat release for C50 reached a maximum of 22.04 J/deg which was 6.3 % lower and peaked 1.80 CAD before ULSD#2. The radiation and convection heat fluxes had similar maximum values of 0.62 MW/m2 and 1.34 MW/m2, respectively. The brake specific fuel consumption (BSFC) of C50 was 211.05 g/kWh, which was 9% higher than for ULSD#2. The mechanical efficiency was maintained relatively constant at 55% while the indicated thermal efficiency of the engine reached 59%. Both fuels produced similar nitrogen oxide (NOx) emissions with ULSD#2 and C50 producing 2.29 g/kWh and 2.23 g/kWh, respectively. The results indicate that the IDI engine can optimally work with concentrations up to 50% biodiesel.
Techniques for Developing an ASME RAM Program
Authors: Wodka Brian
Published: November 2016

The recent ASME RAM-1-2013 Standard provided high-level guidance for the development of a Reliability, Availability, and Maintainability (RAM) Program for power plants and critical facilities. The intentional vagueness of the standard permitted a large scope of different power plants and critical facilities over a wide variety of applications. Even though this allowed for the most freedom in customization in developing a RAM Program, it provided little specific guidance on exactly how to do it. This paper provides some of the specific industry techniques that can be used as direct guidance to develop the various aspects of a RAM Program.
Enhancement in Photovoltaic Performance of Dye Sensitized Solar Cells Using Cu and Cu:Ag Co-Doped TiO2 Photoanode
Authors: Shakir Sehar , Abd-ur-Rehman Hafiz M.
Published: November 2016

Dye Sensitized Solar Cells (DSSCs) are low cost solar cells offering big room for improvements in its photovoltaic performance by maneuvering semiconductor properties, dye adsorption, electrolyte stability etc. For the first time, we have co-doped TiO2 with silver (Ag) and copper (Cu) to enhance both charge collection and light absorption as well as reduce recombinations for DSSCs. For high solar cell efficiency 3wt% Cu and 3wt% Cu:Ag doped TiO2 nps were successfully prepared for Dye Sensitized Solar Cells (DSSCs). Modified photoanode was prepared using surface adsorbed N719 dye on doctor blade coated TiO2, Cu:TiO2 and Cu:Ag:TiO2 thin films. It was observed that optimum doping concentration of Cu and silver was 3wt% each. DSSCs with Cu:Ag:TiO2 thin film showed higher conversion efficiency under full sunlight illumination when compared to DSSCs assembled using Cu:TiO2 and undoped TiO2. The obtained efficiencies for DSSCs with undoped TiO2, Cu:TiO2 and Cu:Ag:TiO2 photoanodes were 2%, 2.7% and 4.5% respectively. Solar cells assembled with Cu only doped TiO2 electrode when compared with cells assembled using pristine TiO2, showed an increase in Voc while Jsc was decreased Furthermore, cells doped with both Ag and Cu showed enhancement in both Voc and Jsc. The enhancement in cell performance has been discussed in context of morphology, crystal phase, presence of bonds etc. in nanoparticles. Considering overall better performance, Cu:Ag doped TiO2 photoanodes can be considered as potential photoanodes in DSSCs.
Feasibility Study of SMART MONOFLOAT Hydrokinetic Power for the Rural Households in Naga Hammadi, Egypt
Authors: Diab Fahd , Lan Hai
Published: November 2016

Hybrid Renewable Energy System (HRES) is an attractive system for stand-alone electrification in remote areas. The hydrokinetic power avoids all the disadvantages of hydropower, unlike dams that have obstructed the natural water flow and ended up displacing animals and people. The main objective of this research work is to provide a feasibility study of using SMART MONOFLOAT hydrokinetic power in hybrid photovoltaic (PV)/HKT/diesel/battery system to satisfy the electrical energy needs for the selected rural households in Naga Hammadi, Egypt in this study. The SMART MONOFLOAT hydrokinetic turbine has been used as it was developed to produce a maximum amount of electrical power with the kinetic energy of flowing water. The well-known Hybrid Optimization of Multiple Electric Renewables (HOMER) software is used as a software tool in this study. The 22-year average monthly solar radiation data for the selected rural households in Naga Hammadi, located at latitude of 26.013 and longitude of 32.32 was obtained from National Aeronautics and Space Administration (NASA) database. The average monthly current velocity data of the Nile River used in this study was collected for a single year during 1991 after construction of the Aswan Dam in 1904. According to the simulation results in this work, it was found that the optimum HRES consisting of; 90 kW PV panels, 90 kW HKTs, 22 kW diesel generators, 60 kW power converters and 225 batteries. In addition to that, a great reduction in greenhouse gases (GHG) emission during the project lifetime could be achieved by using the optimum system.
Analytical Study of the Effects of Grid Resistance on Grid-Connected PV Systems: Modeling and Simulation
Authors: Al-Gahtani S. F. , Nelms R. M.
Published: November 2016

