Emission Scheme Research Articles

Long-range transport impact of a severe dust storm over the Yangtze River Basin region and its modeling sensitivity to dust emission scheme

Dust storms frequently occur in the spring over East Asia, affecting southern Mongolia and northeast China. An exceptionally powerful dust storm occurred in East Asia from March 14th to March 18th, 2021. To investigate the ability of climate models to simulate severe dust storms, we employed the Weather Research Forecast model coupled with chemistry (WRF-Chem) with Goddard Chemistry Aerosol Radiation and Transport (GOCART), SHAO and KOK dust emission schemes to simulate the evolution of this event and to characterize dust aerosols long-range transport. Results showed that this storm was caused by a Mongolian cyclone depicted at 850 hPa with a cold front, which swept dust aerosols southeastward across southern Mongolia to northeast China. Model evaluation with satellite-retrieved Aerosol Optical Depth (AOD) and observational PM10 concentrations revealed that the SHAO dust emission scheme performed better in simulating spatial and temporal distribution of AOD over the Gobi Desert (GD) but overestimated them over Taklimakan Desert (TD). In contrast, the GOCART dust emission scheme underestimated AOD over most areas except the Taklimakan Desert; the KOK dust emission scheme overestimated them over both TD and GD. Overall, the SHAO dust emission scheme had good performance in simulating the surface PM10 concentrations over the Yangtze River Basin (YRB) and depicted an increase in PM10 concentrations, which denoted the transport of dust aerosols over YRB. As a better description of the physical process of dust emission flux over the eastern region of the Gobi Desert, the SHAO dust emission scheme depicted well the spatial and temporal evolution of dust plume episodes, especially over northeast China and YRB. The significant differences in dust emission fluxes between the three dust emission schemes were attributed to the sensitivity of threshold friction velocity and erodibility factor. Thereunto, the SHAO dust emission scheme incorporated well soil particle size distribution and threshold velocity to produce the dust emission flux, which allowed higher dust emission flux over the eastern GD and under strong southwesterly transported dust aerosols to East Central China's region of North China Plain (NCP) and YRB. This study will help further the simulation of extreme dust events more accurately and the exploration of climate change's effect on dust events over East Asia.

Exploring the Transport Path of Oceanic Microplastics in the Atmosphere.

Microplastics (MP) have been recognized as an emerging atmospheric pollutant, yet uncertainties persist in their emissions and concentrations. With a bottom-up approach, we estimate 6-hourly MP fluxes at the ocean-atmosphere interface, using as an input the monthly ocean surface MP concentrations simulated by the global oceanic model (NEMO/PISCES-PLASTIC, Nucleus for European Modeling of the Ocean, Pelagic Interaction Scheme for Carbon and Ecosystem Studies), a size distribution estimate for the MP in the micrometer range, and a sea salt emission scheme. The atmospheric dispersion is then simulated with the Lagrangian model FLEXPART. We identify hotspot sources in the tropical regions and highlight the seasonal variability of emissions, atmospheric concentrations, and deposition fluxes both on land and ocean surfaces. Due to the variability of MP concentration during the year, the MP flux from the sea surface appears to follow a seasonality opposite to that of sea salt aerosol emissions. The comparison with existing observations of MP in the marine atmosphere suggests an underestimation of one to 2 orders of magnitude in our current knowledge of the MP in the oceans' surface. In addition, we show that the MP in the micrometer range is transported efficiently around the globe and can penetrate and linger in the stratosphere over time scales of months. The interaction of these particles with the chemistry and physics of the atmosphere is still mostly unknown and deserves to be further investigated.

Continuous Emission Ultrasound: A New Paradigm to Ultrafast Ultrasound Imaging.

Current imaging techniques in echography rely on the pulse-echo (PE) paradigm which provides a straight-forward access to the in-depth structure of tissues. They inherently face two major challenges: the limitation of the pulse repetition frequency, directly linked to the imaging framerate, and, due to the emission scheme, their blindness to the phenomena that happen in the medium during the majority of the acquisition time. To overcome these limitations, we propose a new paradigm for ultrasound imaging, denoted by continuous emission ultrasound imaging (CEUI) [1], for a single input single output (SISO) device. A continuous insonification of the medium is done by the probe using a coded waveform inspired from the radar and sonar literature. A framework coupling a sliding window approach (SWA) and pulse compression methods processes the recorded echoes to rebuild a motion-mode (M-mode) image from the medium with a high temporal resolution compared to state-of-the-art ultrafast imaging methods. A study on realistic simulated data, with regards to the motion of the medium, has been carried out and, achieved results assess an unequivocal improvement of the slow time frequency up to, at least, two orders of magnitude compared to ultrafast US imaging methods. This enhancement leads, therefore, to a ten times improvement in the temporal separability of the imaging system. In addition, it demonstrates the capability of CEUI to catch relatively short and quick events, in comparison to the imaging period of PE methods, at any instant of the acquisition.

