Measurement of dry deposition to bulk precipitation collectors using a novel flushing sampler

Bulk precipitation samplers, which are continuously open, also sample gases and particles deposited on the funnel surface. Wet-only samplers, which open only during precipitation, avoid this problem, but can be bulky (leading to disruption of air flow and droplet collection) and need electrical power. We describe here a simple battery-powered modification to a standard bulk sampler that allows the separate measurement of deposition to the funnel surface and wet deposition by washing the funnel surface when precipitation is detected. Comparison of this design with a standard bulk sampler over 3 months at a site in eastern Scotland showed that dry deposition to the funnel surface contributed around 20% of sulphate, 20-30% of nitrate and 20-40% of ammonium ions. There was also a significant loss of ammonium and nitrate in the modified sampler, presumably in the tubing, even though a biocide had been added to the sample bottles. This observation has implications for bulk samplers of similar design, with a sample bottle at ground level. Deposition of sea salts and calcium was greater to the flushing collectors than to the bulk collectors, implying that regular cleaning of funnel surfaces with 10% methanol solution subtly alters the capture efficiency for larger particles

EXPERIMENTAL CHARACTERIZATION OF THE SEMIPERMEABLE MEMBRANE BEHAVIOUR OF PIERRE SHALE AT SOUTHERN SASKATCHEWAN

Chemical osmosis is a process in which fluid movement occurs through a porous media in response to a chemical concentration gradient within the pore fluid. The porous media acts as a semipermeable membrane that restricts solute transport while allowing pore fluid flow in response to osmotic gradients. Knowledge of the semipermeability character and the factors governing the semipermeability of a membrane is required to fully assess the impact of chemical osmosis. In this study the semipermeable membrane was a sample of Cretaceous-aged Pierre Shale collected at a depth of 121 m from Mosaic Company’s K2 mine, located approximately 15 km east of the town of Esterhazy, Saskatchewan within the Williston Basin. Two approaches were used to characterize the semipermeability of the samples. The main approach was through direct measurements of osmotic pressure which could then be used to calculate the osmotic efficiency. The value of osmotic efficiency ranges from zero (indicating no restriction to pore fluid flow) to one (indicating a perfect membrane that inhibits pore fluid flow). The second approach was through back analyses of the observed solute transport. The observed solutes were cations and anions transported in and out of the sample as a result of advection, diffusion as well as partitioning with the solid phase

3D Modeling and Computer Graphics in Virtual Reality

In the era of digital information technologies, 3D modeling and computer graphics techniques not only apply to the development of virtual models for computer simulation, artificial intelligence (AI), big data analytics, etc., but also they can be applied in many different applications in virtual reality (VR). However, the computer graphics effect and visual realism are usually the trade-offs with the real-time and realistic interaction in VR. In this book chapter, we would like to review the general flow of the VR program development process, and the recent 3D modeling and texture painting techniques used in VR. On the other hand, we would introduce some of the key 3D modeling and computer graphics techniques that can be applied in VR in order to enhance the speed of interaction. The key techniques including smoothing techniques and mesh editing modifiers are not only useful for the designers to learn the 3D modeling process, but it also helps to create less complex mesh models maintaining good visual effects. The techniques are particularly important in the development of 3D models to satisfy the demanding computation requirement of real-time interaction in VR program

The role of unit evaluation, learning and culture dimensions related to student cognitive style in hypermedia learning

Recent developments in learning technologies such as hypermedia are\ud becoming widespread and offer significant contributions to improving the delivery\ud of learning and teaching materials. A key factor in the development of hypermedia\ud learning systems is cognitive style (CS) as it relates to users‟ information\ud processing habits, representing individual users‟ typical modes of perceiving,\ud thinking, remembering and problem solving.\ud \ud \ud \ud \ud A total of 97 students from Australian (45) and Malaysian (52) universities\ud participated in a survey. Five types of predictor variables were investigated with\ud the CS: (i) three learning dimensions; (ii) five culture dimensions; (iii) evaluation\ud of units; (iv) demographics of students; and (v) country in which students studied.\ud Both multiple regression models and tree-based regression were used to analyse\ud the direct effect of the five types of predictor variables, and the interactions within\ud each type of predictor variable. When comparing both models, tree-based\ud regression outperformed the generalized linear model in this study. The research\ud findings indicate that unit evaluation is the primary variable to determine students‟\ud CS. A secondary variable is learning dimension and, among the three dimensions,\ud only nonlinear learning and learner control dimensions have an effect on students‟\ud CS. The last variable is culture and, among the five culture dimensions, only\ud power distance, long term orientation, and individualism have effects on students‟\ud CS. Neither demographics nor country have an effect on students‟ CS.\ud These overall findings suggest that traditional unit evaluation, students‟\ud preference for learning dimensions (such as linear vs non-linear), level of learner\ud control and culture orientation must be taken into consideration in order to enrich\ud students‟ quality of education. This enrichment includes motivating students to\ud acquire subject matter through individualized instruction when designing,\ud developing and delivering educational resources

