Emission Measurements Research Articles

On-road measurement of post-catalyst ammonia emissions from gasoline and hybrid vehicles using quantum cascade laser detector.

Ammonia emissions from gasoline vehicles have been confirmed an essential precursor of urban secondary aerosols. To more comprehensively understand the formation mechanisms and better control vehicle-related ammonia, this paper measured the on-road ammonia emissions from six conventional and four hybrid vehicles using a state-of-the-art Quantum Cascade Laser analyzer on urban, rural, and highway routes. The test vehicles emitted 0.01 to 4.27 mg/km of ammonia emissions, with a fleet average of 1.04 mg/km. Compared to the previous laboratory tests, the results of this study were low because of the high emission standards of the vehicles and the near-zero emissions during rural driving. Most test vehicles showed high ammonia emissions during engine warm-up, while some vehicles also had ammonia peaks during dynamic highway driving. On average, hybrid vehicles emitted 60.7% less ammonia emissions than the conventional candidates. It is confirmed that ammonia was formed when incomplete oxidation products presented on a warm catalyst. Engine warm-up, dynamic highway driving, particulate filter regeneration, and hybrid engine re-starting could be important sources. It is hypothesized that the ammonia formed on the upstream catalyst could be consumed by the downstream catalyst at moderate catalyst temperature, resulting in the near-zero ammonia emissions during rural driving.

Alternative Analyzers for the Measurement of Gaseous Compounds During Type-Approval of Heavy-Duty Vehicles

Emissions standards describe the fuels, the procedures, and, among others, the analyzers to be used for the measurement of the different compounds during the type-approval of heavy-duty engines and vehicles. Traditionally, NOx, CO, hydrocarbons, and CO2 were the gaseous compounds measured within the Euro standard, with the later addition of CH4 and NH3. Euro 7, introduced in early 2024, expanded those compounds, requiring the measurement of N2O and HCHO. With an increasing number of molecules that need to be measured and introducing carbonless fuels, such as hydrogen, that present different requirements compared to carbon-based fuels, the test procedure needs to be updated. The performances of three laboratory-grade instruments and three portable emissions measurement systems based on Fourier-transformed infrared (FTIR) or quantum cascade laser infrared (QCL-IR) technologies were investigated while measuring from the tailpipe of a Diesel engine and a compressed natural gas (CNG) vehicle. All instruments presented good agreement when emissions of NOx, CO, CH4, NH3, N2O, HCHO, and CO2 were compared using: Z-score, F-test and two tail t-test of student. Water concentration measured by the four FTIRs was also in good agreement. Moreover, the dry emissions of CO2 and CO measured by the laboratory non-dispersive infrared (NDIR) and corrected using water were a few percentages different from those obtained using the regulated carbon-based approach. The results indicate that all the investigated systems are suitable for the measurement of the investigated gaseous compounds, including CO2 and H2O.

Prediction of the Released Mechanical Energy of Loaded Lap Shear Joints by Acoustic Emission Measurements

In lightweight design, the usage of different optimised materials is widespread. The interfaces between two different materials are prone to damage and, therefore, the Structural Health Monitoring (SHM) of these areas is of interest. A new method for the damage evaluation of joints is developed and validated. The released mechanical energy (RME) during static loading of a metal–composite lap shear joint is considered as a damage assessment parameter and is set into relation to the detected Acoustic Emission (AE) energy. Eleven specimens with identical geometry but different surface treatments are used to form a statistical database for the method, i.e. to calculate the energy ratio and the fluctuation range, and the twelfth specimen is used for the validation of the method. The energy ratio varies significantly, but, considering the fluctuation analysis, the RME with a known range can be predicted on the basis of the AE signal. The whole process is repeated twelve times to validate the methodology. This method can be applied to different geometries and load cases without sophisticated modelling of the damage behaviour. However, load–displacement curves of the pristine joint need to be known, and the monitored joints need to be damage-tolerant and must show similar damage behaviour.

