batterydata/paper-abstracts huggingface dataset:
This paper presents the results of a European study investigating the extent to which the Dynamic Approach to School Improvement (DASI) can help schools situated in socially disadvantaged areas to improve their effectiveness. At the beginning of the school year 2015–2016, a sample of 72 primary schools in four European countries (Cyprus, England, Greece and Ireland) was randomly allocated into the experimental and control groups. A questionnaire measuring the functioning of school factors related with the school learning environment, school policy for teaching and school evaluation was administered to all teachers of the school sample (n = 762). A battery of mathematics tests and a questionnaire measuring students’ socioeconomic status (SES) were administered to all students of grades 4–6 of the school sample (n = 5560). The experimental group made use of DASI to develop improvement strategies and action plans. Feedback was provided to the control group regarding their students’ achievement and the functioning of school factors in their school. Ιn each country, DASI had an effect on promoting student learning outcomes. For the control group of each country, the total effect of SES on student achievement at the end of the intervention was bigger than the effect of SES at the beginning of the intervention. No increase in the effect of SES was identified in the schools of the experimental group. Implications of findings for establishing a theory-driven and evidence-based approach to improve the quality and the equity dimensions of school effectiveness are discussed and suggestions for future studies are provided.
Photovoltaic (PV) generation of electricity is an important renewable energy source. One way to increase the value of small-scale renewable generators is to aggregate and control their output so they appear to the wider grid as one larger generator. This paper introduces our Virtual Power Station system which aggregates multiple geographically dispersed small-scale photovoltaic generators together to present to the wider electricity system as a single dispatchable quantity in an energy market. As such a quantity has greater benefit to the wider system than the individual responses of many uncoordinated energy sites, the Virtual Power Station can improve the payback period for renewable energy systems. This paper describes a Virtual Power Station deployment with a diverse range of sites, and PV output, which are then coordinated together with an intelligent battery controller. We also introduce an optimal control strategy that manages the energy storage to allow a firm commitment of output energy from the Virtual Power Station.
A nanoflakes assembled hydrangea-like Fe2O3@C@MoS2@C has been synthesized as anode material for lithium/sodium ion battery via hydrothermal method. In the as-prepared nanocomposite, Fe2O3 possesses a hollow ring structure with size of 80 nm and MoS2 shows the flower-like nanosheet morphology with thickness of 40 nm. When used as anode material for lithium ion battery, the nanocomposite shows excellent cycling stability and rate performance. It delivers a high reversible capacity of 1078 mAh g−1 after 200 cycles at a current density of 200 mA g−1, and a discharge capacity of 536.7 mAh g−1 even at a current density of 1000 mA g−1. Employed as anode materials for sodium ion batteries, it also provides an excellent reversible capacity of 498 mAh g−1after 200 cycles at a current density of 200 mA g−1. These excellent electrochemical performances can be attributed to the synergic effects of double carbon coating on the surface of Fe2O3 and MoS2, hollow ring of Fe2O3, and multi edge nanosheets of hydrangea-like MoS2. Double carbon layers can not only buffer huge volume change during Li/Na insertion/extraction process, but also enhance the electrical conductivity of Fe2O3 and MoS2. The multi-edged nanosheets of MoS2 are favorable for increasing Li/Na storage capacity of the nanocomposite. We believe that such nanocomposite of hollow rings of Fe2O3@C loaded with multi edged nanosheets of MoS2@C is a good candidate for high-performance lithium/sodium ion battery.
Micro-supercapacitors have attracted considerable research attention for on-chip energy storage due to their unique properties and potential applications in various smart electronic devices. Although significant advances have been reported on their power performances, they still cannot compete with micro-batteries in terms of energy densities for mobile, portable and self-powered applications. Herein, we demonstrate the fabrication of vertically aligned carbon nanowalls (CNW) decorated with porous ruthenium oxide as a high-performance electrode for all-solid-state micro-supercapacitors. The decorated CNW electrode, essentially consisting of thin carbon sheets assembled from graphene domains, delivers specific capacitance in excess of 1000mFcm−2 (which is three orders of magnitude higher than state-of-the-art micro-supercapacitors) and energy density comparable to that of lithium-ion micro-batteries, but with superior power and cycling stability. Our findings demonstrate a route towards the integration of microfabricated supercapacitors combining fast charge/discharge rates with high energy densities.
