Effect of gas flow rate and discharge volume on CO2 methanation with plasma catalysis

CO2 methanation can be a key technology for realizing a sustainable society. CH4 is used as an energy carrier and raw material for chemical products, thereby contributing to the reduction of CO2 emissions. Methanation with plasma catalysis lower the process temperature, which can improve the throughput and stability. In this study, we investigated the effect of the gas flow rate and the discharge volume on CO2 methanation, using a low- pressure CCP reactor. Higher gas flow rates can increase the rate of CO2 throughput, but the CH4 selectivity decreases owing to the reduced transportation rate of the reactants to the catalyst surface. Increasing the discharge volume is effective in improving the transportation rate. This study suggested that the structure of the reactor significantly affect the CH4 generation rate.

Improvement of Nanostructured Polythiophene Film Uniformity Using a Cruciform Electrode and Substrate Rotation in Atmospheric Pressure Plasma Polymerization

In atmospheric pressure (AP) plasma polymerization, increasing the effective volume of the plasma medium by expanding the plasma-generating region within the plasma reactor is considered a simple method to create regular and uniform polymer films. Here, we propose a newly designed AP plasma reactor with a cruciform wire electrode that can expand the discharge volume. Based on the plasma vessel configuration, which consists of a wide tube and a substrate stand, two tungsten wires crossed at 90 degrees are used as a common powered electrode in consideration of two-dimensional spatial expansion. In the wire electrode, which is partially covered by a glass capillary, discharge occurs at the boundary where the capillary terminates, so that the discharge region is divided into fourths along the cruciform electrode and the discharge volume can successfully expand. It is confirmed that although a discharge imbalance in the four regions of the AP plasma reactor can adversely affect the uniformity of the polymerized, nanostructured polymer film, rotating the substrate using a turntable can significantly improve the film uniformity. With this AP plasma reactor, nanostructured polythiophene (PTh) films are synthesized and the morphology and chemical properties of the PTh nanostructure, as well as the PTh-film uniformity and electrical properties, are investigated in detail.

Augmentation and Use of WRF-Hydro to Simulate Overland Flow- and Streamflow-Generated Debris Flow Hazards in Burn Scars

In steep wildfire-burned terrains, intense rainfall can produce large volumes of runoff that can trigger highly destructive debris flows. The ability to accurately characterize and forecast debris-flow hazards in burned terrains, however, remains limited. Here, we augment the Weather Research and Forecasting Hydrological modeling system (WRF-Hydro) to simulate both overland and channelized flows and assess postfire debris-flow hazards over a regional domain. We perform hindcast simulations using high-resolution weather radar-derived precipitation and reanalysis data to drive non-burned baseline and burn scar sensitivity experiments. Our simulations focus on January 2021 when an atmospheric river triggered numerous debris flows within a wildfire burn scar in Big Sur – one of which destroyed California’s famous Highway 1. Compared to the baseline, our burn scar simulation yields dramatic increases in total and peak discharge, and shorter lags between rainfall onset and peak discharge. At Rat Creek, where Highway 1 was destroyed, discharge volume increases eight-fold and peak discharge triples relative to the baseline. For all catchments within the burn scar, we find that the median catchment-area normalized discharge volume increases nine-fold after incorporating burn scar characteristics, while the 95th percentile volume increases 13-fold. Catchments with anomalously high hazard levels correspond well with post-event debris flow observations. Our results demonstrate that WRF-Hydro provides a compelling new physics-based tool to investigate and potentially forecast postfire hydrologic hazards at regional scales.

Future Climate Change Impacts on River Discharge Seasonality for Selected West African River Basins