GREEN LOGISTICS PRACTICES AND FIRM PERFORMANCE: THE MEDIATING EFFECT OF ENVIRONMENTAL PERFORMANCE AMONG LOGISTICS FIRMS IN KENYA

Objective: The objective of this study was to determine the effect of green logistics practices on performance and mediating effect of environmental performance on this relationship in logistics companies in Kenya. Theoretical Framework: This study is anchored on the resource-based view and the natural resource-based view. Method: The study employs cross-sectional survey research design. A structured questionnaire is used to collect data from a sample of 300 firms which is analyzed using CB-SEM. Results and Discussion: Study establishes a significant positive relationship between green logistics practices and performance which is in line with the argument of the natural resource-based view. Secondly, the mediating effect of environmental performance on the relationship between green logistics practices and firm performance is found to be non-significant. Research Implications: The study recommends that logistics firms should implement environment-friendly practices of green packaging, route optimization, fuel efficiency, carbon emission measurement and reverse logistics. The expenses associated with implementing these practices impede the firm’s ability to improve performance in the context of a developing country. The findings provide a basis for the development regulatory framework in pursuit of environmental sustainability. Originality/Value: Research on ecological sustainability has mainly concentrated on the entire supply chain. This study concentrates on the logistics aspect which is responsible for a quarter of emissions of Green House Gases (CHGs). The research employs a measurement model of green logistics practices construct in the service sector hence moving away from the manufacturing organizations.

A Measurement Device for the Normal Spectral Emissivity of Materials Under Low-Temperature and Vacuum Conditions

Based on parallel light, a device for measuring sample emissivity under vacuum and low temperature was established. In this paper, a new emissivity measurement formula was designed, which replaces the derivation of Kirchhoff’s law of thermal radiation. The device is designed with a light-weight blackbody, an improved cooling speed, and an improved PID temperature control system to achieve a good temperature stability, close to 1 mK. The device is capable of measuring within a wavelength range of 4 μm to 16 μm. The results of the uncertainty assessment show that the uncertainty of the normal emissivity is better than 1.6% in the range of 4 μm to 7 μm, and better than 0.6% in the range of 7 μm to 14 μm (k = 1) at 0 °C.

Dual-Responsive Nanoparticles for Smart Drug Delivery: A NIR Light-Sensitive and Redox-Reactive PEG-PCL-Based System.

Stimuli-responsive polymeric nanoparticles (NPs) can serve as smart drug delivery systems (DDSs) by triggering drug release upon external or internal stimuli. A dual-responsive DDS made of a triblock poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-SS-PEG-SS-PCL) copolymer, bearing disulfide bonds between PCL and PEG, was synthesized. The copolymer was functionalized with coumarin and sensitive to near-infrared (NIR) light irradiation, while the S-S bonds could be cleaved by GSH (10 mM). Characterization was achieved by nuclear magnetic resonance, size exclusion chromatography, and Fourier transform infrared analyses. Nile Red (NR)-loaded NPs were prepared through self-assembly of the copolymer in water and analyzed by dynamic light scattering and field-emission scanning electron microscopy. The NR release upon ultraviolet (UV)/NIR light irradiation as well as by GSH concentrations was monitored by using fluorescence spectroscopy, while simultaneous exposure to UV/NIR light and intracellular GSH concentration led to faster NR release. AlamarBlue assay showed satisfactory cell viability of the NR-loaded NPs, while their cellular uptake in human dermal fibroblast cells was investigated by fluorescence microscopy and fluorescence emission measurements.

Analysis of Carbon Footprint from a Drilling Project in Niger Delta, Nigeria

Abstract: The oil and gas industry plays a significant role in the release of carbon emissions into the atmosphere. Therefore, it is crucial to accurately gauge and minimize its carbon footprint which requires the thorough measurement of emissions and the identification of the primary sources of carbon emissions. By doing so, we can then determine the most effective methods for reducing these emissions. This study aims to precisely quantify and decrease the carbon footprint associated with drilling operations. To achieve this, we evaluated the diesel and petrol consumption from an onshore drilling project in the Niger Delta and used an emissions model to assess carbon dioxide (CO2) emissions from a drilling rig, thus gaining a comprehensive understanding of current emission levels and the potential for reduction. The data collected included the daily fuel consumption for power generation, transportation, and handling vehicles. The CO2 emissions resulting from fuel consumption were calculated and measured to be 103.5 metric tonnes. Our analysis determined that the primary contributor to the emissions was the energy generation on the site, primarily from the generators. Additionally, it was found that the circulating system on the rig was the main source of CO2 emissions. The study underscores the necessity for long-term impact assessments of drilling fluids and new technologies, emphasizing the need for innovative solutions to further decrease emissions.

