A Hybrid Neural Network Model for Marine Dissolved Oxygen Concentrations Time-Series Forecasting Based on Multi-Factor Analysis and a Multi-Model Ensemble

Dissolved oxygen(DO)is an important indicator of aquaculture,and its accurate forecasting can effectively improve the quality of aquatic products.In this paper,a new DO hybrid forecasting model is proposed that includes three stages:multi-factor analysis,adaptive decomposition,and an optimizationbased ensemble.First,considering the complex factors affecting DO,the grey relational(GR)degree method is used to screen out the environmental factors most closely related to DO.The consideration of multiple factors makes model fusion more effective.Second,the series of DO,water temperature,salinity,and oxygen saturation are decomposed adaptively into sub-series by means of the empirical wavelet transform(EWT)method.Then,five benchmark models are utilized to forecast the sub-series of EWT decomposition.The ensemble weights of these five sub-forecasting models are calculated by particle swarm optimization and gravitational search algorithm(PSOGSA).Finally,a multi-factor ensemble model for DO is obtained by weighted allocation.The performance of the proposed model is verified by timeseries data collected by the pacific islands ocean observing system(PacIOOS)from the WQB04 station at Hilo.The evaluation indicators involved in the experiment include the Nash–Sutcliffe efficiency(NSE),Kling–Gupta efficiency(KGE),mean absolute percent error(MAPE),standard deviation of error(SDE),and coefficient of determination(R^(2)).Example analysis demonstrates that:①The proposed model can obtain excellent DO forecasting results;②the proposed model is superior to other comparison models;and③the forecasting model can be used to analyze the trend of DO and enable managers to make better management decisions.

Relationship of Abundance of Oceanic Sea Skaters, Halobates in the Tropical Pacific Ocean to Surface Biomass and Chlorophyll/Oxygen Concentrations

Relationship of population density of oceanic sea skaters collected from tropical and subtropical zones in the Pacific Ocean was examined to chlorophyll concentration/Dissolved Oxygen concentration and biomass in surface sea water. The four parameters shown above were measured at the site of 12oN 135oN during the cruise, MR13-03 cruise, and at the site of 25oN 160oE during another cruise KH-14-02. Significant and positive correlation between all biomass (especially invertebrates) and population density of oceanic sea skaters collected with a Neuston-Net trailing during 15 min was shown in overall analysis on the data of the both samplings (p oN 160oE than that at 12oN 135oN with similar value of chlorophyll value (p oN 160oE than that at 12oN 135oN for keeping high density population of oceanic sea skaters.

Detection of Oxygen Based on Host-Guest Doped Room-Temperature Phosphorescence Material

Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response of the triplet excitons of phosphorescence to oxygen,pure organic room-temperature phosphorescence(RTP)materials have garnered widespread attention in recent years for oxygen detection.However,simultaneously achieving ultralong phosphorescence at room temperature and quantitative oxygen detection from pure organic host-guest doped materials poses challenges.The d ensely packed materials may decrease non-radiative decay to increase the phosphorescence,but are unsuitable for oxygen diffusion in oxygen detection.Herein,the oxygen sensitivity of host-guest doped RTP materials using 4-bromo-N,N-bis(4-(tertbutyl)phenyl)aniline(TPABuBr)as the host and 6-bromo-2-butyl-1H-benzo[de]isoquinoline-1,3(2H)-dione(NIBr)as the guest was developed.The doped material exhibits fluorescence-phosphorescence dual-emission behavior at room temperature.The tert-butyl groups in TPABuBr facilitate appropriate intermolecular spacing in the crystal state,enhancing oxygen permeability.Therefore,oxygen penetration can quench the phosphorescence emission.The observed linear relationship between the phosphorescence intensity of the doped material and the oxygen volume fraction conforms to the Stern-Volmer equation,suggesting its potential for quantitative analysis of oxygen concentration.The calculated limit of detection is 0.015%(φ),enabling the analysis of oxygen with a volume fraction of less than 2.5%(φ).Moreover,the doped materials demonstrate rapid response and excellent photostability,indicating their potential utility as oxygen sensors.This study elucidates the design and characteristics of NIBr/TPABuBr doped materials,highlighting their potential application in oxygen concentration detection and offering insights for the design of oxygen sensors.