Time-bin entanglement in the deterministic generation of linear photonic cluster states

We theoretically investigate strategies for the deterministic creation of trains of time-bin entangled photons using an individual quantum emitter described by a Λ-type electronic system. We explicitly demonstrate the theoretical generation of linear cluster states with substantial numbers of entangled photonic qubits in full microscopic numerical simulations. The underlying scheme is based on the manipulation of ground state coherences through precise optical driving. One important finding is that the most easily accessible quality metrics, the achievable rotation fidelities, fall short in assessing the actual quantum correlations of the emitted photons in the face of losses. To address this, we explicitly calculate stabilizer generator expectation values as a superior gauge for the quantum properties of the generated many-photon state. With widespread applicability in other emitter and excitation–emission schemes also, our work lays the conceptual foundations for an in-depth practical analysis of time-bin entanglement based on full numerical simulations with predictive capabilities for realistic systems and setups, including losses and imperfections. The specific results shown in the present work illustrate that with controlled minimization of losses and realistic system parameters for quantum-dot type systems, useful linear cluster states of significant lengths can be generated in the calculations, discussing the possibility of scalability for quantum information processing endeavors.

Unusual emission from 2F5/2 two lowest excited levels of Yb3+-doped LuPO4 nano/micro-crystalline materials

Yb3+-doped inorganic materials are constantly in demand due to a strong interest in fundamental and applied research. The simplicity of the 4f1³ electronic structure minimizes de-excitation processes and enables a quasi-three-level laser emission scheme at 1 μm employed for IR laser devices.In this work, we present an unusual simultaneous emission from two of the lowest levels of the 2F5/2 excited state observed at 77 K, measured for the first time and confirmed by the barycenter law for Yb3+-doped tetragonal LuPO4 revealing the lowest crystal field among Yb3+ ion-activated oxide crystals.Three series of tetragonal lutetium orthophosphate powders, containing various concentrations of Yb3+ ions (0.5–5 mol %), were analyzed in nano and micro-crystalline forms. The ionic liquid-assisted (IL) hydrothermal (HT) method was used for the nano-powders' preparation. This route enabled the fabrication of fine nano-powders with particle sizes of 15 nm in an ethylene glycol (GE) reaction medium and 30 nm in a water (W) medium, each exhibiting the desired well-crystallized single-phase phosphate. For comparative studies, the micro-crystalline samples were synthesized via reaction in the solid phase at a relatively high temperature.The Yb3+ ion also served as a structural probe, its spectroscopy i.e., absorption at 4.2 K, selectively excited luminescence at 77 K, and fluorescence decays were used to assign Yb3+ energy levels in only one D2d center precisely. This assignment was based on exceptional features due to the unique emissions observed from the two lowest levels of the 2F5/2 excited state, split only by 27 cm−1, confirmed by calculation of the crystal field parameters from Zeeman spectra.

Characteristics of dust emission over desert steppe

Desert steppe is widely distributed in wind erosion regions, and is also an important potential dust emission source in the regions. Recognition of dust emission characteristics of desert steppe is the foundation for accurate simulation of dust emission in wind erosion regions; however, few related studies have been conducted in desert steppe areas. In this study, we selected four sites in a region of desert steppe to conducting dust emission observations, analyzing the characteristics of horizontal saltation flux and vertical dust flux, identifying the suitable models for desert steppe, and examining the relationship between saltation bombardment efficiency and wind friction speed (u*). The results revealed the following: the supply of saltation particles in most desert steppe is unlimited, the intensity of saltation is reasonably high, and the modified Owen-type model is suitable for predicting sediment transport above desert steppe. Dust emission intensity in desert steppe is lower than that in other land use types under similar wind speeds. Schemes based on saltation bombardment theory (i.e., the MB95, Shao93, and Kok12 schemes) were found suitable for predicting vertical dust flux above desert steppe, the Kok12 dust emission scheme performed slightly better than the other two schemes. Saltation bombardment is the main mechanism for dust emission when u*s exceeds a threshold u*s (u*ts), but aerodynamic entrainment also plays an important role in dust emission, especially when u*s < u*ts. The saltation bombardment efficiency of desert steppe is less than that of other land use types. The trend of change in saltation bombardment efficiency with wind speed varies at different sites. Soil properties affect the dependence of saltation bombardment efficiency on u*. Desert steppe is an important dust emission source in certain regions, and improved understanding of dust emission in desert steppe areas is required.