Study on the Thermal Control Performance of Mg-Li Alloy Micro-Arc Oxidation Coating in High-Temperature Environments

This paper reports on the successful preparation of a low absorption–emission thermal control coating on the surface of LAZ933 magnesium–lithium alloy using the micro-arc oxidation method. This study analyzed the microstructure, phase composition, and thermal control properties of the coating using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), UV–visible near-infrared spectroscopy (UV-VIS-NIR) and infrared emissivity measurements. The results indicate that the hemispherical emissivity of the coating remains unaffected with an increase in temperature and holding time, while the solar absorption ratio gradually increases. The thermal control performance of the coating after a high-temperature experiment was found to be related to the diffusion of the Li metal element in the magnesium lithium alloy matrix, as determined by X-ray photoelectron spectroscopy (XPS), flame graphite furnace atomic absorption spectrometry (GFAAS) and Glow Discharge Optical Emission Spectroscopy (GD-OES). As the holding time is extended, the coating structure gradually loosens under thermal stress. The Li metal element in the substrate diffuses outward and reacts with O2, H2O and CO2 in the air, forming LiO2, LiOH, Li2CO3 and other products. This reaction affects the coating’s solar absorption ratio in the end.

Deciphering the Evolution of Thermodynamic Properties and their Connection to the Global Kinematics of High-Speed Coronal Mass Ejections Using FRIS Model

Abstract Most earlier studies have been limited to estimating the kinematic evolution of coronal mass ejections (CMEs), and only limited efforts have been made to investigate their thermodynamic evolution. We focus on the interplay of the thermal properties of CMEs with their observed global kinematics. We implement the Flux rope Internal State (FRIS) model to estimate variations in the polytropic index, heating rate per unit mass, temperature, pressure, and various internal forces. The model incorporates inputs of 3D kinematics obtained from the Graduated Cylindrical Shell (GCS) model. In our study, we chose nine fast-speed CMEs from 2010 to 2012. Our investigation elucidates that the selected fast-speed CMEs show a heat-release phase at the beginning, followed by a heat-absorption phase with a near-isothermal state in their later propagation phase. The thermal state transition, from heat release to heat absorption, occurs at around 3(±0.3) to 7(±0.7) R⊙ for different CMEs. We found that the CMEs with higher expansion speeds experience a less pronounced sharp temperature decrease before gaining a near-isothermal state. The differential emission measurement (DEM) analysis findings, using multi-wavelength observation from SDO/AIA, also show a heat release state of CMEs at lower coronal heights. We also find the dominant internal forces influencing CME radial expansion at varying distances from the Sun. Our study shows the need to characterize the internal thermodynamic properties of CMEs better in both observational and modeling studies, offering insights for refining assumptions of a constant value of the polytropic index during the evolution of CMEs.

Uncovering upconversion photoluminescence in layered PbI2 above room temperature.

As a van der Waals (vdW) layered semiconductor material, lead iodide (PbI2) possessing a direct bandgap with strong photoluminescence emission in visible range has gained wide attention in applications of photonic and optoelectronic devices. Here, upconversion photoluminescence (UPL) in exfoliated PbI2 flakes is demonstrated at room temperature and elevated temperatures. The linear power dependence of UPL emission with 532nm excitation suggests the one-photon involved multiphonon-assisted UPL emission process, which is revealed by the temperature-dependent UPL emission measurement. Meanwhile, the nonlinear power dependence of UPL emission with 561nm excitation indicates the transition of UPL emission mechanism from linear to nonlinear regime, and the temperature-dependent UPL emission study further shows that the upconversion is contributed by both the multiphonon-assisted UPL process and the two-photon absorption induced PL process. This study will provide an insight to the understanding of photon upconversion in vdW layered semiconductors and advancing applications in temperature-controlled photon upconversion, tunable photonics, photodetection and imaging.