Nitrogen removal from wastewater and bacterial diversity in activated sludge at different COD/N ratios and dissolved oxygen concentrations

The impact of the organic carbon to nitrogen ratio （chemical oxygen demand （COD）/N） in wastewater and dissolved oxygen （DO） concentration on carbon and nitrogen removal efficiency, and total bacteria and ammonia-oxidizing bacteria （AOB） communities in activated sludge in constantly aerated sequencing batch reactors （SBRs） was determined. At DO of 0.5 and 1.5 mg O2/L during the aeration phase, the efficiency of ammonia oxidation exceeded 90%, with nitrates as the main product. Nitrification and denitrification achieved under the same operating conditions suggested the simultaneous course of these processes. The most effective nitrogen elimination （above 50%） was obtained at the COD/N ratio of 6.8 and DO of 0.5 mg O2/L. Total bacterial diversity was similar in all experimental series, however, for both COD/N ratios of 6.8 and 0.7, higher values were observed at DO of 0.5 mg O2/L. The diversity and abundance of AOB were higher in the reactors with the COD/N ratio of 0.7 in comparison with the reactors with the COD/N of 6.8. For both COD/N ratios applied, the AOB population was not affected by oxygen concentration. Amplicons with sequences indicating membership of the genus Nitrosospira were the determinants of variable technological conditions.

An experimental study on ignition of single coal particles at low oxygen concentrations

An experimental study on the ignition of single coal particles at low oxygen concentrations (XO_(2)<21%) was conducted using a tube furnace. The surface temperature (Ts) and the center temperature (Tc) of the coal particles were obtained from the images taken by an infrared camera and thermocouples respectively. The ignition processes were recorded by a high-speed camera at different XO_(2) values and furnace temperatures Tw. Compared with literature experimental data obtained at a high XO_(2) value, the ignition delay time τi decreases more rapidly as XO_(2) increases at the low XO_(2) region. The responses of Ts and Tc to the variation of XO_(2) are different: Ts decreases while Tc remains nearly constant with increasing XO_(2) at a low XO_(2) value. In addition, τi is less sensitive to Tw while the ignition temperature Ti is more sensitive to Tw at a low XO_(2) value than in air. Observations of the position of flame front evolution illustrate that the ignition of a coal particle may change from a homogeneous mode to a heterogeneous or combined ignition mode as XO_(2) decreases. At a low XO_(2) value, buoyancy plays a more significant role in sweeping away the released volatiles during the ignition process.

Exploring the contribution of oxygen reduction reaction to Mg corrosion by modeling assisted local analysis

Oxygen reduction reaction(ORR)has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion.This work elaborates on the contribution of ORR to the total corrosion process of pure Mg at different impurity levels in NaCl electrolyte with the assistance of local techniques.A finite element based numerical model taking into account the contribution of ORR during the corrosion of the Mg test materials has been designed in this study considering the local oxygen concentration.Respective computational simulations were calibrated based on the experimental data and evaluated accordingly.Finally,the simultaneous monitoring of local concentration of H_(2) and O_(2),and the combined modeling study reveal the relation between ORR and hydrogen evolution reaction.

Prediction of oxygen concentration and temperature distribution in loose coal based on BP neural network

An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal. In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles, it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion. For laboratory conditions, we designed our own experimental equipment composed of a control-heating system, a coal column and an oxygen concentration and temperature monitoring system, for simulation of spontaneous combustion of block coal （13-25 mm） covered with fine coal （0-3 mm）. A BP artificial neural network （ANN） with 150 training samples was gradually established over the course of our experiment. Heating time, relative position of measuring points, the ratio of fine coal thickness, artificial density, voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables. Then our trained network was applied to predict the trend on the untried experimental data. The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal - 6% by covering the coal pile with fine coal, which would meet the requirement to prevent spontaneous combustion of coal stockpiles. Based on the prediction of this ANN, the average errors of oxygen concentration and temperature were respectively 0.5% and 7 ℃, which meet actual tolerances. The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles.

Effects of argon gas flow rate and guide shell on oxygen concentration in Czochralski silicon growth

φ200 mm silicon single crystals were grown in the φ450 mm hot zone of a Czochralski （CZ） furnace. By modifying the pattern and the velocity of the argon flow, the silicon single crystals with different oxygen concentrations were obtained. Through numerical simulation, the velocity of the argon gas flow was plotted for the first time. The experiment resuits were analyzed and the optimum condition of the argon flow with the lowest oxygen concentration was obtained.

