Cumulative Energy Density Research Articles

A Full Resolution of the 450 μm Extragalactic Background Light

The extragalactic background light (EBL) is the cumulative radiation outside the Milky Way. The determination of its corresponding primary emitting sources as well as its total energy level across the entire electromagnetic spectrum has profound implications for both cosmology and galaxy formation. However, the detailed origin of the EBL at far-infrared wavelengths, particularly those close to the peak of the cosmic infrared background, remains unclear. Here we report the results of our ongoing SCUBA-2 450 μm survey of 10 massive galaxy cluster fields. By exploiting the strong gravitational lensing offered by these clusters, we obtain significant counts down to an unprecedented depth of ∼0.1 mJy at this wavelength, about 10 times deeper than that reached by any other previous survey. The cumulative energy density based on the counts is 138.1 −19.3+23.9 Jy deg−2 or 0.45 −0.06+0.08 MJy sr−1. Comparing our measurements to those made by the COBE and Planck satellites, we find that at this flux density level, the 450 μm EBL is entirely resolved by our SCUBA-2 observations. Thus, we find for the first time that discrete sources produce fully to the 450 μm EBL, and that about half of it comes from sources with sub-mJy flux densities. Our deep number counts provide strong constraints on galaxy formation models.

A rechargeable Mg|O2 battery

SummaryRechargeable Mg|O2 batteries (RMOBs) offer several advantages over alkali metal-based battery systems owing to Mg’s ease of transport/storage in ambient environment, low cost originating from its high abundance, as well as the high theoretical specific energy of RMOBs. However, research on RMOBs has been stagnant for the past decade, largely owing to unacceptably poor electrochemical performance. Here, we present a RMOB that employs Mg anode, Mg((CF3SO2)2N)2-MgCl2 in diglyme (G2) electrolyte, and commercial Pt/C on carbon fiber paper (Pt/C@CFP) oxygen cathode. This battery demonstrates unparalleled improvement over existing RMOBs by rendering a discharge capacity over 1.6 mAh cm−2, achieving cycle lives up to 35 cycles with a cumulative energy density of ∼3.2 mWh cm−2 at room temperature. This RMOB system seeks to reignite the pursuit of novel electrochemical systems based on Mg-O2 chemistries.

Atomistic and macroscopic characterization of nanoscale thin film liquid-vapor phase change phenomena

Phase change characteristics of thin film liquid argon subjected to ultrafast boundary heating for different liquid film thicknesses (3 nm ~ 6 nm), boundary heating rates (8 × 109 K/s ~ 320 × 109 K/s) for different surface wetting conditions are main objectives of the present study. Molecular dynamics (MD) simulation has been conducted involving a three-phase domain where liquid and vapor argon (Ar) atoms are placed over the solid platinum-like (Pt) surface. Depending on the combination of boundary heating rate and liquid film thickness, two types of phase change phenomena have been observed namely-diffusive evaporation and explosive boiling. The variations in the system temperature, net evaporation number and wall heat flux normal to the surface over time are closely investigated to explicate the evolution of thin film phase change characteristics. Besides, to get a better understanding of phase change phenomena of thin film liquid, the time-averaged wall heat flux (qavg) obtained from the MD simulation has been compared with classical thermodynamics prediction. The thermodynamic heat flux (qtherm) values are in excellent agreement with the time-averaged wall heat flux (qavg) for diffusive evaporation cases while they differ significantly for explosive boiling cases. A comparative study has been performed on the estimation of cumulative energy density in the liquid film prior to the explosive boiling both from macroscopic as well as MD viewpoints based on simplified control volume approach. The cumulative energy density within the liquid film as obtained from macroscopic viewpoint reasonably matches with that obtained in MD approach for hydrophilic and super-hydrophilic surfaces. Interestingly, for all explosive boiling cases, accumulated energy density at the boiling explosion assumes a mean value with 95% confidence level within 5.6% of the mean, which refers to a critical condition in context to energy content of the liquid film in atomistic approach which is in agreement with other macroscopic model prediction.

A spiral shaped regenerative microfluidic fuel cell with Ni‐C based porous electrodes

Microchannel geometry, electrode surface area, and better fuel utilization are important aspects of the performance of a microfluidic fuel cell (MFC). In this communication, a membraneless spiral-shaped MFC fabricated with Ni as anode and C as a cathode supported over a porous filter paper substrate is presented. Vanadium oxychloride and dilute sulfuric acid solutions are used as fuel and electrolyte, respectively, in this fuel cell system. The device generates a maximum open-circuit voltage of ~1.2 V, while the maximum energy density and current density generated from the fuel cell are ~10 mW cm−2 and ~51 mA cm−2, respectively. The cumulative energy density generated from the device after five cycles are measured as ~200 mW after regeneration of the fuel by applying external voltage. The spiral design of the fuel cell enables improved fuel utilization, rapid diffusive transport of ions, and in-situ regeneration of the fuel. The present self-standing spiral-shaped MFC will eliminate the challenges associated with two inlet membrane-less fuel cells and has the potential to scale up for commercial application in portable energy generation.