Non-invasive methods to assess seed quality based on ultra-weak photon emission and delayed luminescence.

Seed quality is the set of physical, genetic, and physiological characteristics, reflecting the overall germination potential. Maintaining an optimal seed quality is essential for agriculture and seed banks to preserve genetic diversity. Compared to conventional methods (e.g., germination tests), non-invasive approaches allow a more sustainable and rapid evaluation of seed quality but this is limited by high costs. The measurement of ultra-weak photon emission (UPE) and delayed fluorescence (DL), defined as biological phenomena potentially related to the physiological status of living systems, may represent a suitable approach to estimate seed quality. To test this hypothesis, seeds of five agriculturally relevant legume species (Phaseolus vulgaris L., Lathyrus sativus L., Cicer arietinum L., Pisum sativum L., and Vicia faba L.), stored at different conditions (room temperature or -18°C) for several years, were analysed using a LIANA© prototype to collect data regarding DL and UPE occurring after UV excitation. The obtained data were integrated with germination parameters which underline species-specific behaviours in response to storage conditions. The prediction models show variable efficiency in classifying seeds based on germination which underline species-dependent links between photon emission and seed quality. Therefore, these measurements represent novel, non-invasive, and rapid approaches to evaluate seed quality.

Cross-calibration and first vertical ECE measurement of electron energy distribution in the TCV tokamak

Abstract This paper describes the first vertical electron cyclotron emission measurement of non-thermal electron distributions in the Tokamak à Configuration Variable. These measurements were conducted in runaway electron scenarios and in the presence of electron cyclotron current drive. Measured intensities of linearly polarized X- and O-mode radiation from fast electrons allow the analysis of the energy distribution. The measurements were made possible through the creation of an operational regime for the diagnostic that is free of thermal background radiation, in relaxed electron density operations. This operational regime notably enables the cross-calibration of the diagnostic system, relying on thermal plasma measurements and modeling with the ray-tracing code SPECE.

Revolutionizing urban emission tracking: Enhanced vehicle ratios via remote sensing techniques

This study presents research that examines the use of several remote sensing methods to quantify automobile emissions in China. The research provides a unified data processing technique, using methodologies such as plume chasing (PCH) and point sampling (P-sampling) to measure vehicle emissions accurately. This method accurately calculates the ratios of gaseous combustion, namely NOx/CO2, in different driving scenarios and verifies the technique using controlled vehicle emissions measurements. The results demonstrate the method’s ability to identify variations in emission levels linked to engine operation and alterations in after-treatment systems. This provides significant information for monitoring emissions in metropolitan areas such as Wuhan, China. The suggested method has substantial promise for improving air quality initiatives in China.

Synthetic measurements of runaway electron synchrotron emission in the SPARC tokamak.

With plasma currents up to 8.7 MA, the SPARC tokamak runs the risk of forming multi-MA beams of relativistic "runaway" electrons (REs), which could damage plasma facing components if unmitigated. The infrared (IR) and visible imaging and visible spectroscopy systems in SPARC are designed with measurements of synchrotron emission from REs in mind. Synchrotron radiation is emitted by REs along their direction of motion, opposite the plasma current. Matched clockwise and counterclockwise wide views are proposed to detect synchrotron and background radiation, allowing observation of RE synchrotron emission in both plasma current configurations. Due to SPARC's high toroidal magnetic field strength, 12.2T on axis, the synchrotron light spectrum is expected to peak in the visible-IR wavelength range. The synthetic diagnostic tool, Synchrotron Orbit-Following Toolkit, is used to model synchrotron images and spectra for three scenarios, with appropriate magnetic equilibria for each: REs generated during plasma current ramp-up, steady-state flat-top (although unlikely, but serving as a reference), and disruptions. Required time resolutions, achievable spatial coverage, and appropriate spectral ranges for various RE energies are assessed.