Synoptic Analysis and WRF‐Chem Model Simulation of Dust Events in the Southwestern United States

AbstractDust transported from rangelands of the Southwestern United States (US) to mountain snowpack in the Upper Colorado River Basin during spring (March‐May) forces earlier and faster snowmelt, which creates problems for water resources and agriculture. To better understand the drivers of dust events, we investigated large‐scale meteorology responsible for organizing two Southwest US dust events from two different dominant geographic locations: (a) the Colorado Plateau and (b) the northern Chihuahuan Desert. High‐resolution Weather Research and Forecasting coupled with Chemistry model (WRF‐Chem) simulations with the Air Force Weather Agency dust emission scheme incorporating a MODIS albedo‐based drag‐partition was used to explore land surface‐atmosphere interactions driving two dust events. We identified commonalities in their meteorological setups. The meteorological analyses revealed that Polar and Sub‐tropical jet stream interaction was a common upper‐level meteorological feature before each of the two dust events. When the two jet streams merged, a strong northeast‐directed pressure gradient upstream and over the source areas resulted in strong near‐surface winds, which lifted available dust into the atmosphere. Concurrently, a strong mid‐tropospheric flow developed over the dust source areas, which transported dust to the San Juan Mountains and southern Colorado snowpack. The WRF‐Chem simulations reproduced both dust events, indicating that the simulations represented the dust sources that contributed to dust‐on‐snow events reasonably well. The representativeness of the simulated dust emission and transport in different geographic and meteorological conditions with our use of albedo‐based drag partition provides a basis for additional dust‐on‐snow simulations to assess the hydrologic impact in the Southwest US.

Carbon emissions assessment of cement mixing piles for soft loess improvement and carbon emission reduction using white mud-cement composite material

During the highway construction in the soft loess region of Northwestern China, there are always tens of thousands of cement mixing piles were used. Which generates a large amount of carbon emissions, thereby affecting the environment. The Simplified Energy and Emissions Assessment Model (SEEAM) is used to quantify carbon emissions considering monitoring data of IoT (Internet-of-Things) system. To reduce the error of the carbon emissions of large samples, Monte Carlo simulation was used to quantify carbon emissions based on the small samples. The results showed that cement had a 47,530.78 t carbon missions contributing the 95.64 % of the total carbon emissions. To concurrently ensure strength and reduce carbon emissions, this study investigates the unconfined compressive strength variations in white mud-cement composite material solidified soft loess. It indicated that 10 % and 20 % white mud provided an alkaline environment and nucleation sites for cement hydration reactions, combining the filling voids. According to the observation results of TG and SEM, the content of 10 % white mud increased the quantity of early hydration product CSH in cement. Which maintained a high level of strength by comparing the cement solidified soft loess. In addition, when the white mud content is 50 %, the white mud-cement composite material reduced 576 % carbon emissions in the cement mixing pile engineering. This study can provide guidance for the selection of engineering construction design schemes, as low-carbon emission schemes are conducive to green and sustainable development of the environment.

Distributionally robust newsvendor problem with partial demand information under carbon emission regulations

Carbon emission schemes are widely adopted and implemented in practice to control greenhouse gas emissions. However, a firm restricted by carbon emission schemes with only partial demand information may face greater challenges. In this paper, we investigate an ordering and pricing newsvendor problem with partial demand information, which considers carbon emissions generated from the processes of ordering and disposing of the excess inventory. We propose three distributionally robust models to maximize the worst-case profit under different carbon emission regulations: carbon tax, cap-and-trade and carbon cap, respectively. We derive the implicit solution under the carbon tax scheme and design heuristic algorithms based on Lagrangian relaxation under the cap-and-trade and carbon cap regulations. Numerical analysis indicates: (i) all three regulations are effective in reducing carbon emissions; (ii) the implementation of carbon schemes leads to higher optimal pricing and lower optimal ordering quantity, both carbon tax and carbon cap regulations will always lead to lower profit, while the retailer may benefit from the cap-and-trade regulation by selling out the carbon credit; (iii) the proposed approach performs well under different distribution specific scenarios.