Renewable energy systems have become common in power systems. Many problems associated with connecting a renewable energy system to utility network have arisen. In the traditional power calculation, the resistance of the line is ignored because of large the X/R ratio. However, the R/X ratio in the distribution network is greater than in transmission. Because of that, the line resistance should be considered in the power calculations. In this paper, the effect of the grid resistance on transfer of power is investigated by calculating the active power between a PV system and the grid where the grid resistance is included. Two models were developed to study the effects of the grid resistance. The sensitivity of real and reactive power to the grid impedance, the current performance and the phase angle for the maximum power were studied under variations of the grid resistance. The results from both models have been compared to emphasize that the transfer of power is really influenced by the resistance of the line impedance.
Rhabdomyolysis in a Female Caucasian Adolescent Distance Runner: A Case Report
Authors: Todd R. Mitchell , Cleary Michelle , Griffith J. Susan
Published: November 2016

We present the case of an adolescent female collegiate distance runner competing in her first 6K race. She presented with multiple systemic symptoms of dizziness, nausea, confusion, muscle cramping, and syncope. The patient was immediately treated for heat stroke and, on follow-up, reported to the AT with a headache, lack of appetite, muscle aches, and dark-colored urine. Rhabdomyolysis should be considered following a heat illness event with necessary treatments performed immediately. Symptomatic patients must be referred to a physician for evaluation and laboratory testing. We present recommendations for a supervised return-to-participation protocol and acclimatization to safely return to competition readiness.
Postural Control Strategies are Dependent on Reach Direction in the Star Excursion Balance Test
Authors: Keith Tyler R. , Condon Tara A. , Phillips Ayana , McKeon Patrick O. , King Deborah L.
Published: November 2016

The Star Excursion Balance Test (SEBT) is a valid and reliable measure of dynamic postural control. Center of pressure (COP) behavior during the SEBT could provide additional information about direction-dependent SEBT balance strategies. The purpose of this study was to quantify spatiotemporal COP differences using COP area and velocity among three different SEBT reach directions (anterior, posteromedial, posterolateral). The anterior direction COP velocity was significantly lower than both posterior directions. However, the anterior COP area was significantly greater than posterior. Based on COP behavior, the anterior and posterior reach directions appear to use different postural control strategies on the SEBT.
Autonomy, Mentorship, and Feedback: The Core of Clinical Education in Athletic Training
Authors: Mazerolle Stephanie M. , Bowman Thomas G. , Barrett Jessica L.
Published: November 2016

Clinical education provides the backbone for the socialization process for athletic trainers. It is the chance for students to engage in the role, within a real-time learning environment that allows for not only the adoption of knowledge, skills, and critical decision making, but also the profession’s foundational behaviors of professional practice. Recent criticisms of the current education model, in which the degree is conferred, center on the lack of critical thinking and confidence in clinical practice for newly-credentialed athletic trainers, as many suggest there is concern for the abilities of students to transition to practice smoothly. We offer three areas of focus for clinical education experiences for students (autonomy, mentorship, and feedback), believing this could support the development of independent thinking and confidence in skills. Our discussions are focused on the evidence available, as well as personal experiences as educators and program administrators.
Attitudes and Opinions of Female High School Athletes About Sports-Focused Mindfulness Training and Practices
Authors: Worthen Douglas , Luiselli James K.
Published: November 2016

