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Experimental investigations of a model Francis turbine during shutdown at synchronous speed

Hydraulic turbines are widely used to meet the real-time electricity demand at moderate to low cost. Intermittency in the power grid due to high penetration of wind and solar power has raised significant concerns for grid stability and reliability. The intermittency results in an increase of the start–stop cycles of hydraulic turbines. Each cycle induces fatigue to the turbine runner because it experiences unsteady pressure loading of high amplitude. The turbine runner accelerates freely due to an instantaneous transition into no load during shutdown. The amplitude of the unsteady pressure pulsation increases as the runner accelerates. To investigate the unsteady pressure pulsation, a shutdown slightly different from the normal shutdown was performed. Guide vanes were closed completely before the generator was disconnected from the load. The runner was spinning at constant angular speed through the generator. Amplitudes of the pressure pulsations were 20% and 35% lower in the vaneless space and the runner, respectively, compared to the normal shutdown of the turbine.

Real-Time Energy Management for Diesel Heavy Duty Hybrid Electric Vehicles

In this paper, a fuzzy-tuned equivalent consumption minimization strategy (F-ECMS) is proposed as an intelligent real-time energy management solution for a conceptual diesel engine-equipped heavy duty hybrid electric vehicle (HEV). In the HEV, two electric motors/generators are mounted on the turbocharger shaft and engine shaft, respectively, which can improve fuel efficiency by capturing and storing energy from both regenerative braking and otherwise wasted engine exhaust gas. The heavy duty HEV frequently involved in duty cycles characterized by start–stop events, especially in off-road applications, whose dynamics is analyzed in this paper. The on-line optimization problem is formulated as minimizing a cost function in terms of weighted fuel power and electric power. In the cost function, a cost factor is defined for both improving energy transmission efficiency and maintaining the battery energy balance. To deal with the nonexplicit relationship between HEV fuel economy, battery state of charge (SOC), and control variables, the cost factor is fuzzy tuned using expert knowledge and experience. In relation to the fuel economy, the air-fuel ratio is an important factor. An online search for capable optimal variable geometry turbocharger (VGT) vane opening and exhaust gas recirculation (EGR) valve opening is also necessary. Considering the exhaust emissions regulation in diesel engine control, the boundary values of VGT and EGR actuators are identified by offline design-of-experiment tests. An online rolling method is used to implement the multivariable optimization. The proposed method is validated via simulation under two transient driving cycles, with the fuel economy benefits of 4.43% and 6.44% over the nonhybrid mode, respectively. Compared with the telemetry equivalent consumption minimization strategy, the proposed F-ECMS shows better performance in the sustainability of battery SOC under driving conditions with the rapid dynamics often associated with off-road applications.

The complete mitochondrial genome of Fulica atra (Avian, Gruiformes, Rallidae)

To analyze the gene structure and the evolutionary roadmap of Fulica atra, the complete mitogenome is sequenced. It is composed of 37 genes and 1 control region, and the structure and arrangement of all genes are identical to other Rallidae. The comparative mitogenome revealed that the start codon and stop codon varied in Rallidae, and the gene lengths are different in ND2, COX1, ND3, ND5 and CYTB due to incompleteness of stop codon, frameshift mutation and various numbers of amino acids. We analyzed the correlation between phylogeny and gene characteristic in Rallidae with respect to the usage of start/stop codon and gene length, but no correlation was found. It indicates these discrepancies might happen independently. This work can afford an in-depth insight of phyletic evolution in Rallidae.

Impact analysis of sampling time interval and battery installation on optimal operational planning of residential cogeneration systems without electric power export

The impact of the sampling time interval for energy demands on the optimal operational planning of residential cogeneration systems without electric power export was analyzed. To improve their operational flexibility, focus was also placed on battery installation. First, an optimal operational planning problem was modeled on the basis of a mixed-integer linear programming. The features of the model are to consider the operational constraints of the cogeneration units, i.e., a daily maximum number of start–stop cycles, minimum up- and downtimes, and starting and shutdown energies, and to introduce a battery in consideration of electric power consumption in a built-in bidirectional inverter. Then, the developed model was applied to an energy-saving analysis of the following residential cogeneration systems under 5–60 min sampling time intervals for the simulated energy demands. A gas engine-based cogeneration system is operated at a constant power output; a polymer electrolyte fuel cell-based cogeneration system employs daily start–stop operation; and a solid oxide fuel cell-based cogeneration system is operated continuously. The results revealed that optimal operational planning under a sufficiently short sampling time interval is required to evaluate not only the energy-saving effect of the residential cogeneration systems without electric power export, but also the effectiveness of battery installation.

