Initial Release Time Research Articles

Simultaneous identification of a non-point contaminant source with Gaussian spatially distributed release and heterogeneous hydraulic conductivity in an aquifer using the LES-MDA method

Space-temporal distribution of the contaminant plumes and aquifer properties is critical for groundwater management. However, most previous studies have focused on point source identification, barely exploring the identification of non-point sources. Xu et al. (2022) proposed to identify non-point sources but did not consider uncertainties in aquifer properties and release mass loading. In this work, we have implemented an application of the localized ensemble smoother with multiple data assimilation (LES-MDA) for the simultaneous identification of Gaussian hydraulic conductivities and non-point source parameters including Gaussian release mass-loading by assimilating both piezometric head and concentration observations in a synthetic confined aquifer. The results prove that the LES-MDA is not only capable of providing accurate identification of the spatial architecture of non-point contaminant sources and related release parameters (such as initial release time, and release duration) but also spatially heterogeneous release mass-loading and hydraulic conductivities.

Study on pyrolysis behavior of agricultural and forestry wastes using thermogravimetric‐Fourier transform infrared spectrometer (TG‐FTIR)

AbstractTo investigate the effective utilization of agricultural and forestry wastes for mitigating the shortage of primary energy and environmental pollution, the pyrolysis behavior of corn straw (CS), wheat straw (WS), and poplar sawdust (PS) was studied using thermogravimetric–Fourier transform infrared (TG‐FTIR) analysis. The activation energies and pyrolysis mechanism functions of different biomass types were calculated. The results showed that the functional group structures of the gaseous products generated from the pyrolysis of different biomass types were similar, mainly including OH, aliphatic CH, CO, aromatic ring skeleton, aromatic CH, and CO groups. These functional group structures mainly existed in oxygen‐containing compounds such as phenols, ketones, aldehydes, acids, esters, alcohols, and ethers. The pyrolysis process of agricultural and forestry wastes exhibited certain differences, with the PS undergoing thermal decomposition more easily, while the thermal decomposition mechanism functions of the two agricultural wastes (CS and WS) were similar. PS had a later initial release time for volatile matter, and the oxygen compounds produced by its pyrolysis were the highest, followed by WS and CS.

Joint identification of contaminant source based on the ensemble Kalman filter integrated with relation coefficient

To reduce the adverse influence of sudden water pollution accidents, it is essential to estimate the unknown contaminant source information (normally including the source location, initial release time, and total release mass) as soon as possible. The ensemble Kalman filter (EnKF) has been proven to be an effective algorithm for such an inverse problem. This paper proposes a new method based on EnKF to identify contaminant source information. The method we called RC-EnKF uses the relation coefficient of concentration instead of timely concentration as a state variable in the assimilation process. The advantage lies in the release source mass that can be decoupled from the parameter group of unknown contaminant information to improve the assimilation speed and reduce interference with the accuracy of assimilation. Two categories of cases are employed for validating the applicability and testing the performance compared with the traditional EnKF method in detail. Sensitivity analyses are carried out with different observation errors, number of observation sites, number of ensemble realizations, and model grid size. The results demonstrate that with the uncertain error of observation data, the RC-EnKF works nicely and shows superiority to the traditional EnKF method reflected in the strong immunity to interference from observation data errors and elevated efficiency with the requirement of fewer observation sites, ensemble realizations, and model grids. It illustrates that the RC-EnKF is a more efficient and robust method for estimating unknown contaminant source information.