Female high school athletes playing volleyball and soccer (N = 32) responded to a social validity questionnaire that inquired about their experiences with a sportfocused mindfulness training program. On average, the student-athletes rated most highly the effects of mindfulness training on emotional awareness and attention focusing, the contribution of mindfulness toward team play, the benefit of having coaches learn mindfulness skills, and the application of mindfulness to other sports. There were dissimilar ratings between the volleyball and soccer student-athletes concerning use of mindfulness when preparing for and during games. Most of the formal mindfulness practices taught during the training program were rated as being helpful to very helpful. We discuss factors influencing these findings and implications for mindfulness–sport performance research.
Papers of note in
Science
Authors: VanHook Annalisa M.
Published: November 2016

This week’s articles highlight the role of aging foam cells in atherosclerosis, the importance of metabolic rewiring in T cell function, the regulation of metabolic flux in yeast, superresolution imaging of endoplasmic reticulum structure, and how a noncoding RNA recruits X chromosomes into silencing domains.
Genetic interrogation of circulating multiple myeloma cells at single-cell resolution
Authors: Lohr Jens G. , Kim Sora , Gould Joshua , Knoechel Birgit , Drier Yotam , Cotton Matthew J. , Gray Daniel , Birrer Nicole , Wong Bang , Ha Gavin , Zhang Cheng-Zhong , Guo Guangwu , Meyerson Matthew , Yee Andrew J. , Boehm Jesse S. , Raje Noopur , Golub Todd R.
Published: November 2016

Circulating tumor cells provide a practical and noninvasive way to monitor multiple myeloma.
The BACE1 inhibitor verubecestat (MK-8931) reduces CNS β-amyloid in animal models and in Alzheimer’s disease patients
Authors: Kennedy Matthew E. , Stamford Andrew W. , Chen Xia , Cox Kathleen , Cumming Jared N. , Dockendorf Marissa F. , Egan Michael , Ereshefsky Larry , Hodgson Robert A. , Hyde Lynn A. , Jhee Stanford , Kleijn Huub J. , Kuvelkar Reshma , Li Wei , Mattson Britta A. , Mei Hong , Palcza John , Scott Jack D. , Tanen Michael , Troyer Matthew D. , Tseng Jack L. , Stone Julie A. , Parker Eric M. , Forman Mark S.
Published: November 2016

The BACE1 inhibitor verubecestat safely reduces β-amyloid deposition in rats, monkeys, healthy human subjects, and patients with Alzheimer’s disease.
Stronger together
Authors: Hulbert Monica L.
Published: November 2016

Improved endothelial progenitor cell proliferation function supports hematopoietic stem cell proliferation after allogeneic stem cell transplant engraftment.
Sodium Nitrite Inhibits Killing of Pseudomonas aeruginosa Biofilms by Ciprofloxacin
Authors: Zemke Anna C. , Kocak Brian R. , Bomberger Jennifer M.
Published: November 2016

Sodium nitrite inhibits bacterial respiration and is in development as an antimicrobial for chronic bacterial infections associated with cystic fibrosis. The goal of the current study was to investigate the interaction between nitrite and ciprofloxacin. Using liquid culture killing assays and a biotic biofilm model, we observed that nitrite induces tolerance of ciprofloxacin.
Frequency of the Paradoxical Effect Measured Using the EUCAST Procedure with Micafungin, Anidulafungin, and Caspofungin against Candida Species Isolates Causing Candidemia
Authors: Marcos-Zambrano Laura Judith , Escribano Pilar , Sánchez-Carrillo Carlos , Bouza Emilio , Guinea Jesús
Published: November 2016

We report data on the frequency of the paradoxical effect of echinocandins against
Candida
spp. (
n
= 602 incident isolates) using the EUCAST definitive document EDef 7.2 procedure. The paradoxical effect for one or more echinocandins was observed in 16% of the isolates. However, differences between species were found, and the paradoxical effect was more common in
Candida tropicalis
(
P
< 0.001). Caspofungin was the drug in which the paradoxical effect was most common, followed by anidulafungin and micafungin (
P
< 0.001).
Borrelia burgdorferi CheY2 Is Dispensable for Chemotaxis or Motility but Crucial for the Infectious Life Cycle of the Spirochete
Authors: Xu Hui , Sultan Syed , Yerke Aaron , Moon Ki Hwan , Wooten R. Mark , Motaleb M. A.
Published: November 2016