A flow field is an indispensable component for fuel cells to macroscopically distribute reactants onto electrodes. However, it is still unknown whether flow fields are also required in all-vanadium redox flow batteries (VRFBs). In this work, the performance of a VRFB with flow fields is analyzed and compared with the performance of a VRFB without flow fields. It is demonstrated that the battery with flow fields has a higher discharge voltage at higher flow rates, but exhibits a larger pressure drop. The maximum power-based efficiency occurs at different flow rates for the both batteries with and without flow fields. It is found that the battery with flow fields Exhibits 5% higher energy efficiency than the battery without flow fields, when operating at the flow rates corresponding to each battery's maximum power-based efficiency. Therefore, the inclusion of flow fields in VRFBs can be an effective approach for improving system efficiency.
Two new-mixed manganese–cobalt oxides for lithium battery positive electrode materials were obtained using original synthesis routes. Compound I, “LMCO” is a new form of LiMnCoO4 obtained by ion exchange from NaMnCoO4. Compound II, “MCO” is a nanometric material with formula Mn1−x Co x O≈2 obtained by quenching in specific conditions. We showed recently that the electrochemical properties of this materials were dramatically enhanced by cobalt doping [P. Strobel, F. Thiéry, C. Darie, O. Proux, A. Ibarra-Palos, M. Bacia and J.B. Soupart, J. Mater. Chem. 15 (2005) 4799]. The effect of cobalt content on its electrochemical behaviour is reported in detail here. Compound I gives rise to two reversible single-phase intercalation reactions centered at 2.7 and 4.4V on discharge, corresponding to Co3+/Co4+ and Mn3+/Mn4+ redox couples, respectively. The initial capacity is 160mAhg−1 at low regime, but stabilizes at ca.100mAhg−1 on extended cycling. Compound II gives a single plateau with a much higher capacity. An optimum ratio of Co:Mn=0.20 was found and gives a capacity of 175mAhg−1 after 60 cycles in the potential window 2.0–4.2V.
Flexoelectricity, as a fundamental electromechanical coupling effect between electric polarization and mechanical strain gradient, or vice versa between electric polarization gradient and mechanical gradient, exists in various categories of materials including solid materials, liquid crystals, polymers, and biomembranes. Dependence of electric or mechanical gradients on geometry requires the adoption of specific structures for different flexoelectric mode applications. Scaling effect associated with gradient suggests that flexoelectric effect can be more significant in micro/nano systems, comparable to or even exceed piezoelectricity. In this review, flexoelectricity in those studied materials will be summarized and compared. Applications in sensors, actuators, capability of tuning the ferroelectric thin film properties, and roles in bio-system mechanosensitivity and mechanotranduction of flexoelectricity will be introduced respectively. Especially, flexoelectricity nano-generator enlightens a new technique for energy harvesting. Comparison with piezoelectric nano-generator suggests that flexoelectric counterpart can yield enhanced performance with specific nanostructures and provide a wider materials choice.
Silicon nitride anodes are prepared by inductively-coupled-plasma and plasma-enhanced chemical vapor deposition techniques (denoted as ICP-CVD and PE-CVD respectively). The main difference of the ICP-CVD and PE-CVD anodes is considerable hydrogen content in the latter. The effects of hydrogen incorporation on the anode performance are investigated by comparing the ICP-CVD anode with the PE-CVD one. The capacity of the ICP-CVD anode maintains a low value (39 mAh g−1 for the 500-nm film) with cycling. For comparison, the capacity of the PE-CVD anode is negligible at first but increases abruptly after several cycles. The 500-nm PE-CVD anode delivers a reversible capacity of 881 mAh g−1 over 300 cycles at 0.6 C. A stable capacity of 773 mAh g−1 can still be obtained even when the anode increases to 900 nm. Due to weak strength of the hydrogen-containing bonds in the PE-CVD anode, hydrogen dissociation happens with cycling, which increases the anode conductivity and reaction kinetics, thus resulting in the high capacity. The hydrogen dissociation also leads to the formation of LiSixNy, which has a high ionic conductivity and also can act as a buffer matrix surrounding the active anode, thus helpful to improve the anode performance.
