381 research outputs found
Influence of surface coating on structure and properties of metallic lithium anode for rechargeable Li-O2 battery
Abstract Amorphous lithium phosphorous oxynitride film was coated directly on pre-treated lithium metal as anode of lithium air battery by radio-frequency sputtering technique from a Li 3 PO 4 target. The structure and composition of modified anode was analyzed before and after charge/discharge test in a lithium-air battery, which comprises 0.5 M LiNO 3 /TEGDME as the electrolyte and super P carbon as cathode. Batteries were galvanostatically discharged by an Arbin BT-2000 battery tester between open current voltage and 2.15 V vs. Li + /Li at various current regimes ranging from 0.1–0.4 mA/cm 2 . Compared with fresh lithium, LIPON-coated anode exhibited better electrochemical performance. Good charging efficiency of 90% at a narrower voltage gap with high ionic conductivity of 9.4 × 10 −5 S/cm was achieved through optimizing lithium pre-treated conditions, sputtering N 2 flows and suitable solute for electrolyte
Short-term effects of forest gap size on soil enzyme activity in a Platycladus orientalis plantation
IntroductionSoil enzymes play a critical role in organic matter decomposition and nutrient cycling in forest ecosystems. However, the effects of forest gaps on soil enzyme activities remain uncertain.MethodsThis study aims to investigate the short-term effects of forest gap size on soil enzyme activities in Platycladus orientalis plantations. We conducted a study in a 50-year Platycladus orientalis plantation in Xuzhou, sampling soils from three levels of forest gap size (4 m radius, S; 8 m radius, M and 12 m radius, L) at different positions (within gap, edge, and outside the gap) and control plots (CK, no gaps) 2a after the creation of gaps. Soil peroxidase, dehydrogenase, urease, and invertase activities were measured.ResultsSpecifically, we found that M and S gaps had significantly (p < 0.05) higher soil peroxidase activity at the outside position in April and October, respectively, than CK. Additionally, L gaps had significantly (p < 0.05) higher soil dehydrogenase activity at the outside position in April than CK. Furthermore, L and S gaps had significantly (p < 0.05) higher soil urease activity at the outside position in October and July, respectively, than CK. Lastly, L and S gaps had significantly (p < 0.05) higher soil urease activity at the outside position in July than CK.ConclusionOur findings highlight the significant impact of canopy gaps on soil enzyme activities, which has important implications for forest management and conservation
Optical limiting using Laguerre-Gaussian beams
We demonstrate optical limiting using the self-lensing effect of a
higher-order Laguerre-Gaussian beam in a thin dye-doped polymer sample, which
we find is consistent with our model using Gaussian decomposition. The peak
phase shift in the sample required for limiting is smaller than for a
fundamental Gaussian beam with the added flexibility that the nonlinear medium
can be placed either in front of or behind the beam focus.Comment: 3 pages, 4 figure
2-(Methoxymethyl)adamantan-2-yl 2-methylacrylate
The title compound, C16H24O3, has a cage-type molecular structure and is of interest with respect to its photochemical properties. The structure displays non-classical intermolecular C—H⋯O hydrogen bonding, which links the molecules into a three-dimensional network
Magnesia-stabilised zirconia solid electrolyte assisted electrochemical investigation of iron ions in the SiO2-CaO-MgO-Al2O3 molten slag at 1723 K
Production of metallic iron through molten oxide electrolysis using inert electrodes is an alternative route for fast ironmaking without CO2 emissions. The fact that many inorganic oxides melt at ultrahigh temperatures (>1500 K) challenges conventional electro-analytical techniques used in aqueous, organic and molten salt electrolytes. However, in order to design a feasible and effective electrolytic process, it is necessary to best understand the electrochemical properties of iron ions in molten oxide electrolytes. In this work, a magnesia-stabilised zirconia (MSZ) tube with a closed end was used to construct an integrated three-electrode cell with the “MSZ | Pt | O2 (air)” assembly functioning as the solid electrolyte, the reference electrode and also the counter electrode. Electrochemical reduction of iron ions was systematically investigated on an iridium (Ir) wire working electrode in the SiO2-CaO-MgO-Al2O3 molten slag at 1723 K by cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP) and potentiostatic electrolysis (PE). The results show that the electro-reduction of the Fe2+ ion to Fe on the Ir electrode in the molten slag follows a single two-electron transfer step, and the rate of the process is diffusion controlled. The peak current on the obtained CVs is proportional to the concentration of the Fe2+ ion in the molten slag and the square root of scan rate. The diffusion coefficient of Fe2+ ions in the molten slag containing 5 wt% FeO at 1723 K was derived to be (3.43 ± 0.06)×10-6 cm2 s-1 from CP analysis. However, a couple of following processes, i.e. alloy formation on the Ir electrode surface and interdiffusion were found to affect the kinetics of iron deposition. An ECC mechanism is proposed to account for the CV observations. The findings from this work confirm that zirconia-based solid electrolytes can play an important role in electrochemical fundamental research in high temperature molten slag electrolytes
Conservative State Value Estimation for Offline Reinforcement Learning
Offline reinforcement learning faces a significant challenge of value
over-estimation due to the distributional drift between the dataset and the
current learned policy, leading to learning failure in practice. The common
approach is to incorporate a penalty term to reward or value estimation in the
Bellman iterations. Meanwhile, to avoid extrapolation on out-of-distribution
(OOD) states and actions, existing methods focus on conservative Q-function
estimation. In this paper, we propose Conservative State Value Estimation
(CSVE), a new approach that learns conservative V-function via directly
imposing penalty on OOD states. Compared to prior work, CSVE allows more
effective in-data policy optimization with conservative value guarantees.