The requirements for bacterial chemotaxis and motility range from dispensable to crucial for host colonization. Even though more than 50% of all sequenced prokaryotic genomes possess at least one chemotaxis signaling system, many of those genomes contain multiple copies of a chemotaxis gene. However, the functions of most of those additional genes are unknown. Most motile bacteria possess at least one CheY response regulator that is typically dedicated to the control of motility and which is usually essential for virulence.
Borrelia burgdorferi
appears to be notably different, in that it has three
cheY
genes, and our current studies on
cheY2
suggests that it has varied effects on different aspects of the natural infection cycle. Mutants deficient in this protein exhibit normal motility and chemotaxis
in vitro
but show reduced virulence in mice. Specifically, the
cheY2
mutants were severely attenuated in murine infection and dissemination to distant tissues after needle inoculation. Moreover, while Δ
cheY2
spirochetes are able to survive normally in the
Ixodes
ticks, mice fed upon by the Δ
cheY2
-infected ticks did not develop a persistent infection in the murine host. Our data suggest that CheY2, despite resembling a typical response regulator, functions distinctively from most other chemotaxis CheY proteins. We propose that CheY2 serves as a regulator for a
B. burgdorferi
virulence determinant that is required for productive infection within vertebrate, but not tick, hosts.
Unique Regulation of the DosR Regulon in the Beijing Lineage of Mycobacterium tuberculosis
Authors: Domenech Pilar , Zou Jason , Averback Alexandra , Syed Nishath , Curtis Daniele , Donato Samuel , Reed Michael B.
Published: November 2016

The DosR regulon, a set of 48 genes normally expressed inMycobacterium tuberculosisunder conditions that inhibit aerobic respiration, is controlled via the DosR-DosS/DosT two-component system. While the regulon requires induction in mostM. tuberculosisisolates, for members of the Beijing lineage, its expression is uncoupled from the need for signaling. In our attempts to understand the mechanistic basis for this uncoupling in the Beijing background, we previously reported the identification of two synonymous single-nucleotide polymorphisms (SNPs) within the adjacent Rv3134c gene. In the present study, we have interrogated the impact of these SNPs ondosRexpression in wild-type strains, as well as a range ofdosR-dosS-dosTmutants, for both Beijing and non-BeijingM. tuberculosisbackgrounds. In this manner, we have unequivocally determined that the C601TdosRpromoter SNP is the sole requirement for the dramatic shift in the pattern of DosR regulon expression seen in this globally important lineage. Interestingly, we also show that DosT is completely nonfunctional within these strains. Thus, a complex series of evolutionary steps has led to the present-day Beijing DosR phenotype that, in turn, potentially confers a fitness advantage in the face of some form of host-associated selective pressure.

IMPORTANCEMycobacterium tuberculosisstrains of the Beijing lineage have been described as being of enhanced virulence compared to other lineages, and in certain regions, they are associated with the dramatic spread of multidrug-resistant tuberculosis (TB). In terms of trying to understand the functional basis for these broad epidemiological phenomena, it is interesting that, in contrast to the other major lineages, the Beijing strains all constitutively overexpress members of the DosR regulon. Here, we identify the mutational events that led to the evolution of this unique phenotype. In addition, our work highlights the fact that important phenotypic differences exist between distinctM. tuberculosislineages, with the potential to impact the efficacy of diagnosis, vaccination, and treatment programs.
Activation of intracellular serine proteinase in Bacillus subtilis cells during sporulation
Authors: Burnett T J , Shankweiler G W , Hageman J H
Published: November 2016

Cells of Bacillus subtilis 168 (trpC2) growing and sporulating in a single chemically defined medium carried out intracellular protein degradation and increased their levels of intracellular serine protease-1 in a manner very similar to what had previously been reported for cells sporulating in nutrient broth. The results were interpreted to mean that these processes are intrinsic to sporulation rather than medium dependent. To determine the cause of these increases in specific activity of proteinases, we purified the protease, prepared rabbit immunoglobulins directed against it, and monitored changes in protease antigen levels by performing rocket immunoelectrophoresis. In cells sporulating in nutrient broth, the protease antigen levels increased about 7-fold, whereas the specific activity increased about 150-fold, for an activation of about 20-fold. In cells sporulating in the single chemically defined sporulation medium, the protease antigen increased about 10-fold, whereas the specific activity increased at least 400-fold, for an activation of about 40-fold. These results were interpreted to mean that a posttranslational event activated the protease in vivo; a previously described endogenous proteinase inhibitor was confirmed to be present in the strain used. Chloramphenicol added to the cultures inhibited both the increases in antigen levels and in the specific activity of the proteinase.
Synthesis of a functional F0 sector of the Escherichia coli H+-ATPase does not require synthesis of the alpha or beta subunits of F1
Authors: Fillingame R H , Porter B , Hermolin J , White L K
Published: November 2016