In this paper, a new charging strategy of lithium-polymer batteries (LiPBs) has been proposed based on the integration of Taguchi method (TM) and state of charge estimation. The TM is applied to search an optimal charging current pattern. An adaptive switching gain sliding mode observer (ASGSMO) is adopted to estimate the SOC which controls and terminates the charging process. The experimental results demonstrate that the proposed charging strategy can successfully charge the same types of LiPBs with different capacities and cycle life. The proposed charging strategy also provides much shorter charging time, narrower temperature variation and slightly higher energy efficiency than the equivalent constant current constant voltage charging method.
Concerns over environment and increased demand of energy have led the world to think about alternate energy sources such as wind, hydro, solar and fuel cells. Out of these, photovoltaic (PV) power generation systems have become increasingly important all over the world due its availability, cleanness, low maintenance cost and inexhaustible nature. But power produced by the photovoltaic system is stochastic in nature due to the variation of solar irradiation and cell temperature throughout the day. In order to track the varying power, a DC-DC converter with maximum power point tracker (MPPT) is used. Different MPPT algorithms have been proposed for tracking peak power from the PV panel. Selection of adequate DC-DC converter is also an important factor since it has an influence on overall performance of the PV system. This paper presents a comparative study on the characteristics of different non-isolated DC-DC converters and highlights the various research works that has been done on DC-DC converters based MPPT PV system. Study shows that selection of converter also has an impact on the overall performance of the PV system. Based on the survey and comparative study, selection criteria to choose DC-DC converter for PV system is described in this paper.
Piezoelectric nanowire based nanogenerator is a promising technology to harvest ambient mechanical energy. It is essential to experimentally quantify the strain–piezopotential relationship on nanowires for the development of high-output nanogenerators. In this paper, 3D Kelvin probe microscopy (3DKPM) is applied to precisely mapping the piezopotential along a bent ZnO microwire (MW). In order to remove the charge screening effect and recover the actual piezopotential generated by the MW, an external DC bias was applied along the axial direction of the bent MW. This external field drove charged species in and outside of the MW to the two oppositely-biased ends, respectively, and thus minimized the screening effect. We also developed a numerical method to calculate the strain distribution along the bent ZnO MW based on its scanning electron microscopy (SEM) image, with which the strain–piezopotential relationship was obtained. The overall theoretical and experimental relationships showed a good match, indicating 3DKPM under biased condition can be an effective approach for quantifying piezopotential from strained nanomaterials. The detected piezopotential is independent of screening charge and external screening effect, and is not affected by the sharp topography variation along the edge of wires. It could serve as an important methodology for revealing nanoscale piezoelectric and flexoelectric properties.
All-solid-state Li/S batteries with Li2S–P2S5 glass–ceramic electrolytes were fabricated and their electrochemical performance was examined. Sulfur–carbon composite electrodes were prepared by grinding with a mortar and milling with a planetary ball-mill apparatus. Milling of a mixture of sulfur, acetylene black and the Li2S–P2S5 glass–ceramic electrolyte resulted in the amorphization of sulfur and a reduction in the particle size of the mixture. The charge–discharge properties of all-solid-state cells with the composite electrode were investigated at temperatures from −20°C to 80°C. The cells retained a reversible capacity higher than 850mAhg−1 for 200 cycles under 1.3mAcm−2 (333mAg−1) at 25°C. The cell performance was influenced by the crystallinity of sulfur and the particle size of the electrode material, whereby improved contact among the electrode components achieved by milling contributed to enhancement of the capacity of an all-solid-state Li/S cell.