Sticking to minimum standards: implementing antibiotic stewardship in intensive care.

In Australia, antimicrobial stewardship programmes are a compulsory component of hospital accreditation. Good documentation around anti-microbial prescribing aids communication and can improve prescribing practice in environments with multiple decision makers. This study aims to develop and implement an intervention to improve antimicrobial prescribing practice in a 24-bed intensive care unit in a tertiary referral adult hospital. We conducted a four-phase (observation, reflection, implementation, evaluation) prospective collaborative before-after quality improvement study. Baseline audits and surveys of antimicrobial prescribing practices identified barriers to and enablers of good prescribing practice. A customised intervention was then implemented over 6 weeks and included a yellow medication record sticker, quarterly education sessions and intensive care unit-specific empiric antimicrobial prescribing guidelines. Post-implementation, the effects were monitored by serial antimicrobial prescribing audits for 1 year. The primary outcomes were clear documentation of the start date, the planned stop date or review date and the indication for an antibiotic. These were all considered the 'minimum standards' for an antimicrobial prescription on the medication record. Documentation of minimum standards specifically addressed by the sticker improved (start date (72% to 90%, P < 0.001), stop date (16% to 63%, P < 0.001), antimicrobial indication documented on medication chart (58% to 83%, P < 0.01)). Overall, adherence to all three minimum standards (start date, stop date and indication) improved from 41/306 (13%) to 306/492 (63%) (P < 0.001). One-year post-implementation, the yellow sticker had become embedded into daily practice. A systematic approach to quality improvement combined with the implementation of a tailored, multi-faceted intervention can improve antimicrobial prescribing practices.

Long term testing of start–stop cycles on high temperature PEM fuel cell stack

A PEM fuel cell with an operating temperature above 100 °C is desired for increasing the kinetics of reactions, reduced sensitivity to impurities of the fuel, as well as for the reduction of the requirements on thermal and water management systems. High Temperature Polymer Electrolyte Membrane Fuel Cells (HT-PEMFC) can effectively be combined with CHP systems to offer a simple system design and higher overall system efficiencies. For HT-PEMFC systems, the development of elaborated start/stop strategies is essential in mitigation of fuel cell degradation during these events. A 5 cell co-flow stack is assembled with BASF P1100W membrane electrode assembly (MEA) with an active area of 163.5 cm2. Continuous operation and more than 1500 start stop cycles have been performed in order to study the degradation effects of both continuous operation and of repeated start stops using a protective start–stop algorithm, which is designed to avoid the formation of aggressive cell potentials. The repeated use of this procedure led to a degradation of 26 μV/cycle at a current density of 0.25 A cm−2 and 11 μV/cycle at a current density of 0.03 A cm−2. At open circuit voltage (OCV), a higher degradation rate of 133 μV/cycle was observed.

The parasite Trichomonasvaginalis expresses thousands of pseudogenes and long non-coding RNAs independently from functional neighbouring genes.

BackgroundThe human pathogen Trichomonas vaginalis is a parabasalian flagellate that is estimated to infect 3% of the world’s population annually. With a 160 megabase genome and up to 60,000 genes residing in six chromosomes, the parasite has the largest genome among sequenced protists. Although it is thought that the genome size and unusual large coding capacity is owed to genome duplication events, the exact reason and its consequences are less well studied.ResultsAmong transcriptome data we found thousands of instances, in which reads mapped onto genomic loci not annotated as genes, some reaching up to several kilobases in length. At first sight these appear to represent long non-coding RNAs (lncRNAs), however, about half of these lncRNAs have significant sequence similarities to genomic loci annotated as protein-coding genes. This provides evidence for the transcription of hundreds of pseudogenes in the parasite. Conventional lncRNAs and pseudogenes are expressed in Trichomonas through their own transcription start sites and independently from flanking genes in Trichomonas. Expression of several representative lncRNAs was verified through reverse-transcriptase PCR in different T. vaginalis strains and case studies exclude the use of alternative start codons or stop codon suppression for the genes analysed.ConclusionOur results demonstrate that T. vaginalis expresses thousands of intergenic loci, including numerous transcribed pseudogenes. In contrast to yeast these are expressed independently from neighbouring genes. Our results furthermore illustrate the effect genome duplication events can have on the transcriptome of a protist. The parasite’s genome is in a steady state of changing and we hypothesize that the numerous lncRNAs could offer a large pool for potential innovation from which novel proteins or regulatory RNA units could evolve.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-906) contains supplementary material, which is available to authorized users.