Saltation‐Induced Dust Emission of Dust Devils in the Convective Boundary Layer—An LES Study on the Meter Scale

AbstractDust devils are vertically oriented, columnar vortices that form within the atmospheric convective boundary layer (CBL) of dry regions. They are able to lift a sufficient amount of soil particles including dust to become visible and are considered as a potentially important dust source for the atmosphere. Mineral dust, a key component of atmospheric aerosols, influences the climate by affecting the radiation budget and cloud formation. Current estimates of the contribution of dust devils to the global, regional, and local dust release vary considerably from less than 1% to more than 50%. To address this uncertainty, we perform the highest resolved large‐eddy simulation (LES) study on dust emission in the CBL to date, using the PALM model system and the saltation‐based Air Force Weather Agency (AFWA) dust emission scheme. Our results show that under desert‐like conditions, dust devils are responsible for an average of 5% of regional dust emissions, with temporary maxima of up to 15%. This contrasts with previous measurement‐based (&gt;35%) and LES‐based estimates (∼0.1%). Local emissions of dust devils (up to 10 mg m−2 s−1) are 1–3 orders of magnitude higher than the emission in the surroundings. This makes dust devils important for air quality and visibility. Additionally, our study reveals previously unknown large‐scale convective dust emission patterns. These patterns are tied to the CBL's cellular flow structure and are the main cause of dust release. Contrary to other studies, our findings clarify the important role of saltation‐induced dust emission.

The direct and indirect radiative effects of sea salt aerosols over the western Pacific using an online-coupled regional chemistry-climate model with a developed sea salt emission scheme

The direct and indirect radiative effects of sea salt aerosols (SSA) over the western Pacific Ocean of East Asia for the year 2014 are investigated by using an online-coupled regional chemistry-climate model (RIEMS-Chem) with a developed sea salt emission scheme (G03SSTRH) by considering the effects of sea surface temperature (SST) and relative humidity (RH) on sea salt generation. Model comparison with observations at coastal and island sites demonstrates the G03SSTRH scheme apparently improve model simulation for sea salt concentration, with the overall model-observation bias for PM10 concentration reduced from 29% to 16% and more evident improvement at northern sites of the western Pacific. It is noteworthy that compared to the experiment with the old SSA emission scheme (G03), the G03SSTRH experiment substantially alters the spatial distribution of mass concentration and radiative effects of sea salt, shifting the maximum value center from the ocean northeast of Japan to the southern parts of the western Pacific with the maximum value increasing to some extent. SSA exerts a negative radiative effect at the top of atmosphere (TOA), in which direct radiative effect (DRESSA) dominates over indirect radiative effect (IRESSA) in the western Pacific. The oceanic and annual mean DRESSA, IRESSA, and total radiative effect (TRESSA) are estimated to be −1.22 W/m2, −0.46 W/m2, and −1.65 W/m2, respectively, from the G03SSTRH experiment, which are 16%, 5%, and 12% stronger than those from the G03 experiment, and the seasonal mean DRESSA in G03SSTRH are approximately 45% and 32% higher than those in G03 in summer and autumn. Distinct seasonality of SSA radiative effects is revealed in the G03SSTRH experiment, showing stronger DRESSA and IRESSA in summer and autumn than those in spring and winter, in marked contrast to the little seasonality in the G03 experiment. This study provides a comprehensive regional estimation of radiative effects induced by SSA and reveals the significant effect of different SSA emission schemes on both mass concentration, radiative effects and seasonal variation of SSA over the western Pacific.