We present the open-source package openQ*D-1.0 (openQ*D. GitLab:
To solve the problem of grid instabilities, regulation in the Pumped Hydro Energy Storage (PHES) plants should quickly respond to the variation of electricity produced by unpredictable renewable energy. In this paper, a power reduction scenario applied to a pump turbine of a PHES is simulated considering the transient closure process of wicket gate. A novel dynamic mesh technique is applied to simulate the rotation of wicket gate vanes from best efficiency point to shutdown condition. Detached Eddy Simulation (DES) turbulence model is utilized to capture complex unsteady flow and the water weak compressibility effect is considered in the transient simulation. Flow rate, torque, power and pressure are analysed by the Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) methods. The results illustrate the delay between the performance parameters flow rate and power and the wicket gate opening angle. The closure of wicket gates affects the flow characteristics downstream the wicket gates greatly, causing intensive pressure fluctuations. The magnitude of pressure fluctuations downstream the wicket gate becomes the highest with the wicket gate closure of about 60%. Aside the blade passage frequency, a low frequency occurs, with the appearance of unsteady flow in pump turbine. Moreover, strong torque pulsations occur on the pin of the wicket vane when the percentage of closure is between 60% and 80%, with peaks much higher than that at the best efficiency point. The transient results can provide meaningful reference to the regulation law of wicket gate for safe operation of the pump turbine.
The design, fabrication, and initial analysis of a continuous energy harvesting and storage device for wireless sensor applications were undertaken. A Si nanowire-based photovoltaic (PV) device and Li ion battery were integrated onto a single Si substrate. The three terminal device consisted of separate positive terminals for each component and a shared negative electrode. The effect of Li+ incorporation into the planar PV electrode was evaluated. The current–voltage behavior of the PV device was tolerant to high Li+ concentrations. A titanium nitride layer between the battery and PV portions of the shared electrode was shown to be an effective diffusion barrier to Li+ incorporation.
There is increasing evidence supporting an association of higher serum vitamin D concentration with better cognitive performance in older individuals. However, to date, consideration of the putative association between vitamin D and cognition has been based principally on studies investigating clinical participant samples manifesting vitamin D deficiency, particularly in older people. Moreover, relationships between vitamin D and cognition are typically not considered in the context of counter-regulatory calcium-modulating hormones or calcium homeostasis.
Background Recent developments in vasectomy research indicate that occluding the vas using cautery combined with fascial interposition (FI) significantly lowers failure rates and is an appropriate technology for low-resource settings. We report the introduction of this technique in Ministry of Health (MOH) vasectomy services in Rwanda. Design In February 2010, an international vasectomy expert trained three Rwandan physicians to become trainers in no-scalpel vasectomy (NSV) with thermal cautery and FI. The training took place over 5 days in five rural health centers. Results A total of 67 men received vasectomies (11–16 per day) and trainees successfully mastered the new occlusion technique. The MOH is now scaling up NSV with cautery and FI services nationwide. The initial cadre of trainers has subsequently trained 46 other physicians in this vasectomy technique across 27 districts of Rwanda. Conclusions No-scalpel vasectomy with thermal cautery and FI was successfully introduced in vasectomy services in Rwanda, and a similar initiative should be evaluated in other national vasectomy services worldwide.
A statistically designed accelerated aging experiment was conducted to investigate the effects of aging time, temperature, and state-of-charge (SOC) on the performance of lithium-ion cells. In this experiment, a number of cells were stored in a variety of static aging environments ranging from 25°C and 60% SOC to 55°C and 100% SOC. The power output of each cell was monitored regularly over the course of 44 weeks via a low current level hybrid pulse power characterization test. A single empirical model of power fade, involving two concurrent degradation processes, was found to be applicable over a wide range of experimental conditions. The first degradation process is relatively rapid (nearly complete within 4 weeks) and is accelerated by temperature with unknown kinetics. The second degradation process (accelerated by temperature and SOC) is less rapid and exhibits time3/2 kinetics.