The uncB, E, F, and H genes of the Escherichia coli unc operon were cloned behind the lac promoter of plasmid pUC9, generating plasmid pBP101. These unc loci code, respectively, for the chi, omega, and psi subunits of the F0 sector and the delta subunit of the F1 sector of the H+-ATP synthase complex. Induction of expression of the four unc genes by the addition of isopropyl-beta-D-thiogalactoside resulted in inhibition of growth. During isopropyl-beta-D-thiogalactoside induction, the three subunits of F0 were integrated into the cytoplasmic membrane with a resultant increase in H+ permeability. A functional F0 was formed from plasmid pBP101 in a genetic background lacking all eight of the unc structural genes coding the F1F0 complex. In the unc deletion background, a reasonable correlation was observed between the amount of F0 incorporated into the membrane and the function measured, i.e., high-affinity binding of F1 and rate of F0-mediated H+ translocation. This correlation indicates that most or all of the F0 assembled in the membrane is active. Although the F0 assembled under these conditions binds F1, only partial restoration of NADH-dependent or ATP-dependent quenching of quinacrine fluorescence was observed with these membranes. Proteolysis of a fraction of the psi subunit may account for this partial deficiency. The experiments described demonstrate that a functional F0 can be assembled in vivo in E. coli strains lacking genes for the alpha, beta, gamma, and epsilon subunits of F1.
Identification of the tip-encoded receptor in bacterial sensing
Authors: Russo A F , Koshland D E
Published: November 2016

A chemotaxis gene encoding a protein with receptorlike properties has been identified in Salmonella typhimurium and termed tip for taxis-involved protein. Based on the stringency of DNA hybridization, the tip gene has about 75% homology with a region of the tar gene encoding the cytoplasmic domain of the aspartate receptor. Introduction of the tip gene into a smooth-swimming Escherichia coli receptor mutant (tar tsr tap) restored both chemotaxis ability on soft-agar-tryptone plates and a wild-type swimming phenotype. We have shown, by overexpressing the CheY protein, that shifting of the mutant swimming bias in the absence of receptors is insufficient to restore chemotaxis ability. This suggests that in addition to resetting the swimming bias, the tip gene product functions as a receptor. By functional criteria, we found that Tip is not a duplicate aspartate (Tar) or serine (Tsr) receptor gene. Based on behavioral properties, the S. typhimurium Tip receptor provides functional features similar to those of the E. coli Tap receptor.
Calcium-sensitive cls4 mutant of Saccharomyces cerevisiae with a defect in bud formation
Authors: Ohya Y , Miyamoto S , Ohsumi Y , Anraku Y
Published: November 2016

A calcium-sensitive cls4 mutant of Saccharomyces cerevisiae ceased dividing in the presence of 100 mM CaCl2, producing large, round, unbudded cells. Since its DNA replication and nuclear division still continued after interruption of normal budding, the cls4 mutant had a defect in bud formation in Ca2+-rich medium. Its calcium content and calcium uptake activity were the same as those of the wild-type strain, suggesting that the primary defect of the mutation was not in a Ca2+ transport system. Genetic analysis showed that the cls4 mutation did not complement the cdc24-1 mutation, which is known to be a temperature-sensitive mutation affecting bud formation and localized cell surface growth at a restrictive temperature. Moreover, cls4 was tightly linked to cdc24, and a yeast 3.4-kilobase-pair DNA fragment carrying both the CLS4 and CDC24 genes was obtained. These results suggest that the cls4 mutation is allelic to the cdc24 mutation. Thus, Ca2+ ion seems to control bud formation and bud-localized cell surface growth.