Storage Reliability Assessment Method for Aerospace Electromagnetic Relay Based on Belief Reliability Theory

The aerospace electromagnetic relay (AEMR) is a key electronic component in aerospace and weaponry systems. It usually lacks sufficient test data to conduct an effective storage reliability assessment at its early development stage. Thus, this paper introduces the theory of belief reliability, a new theory in the field of reliability engineering. Under its theoretical framework, firstly, through the analysis of the storage degradation mechanism of AEMR, the performance degradation characterization parameters are selected to build a storage degradation model. Then, the failure criterion conditions of AEMR are analyzed, and the degradation characterization parameters are used as the ‘smaller the better’ performance parameters to build a margin equation. Then, the margin equation is combined with the storage degradation model, and the uncertainties of the model parameters are quantified to complete the belief reliability model of AEMR. Finally, a certain AEMR is used as the object for validation. In solving the belief reliability model, the manufacturing information of the product, the degradation simulation data, and the test data are fully utilized to solve the model parameters by utilizing the uncertainty maximum likelihood estimation (UMLE) method. The results show that the method can obtain more accurate assessment results with small test data samples, and the MAE is reduced, compared to only simulation data, by 29.3%. By analyzing the uncertainty of the model parameters, it is found that the main sensitive factor affecting the storage reliability of batch aerospace relays is the initial release time. It was also found that the accuracy of the calculations could be significantly improved by considering the uncertainty of the threshold values when calculating.

Principles of Fasciotomy Closure After Compartment Syndrome Release.

Acute compartment syndrome is a surgical emergency in the extremities resulting from increased compartmental pressure, requiring immediate fasciotomy to resolve muscular compromise. As the mainstay treatment, fasciotomies involve substantial skin incisions and are thus prone to complications such as skin necrosis, wound infection, and permanent disability. Multidisciplinary care instituted at the time of fasciotomy can facilitate timely closure and minimize the complication profile. Several approaches are available to enhance outcomes of fasciotomy wounds, and a comprehensive knowledge of these options affords the treating surgeon greater flexibility and confidence in optimal management. Common techniques include early primary closure, gradual approximation, skin grafting, and negative pressure therapy. There is currently no consensus on the best method of closure. The purpose of this study was to review fasciotomy wound management from the time of initial release to final closure. Highlights include preparation for closing these wounds; the various techniques for fasciotomy closure, including adjunct options; evaluation of timing and staging; and injury-specific features, such as fracture management, limited subcutaneous tissues, and hand fasciotomies. Combining the perspectives of orthopaedic and plastic surgery, this review evaluates the benefits of multiple closure methods and highlights the importance of planning closure at the time of release.

Spatiotemporal variability of water exchanges in the Pearl River Estuary by interactive multiscale currents

Driven by interactive multiscale motions, the water exchange between the Pearl River Estuary (PRE) and coastal seas exhibits complex spatial structures and significant temporal variability. In this study, the exposure time (θ‾) was calculated using the adjoint method to examine the spatiotemporal characteristics of water exchange and illustrate the substance movement pathway in the PRE and the adjacent shelf. Seasonal variations in water exchange are generally determined by subtidal motion in the estuary and adjacent shelf. In summer, the θ‾ gradually increases from approximately 5 days near the lower estuary to 15 days in the upper estuary. In winter, associated with the weaker river discharge and prevailing northeasterly winds, the water exchange is suppressed and θ‾ increases to approximately 35 days in the upper estuary. Owing to the surface/bottom subtidal offshore/onshore transport in the water column, the θ‾ of the bottom water increases by 10 days compared to the surface water. Outside the estuary, the seasonally reversing shelf current and onshore transport move the shelf substance back into the PRE. The θ‾ to the southwest and northeast of the PRE is approximately 5 and 10 days in summer and winter, respectively. Temporally, the interplay between the periodic tidal motion and shelf current induces a significant intra-tidal variation of θ‾, predominantly in the middle estuary, where the water exchange is sensitive to the initial release time. The θ‾ with the initial release time of high/low tide generally has shorter/longer values. The intra-tidal variation of θ‾ is approximately three days and two weeks in summer and winter, respectively. The distinct three-dimensional structure and intra-tidal variability of water exchange illustrated in this study help to better utilize fluid motion that refreshes the water inside the estuary.