Cellulose, the most abundant organic polymer on Earth, is a sustainable source of carbon to use as a negative electrode for sodium ion batteries. Here, hard carbons (HC) prepared by cellulose pyrolysis were investigated with varying pyrolysis temperature from 700°C to 1600°C. Characterisation methods such as Small Angle X-ray Scattering (SAXS) measurements and N2 adsorption were performed to analyse porosity differences between the samples. The graphene sheet arrangements were observed by transmission electron microscopy (TEM): an ordering of the graphene sheets is observed at temperatures above 1150°C and small crystalline domains appear over 1400°C. As the graphene sheets start to align, the BET surface area decreases and the micropore size increases. To correlate hard carbon structures and electrochemical performances, different tests in Na//HC cells with 1M NaPF6 ethylene carbonate/dimethyl carbonate (EC/DMC) were performed. Samples pyrolysed from 1300°C to 1600°C showed a 300mAh/g reversible capacity at C/10 rate (where C =372mA/g) with an excellent stability in cycling and a very good initial Coulombic efficiency of up to 84%. Furthermore, hard carbons showed an excellent rate capability where sodium extraction rate varies from C/10 to 5C. At 5C more than 80% of reversible capacity remains stable for hard carbons synthesized from 1000°C to 1600°C.
To achieve a higher capacity and rate capability, the electrochemical performance of doped Li-rich layered oxide (LLO), in which Co and O ions are substituted with various dopants (Ti, Zr, Ce, Mo, W, and F), is investigated using first-principles calculations. W and Mo are candidate dopants to enhance the phase stability but are excluded due to the decreased average cell voltage of 2.5–5.4 %, lowering the energy density of a battery. Instead, F is selected as a promising dopant because F-doped LLO can achieve high structural stability without a reduction in the average cell voltage compared with un-doped LLO. The Li slab distance in F-doped LLO expands approximately 3–8% depending on the Li concentration, and the activation energy for Li hopping is reduced about 30%, suggesting faster Li ion diffusion. The enthalpy of formation of F-doped LLO is reduced to 5.3–12.4 kJ mol−1 during de-lithiation, implying an increase in phase stability. Based on the DFT prediction, we experimentally demonstrate F-doped LLO (Li1.17Ni0.17Co0.17Mn0.50O1.96F0.04) exhibits a high capacity of 252.2 mAh g−1 at 0.33C rate in the cut-off voltage range of 3.0–4.6 V. The rate capability is enhanced, and the capacity is retained up to 83% at 3C compared with the 0.33C rate.
The structure of polyvinylchloride (PVC) and polyethylene (PE)-separators was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). PE-separators are built up of a nanometer structured network of PE and silica. Carbon black is distributed equally with in the structure. After oxidation cracks appear which decrease the mechanical strength of PE-separator.
Radiation pneumonitis (RP) is a frequent complication of concurrent chemoradiotherapy (CCRT) and is associated with severe symptoms that decrease quality of life and might result in pulmonary fibrosis or death. The aim of this study is to identify whether pulmonary function test (PFT) abnormalities may predict RP in non-small cell lung cancer (NSCLC) patients.
We review the history of, and recent advances in, ferroelectric memory, including ferroelectric random access memory (FRAM or FeRAM). FRAM is the first among advanced non-volatile memories, such as magnetoresistive random-access memory (MRAM), phase-change random access memory (PRAM) and resistive random access memory (ReRAM), to be commercialized. Highly reliable FRAM with a memory density of a few Mb is currently available. Since FRAM has excellent electric properties, such as a high speed read/write (<50 ns), high switching endurance (≧1013) and low power consumption, it has been applied to radio frequency identification (RFID) tags, advanced smartcards and so on. We also describe newly developed materials, fabrication processes and circuit technology, which are expected to overcome the scalability problem of FRAM.