Further, we apply CSVE and develop a practical actor-critic algorithm in which
the critic does the conservative value estimation by additionally sampling and
penalizing the states \emph{around} the dataset, and the actor applies
advantage weighted updates extended with state exploration to improve the
policy. We evaluate in classic continual control tasks of D4RL, showing that
our method performs better than the conservative Q-function learning methods
and is strongly competitive among recent SOTA methods
Comparison of progressive collapse resistance of frame with specially shaped columns and frame with rectangular columns
Konstrukcije okvira od armiranog betona (RC - reinforced concrete) s posebno oblikovanim stupovima i RC konstrukcije okvira s pravokutnim stupovima su različite vrste konstrukcija s različitim poprečnim presjecima stupova. Predlaže se model za analizu progresivnog kolapsa RC okvira primjenom elementa greda-stup i veznog elementa na temelju programa OpenSees. Simulirao se progresivni kolaps eksperimentalnog okvira i rezultati proračuna su se poklapali s rezultatima dobivenim eksperimentom. Karakteristike progresivnog kolapsa okvira s posebno oblikovanim stupovima analizirale su se usporedbom otpora progresivnom kolapsu jednog okvira s posebno oblikovanim stupovima i onog s tri okvira s pravokutnim stupovima koji su konstruirani u skladu s tri različita principa. Vidjelo se iz rezultata da su otpor progresivnom kolapsu okvira s posebno oblikovanim stupovima i okvira s pravokutnim stupovima s istom armaturom pod istim seizmičkim ojačanjem, konstrukcijom i uvjetima primjene bili jednaki. Okvir s posebno oblikovanim stupovima bolje je reagirao u otporu na progresivni kolaps.RC frame structures with specially shaped columns and RC frame structures with rectangular columns are different types of structures with different column sections. A progressive collapse analysis model of RC frames was proposed using the beam-column element and joint element based on the program OpenSees. Progressive collapse performance of the experimental frame was simulated and the calculation results were in good agreement with the experimental results. The characteristics of progressive collapse performance of frames with specially shaped columns were studied by comparing the progressive collapse resistance of one frame with specially shaped columns with that of three frames with rectangular columns which were designed in accordance with three different principles. It was observed from the results that the progressive collapse resistance of frame with specially shaped columns and frames with rectangular columns with the same reinforcement under the same seismic fortification, design and application conditions were equivalent. The frame with specially shaped columns had a superior performance to resist progressive collapse
Penerapan Pendekatan Pengajaran Terbalik (Reciprocal Teaching) Untuk Meningkatkan Kemandirian Belajar Biologi Siswa Kelas Vii-g SMP N 5 Karanganyar Tahun Pelajaran 2010/ 2011
– The objective of this study is to improve student independence in learning biology by implementing Inverted Teaching Approach (Reciprocal Teaching) on Environmental Management material. This research is a classroom action research. This research was conducted in two cycles. Each cycle consisted of planning, implementation of the action,observation, and reflection. The subjects of the study were VII-G class students of SMP Negeri 5 Karanganyar in the academic year of 2010/2011. The number of the students was 32. The technique and instrumen of collectiing data were questionnaire, observation, and interviews. The technique of analyzing data was descriptive analysis techniques. Triangulation technique was used in data validation. The results proved that by implementing Inverted Teaching Approach (Reciprocal Teaching) students\u27 independence in learning biology enhanced. It is based on the results of questionnaires, observations and interviews. The questionnaire of students\u27 learning independence showed that the mean percentage of students\u27 achievement in each indicator in pre-cycle, cycle I, and cycle II was 67.97%, 72.55%, and 77.58% respectively. The observation of students\u27 learning independence showed that the mean percentage of students\u27 achievement in each indicator in pre-cycle, cycle I, and cycle II was 39.68%, 67.5%, and 80.62% respectively. It can be concluded that the implementation of Inverted Teaching Approach (Reciprocal Teaching) can enhance students learning independence
Temperature- and field angular-dependent helical spin period characterized by magnetic dynamics in a chiral helimagnet
The chiral magnets with topological spin textures provide a rare platform to
explore topology and magnetism for potential application implementation. Here,
we study the magnetic dynamics of several spin configurations on the monoaxial
chiral magnetic crystal via broadband ferromagnetic resonance (FMR)
technique at cryogenic temperature. In the high-field forced ferromagnetic
state (FFM) regime, the obtained frequency f vs. resonance field Hres
dispersion curve follows the well-known Kittel formula for a single FFM, while
in the low-field chiral magnetic soliton lattice (CSL) regime, the dependence
of Hres on magnetic field angle can be well-described by our modified Kittel
formula including the mixture of a helical spin segment and the FFM phase.
Furthermore, compared to the sophisticated Lorentz micrograph technique, the
observed magnetic dynamics corresponding to different spin configurations allow
us to obtain temperature- and field-dependent proportion of helical spin
texture and helical spin period ratio L(H)/L(0) via our modified Kittel
formula. Our results demonstrated that field- and temperature-dependent
nontrivial magnetic structures and corresponding distinct spin dynamics in
chiral magnets can be an alternative and efficient approach to uncovering and
controlling nontrivial topological magnetic dynamics.Comment: 29 pages (including Supporting Information), 7 figures, accepted by
SCIENCE CHINA Physics, Mechanics & Astronom
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