Direct adhesion contrast patterning on PDMS substrate by ArF excimer laser scanning for on-demand printing of functional layers

Adhesion contrast planography (ACP) is a printing method wherein a difference in adhesion forces between a semi-dried ink layer and a polydimethylsiloxane (PDMS) surface is used to form fine patterns. In the present study, direct laser surface modification of PDMS surfaces by a 193-nm excimer laser aiming at the use as an ACP printing plate was investigated in order to realize on-demand printed electronics. Various processing parameters were investigated systematically, including laser energy, laser pulse repetition frequency, scanning rate, and a thin primer film composed of a silane coupling agent. The results showed that appropriate laser conditions for a subsequent ACP process were found such that a cumulative energy density given at silane coupling agent-mediated PDMS surfaces by laser irradiation was in the range of 8–11 mJ/mm2. Under such conditions, the adhesion force on the treated PDMS surface was changed from 2.3 to 3.8 μN against a silica probing sphere. Complementary atomic force microscopy measurements on the laser-treated and pristine PDMS surfaces showed a gradual increase of the surface stiffness of PDMS, validating the idea that laser irradiation induced a conversion of PDMS into a mineralized SiO2 network. To further test the applicability of the present process, several complicated shapes were also examined.

Design principles and field performance of a solar spectral irradiance meter

A solar spectral irradiance meter (SSIM), designed for measuring the direct normal irradiance (DNI) in six wavelength bands, has been combined with models to determine key atmospheric transmittances and the resulting spectral irradiance distribution of DNI under all sky conditions. The design principles of the SSIM, implementation of a parameterized transmittance model, and field performance comparisons of modeled solar spectra with reference radiometer measurements are presented. Two SSIMs were tested and calibrated at the National Renewable Energy Laboratory (NREL) against four spectroradiometers and an absolute cavity radiometer. The SSIMs’ DNI was on average within 1% of the DNI values reported by one of NREL’s primary absolute cavity radiometers. An additional SSIM was installed at the SUNLAB Outdoor Test Facility in September 2014, with ongoing collection of environmental and spectral data. The SSIM’s performance in Ottawa was compared against a commercial pyrheliometer and a spectroradiometer over an eight month study. The difference in integrated daily spectral irradiance between the SSIM and the ASD spectroradiometer was found to be less than 1%. The cumulative energy density collected by the SSIM over this duration agreed with that measured by an Eppley model NIP pyrheliometer to within 0.5%. No degradation was observed.

Stimulation and Inhibition of Arabidopsis Seed Germination with Repetitive Barrier Discharges Produced by Polarity‐Reversed Voltage Pulses

SUMMARYThis paper presents an experimental study of control of the germination of Arabidopsis seed with a barrier discharge produced by polarity‐reversed voltage pulses. 100 ns‐width polarity‐reversed pulses were applied to the seeds between plane electrodes covered by glass barriers. The electrode configuration allowed barrier discharge propagation along the seed surface at a relatively low voltage. After the discharge treatment, the seeds were incubated for 2 or 3 days to measure the germination rate. The relationships between the cumulative input energy density into the plasma and the germination rate were investigated. The germination rate was significantly reduced at 20 J/cm3. However, it increased at cumulative energy densities up to 50 J/cm3 and then decreased again on further energy input. These results suggest a superposition of two effects, stimulation and inhibition, of the discharge treatment on the germination of Arabidopsis seed. The results of Evans Blue dyeing of the discharge‐exposed seeds indicate that necrosis of the seed coat is caused by the discharge treatment.

Homogeneous Boiling Explosion Condition: From an Energy Point of View

When a liquid undergoes boiling by homogeneous nucleation during non-equilibrium heating is very important as the characteristics of the system before and after the occurrence of homogeneous boiling explosion is significantly different. In the present study, we studied homogeneous boiling explosion condition from an energy point of view: how much energy is required to boil the liquid by homogeneous nucleation from a given initial temperature. As a representative one, water heating at atmospheric pressure has been considered under three different heating conditions namely; i) linear heating at the boundary ii) high heat flux pulse heating and iii) liquid contact with high temperature surface. The analytical formulations for cumulative energy distribution in the liquid under various liquid heating conditions have been derived and the cumulative energy density within the liquid are calculated. It has been found that the instantaneous cumulative energy density very near to the liquid boundary is several times higher than that corresponding to the thermal penetration depth for all liquid heating cases. The present study shows that, the cumulative energy density at the boiling explosion over a characteristic liquid cluster being equal to the size of a critical embryo is independent of the heating parameter and for a given initial condition, it has been found to be almost constant for all liquid heating conditions. However, the cumulative energy density at the boiling explosion decreases as the liquid initial temperature increases for all liquid heating cases. The obtained results are compared with other numerical results reported in the literature for water subjected to uniform volumetric heating at atmospheric pressure.