The complete mitochondrial genome of the giant electric ray, Narcine entemedor (Elasmobranchii: Torpediniformes)

The complete mitochondrial genome of the giant electric ray is 17,081 bp long (GenBank accession KM386678) and includes 2 ribosomal RNA, 22 transfer RNA, 13 protein-coding genes, an origin of replication, 2 non-coding regions. The mitochondrial gene arrangement is similar to that found in other batoids. The control region possessed a set of tandem repeats. Start codon ATG and stop codon TAA/T were found in most protein-coding genes. The base composition of the genome is 36.2% A, 29.9% T, 21.9% C, and 11.9% G.

Experimental investigation of the evaporation characteristics of the fuel in a direct-injection spark ignition engine subjected to a direct-start process

Because stopping an engine in the idling state and quickly restarting the engine can improve the engine’s fuel consumption, this paper studied the direct start of a direct-injection spark ignition engine that does not require a larger electrical starter for the conventional start–stop system. The formation of the fuel–air mixture before the first combustion determines the success of the direct start because the explosion energy acquired from first combustion to move the crankshaft is relatively small. The purpose of this study is to explore the evaporation characteristics of the gasoline in a spray chamber that was designed to simulate the cylinder of a direct-injection spark ignition engine. Fundamental studies were conducted to investigate the evaporation process under direct-start conditions. A numerical study was also conducted using evaporation and wall interaction models. The measurements obtained using a fast-response flame ionization detector hydrocarbon detection system (HFR500) indicated that the evaporation ratio of the gasoline spray increased with increasing temperature and achieved an upper limit of 90% at an ambient temperature of 140 °C. The lower limit of the equivalence ratio for a successful direct start should be 1.4–1.7 when the temperature is less than 100 °C. Suitable ignition timing of the first combustion should be 25 ms after the start of injection. Methanol–gasoline and ethanol–gasoline were tested in this study, and a poor evaporation performance was observed owing to the higher evaporation heat values of these fuels. Consequently, gasoline is preferable to oxygenated fuels for the direct start of direct-injection spark ignition engines.

The mitochondrial genome of the banded guitarfish, Zapteryx exasperata (Jordan and Gilbert, 1880), possesses a non-coding duplication remnant region

The complete mitochondrial genome of the banded guitarfish is 17,310 bp long and includes 2 ribosomal RNA, 22 transfer RNA, and 13 protein-coding genes, a replication origin and a control region (GenBank accession number KM370325). Gene arrangement is similar to that found in other batoids. An extra non-coding region was found between the genes coding for transfer RNA proline and threonine possessing a set of tandem repeat motifs pointing to its origin as a duplication remnant. Start codon ATG and stop codon TAA/T were found in most protein-coding genes. The base composition of the genome is 32.3% A, 30.2% T, 24.3% C and 13.1% G.

Analysis of tilting-pad thrust bearing static instability and lubrication performance under the bistability

Purpose – The purpose of this paper is to analyze the problems of tilting-pad thrust bearing static instability and lubrication performance under static bistability. Design/methodology/approach – The static equilibrium state of tilting-pad thrust bearing is analyzed, and key parameters are extracted from the general lubrication model. Then, a distribution area of bearing static equilibrium points is achieved by solving the model. The area is divided into three sub-areas which represent monostabillity, bistability and instability, and an unstable boundary of the area is discovered. By these findings, a reversible lubrication failure phenomenon is explained. A calculation method is proposed to obtain bearing lubrication performance under the bistability. Findings – The variation of working conditions can lead to migration of unstable boundary and static instability. After resuming the working conditions, unstable boundary will resume in situ, and the bearing will operate steadily again. Moreover, there is a big difference between the two groups of lubrication performance solutions under the bistability. Practical implications – The static stability acceptance test of tilting-pad thrust bearing should be implemented under start–stop, accidental excitation and other conditions before service to prevent such lubrication failure phenomenon. Moreover, fulcrum position of the bearing pad should be kept away from the bistable area. Originality/value – This paper has preliminarily revealed a static instability mechanism of tilting-pad thrust bearing, analyzed bistability lubrication performance and proposed some suggestions to improve the bearing stability.

Occurrence of High Pressure Spike in Unidirectional Start–Stop–Start Point Contacts

The transient film thickness and pressure distributions in point elastohydrodynamic lubrication (EHL) contacts during start–stop–start motion are discussed based on experimental and numerical analyses. When the machine element starts to move after the stopping, where the oil is entrapped between two surfaces, the pressure at the exit area increases very much. The pressure increase depends markedly on the overall film thickness before the stopping of the motion, but is hardly controlled by the acceleration after the stopping. It can be considered that this phenomenon affects the rolling contact fatigue damage.