Research on carbon emission measurement techniques for accounting and grid auxiliary services

Abstract Comprehensive and accurate carbon measurement in industrial parks is an important prerequisite for grasping the current status of carbon emissions in industrial parks and exploring their carbon reduction potential. In industrial parks, a large amount of indirect or direct carbon emissions will be generated in common processes such as power use, fuel consumption, and industrial processes, and how to realize the real-time and accurate measurement of indirect and direct carbon emissions in industrial parks will become the key foundation for promoting carbon reduction and emission reduction in industrial parks. This paper focuses on the impact of auxiliary services provided by distributed power generation on carbon emissions and the integration of multi-energy carbon emission measurement technology to carry out carbon emission accurate measurement technology research, puts forward an accurate measurement method of indirect electricity carbon emission in industrial parks considering auxiliary services, and forms a carbon emission measurement technology solution in line with the new energy power generation and multiple energy use in industrial parks to provide data support for the low-carbon transformation of electric power in the parks. The study will provide data support for the low-carbon transformation of electric power and energy in the industrial park.

Temperature measurement method with line and continuum emissions in Ar-N2 DC arc

This study discusses a technique for accurate temperature measurement of thermal plasmas with a high-speed camera. The temperature of thermal plasmas is an important parameter for plasma processes. High-speed cameras are useful to measure plasma temperatures in two dimensions. Measurements of plasma emission with a high-speed camera and band-pass filter provide only the spectral intensity of the entire transmitted wavelength range. Temperature measurements with high-speed cameras by the Boltzmann plot method or Fowler⎯Milne method are less accurate. Theoretical consideration of the line and continuum emissions has improved the accuracy of plasma temperature measurement. The measurement target was a free-burning arc in an argon and nitrogen atmosphere. Temperature errors were estimated based on the deviation from the true emission coefficient. The calculation and measurement errors were discussed as the factors of the deviation. Error estimation provides important insight into the selection of the measurement wavelength.

Improved tools for estimation of ammonia emission from field-applied animal slurry: Refinement of the ALFAM2 model and database

Ammonia volatilization from animal slurry applied to agricultural fields reduces nitrogen use efficiency in agriculture and pollutes the environment. This work presents new versions of a model and database focused on this route of N loss. The public ALFAM2 database (https://github.com/AU-BCE-EE/ALFAM2-data) was expanded with ammonia emission and ancillary measurements for >700 additional field plots. The ALFAM2 model (https://github.com/AU-BCE-EE/ALFAM2, https://zenodo.org/records/13312251) was extended with the addition of an ammonia sink for more plausible predictions over extended durations and to better reflect the expected reduction in emission rate several days after slurry application. A new parameter set was developed for the model taking into account the newly available measurement data. Model efficiency improved to 0.67 for the parameter estimation subset (0.52 for cross-validation) and mean absolute error was around 10% of applied total ammoniacal nitrogen. As in earlier versions, predicted emission is sensitive to application method, slurry dry matter and pH, air temperature, and wind speed. A collection of parameter sets for estimating uncertainty in average predictions was developed using a bootstrap approach. Predicted uncertainty is not trivial, and is high for some variable combinations, highlighting the challenge of making predictions based on available measurement data. Still, this work has resulted in more accurate, comprehensive, transparent, and flexible tools for emission inventory and related work on ammonia loss from field-applied slurry.

In situ high-temperature emissivity measurements of heat-treated, silicon coated stainless steel for solar thermal applications

Understanding thermal emissivity at high temperatures is crucial for developing efficient materials for solar thermal applications. We present a new approach for creating an efficient material for solar absorber by developing a nano structured surface on stainless steel substrate through Si deposition and annealing. We prepare five samples by annealing them at five temperatures between 700 °C and 1100 °C. Afterwards, we perform a systematic study of the spectral emissivity at elevated temperatures, focusing on different parameters: angle dependence, wavelength dependence, and temperature dependence. The spectral directional emissivity experiments performed in the mid-infrared range reveal a dielectric behavior of the samples in the short wavelength region (λ < 6 μm) and metallic behavior in the long wavelength region (λ > 12 μm). The results indicate an increase in hemispherical and total normal emissivity with measurement temperature (from 200 °C to 700 °C), influenced by oxide/silicide formation due to interdiffusion, and by surface roughness. Notably, samples annealed at 900 °C and 1000 °C demonstrate enhanced thermal stability at 700 °C, showcasing promising characteristics for high-temperature applications. Consequently, this study presents a viable method for developing cost-effective silicon-based solar absorber coatings on stainless steel with tailored properties for solar thermal applications along with its real time high temperature emissivity details.