The changing climate is a concern to sustainable water resources. This study examined climate change impacts on river discharge seasonality in two West African river basins; the Niger river basin and the Hadejia-Jama’are Komadugu-Yobe Basin (HJKYB). The basins have their gauges located within Nigeria and cover the major climatic settings. Here, we set up and validated the hyper resolution global hydrological model PCR-GLOBWB for these rivers. Time series plots as well five performance evaluation metrics such as Kling–Gupta efficiency (KGE),); the ratio of RMSE-observations standard deviation (RSR); per cent bias (PBIAS); the Nash–Sutcliffe Efficiency criteria (NSE); and, the coefficient of determination (r2), were employed to verify the PCR-GLOBWB simulation capability. The validation results showed from satisfactory to very good on individual rivers as specified by PBIAS (−25 to 0.8), NSE (from 0.6 to 0.8), RSR (from 0.62 to 0.4), r2 (from 0.62 to 0.88), and KGE (from 0.69 to 0.88) respectively. The impact assessment was performed by driving the model with climate projections from five global climate models for the representative concentration pathways (RCPs) 4.5 and 8.5. We examined the median and range of expected changes in seasonal discharge in the far future (2070–2099). Our results show that the impacts of climate change cause a reduction in discharge volume at the beginning of the high flow period and an increase in discharge towards the ending of the high flow period relative to the historical period across the selected rivers. In the Niger river basin, at the Lokoja gauge, projected decreases added up to 512 m3/s under RCP 4.5 (June to July) and 3652 m3/s under RCP 8.5 (June to August). The three chosen gauges at the HJKYB also showed similar impacts. At the Gashua gauge, discharge volume increased by 371 m3/s (RCP8.5) and 191 m3/s (RCP4.5) from August to November. At the Bunga gauge, a reduction/increase of -91 m3/s/+84 m3/s (RCP 8.5) and -40 m3/s/+31 m3/s/(RCP 4.5) from June to July/August to October was simulated. While at the Wudil gauge, a reduction/increase in discharge volumes of −39/+133 m3/s (RCP8.5) and −40/133 m3/s (RCP 4.5) from June to August/September to December is projected. This decrease is explained by a delayed start of the rainy season. In all four rivers, projected river discharge seasonality is amplified under the high-end emission scenario (RCP8.5). This finding supports the potential advantages of reduced greenhouse gas emissions for the seasonal river discharge regime. Our study is anticipated to provide useful information to policymakers and river basin development authorities, leading to improved water management schemes within the context of changing climate and increasing need for agricultural expansion.

Trade Exports Predict Regional Ballast Water Discharge by Ships in San Francisco Bay

Biological invasions often result from transfers of organisms during trade activities. In coastal ecosystems, commercial ships are a dominant source of species transfers globally, and ships’ ballast water (BW) is a major focus of biosecurity management and policy to reduce invasions. While trade drives shipping patterns, diverse vessel types and behaviors exist such that the quantitative relationship between trade and BW dynamics is still poorly resolved, limiting both science and management. Here, we evaluated a new method to predict BW discharge using trade data, by explicitly considering known BW practices according to vessel and commodity type. Specifically, we estimated the relationship between tonnage of overseas exports and BW discharge volume for San Francisco Bay (SFB), California, as a model system to demonstrate this approach. Using extensive datasets on shipborne exports and BW discharge, we (a) evaluated spatial and temporal patterns across nearly 20 ports in this estuary from 2006 to 2014 and (b) developed a predictive model to estimate overseas BW discharge volume from foreign export tonnage for the whole estuary. Although vessel arrivals in SFB remained nearly constant from 2006 to 2014, associated tonnage of exported commodities more than doubled and BW discharge more than tripled. Increased BW volume resulted from increased frequency and per capita discharge of bulk carriers from Asia and tankers from western Central America and Hawaii, reflecting shifts in direction of commodity movement. The top 11 export commodities (59% of total export tonnage) were transported on bulk carriers or tankers. In a multivariate linear model, annual tonnage of these top 11 export commodities by vessel type were strong predictors of total bay-wide overseas BW discharge (adjusted R2 = 0.92), creating the potential to estimate past or future BW delivery in SFB. Bulk export tonnage provides valuable insights into BW flux, since most BW discharge to ports is driven by trade of bulk commodities and the behavior of bulk and tank ships. BW discharge data are unavailable for many regions and time periods, whereas trade data are widely available and can provide a reliable proxy estimate of BW volume and geographic source, which are both critical to evaluate invasion risk.