Study on Release and Migration of Radionuclides under the Small Break Loss of Coolant Accident in a Marine Reactor

Using severe accident analysis program MELCOR, the small break loss of coolant accident (SBLOCA) analysis model was established for a marine reactor. The release and migration of radionuclides were analyzed during a severe accident induced by SBLOCA. The analysis of the hydrogen source term release showed that the maximum hydrogen release amount was 248.567 kg, and the hydrogen release amount accounted for less than 4% of the air volume. So, there would be no danger of hydrogen explosion accidents. The research mainly focused on the behaviors of the release, the transport, the retention, and the final distribution of inert gases represented by Xe, volatile gases represented by CsI, and nonvolatile nuclides represented by Ba. The results showed that the reactor core exposed completely with a lagging by 510 s and the initial release time of nuclides was lagged by 1916 s. The release shares of Xe in the primary circuit system, the containment, and the environment were 0.013%, 0.06%, and 32.71%, respectively. Also, Ba shared 0.016%, 0.0032%, and 3.28%, respectively, and CsI shared 0.0145%, 0.0012%, and 2.845%, respectively.

COVID-Net: a tailored deep convolutional neural network design for detection of COVID-19 cases from chest X-ray images

The Coronavirus Disease 2019 (COVID-19) pandemic continues to have a devastating effect on the health and well-being of the global population. A critical step in the fight against COVID-19 is effective screening of infected patients, with one of the key screening approaches being radiology examination using chest radiography. It was found in early studies that patients present abnormalities in chest radiography images that are characteristic of those infected with COVID-19. Motivated by this and inspired by the open source efforts of the research community, in this study we introduce COVID-Net, a deep convolutional neural network design tailored for the detection of COVID-19 cases from chest X-ray (CXR) images that is open source and available to the general public. To the best of the authors’ knowledge, COVID-Net is one of the first open source network designs for COVID-19 detection from CXR images at the time of initial release. We also introduce COVIDx, an open access benchmark dataset that we generated comprising of 13,975 CXR images across 13,870 patient patient cases, with the largest number of publicly available COVID-19 positive cases to the best of the authors’ knowledge. Furthermore, we investigate how COVID-Net makes predictions using an explainability method in an attempt to not only gain deeper insights into critical factors associated with COVID cases, which can aid clinicians in improved screening, but also audit COVID-Net in a responsible and transparent manner to validate that it is making decisions based on relevant information from the CXR images. By no means a production-ready solution, the hope is that the open access COVID-Net, along with the description on constructing the open source COVIDx dataset, will be leveraged and build upon by both researchers and citizen data scientists alike to accelerate the development of highly accurate yet practical deep learning solutions for detecting COVID-19 cases and accelerate treatment of those who need it the most.

Synthesis of ammonium persulfate microcapsule with a polyaniline shell and its controlled burst release

AbstractPolymer hydraulic fracturing is important for increasing production during petroleum exploitation. After fracturing, the high‐viscosity polymer should be completely decomposed by gel breakers (ammonium persulfate [APS]) to realize high conductivity in the proppant pack. A new series of polyaniline microcapsules loaded with APS for the preparation of delayed‐release gel breakers were synthesized via in situ polymerization. The silica nanoparticles were doped in polyaniline to control the release of the encapsulated APS. The morphology, shell wall thickness, and elemental composition of the microcapsules were characterized by scanning electron microscopy, transmission electron microscopy, and two‐dimensional scanned energy‐dispersive X‐ray spectroscopy. The results revealed that the microcapsules were irregularly spherical with average diameters of about 5–6 μm and had shell thicknesses of 150–300 nm, and the silica nanoparticles had been successfully doped in the polyaniline shell. The microcapsules had a burst release pattern, and their initial release time was precisely controlled by adjusting the concentration and temperature of the sodium hydroxide solution. With increased demands for high performance delayed‐release microcapsules, the prepared polyaniline microcapsules loaded with APS show great potential for practical applications in petroleum exploitation, self‐healing coating, fiber printing, and grease.