A relationship to describe the cumulative impact of storm clusters on beach erosion

Estimation of erosion volumes for adequate dry beach buffer zones is commonly estimated on the basis of a single extreme event, such as the 1 in 100year storm. However, the cumulative impact of several smaller, closely spaced storms can lead to equal, if not more, dry beach loss, but this is often not quantified. Here we use a calibrated model for dune erosion, XBeach, to hindcast the cumulative erosion impact of a series of historical storms that impacted the Gold Coast, Queensland region in 1967. Over a 6-month period, four named cyclones (Dinah, Barbara, Elaine, and Glenda) and three East Coast Lows caused a cumulative erosion volume greater than the predicted 1 in 100year event. Results presented here show that XBeach was capable of reproducing the measured dry beach erosion volume to within 21% and shoreline retreat to within 10%. The storms were then run in 17 different sequences to determine if sequencing influenced final modeled erosion volumes. It is shown that storm sequencing did not significantly affect the total eroded volumes. However, individual storm volumes were influenced by the antecedent state of the beach (i.e. prior cumulative erosion). Power-law relationships between cumulative energy density (∑E) and eroded volume (∆V) as well as cumulative wave power ((∑P)) and eroded volume (∆V) both explained more than 94% of the modeled dry beach erosion for the 1967 storm sequences. When the relationship was compared with observed and modeled erosion volumes for similar beaches but different storm forcing, the inclusion of pre-storm beach swash slope (βswash) in the parameterization was found to increase the applicability of the power-law relationship over a broader range of conditions.

Stimulation and Inhibition of <i>Arabidopsis</i> Seed Germination with Repetitive Barrier Discharges Produced by Polarity-Reversed Voltage Pulses

SUMMARY This paper presents an experimental study of control of the germination of Arabidopsis seed with a barrier discharge produced by polarity-reversed voltage pulses. 100 ns-width polarity-reversed pulses were applied to the seeds between plane electrodes covered by glass barriers. The electrode configuration allowed barrier discharge propagation along the seed surface at a relatively low voltage. After the discharge treatment, the seeds were incubated for 2 or 3 days to measure the germination rate. The relationships between the cumulative input energy density into the plasma and the germination rate were investigated. The germination rate was significantly reduced at 20 J/cm3. However, it increased at cumulative energy densities up to 50 J/cm3 and then decreased again on further energy input. These results suggest a superposition of two effects, stimulation and inhibition, of the discharge treatment on the germination of Arabidopsis seed. The results of Evans Blue dyeing of the discharge-exposed seeds indicate that necrosis of the seed coat is caused by the discharge treatment.

Use of an instrumented disc coulter for mapping soil mechanical resistance

A soil mechanical resistance sensor with a large-diameter disc coulter was developed to delineate areas of differing soil strength across agricultural fields. The instrumented disc coulter consisted of a 76.2 cm disc with two depth-measuring sensors (rotary potentiometer and ultrasonic proximity sensor) along with a global positioning system (GPS) receiver to georeference operating depth measurements. The consistency and repeatability of the system response were evaluated by making six passes across long-term tillage comparison plots with different degrees of soil disturbance, including: 20 cm plowing, 15 cm disking, 30 cm chiseling, and no-till in several combinations. At the time of testing, standard soil cone penetrometer measurements were taken. The relationship between the average cone index in the 0–30 cm soil profile (CI 0–30 cm ) and the disc operating depth was evaluated. In addition, the cumulative energy density of the given depth of penetration defined as specific cone penetration energy (J m −2 or N cm −1) for each tillage plot was calculated using the cone index profiles. The average measured depth in each tillage plot was compared to the average predicted depth ( d ci) of a fixed specific cone penetration energy ( P ci). Static calibration tests on the depth sensors showed excellent linearity with coefficients of determination ( R 2) greater than 0.99. The results showed that, on the average, the changes in the depth measured with the rotary potentiometer were 44 and 68% of the changes in the depth measured with the ultrasonic proximity sensor while the disc coulter was passing across, or along, the tillage plots. This difference was primarily due to the sinkage of the tractor wheels. The depth measured with the ultrasonic sensor had significant correlation with both CI 0–30 cm and d ci. This was partially due to the fact that a significantly high correlation ( R 2 = 0.97) between the CI 0–30 cm and d ci was observed, which was not expected and originated from the type of soil profiles present. The instrumented disc coulter is a low soil disturbance system and could be used as an inexpensive and simple sensor to obtain information about the mechanical condition of the soil for spot tillage or other management decisions.