Ultraviolet Radiation Fields in Star-forming Disk Galaxies: Numerical Simulations with TIGRESS-NCR

With numerical simulations that employ adaptive ray-tracing (ART) for radiative transfer at the same time as evolving gas magnetohydrodynamics, thermodynamics, and photochemistry, it is possible to obtain a high-resolution view of ultraviolet (UV) fields and their effects in realistic models of the multiphase interstellar medium. Here, we analyze results from TIGRESS-NCR simulations, which follow both far-UV (FUV) wavelengths, important for photoelectric heating and polycyclic aromatic hydrocarbon excitation, and the Lyman continuum (LyC), which photoionizes hydrogen. Considering two models, representing solar neighborhood and inner-galaxy conditions, we characterize the spatial distribution and time variation of UV radiation fields, and quantify their correlations with gas. We compare four approximate models for the FUV to simulated values to evaluate alternatives when full ART is infeasible. By convolving FUV radiation with density, we produce mock maps of dust emission. We introduce a method to calibrate mid-IR observations, for example from JWST, to obtain high-resolution gas surface density maps. We then consider the LyC radiation field, finding most of the gas exposed to this radiation to be in ionization–recombination equilibrium and to have a low neutral fraction. Additionally, we characterize the ionization parameter as a function of the environment. Using a simplified model of the LyC radiation field, we produce synthetic maps of emission measure (EM). We show that the simplified model can be used to extract an estimate of the neutral fraction of the photoionized gas and mean free path of ionizing radiation from observed EM maps in galaxies.

Spatially resolved plasma composition evolution in a solar flare – The effect of reconnection outflow

Context. Solar flares exhibit complex variations in elemental abundances compared to photospheric values. These abundance variations, characterized by the first ionization potential (FIP) bias, remain challenging to interpret. Aims. We aim to (1) examine the spatial and temporal evolution of coronal abundances in the X8.2 flare on 2017 September 10, and (2) provide a new scenario to interpret the often observed high FIP bias loop top, and provide further insight into differences between spatially resolved and Sun-as-a-star flare composition measurements. Methods. We analyzed 12 Hinode/Extreme-ultraviolet Imaging Spectrometer (EIS) raster scans spanning 3.5 hours, employing both Ca XIV 193.87 Å/Ar XIV 194.40 Å and Fe XVI 262.98 Å/S XIII 256.69 Å composition diagnostics to derive FIP bias values. We used the Markov Chain Monte Carlo (MCMC) differential emission measure (DEM) method to obtain the distribution of plasma temperatures, which forms the basis for the FIP bias calculations. Results. Both the Ca/Ar and Fe/S composition diagnostics consistently show that flare loop tops maintain high FIP bias values of &gt; 2–6, with peak phase values exceeding 4, over the extended duration, while footpoints exhibit photospheric FIP bias of ∼1. The consistency between these two diagnostics forms the basis for our interpretation of the abundance variations. Conclusions. We propose that this variation arises from a combination of two distinct processes: high FIP bias plasma downflows from the plasma sheet confined to loop tops, and chromospheric evaporation filling the loop footpoints with low FIP bias plasma. Mixing between these two sources produces the observed gradient. Our observations show that the localized high FIP bias signature at loop tops is likely diluted by the bright footpoint emission in spatially averaged measurements. The spatially resolved spectroscopic observations enabled by EIS prove critical for revealing this complex abundance variation in loops. Furthermore, our observations show clear evidence that the origin of hot flare plasma in flaring loops consists of a combination of both directly heated plasma in the corona and from ablated chromospheric material; and our results provide valuable insights into the formation and composition of loop top brightenings, also known as EUV knots, which are a common feature at the tops of flare loops.