Effect of the start–stop cycle of center-pivot towers on irrigation performance: Experiments and simulations

The simulation of center-pivot performance has been the subject of research efforts since the 1960s. Center-pivot models frequently use empirical equations relating pressure and sprinkler radial application pattern. Individual, stationary water application patterns are overlapped and the resulting water application is mapped in the field. Such models use constant tower angular velocity, neglecting the effect of tower alignment. In this work the discontinuous tower movement has been experimentally characterized and modelled, and a complete model has been developed by using a ballistic model of the center-pivot sprinklers considering nozzle diameter, operating pressure and wind speed. A detailed kinetic analysis of a four-tower commercial center-pivot was performed. Each tower was monitored using a high precision GPS, recording tower positions at high frequency. The experimental center-pivot was equipped with fixed spray plate sprinklers (FSPS). Five experimental center-pivot irrigation events were evaluated using catch-cans. The analysis of tower location data permitted to conclude that two key variables (linear speed and switching angle) showed normal distribution patterns. The center-pivot model was validated with catch-can data. Finally, the simulation tool was used to assess the effect of variable tower alignment quality, center-pivot travel speed and wind conditions on irrigation performance. Comparisons were performed in terms of radial, circular and total irrigation uniformity. Results indicate that the observed tower dynamics had no measurable effect on irrigation uniformity. Tower alignment quality started to be relevant when the switching angle lag was equal to or larger than 2°. In the conditions of this analysis, wind speed showed a clear effect on uniformity. As wind speed increased, uniformity first decreased and then increased. Further research is required to generalize these results to other center-pivot sizes and designs (sprinkler packages).

The Stribeck curve as a suitable characterization method of the lubricity of biodiesel and diesel blends

The adequacy of Stribeck curves for the characterization of the lubricity of biodiesels, B20 blends and diesel fuel is demonstrated. Ball-on-disk tests in the speed range 2–1570 mm/s were performed to obtain the Stribeck plots and the results are compared to those from the conventional HFRR (high frequency reciprocating rig) ball-on-disk method (ASTM (American Society for Testing and Materials) D6079). Contrarily to the HFRR method, in the Stribeck tests very clear ball wear marks are seen without significant wear of the flat counterbody. These characteristics provide more confidence in the lubricity assessment of fuels. Moreover, in the Stribeck method higher lubricity at 60 °C is revealed for all biodiesels and the respective blends, related to the formation of protective oxide tribolayers. When evaluated by the HFRR test method, such temperature effect on the lubricity performance is not identified. From the point of view of the energy loss of the system, or friction response, lubricity is also better depicted by the Stribeck test method. The friction coefficient plots reveal that the major difference among the fuels occurs in the low velocity range, or in the start–stop stage of moving components, where the poorest lubricity is attained with the neat diesel fuel and the best lubricity with the animal fat biodiesel.

Based on PLC Control of Double Constant Pressure No Tower Water Supply System Design

In view of the traditional double motor constant pressure water supply system without tower in the operation process of the problem of short service life, the design of a new type of dual voltage no tower water supply control system. The control system uses PLC, soft starter and frequency converter technology, the soft starter can make the motor to realize soft start and soft stop, no impact on the motor, can extend the service life of the motor, avoid pumping station "door" damage, reduce repair costs and repair work. The running results show that, after the reformation of water supply system can save more than 21% energy, but also improve the quality and reliability of the water supply.

Influences of Tennis Shoe Sole with Different Materials on Athletes’ Movement

Different sole materials impose very important influences on athletes movement effects. Sole materials of tennis shoes to a large extent decide athletes start and sudden stop etc. Through the study of the influences of common abrasion resistant rubber, DRC abrasion resistant rubber and adiWEAR composite of tennis shoe soles on non-slip performance of the tennis shoes, it is concluded that DRC abrasion resistant rubber has the best effect on sudden stop of athletes; common abrasion resistant rubber is more beneficial to abrupt changes in athletes movement than adiWEAR composite, but in terms of start and acceleration, common abrasion resistant rubber is worse than adiWEAR composite. Meanwhile, common abrasion resistant rubber has better support effects for long-time competitions and is more beneficial to diversified movement changes of athletes.