A new process-based and scale-aware desert dust emission scheme for global climate models – Part II: Evaluation in the Community Earth System Model version 2 (CESM2)

Abstract. Desert dust is an important atmospheric aerosol that affects the Earth's climate, biogeochemistry, and air quality. However, current Earth system models (ESMs) struggle to accurately capture the impact of dust on the Earth's climate and ecosystems, in part because these models lack several essential aeolian processes that couple dust with climate and land surface processes. In this study, we address this issue by implementing several new parameterizations of aeolian processes detailed in our companion paper in the Community Earth System Model version 2 (CESM2). These processes include (1) incorporating a simplified soil particle size representation to calculate the dust emission threshold friction velocity, (2) accounting for the drag partition effect of rocks and vegetation in reducing wind stress on erodible soils, (3) accounting for the intermittency of dust emissions due to unresolved turbulent wind fluctuations, and (4) correcting the spatial variability of simulated dust emissions from native to higher spatial resolutions on spatiotemporal dust variability. Our results show that the modified dust emission scheme significantly reduces the model bias against observations compared with the default scheme and improves the correlation against observations of multiple key dust variables such as dust aerosol optical depth (DAOD), surface particulate matter (PM) concentration, and deposition flux. Our scheme's dust also correlates strongly with various meteorological and land surface variables, implying higher sensitivity of dust to future climate change than other schemes' dust. These findings highlight the importance of including additional aeolian processes for improving the performance of ESM aerosol simulations and potentially enhancing model assessments of how dust impacts climate and ecosystem changes.

The implementation of dust mineralogy in COSMO5.05-MUSCAT

Abstract. Mineral dust aerosols are composed of a complex assemblage of various minerals depending on the region in which they originated. Given the different mineral composition of desert dust aerosols, different physicochemical properties and therefore varying climate effects are expected. Despite the known regional variations in mineral composition, chemical transport models typically assume that mineral dust aerosols have uniform composition. This study adds, for the first time, mineralogical information to the mineral dust emission scheme used in the chemical transport model COSMO–MUSCAT. We provide a detailed description of the implementation of the mineralogical database, GMINER (Nickovic et al., 2012), together with a specific set of physical parameterizations in the model's mineral dust emission module, which led to a general improvement of the model performance when comparing the simulated mineral dust aerosols with measurements over the Sahara region for January–February 2022. The simulated mineral dust aerosol vertical distribution is tested by a comparison with aerosol lidar measurements from the lidar system PollyXT, located at Cape Verde. For a lofted mineral dust aerosol layer on 2 February at 05:00 UTC the lidar retrievals yield a dust mass concentration peak of 156 µg m−3, while the model calculates the mineral dust peak at 136 µg m−3. The results highlight the possibility of using the model with resolved mineral dust composition for interpretation of the lidar measurements since a higher absorption in the UV–Vis wavelengths is correlated with particles having a higher hematite content. Additionally, the comparison with in situ mineralogical measurements of dust aerosol particles shows that more of them are needed for model evaluation.

On the formation of biogenic secondary organic aerosol in chemical transport models: an evaluation of the WRF-CHIMERE (v2020r2) model with a focus over the Finnish boreal forest

Abstract. We present an evaluation of the regional chemical transport model (CTM) WRF-CHIMERE (v2020r2) for the formation of biogenic secondary organic aerosol (BSOA) with a focus over the Finnish boreal forest. Formation processes of biogenic aerosols are still affected by different sources of uncertainties, and model predictions vary greatly depending on the levels of details of the adopted chemical and emissions schemes. In this study, air quality simulations were conducted for the summer of 2019 using different organic aerosol (OA) schemes (as currently available in the literature) to treat the formation of BSOA. First, we performed a set of simulations in the framework of the volatility basis set (VBS) scheme carrying different assumptions for the treatment of the aging processes of BSOA. The results of the model were compared against high-resolution (i.e., 1 h) organic aerosol mass and size distribution measurements performed at the Station for Measuring Ecosystem–Atmosphere Relations (SMEAR-II) site located in Hyytiälä, in addition to other gas-phase species such as ozone (O3), nitrogen oxides (NOx), and biogenic volatile organic compound (BVOC) measurements of isoprene (C5H10) and monoterpenes. We show that WRF-CHIMERE could reproduce well the diurnal variation of the measured OA concentrations for all the investigated scenarios (along with the standard meteorological parameters) as well as the increase in concentrations during specific heat wave episodes. However, the modeled OA concentrations varied greatly between the schemes used to describe the aging processes of BSOA, as also confirmed by an additional evaluation using organic carbon (OC) measurement data retrieved from the EBAS European databases. Comparisons with isoprene and monoterpene air concentrations revealed that the model captured the observed monoterpene concentrations, but isoprene was largely overestimated, a feature that was mainly attributed to the overstated biogenic emissions of isoprene. We investigated the potential consequences of such an overestimation by inhibiting isoprene emissions from the modeling system. Results indicated that the modeled BSOA concentrations increased in the northern regions of the domain (e.g., Finland) compared to southern European countries, possibly due to a shift in the reactions of monoterpene compounds against available radicals, as further suggested by the reduction in α-pinene modeled air concentrations. Finally, we briefly analyze the differences in the modeled cloud liquid water content (clwc) among the simulations carrying different chemical schemes for the treatment of the aging processes of BSOA. The results of the model indicated an increase in clwc values at the SMEAR-II site, for simulations with higher biogenic organic aerosol loads, most likely as a result of the increased number of biogenic aerosol particles capable of activating cloud droplets.