Analisis Hidrologi Model Soil Moisture Accounting Menggunakan Program HEC-HMS (Studi Kasus : DAS Rokan AWLR Pasir Pangaraian)

(ID) Hidrologi suatu Daerah Aliran Sungai (DAS) rumit untuk diprediksi karena kekurangan data dan membutuhkan biaya yang mahal. Pada penelitian ini mengambil lokasi di sub DAS Rokan Hulu stasiun Pasir Pengaraian yang hampir setiap tahun terjadi banjir. Perencanaan dan pengolahan sumber daya air di suatu wilayah daerah aliran sungai sangat penting, maka dari itu perlunya mengetahui karakteristik suatu DAS. Perencanaan dan pengolaan sumber daya air memerlukan data debit aliran yang lengkap. Pada sub DAS ini data hujan, data debit dan data klimatologi menggunakan periode data sepuluh tahun yaitu dari tahun 2008-2017. Pemodelan hidrologi dilakukan pendekatan dengan beberapa metode, salah satunya metode soil moisture accounting di program HEC-HMS yang mana metode tersebut mensimulasikan suatu pergerakan air pada vegetasi, permukaan tanah dan di bawah permukaan tanah. Penyusunan periode kalibrasi dan verifikasi disusun dalam sembilan skema yang diharapkan mampu menghasilkan hasil yang paling optimal. Sembilan skema untuk Kalibrasi dan Verifikasi ini menggunakan metode objective function yaitu percent error in discharge volume. Skema yang paling optimal adalah skema VII (7 tahun kalibrasi 3 tahun Verifikasi), dengan nilai verifikasi 10,1%”Baik” dan Kalibrasi 0,0% “Sangat Baik”. (EN) The hydrology of a watershed is difficult to predict because of the lack of data and requires high costs. In this study taking location in the Rokan Hulu sub-watershed, Pasir Pengaraian station Almost every year flooding occurs. Planning and management of water resources in a watershed is very important and therefore it is necessary to know the characteristics of the watershed. Planning and management of water resources require complete data. in this sub-watershed rainfall data, discharge data and climatology data use a ten-year data period from 2008-2017. Hydrological modeling is approached with several methods, one of them is soil moisture accounting method in the HEC-HMS program where the method simulates a movement of water on vegetation, soil surface and below ground level. The preparation of the calibration and verification periods arranged in nine schemes is expected to produce the most optimal results. The nine schemes for Calibration and Verification use the objective function method, which is the percentage error in discharge volume. The most optimal scheme is the scheme VII (7 years calibration 3 years Verification), with a verification value of 10.1% "Good" and Calibration 0.0% "Very Good".

Abstract WP354: The Rural Health Care Penalty: Urban-rural Disparities in Stroke Center Performance

Goal: To determine hospital and stroke system characteristics associated with higher levels of stroke center performance. Methods: We included all Centers for Medicare and Medicaid Services designated Acute Care Hospitals and Critical Access Centers (ACH/CAC) from January 1, 2005 to December 31, 2014. Higher stroke center performance was defined as earning a performance achievement award (PAA) on a predefined set of 7 evidence-based measures in a national quality program, Get-With-The-Guidelines-Stroke (GWTG-S). Generalized Estimating Equations were used to model characteristics associated with attaining a PAA over nine years of data. Hospital variables included total, ischemic and hemorrhagic stroke discharge volumes; medicaid discharge volume; patient race/ethnicity; ownership; rurality (Truven Health MarketScan); and state and/or national stroke center certification. Stroke system variables included emergency medical service (EMS) stroke routing protocol; stroke center directives (legislation, regulation, or department of health initiatives); and location in a region with a stroke consortium. Results: As a percentage of all ACH/CACs, GWTG-S hospitals with PAA increased significantly over time from 0.001% (5/4530) in 2005 to 24% (1086/4526) in 2014 (linear and nonlinear p’s<0.0001). Variables associated with PAA status at the p<0.05 level were included in the combined analysis. Significant independent predictors of PAA status included urban location (p<0.0001); total (p=0.0016) and ischemic stroke (p<0.0048) discharge volumes; national stroke center designation (p<0.0001); and presence of state stroke center directives (p=0.0012). EMS routing was not statistically significant but there was an EMS-by-time interaction; hospitals with EMS routing had a significantly increased rate of earning PAA (p = 0.0463). Conclusions: There has been rapid improvement in stroke center performance from 2005 to 2014. Urban location, higher hospital discharge volume, national stroke center designation, and state stroke directives are independently associated with better stroke center performance. After controlling for hospital and stroke system factors, there are significant urban-rural disparities in stroke center performance.