Integrated hydrogeophysical modelling and data assimilation for geoelectrical leak detection

Time-lapse electrical resistivity tomography (ERT) measurements provide indirectobservations of hydrological processes in the Earth's shallow subsurface at high spatial and temporal resolution. ERT has been used in the past decades to detect leaks and monitor the evolution of associated contaminant plumes. Specifically, inverted resistivity images allow visualization of the dynamic changes in the structure of the plume. However, existing methods do not allow the direct estimation of leak parameters (e.g. leak rate, location, etc.) and their uncertainties. We propose an ensemble-based data assimilation framework that evaluates proposed hydrological models against observed time-lapse ERT measurements without directly inverting for the resistivities. Each proposed hydrological model is run through the parallel coupled hydro-geophysical simulation code PFLOTRAN-E4D to obtain simulated ERT measurements. The ensemble of model proposals is then updated using an iterative ensemble smoother. We demonstrate the proposed framework on synthetic and field ERT data from controlled tracer injection experiments. Our results show that the approach allows joint identification of contaminant source location, initial release time, and solute loading from the cross-borehole time-lapse ERT data, alongside with an assessment of uncertainties in these estimates. We demonstrate a reduction in site-wide uncertainty by comparing the prior and posterior plume mass discharges at a selected image plane. This framework is particularly attractive to sites that have previously undergone extensive geological investigation (e.g., nuclear sites). It is well suited to complement ERT imaging and we discuss practical issues in its application to field problems.

Statistical analysis of the relationship between type II radio enhancement and solar energetic particle event

In this paper, we investigated 82 type-II radio burst events detected by some ground stations Learmonth, YNAO, and BIRS and spacecraft Wind/WAVES, STEREO/WAVES from January 2007 to December 2015. And we identified 39 events associated with radio enhancement and 43 events without enhancement. We found that: 1) The CME velocity, mass, kinetic energy and flare class with respect to type II radio enhancement events were generally higher than that of no enhancement events, and these properties in the solar energetic particle (SEP) events were significantly higher than that no SEP event, regardless of whether radio enhancement or not. 2) As shown in the characteristic time analysis, the initial release time of SEPs is generally earlier than the start time of radio enhancement, so we can the radio enhancement is only as a signature of the shock enhancement rather than the direct generator of SEP events. 3) Whether radio enhancement or not, the onset height of type IIs associated with SEP event is slightly lower than that of event without SEP. For the absence height, the SEP events are significantly higher than the no-SEP events, and that the absence height of enhancement events are also distinctly higher than that non-enhancement events, which reveals that the enhanced CME shock characterized by enhanced radio burst can keep propagating to more higher or further space. 4) When one fast and wide CME fully sweeps over another slow and narrow preceding CME, CME interaction can more easily generate radio enhancement, but no distinctive difference between SEP events and non-SEP events. So the results of this paper reveal that radio enhancement can be regarded as a manifestation of CME shock becoming strong during interacting with other CME, and the enhanced shock can accelerate the particle to generate large SEP events more easily. However, the type II radio enhancement is not the direct producer or causer that generate large SEP event.

Catalytic effects of CaO, Al2O3, Fe2O3, and red mud on Pteris vittata combustion: Emission, kinetic and ash conversion patterns

Abstract Catalytic effects of red mud (RM), calcium oxide (CaO), aluminum trioxide (Al2O3), and ferric oxide (Fe2O3) were quantified on the combustion, emission and ash characteristics of aboveground (PA) and belowground (PB) biomass of Pteris vittata using thermogravimetric, Fourier transform infrared, X-ray fluorescence and FactSage analyses. CaO affected the specific formation pathways of tar species and inhibited the CO2, HCN and SO2 emissions. Fe2O3 shortened the initial release time of the emissions. Al2O3 inhibited the final NO emission but did not control the N-containing products. RM catalyzed the combustion by suppressing the emissions. The enthalpy of PA was catalytically enhanced in the following order: CaO > RM > Fe2O3 > Al2O3. Only Fe2O3 increased the enthalpy of PB. The stationary index value of PB declined with the catalysts. The comprehensive combustion index of PA was high at 20 °C/min. Al2O3 reduced the risks of slagging, and fouling for PA and PB, while RM exerted a more pronounced effect on PA than PB. The fusion of low-melting point minerals accelerated the mass and heat transfers, and the ash melting. Activation energy was reduced by 275.99% with RM and by 119.82 and 115.81% with Al2O3, and Fe2O3 for PA, respectively. Our results pave the way for cleaner and sustainable production strategies with the catalytic biomass combustion.