EU trilogue results for the aviation sector – key issues and expected impacts

In July 2021, the European Commission had proposed additional and tightening measures to reduce the climate impact of the air transport sector as part of its ‘Fit for 55 package’. In December 2022, so-called trilogue negotiations of the European Commission, the European Parliament and the Council of the European Union came to new rules for the EU emissions trading scheme (EU ETS) for aviation. In April 2023, further trilogue agreements on mandatory blending quotas for sustainable aviation fuels (SAF) were reached. This paper aims at identifying and illustrating the agreed new rules and regulations for the aviation sector in comparison with the previous regime. In addition, key impacts on stakeholders and the environment will be discussed. So far, the trilogue parties have reached an agreement on a strengthened EU ETS for aviation, which integrates the global offsetting scheme CORSIA and creates incentives for the increasing use of SAF. Also, a monitoring, reporting and verification scheme for aviation's climate relevant so-called non-CO2 emissions will be introduced as a basis for a later integration of these emissions into the EU ETS. Aviation's non-CO2 emissions include H2O, aerosols, NOx, contrails and cirrus clouds. Moreover, a mandatory sustainable aviation fuels (SAF) blending quota, which rises gradually up to 70 per cent in the year 2050, has been agreed. However, further policy measures originally proposed within the ‘Fit for 55 package’, such as a European kerosene tax, are still subject to final negotiations. As our analysis indicates, several and diverse economic and environmental effects arising from these climate protection policies for European aviation can be expected.

Assessment of Carbon-Dioxide Emission from Non-Road Equipment Construction Sources at a Flyover Development Site in Port Harcourt, Nigeria

It is emphasized that global warming and climate change vary directly with the increase in the concentration of greenhouse gases, particularly carbon dioxide across domains. The constructions of social and economic infrastructures in developing counties such as Nigeria at a higher rate increases the emissions of carbon dioxide (CO2) into the lower atmosphere. Non-road construction equipment sources powered by fossil fuels are considered to be primary emitters of greenhouse gases during the construction stages of large infrastructure project. In this study, inventory of non-road construction machinery emissions from the Tank junction flyover construction site along East-West Road in Port Harcourt metropolis were estimated via field data gathering. Results showed that an average of about 398.7 g/s (4134.4 ton/year) of CO2 is released from the construction site in Port Harcourt, Nigeria. Among the various types of non-road engines considered, the mobile crane was the largest single contributor to the total CO2 emissions, accounting for 18.5%. Machinery with power above 300 kW were 8 out of 30 equipment on site and accounted for the largest share (52.87%) of total CO2 emissions. Based on the findings from current research literature and the case study, control strategies such as enforcing standards and policy, conducting impact assessment, adopting low carbon technology, and restricting energy utilization need to be implemented in other reduce the impact of global warming and alleviate climate change. Therefore, CO2 emission mitigation plans and schemes are necessary alongside standardized frameworks and guidelines. All stakeholders must play their roles efficiently to reduce CO2 emissions and aid in mitigating the effects of climate change.

Photon Diagnostics for the High-Gain THz FEL at PITZ

Research and development of an accelerator-based THz source prototype for pump-probe experiments at the European XFEL are ongoing at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). Proof-of-principle experiments have been performed to generate a high-gain THz Free-electron Laser (FEL) based on the Self-Amplified Spontaneous Emission scheme. The FEL radiation pulses with a central wavelength of about 100 μm (3 THz) and single pulse energy of several tens μm can be generated. In this paper, we present and discuss the photon diagnostic setup for the THz FEL together with examples of diagnostic results, including pulse energy and an FEL gain curve. The upgraded photon diagnostic setup, capable of measuring pulse energy, transverse distribution, and spectral distribution, is expected to be operational in the spring of 2023.