Effects of seismic energy releases on the survival and development of zoeal larvae of dungeness crab ( Cancer magister)

In blind, controlled field experiments, early Stage II zoeae of Dungeness crab ( Cancer magister DANA) were exposed to sounds from single discharges of a 13·8-litre array of seven air guns. Their survival and development were followed during subsequent laboratory culture. Immediate mortality was low (0 to 2%) and showed no significant difference between control and exposed larvae ( α > 0·05). Across all treatments and blocks of the experiment, survival to the molt to Stage III averaged 88·8%. The conditional Stage IV survival rate averaged 69·8%. The times to the molts to Stage III and Stage IV averaged 14·4 and 34·9 days, respectively. For immediate and long-term survival and time to molt, the field experiment revealed no statistically significant ( α > 0·05) effects on zoeae for exposures as close as I m from the array, nor for mean sound pressure as high as 231 dB re 1 μPa and cumulative energy density up to 251 J/M 2. Post hoc power calculations showed that any reduction in zoeal survival as a result of sound exposure was less than 7% for survival to Stage III and less than 12% for Stage IV conditional survival (1- β = 0·90, α = 0·05 one-tailed). The sound exposures in our study were at the maximum levels likely to be experienced by a zoea during an actual survey.

Effect of ultraviolet light, solar radiation, XeCl laser and xenon arc lamp on the nuclear track recording properties of CR-39

Abstract CR-39 nuclear track detectors were exposed in air to various light sources such as three ultraviolet (u.v.) lamps ( λ = 253.7, 300 and 350 nm ), a xenon chloride (XeCl) excimer laser ( λ = 308 nm ), a xenon arc lamp and sunlight. A visible change of colour (yellowing) of detectors under heavy doses was noticed with the first three sources. The exposure to u.v. light sources resulted in degradation of the surface and in an increase of the bulk ( V b ) and track ( V t ) etch rates at wavelengths of 253.7 and 350 nm, while at 300 nm no such increase was observed. In an attempt to explain this odd behaviour u.v. absorption spectra of CR-39 obtained after exposure to the various u.v. sources were also studied. However, no clear answer emerged. On the other hand, a slight enhancement in detector sensitivity ( V = V t / V b ) was observed for the samples exposed to 253.7 and 350 nm only. At a wavelength of 350 nm different exposure times resulted in different etch induction times. In fact, etch induction time for fission fragments shortened from 28 min for unexposed samples to 2 min in the samples exposed for 86 h and V b decreased with the depth of the plastic. On the other hand, the exposure to an excimer laser resulted in apparent softening of the surfaces for a cumulative energy density up to 30 J cm -2 and hardening started from 30 up to 230 J cm -2 . The laser hardening, however, was found to saturate above an exposure dose of 40 J cm -2 . The surface of the detectors was also damaged when exposed to a high dose from a xenon arc lamp. However, for shorter exposure times, the effect was a slight decrease in V b and V t . Finally, a controlled exposure to natural sunlight caused an increase of both the V b and V t up to 30 h of exposure, and saturation started after that, while no enhancement was noticed in V . Long exposures (2 months) resulted in constant V b , and increase in V t and V with etching time.

Estimation of the extreme values of wave-induced ship motions and accelerations for the First Nuclear Ship in Japan

For the purpose of predicting extreme values of ship motions and accelerations induced by waves on the First Nuclear Ship in Japan, a model test in the Ship Research Institute's experimental basin as well as theoretical computations were carried out. Firstly, the response character of the ship in regular waves was obtained and the influences of wave directions as well as ship speed upon the responses were investigated. Secondly, the power spectrum and the cumulative energy density of the responses in certain given irregular waves were obtained by two kinds of methods, the one experimental and the other theoretical. The short-term probability distribution of the ship responses in various sea states were determined and the extreme values expected to be encountered in the most severe sea state were estimated. Finally, the long-term distribution of the responses was calculated by using the short-term probability distributions of the above mentioned responses and the statistical probability of occurrence of sea state in the northern North Atlantic Ocean, from which the extreme values expected to encounter for long periods of time as one year or all her life could be estimated. The estimated extreme values were compared with those obtained by various methods already derived. As a result, it is recognized that the probable extreme values of accelerations and ship motions are within the design standard of safety for the nuclear ship.