COVID-19 Crisis: Exploring Community of Inquiry in Online Learning for Sub-Degree Students

The COVID-19 pandemic has brought a tremendous impact on the pedagogy and learning experience of students in sub-degree education sector of Hong Kong. Online learning has become the “sole” solution to deal with student learning challenges during this chaotic period. In this study, we explore online learning for sub-degree students by using a community of inquiry (CoI). As such, confirmatory factor analysis (CFA) was conducted on survey data gathered from 287 sub-degree students from the business and engineering disciplines. Results indicated that the network speed for online education determines the perceived cognitive presence, social presence, and teaching presence of students, whereas gender and academic disciplines of students are not moderating factors that create a significant difference in perceived cognitive presence, social presence, and teaching presence of students. Our study findings for creating and sustaining a purposeful online learning community are highlighted

Development and application of low-cost monitoring approaches for atmospheric ammonia, acid gases and ammonium aerosols

Ammonia (NH3) is the major alkaline gas in the atmosphere, with around 90 % of the total anthropogenic emissions in Europe coming from agriculture-related sources. Following emission to the atmosphere, the neutralisation reaction between NH3 and the acid gases sulfur dioxide (SO2), nitric acid (HNO3) and hydrochloric acid (HCl) produces secondary inorganic aerosols (ammonium nitrate (NH4NO3), ammonium sulfate ((NH4)2SO4) and ammonium chloride (NH4Cl)). With longer atmospheric lifetimes than the gases, the aerosols also contribute to transboundary pollution problems. The gases and aerosols are removed from the atmosphere by wet (in precipitation) or dry (direct uptake by vegetation and surfaces) deposition processes. Together, they can negatively impact the natural environment through the input of excess acidity and nutrient nitrogen and harm human health through the formation of aerosols that contributes to fine-mode particulate matter (PM2.5). They can also potentially influence climate change from the radiative forcing properties of the aerosols and the inputs of nitrogen that can alter the carbon cycle.Monitoring data are necessary for assessing the spatial and temporal extent of pollution and as evidence to detect changes in pollutant concentrations in response to current and future policies to mitigate emissions of NOx, SO2 and NH3. Combined with models, the concentration data are also used to estimate the different fractions of the total sulfur or nitrogen input and different chemical forms of the pollutants. Since the spatial and temporal patterns and atmospheric behaviours of gases and aerosols differ, measurements therefore need to distinguish between the phases. The development of simple, low-cost, time-integrated air sampling methods and their application in cost-efficient monitoring strategies to assess temporal, spatial and trends in the gas and aerosol pollutants in the UK and across Europe is described. An active diffusion denuder method (DELTA®) and a passive sampler (ALPHA®) are implemented at a large number of sites (> 70) in the UK National Ammonia Monitoring Network (NAMN, established 1996) to measure NH3 with a monthly frequency. An extension of the DELTA® method provided additional, monthly measurements of particulate NH4+ (for the NAMN) and of the acid gases (SO2, HNO3, HCl) and aerosol species (NO3 , SO42-, Cl , Na+, Ca2+, Mg2+) for the UK Acid Gas and Aerosol network (AGANet, established 1999) at a subset of NAMN sites. The close integration of the two networks demonstrated the cost-effectiveness of the DELTA® approach, which provided quality assured, concurrent speciated measurement data on multiple pollutants at multiple sites, and also simplicity of operation by a large network of site operators, some of whom have no technical or scientific background. The DELTA® approach and quality protocol developed in the UK networks was further applied to a pan-European NitroEurope (NEU) DELTA® network (20 countries: 2006 – 2010), with knowledge sharing and collaboration between multiple laboratories and research organisations. Important features in the spatial variability and seasonality in the gas and aerosol components were captured in the UK and European networks. The gases, with shorter lifetimes in the atmosphere were found to be spatially more heterogeneous, with a wider range of concentrations than their aerosol counterparts. Variations on a spatial scale were correlated with distributions and magnitude of emission sources, e.g. NH3 and NH4+ concentrations were highest in intensively farmed areas (e.g. East Anglia in eastern England, NAMN) and countries (e.g. the Netherlands, NEU DELTA®). In the UK, evidence is also presented of the contribution by long-range transboundary sources to enhancement of concentrations of NH4NO3 and (NH4)2SO4.Distinct and contrasting seasonal cycles in the gas and aerosol phase components were established, important for identifying periods of pollution and for targeting abatement measures. The observed variations were attributed to seasonal changes in emission sources, atmospheric interactions and the influence of climate on partitioning between the gases and aerosols. For NH3, peaks in concentrations occur from increased volatilisation promoted by warm, dry conditions (summer) and also from agriculture-related emissions, with a main peak in spring and a smaller peak in autumn. Concentrations of SO2 were higher in winter (increased combustion), except in Southern Europe where the peak period was in summer. HNO3 concentrations were more complex, with small peaks in the seasonal cycle related to traffic and industrial emissions, photochemistry, meteorology and the influence of climate on HNO3:NH4NO3 equilibrium. In comparison, the springtime peak in NH4NO3 was attributed to the reaction of a surplus of NH3 with HNO3 to form NH4NO3 in the aerosol phase under cooler, wetter conditions. A summertime peak in particulate SO42- was observed in Southern Europe, coinciding also with peaks in SO2, NH3 and HNO3 concentrations. While the high HNO3 concentrations suggests increased oxidative capacity for formation of H2SO4 (from SO2) and reaction with NH3 to form (NH4)2SO4, the absence of an NH4+ peak illustrates the larger influence of the more abundant NH4NO3 in controlling the seasonality of particulate NH4+.Important changes in the atmospheric concentrations and partitioning between the different gas and aerosol components were captured. The measurement data highlighted the dominance of NH3 and NH4NO3 in rural air, as the emissions of SO2 and NOx continues to fall, against a backdrop of increasing NH3 emissions in the UK and across Europe since 2013. The observed shift in the form of NH4+ aerosol from the stable (NH4)2SO4 to the semi-volatile NH4NO3 is expected to maintain a larger fraction of the NH3 and HNO3 in the gas phase. NH4NO3 can act as a reservoir and release the gases in warm weather, which may partly explain the observed non-linearity between emissions and measured concentrations of NH3 in the UK data. The current and projected trends in the emissions of the gases SO2, NOx and NH3 suggest that NH3 and NH4NO3 can be expected to continue to dominate the inorganic pollution load over the next decades