Simultaneous identification of a contaminant source and hydraulic conductivity via the restart normal-score ensemble Kalman filter

Detecting where and when a contaminant entered an aquifer from observations downgradient of the source is a difficult task; this identification becomes more challenging when the uncertainty about the spatial distribution of hydraulic conductivity is accounted for. In this paper, we have implemented an application of the restart normal-score ensemble Kalman filter (NS-EnKF) for the simultaneous identification of a contaminant source and the spatially variable hydraulic conductivity in an aquifer. The method is capable of providing estimates of the spatial location, initial release time, the duration of the release and the mass load of a point-contamination event, plus the spatial distribution of hydraulic conductivity together with an assessment of the estimation uncertainty of all the parameters. The method has been applied in synthetic aquifers exhibiting both Gaussian and non-Gaussian patterns. The identification is made possible by assimilating in time both piezometric head and concentration observations from an array of observation wells. The method is demonstrated in three different synthetic scenarios that combine hydraulic conductivities with unimodal and bimodal histograms, and releases in high and low conductivity zones. The results prove that the specific implementation of the EnKF is capable of recovering the source parameters with some uncertainty and of recovering the main patterns of heterogeneity of the hydraulic conductivity fields by assimilating a sufficient number of state variable observations. The proposed approach is an important step towards contaminant source identification in real aquifers, which may have logconductivity spatial distributions with either Gaussian or non-Gaussian features, yet, it is still far from practical applications since the transport parameters, the external sinks and sources and the initial and boundary conditions are assumed known.

Inferring stratified parasitoid dispersal mechanisms and parameters from coarse data using mathematical and Bayesian methods.

Biological invasions have movement at the core of their success. However, due to difficulties in collecting data, medium- and long-distance dispersal of small insects has long been poorly understood and likely to be underestimated. The agricultural release of parasitic hymenoptera, a group of wasps that are critical for biological pest control, represents a rare opportunity to study the spread of insects on multiple spatial scales. As these insects are typically less than 1 mm in size and are challenging to track individually, a first-time biocontrol release will provide a known spatial position and time of initial release for all individuals that are subsequently collected. In this paper, we develop and validate a new mathematical model for parasitoid wasp dispersal from point release, as in the case of biocontrol. The model is derived from underlying stochastic processes but is fully deterministic and admits an analytical solution. Using a Bayesian framework, we then fit the model to an Australian dataset describing the multi-scale wind-borne dispersal pattern of Eretmocerus hayati Zolnerowich & Rose (Hymenoptera: Aphelinidae). Our results confirm that both local movements and long-distance wind dispersal are significant to the movement of parasitoids. The model results also suggest that low velocity winds are the primary indicator of dispersal direction on the field scale shortly after release, and that average wind data may be insufficient to resolve long-distance movement given inherent nonlinearities and heterogeneities in atmospheric flows. The results highlight the importance of collecting wind data when developing models to predict the spread of parasitoids and other tiny organisms.

Joint identification of contaminant source location, initial release time, and initial solute concentration in an aquifer via ensemble Kalman filtering

AbstractWhen a contaminant is detected in a drinking well, source location, initial contaminant release time, and initial contaminant concentration are, in many cases, unknown; the responsible party may have disappeared and the identification of when and where the contamination happened may become difficult. Although contaminant source identification has been studied extensively in the last decades, we propose—to our knowledge, for the first time—the use of the ensemble Kalman filter (EnKF), which has proven to be a powerful algorithm for inverse modeling. The EnKF is tested in a two‐dimensional synthetic deterministic aquifer, identifying, satisfactorily, the source location, the release time, and the release concentration, together with an assessment of the uncertainty associated with this identification.