Design of a power-split hybrid electric vehicle control system utilizing a rule-based controller and an equivalent consumption minimization strategy

The paper proposes a power-split hybrid electric vehicle control strategy that combines a rule-based controller, including a state-of-charge controller and engine start–stop logic, with a precisely formulated equivalent consumption minimization strategy. A one-dimensional directional search-based instantaneous equivalent consumption minimization strategy optimization and a two-dimensional directional search-based instantaneous equivalent consumption minimization strategy optimization are used to find optimal powertrain points in high-efficiency engine map regions that are previously determined by an offline optimization approach. The simulation results confirm that the rule-based controller performance can be significantly improved when extended with the proposed equivalent consumption minimization strategy formulation, without requiring an adaptive empirical penalty factor to satisfy the state-of-charge sustainability condition. The proposed rule-based + equivalent consumption minimization strategy control strategies were verified against a dynamic-programming-based optimization benchmark for different certification driving cycles.

Evaluation of lithium ion cells with titanate negative electrodes and iron phosphate positive electrode for start–stop applications

Start–stop systems require the battery to provide high power, endure shallow cycling, and exhibit long cycle life. The LFP/LTO (lithium iron phosphate/lithium titanate) battery is a potential candidate to meet such requirements because, at room temperature, both materials can be operated at high rate and have good stability (calendar and cycle life). In this work, we have investigated the feasibility of using LixFePO4/Li4+3yTi5O12 (0 < x < 1, 0 < y < 1) lithium ion batteries for start–stop systems. We evaluate both the rate and temperature dependence of LFP/LTO cells subjected to galvanostatic charge/discharge cycling. Excellent rate performance was observed at temperatures above or at ambient. However, at low temperatures, significant resistance is observed, and this must be addressed for the LFP/LTO system to be viable. In addition, we investigate the SOC dependence of equivalent circuit parameters using triangular current and voltage excitation method to facilitate the implementation of circuit-based control algorithms for vehicle applications. Parameter values are nearly constant over the broad voltage-plateau region of the substantially two-phase behavior of both the LFP and LTO materials.

Origin and Length Distribution of Unidirectional Prokaryotic Overlapping Genes

Prokaryotic unidirectional overlapping genes can be originated by disrupting and replacing of the start or stop codon of one protein-coding gene with another start or stop codon within the adjacent gene. However, the probability of disruption and replacement of a start or stop codon may differ significantly depending on the number and redundancy of the start and stop codons sets. Here, we performed a simulation study of the formation of unidirectional overlapping genes using a simple model of nucleotide change and contrasted it with empirical data. Our results suggest that overlaps originated by an elongation of the 3′-end of the upstream gene are significantly more frequent than those originated by an elongation of the 5′-end of the downstream gene. According to this, we propose a model for the creation of unidirectional overlaps that is based on the disruption probabilities of start codon and stop codon sets and on the different probabilities of phase 1 and phase 2 overlaps. Additionally, our results suggest that phase 2 overlaps are formed at higher rates than phase 1 overlaps, given the same evolutionary time. Finally, we propose that there is no need to invoke selection to explain the prevalence of long phase 1 unidirectional overlaps. Rather, the overrepresentation of long phase 1 relative to long phase 2 overlaps might occur because it is highly probable that phase 2 overlaps are retained as short overlaps by chance. Such a pattern is stronger if selection against very long overlaps is included in the model. Our model as a whole is able to explain to a large extent the empirical length distribution of unidirectional overlaps in prokaryotic genomes.

Optimal structural design of residential cogeneration systems in consideration of their operating restrictions

An optimal structural design model of a residential cogeneration system, known as combined heat and power, considering various kinds of operating restrictions is developed from the energy-saving viewpoint. As principal operating restrictions of cogeneration units, a constant power output operation, a daily start–stop operation, and a continuous operation are focused on. The developed model results in a mixed-integer linear programming problem and the selection and multi-period operation are simultaneously optimized. Moreover, the model is applied to the structural design of a residential cogeneration system, consisting of a cogeneration unit and its peripheral devices, for simulated energy demands in a Japanese residence. The candidates for a cogeneration unit are a gas engine employing a constant power output operation, a polymer electrolyte fuel cell employing a daily start–stop operation, and a solid oxide fuel cell employing a continuous operation, and the candidates for peripheral devices are an electric water heater and an air-cooled heat exchanger. The optimization results reveal that the selection of the cogeneration unit is influenced more by their operating restrictions than by the consistency in the heat-to-power ratios of the cogeneration unit and energy demands. In addition, it is found that the selection of the peripheral devices varies with the selected cogeneration unit and energy demands.