Effect of Oxygen Concentration and Annealing Theatment on the Optical Properties of the Transparent Conductive CdIn_2O_4 Thin Films

Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε') and imaginary part (ε') of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also investigated

Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposecl to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

Atmospheric Pressure Cold Argon/Oxygen Plasma Jet Assisted by Preionization of Syringe Needle Electrode

An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.

Effects of oxygen concentration and irradiation defects on the oxidation corrosion of body-centered-cubic iron surfaces:A first-principles study

Oxidation corrosion of steels usually occurs in contact with the oxygen-contained environment, which is accelerated by high oxygen concentration and irradiation. The oxidation mechanism of steels is investigated by the adsorption/solution of oxygen atoms on/under body-centered-cubic(bcc) iron surfaces, and diffusion of oxygen atoms on the surface and in the near-surface region. Energetic results indicate that oxygen atoms prefer to adsorb at hollow and long-bridge positions on the Fe(100) and(110) surfaces, respectively. As the coverage of oxygen atoms increases, oxygen atoms would repel each other and gradually dissolve in the near-surface and bulk region. As vacancies exist, oxygen atoms are attracted by vacancies, especially in the near-surface and bulk region. Dynamic results indicate that the diffusion of O atoms on surfaces is easier than that into near-surface, which is affected by oxygen coverage and vacancies. Moreover, the effects of oxygen concentration and irradiation on oxygen density in the near-surface and bulk region are estimated by the Mc Lean’s model with a simple hypothesis.

Quantitative Determination of Density of Ground State Atomic Oxygen from Both TALIF and Emission Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence （TALIF） using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy （OES）. In this case, we compared the spectra intensities of a specific atomic oxygen line （844 nm） and the closest wavelength xenon line （823 nm）. The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon （1% Xe） of this chemically inert gas inside the air while a further small quantity of H2 （2~） is also added in the mixture in order to collect OH（A- X） and NH（A-X） spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09× 1017＋ 0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×101T cm-3.

Effects of oxygen concentration and flow rate on cognitive ability and physiological responses in the elderly

The supply of highly concentrated oxygen positively affects cognitive processing in normal young adults. However, there have been few reports on changes in cognitive ability in elderly subjects following highly concentrated oxygen administration. This study investigated changes in cognitive ability, blood oxygen saturation （%）, and heart rate （beats/min） in normal elderly subjects at three different levels of oxygen [21% （1 L/min）, 93% （1 L/min）, and 93% （5 L/min）] administered during a 1-back task. Eight elderly male （75.3 ＋ 4.3 years old） and 10 female （71.1 ＋ 3.9 years old） subjects, who were normal in cognitive ability as shown by a score of more than 24 points in the Mini-Mental State Examination-Korea, participated in the experiment. The experiment consisted of an adaptation phase after the start of oxygen administration （3 minutes）, a control phase to obtain stable baseline measurements of heart rate and blood oxygen saturation before the task （2 minutes） and a task phase during which the 1-back task was performed （2 minutes）. Three levels of oxygen were administered throughout the three phases （7 minutes）. Blood oxygen saturation and heart rate were measured during each phase. Our results show that blood oxygen saturation increased, heart rate decreased, and response time in the 1-back task decreased as the concentration and amount of administered oxygen increased. This shows that administration of sufficient oxygen for optimal cognitive functioning increases blood oxygen saturation and decreases heart rate.

Experimental Study of Dissolved Oxygen Transport by Regular Waves Through a Perforated Breakwater

The perforated breakwater is an environmentally friendly coastal structure, and dissolved oxygen concentration levels are an important index to denote water quality. In this paper, oxygen transport experiments with regular waves through a vertical perforated breakwater were conducted. The oxygen scavenger method was used to reduce the dissolved oxygen concentration of inner water body with the chemicals Na2SO3 and COC12. The dissolved oxygen concentration and wave parameters of 36 experimental scenarios were measured with different perforated arrangements and wave conditions. It was found that the oxygen transfer coefficient through wave surface, K1α1, is much lower than the oxygen transport coefficient through the perforated breakwater, K2α2. If the effect of K1α1 is not considered, the dissolved oxygen concentration computation for inner water body will not be greatly affected. Considering the effect of a permeable area ratio a, relative location parameter of perforations 6 and wave period T, the aforementioned data of 30 experimental scenarios, the dimensional analysis and the least squares method were used to derive an equation of K2α2 （K2α2=0.0042aσ56δ2T1）. It was validated with 6 other experimental scenarios data, which indicates an approximate agreement. Therefore, this equation can be used to compute the DO concentration caused by the water transport through perforated breakwater.