Optimal parameters of Monte Carlo ray tracing solver with line-by-line spectral database for radiation modeling in fire

Thermal radiation is an important heat transfer mechanism in fire, but its modeling has often been over-simplified due to computational expense. In this study, we assess whether the Monte Carlo ray tracing (MCRT) method using the line-by-line (LBL) spectral database can serve as a fast and accurate candidate for solving radiation in fire. Using a snapshot extracted from a previous well-resolved simulation of a small turbulent pool fire, the radiation field is solved using a recently developed MCRT-LBL solver with three varying parameters: the number of rays per computational cell, the energy emission scheme, and the resolution of the LBL database. The energy equation is subsequently solved for one time step to assess the propagation of statistical noise into the temperature field. The radiative absorption is well predicted even with only one ray emitted per cell. Adaptive emission, where more rays are emitted at locations with stronger volumetric radiative emission, converges faster than the standard approach, where the same number of rays are emitted from every cell, although the advantage of the former is only pronounced when a sufficiently large number of rays are emitted. The statistical noise is smoothed in the calculation of the radiative heat source because the radiative emission is always predicted accurately regardless of the solver’s parameters. Further damping is provided by the energy equation, yielding a temperature field with negligible noise. Coarsening the LBL database only marginally affects the accuracy of the results, but it reduces the memory required to store the data to less than 10% of that of the original database. Lastly, when soot dominates radiative emission, the statistical noise of the radiation source is further reduced. In conclusion, the study indicates reasonable feasibility for applying MCRT-LBL in fire modeling, and we will further demonstrate this possibility in future studies using larger fires.

Urban water resources management with energy constraint and carbon emission intensity under uncertainty: A dual objective optimization model

Water production, utilization and recycle in urban system associated with a large amount of energy consumption and carbon emission that has increasingly international attention under sustainable development goals. In this study, a comprehensive urban water resources system management model is proposed under water-energy-carbon nexus and multiple uncertainties. The water-energy-carbon nexus was reflected in the processes of water extraction, water production and sewage treatment, and two objectives of maximizing the system benefit and minimizing carbon emission is transformed into two linear programming problem through the dual-objective interval fractional programming. Considering the interaction among water supply/demand, pollutants discharge control, energy consumption and self-energy utilization, indirect carbon emission as the main constraints, the developed model is applied to a typical water and energy sources shortage area of Qingdao city in north China. Multiple scenarios related to energy consumption and carbon emission control are designed to search the relationship among energy consumption, carbon emission and water resources allocation schemes. The results indicated that water demand as the main driving factor of energy consumption and carbon emission in urban water system cannot be directly limited through water supply structure adjustment. Through introducing self-energy supply (sludge utilization) and energy consumption control, water resources allocation schemes and water supply structure would be changed to improve energy saving potential with an obvious decrease trend of carbon emission intensity from 0.7921 tCO2/MWh to 0.5544 tCO2/MWh. The model could effectively provide reasonable urban water system management strategies under different water allocation demands and carbon emission challenges scenarios and deal with multiple uncertainties in decision-making process.

Optimal integration of electricity supply chain and sustainable closed-loop supply chain

This study presents an innovative multi-objective robust mixed-integer linear model to integrate an original capacitated Electricity Supply Chain (ESC) and a Closed-Loop Supply Chain (CLSC). The multifaceted relationships between the three dimensions of sustainability, different Carbon Emission Schemes (CES), and robustness have been carefully examined considering the Decision Maker’s (DM’s) various risk preferences. Results demonstrate the direct effect of the selected CES on the network configuration. Under each CES, the total cost increases by increasing the conservatism of the DM. At lower carbon emission capacity, the Carbon Cap Policy (CCP) has lower emissions at the highest cost compared to other policies. However, the emission capacity does not affect the emission under the Carbon Tax Policy (CTP) and Carbon Cap and Trade Policy (CCTP) but increases the network cost in both policies. A conservative DM is willing to adopt CTP with lower cost and emission at a higher emission capacity. At any level of emission capacity, CCTP has a higher priority than CTP only for non-conservative carbon-sensitive DM. The higher the DM conservatism, the lower the carbon credits sold under the CCTP, and the higher the need to purchase credits. Contrary to the insignificant effect of CESs, increasing the DM’s conservatism improves the robustness.