A novel subcutaneous infusion delivery system based on osmotic pump: in vitro and in vivo evaluation

An economical, convenient portable drug delivery system combining osmotic pump with subcutaneous infusion was developed, which was composed of three primary components: water chamber, osmotic pump chamber and support base. Ceftriaxone sodium (CRO) was selected as the model drug and osmotic pump tablets were prepared. The influence of osmotic agents on drug release profiles was evaluated. As the adjustment made by the osmotic agents was limited, the compositions of semipermeable membrane were investigated to determine significant associations of factors based on orthogonal design. The in vitro release profiles of the optimum formulation achieved to the predetermined value (15 ± 3 min for the initial release time Ti and 5.75 ± 0.25 h for the extent release time Te). The pharmacokinetic profiles of this drug delivery system were evaluated in Beagle dogs. In vivo results demonstrated that the osmotic pump subcutaneous infusion administration was equivalent to intravenous injection administration in terms of bioavailability. Moreover, constant drug plasma levels with minimized fluctuations could be achieved with this osmotic pump subcutaneous infusion system, compared with intravenous injection.

Effect of FeSO<sub>4</sub> on the Reactivity of Petroleum Coke with CO<sub>2</sub> by TG-FTIR

The petroleum coke (refered to as PC) with the addition of FeSO4 was obtained by impregnation method, and the reactivity of PC with CO2 are analysed by TG.PC samples were heated from room temperature to 1300 °C with heating rate of 20 °C / min at the atmosphere of CO2 (40 ml/min) and N2 (60 ml/min).At the same time, FTIR spectral of the gasflowing was obtained every 30 seconds. The results show that the TG curve of raw petroleum coke begin to decline, and the CO peak in its 3D infrared spectrogram plot has appeared at the temperature of 1100°C, which proved that the raw petroluem coke (refered to as RPC) has reacted with CO2 at 1100°C. And as the FeSO4 added amount increased,the gasification beginning temperature and initial release time of CO are all in advance,which prove that FeSO4 can enhance the reactivity of PC carbon dioxide gasification.

On scheduling a single machine with resource dependent release times

We consider a single machine scheduling problem with resource dependent release times that can be controlled by a non-increasing convex resource consumption function. The objective is to minimize the weighted total resource consumption and sum of job completion times with an initial release time greater than the total processing times. It is known that the problem is polynomially solvable in O( n 4) with n the number of jobs. We describe an improved algorithm of complexity O( n log n). We show further how to perform sensitivity analysis on the processing time of a job without increasing the complexity.

Single machine scheduling problems with resource dependent release times

We consider two single machine scheduling problems with resource dependent release times that can be controlled by a non-increasing convex resource consumption function. In the first problem, the objective is to minimize the total resource consumption with a constraint on the sum of job completion times. We show that a recognition version of the problem is NP-complete. In the second problem, the objective is to minimize the weighted total resource consumption and sum of job completion times with an initial release time greater than the total processing times. We provide some optimality conditions and show that the problem is polynomially solvable.

Camitz palmaris longus abductorplasty for severe thenar atrophy secondary to carpal tunnel syndrome

This is a retrospective review of 29 patients (33 hands) who underwent a palmaris longus transfer because of severe thenar atrophy secondary to median nerve entrapment at the wrist. The mean follow-up was 17 months. Ninety-four percent of our patients were satisfied because their thumb function improved. Twenty-six of the patients had the transfer at the time of initial release of the carpal tunnel, and three patients had the transfer when the carpal tunnel was released a second time. The transfer helps with thumb palmar abduction, and the palmaris longus is an expendable muscle for transfer.