STUDY ON NODULE RATIO AND COMPACTED GRAPHITE RATIO OF IRON FLUID TREATED BY RARE EARTH MAGNESIUM ALLOY QUICKLY EXAMINED BY CONCENTRATED DIFFERENCE FIXING OXYGEN

The article uses the method of regression statistics to obtain the regression formula of iron fluid nodule ratio Q and compacted graphite ratio R, through rare earth magnesium treatment. At the same time it has given thejudging figure of Q and R, considering oxygen activity and temperature. When using oxygen activity to judgenodule ratio and compacted graphite ratio of the ironfluid treated by rare earth magnesium alloy, its limit value changes with the change of temperature.

The Influence of Oxygen on the Development of Nanorana parkeri Tadpoles

Ectothermic animals are tolerant of variable oxygen availability, whether low-oxygen levels constrain the fitness of ectotherms remains unclear. Nanorana parkeri, an anuran endemic to the southern Tibetan plateau, is an excellent model with which to answer this question. In this study, we raised tadpoles ofN. parkeri in oxygenated water （high-oxygen group） and deoxygenated unchlorinated tap water （low-oxygen group） and monitored their growth, mortality, and telomere length. The growth rate for body length and body weight was higher in the low-oxygen group than in the high-oxygen group. However, dissolved oxygen did not affect development time, mortality, and telomere length of the tadpoles. These results suggest that although the oxygen concentration influenced some phenotype traits of plateau tadpoles, but it didn＇t influence the telomere length and survival rate, potential explanations are the local adaptation and N. parkeri tadpoles＇ wide oxygen tolerance, and fluctuant toxic content that resulted in little oxidative stress on tadpoles. These results indicated that low oxygen was not a stress to N. parkeri tadpoles＇ fitness and survival. This study is helpful in understanding the adaptation mechanisms of Tibetan plateau amphibians.

Multiple Respiratory Gas Monitoring Causes Changes of Inspired oxygen Concentration in Closed Anesthesia System

Effect of multiple respiratory gas monitoring (MRGM ) on inspiredconcentration of oxygen in circult system during closed anesthesia was studied in 5l adult patients scheduled for abdominal surgery. Required flow rate of fresh oxygen (OFR), inspired oxygen concentration (FiO2 ) and oxygen saturation of pulse oximeter (SpO2) were measured continu0usly. Patients were equally divided into three groups at randorn, group C (no MRGN used ), group M, (using MRGM with its tail gas returned to circuit system), group M2 (using MRGM without tail gas returned ). The results revealed that during 180 min of closed anesthesia, OFR required in group C and M, were about 200-230 ml/min, and in group M, it was ab0ut 400 ml/min. In group C FiO2 decreased by about 10 % after 60 min of closed anesthesia (P<0. 01, 60 min vs 0 min ) and then stayed stable at this level. In group M,, FiO2 decreased by 16% at 60 min and 34 % at 180 min and the decrease was significantly greater than that in gr0up C (P<0. 01). In group Me, FiO2 remained c0nstant during closed anesthesia, which was much high(Jr than those in group C and M,. The tail gas of Capnomac Ultima MRGM contained less oxygen than its sample gas drawn fr0m circuit system simuItaneously.

Effects of Oxygen Concentration in Monocrystalline Silicon on Reverse Leakage Current of PIN Rectifier Diodes

The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.

Simulation of VGT control based on charge oxygen concentration

A turbocharged diesel engine model was built with the GT-Power software,and experimentally verified.Then two different control variables for the control of the variable geometry turbocharger（VGT）were described,and their distinct effects on engine performance,i.e.NOxand soot emissions and fuel consumption,were simulated and compared on the basis of this model.The results showed that NOxemissions decreased obviously with the increase of exhaust gas recirculation（EGR）rate at constant boost pressure condition,but soot emissions and fuel consumption considerably increased.It was a good way to reduce NOxemissions without increasing fuel consumption and soot emissions when VGT was controlled to maintain the excess oxygen ratio unchanged as EGR rate increases.