Radiative absorption enhancement of dust mixed with anthropogenic pollution over East Asia

The particle mixing state plays a significant yet poorly quantified role in aerosol radiative forcing, especially for the mixing of dust (mineral absorbing) and anthropogenic pollution (black carbon absorbing) over East Asia. We have investigated the absorption enhancement of mixed-type aerosols over East Asia by using the Aerosol Robotic Network observations and radiative transfer model calculations. The mixed-type aerosols exhibit significantly enhanced absorbing ability than the corresponding unmixed dust and anthropogenic aerosols, as revealed in the spectral behavior of absorbing aerosol optical depth, single scattering albedo, and imaginary refractive index. The aerosol radiative efficiencies for the dust, mixed-type, and anthropogenic aerosols are −101.0, −112.9, and −98.3 Wm⁻²τ⁻¹ at the bottom of the atmosphere (BOA); −42.3, −22.5, and −39.8 Wm⁻²τ⁻¹ at the top of the atmosphere (TOA); and 58.7, 90.3, and 58.5 Wm⁻²τ⁻¹ in the atmosphere (ATM), respectively. The BOA cooling and ATM heating efficiencies of the mixed-type aerosols are significantly higher than those of the unmixed aerosol types over the East Asia region, resulting in atmospheric stabilization. In addition, the mixed-type aerosols correspond to a lower TOA cooling efficiency, indicating that the cooling effect by the corresponding individual aerosol components is partially counteracted. We conclude that the interaction between dust and anthropogenic pollution not only represents a viable aerosol formation pathway but also results in unfavorable dispersion conditions, both exacerbating the regional air pollution in East Asia. Our results highlight the necessity to accurately account for the mixing state of aerosols in atmospheric models over East Asia in order to better understand the formation mechanism for regional air pollution and to assess its impacts on human health, weather, and climate

Signature of stratospheric air at the Tibetan Plateau

Current estimates of gross carbon flux tend to ignore the downwelling flux of CO_2 from the stratosphere. Observations showed that there is a phase shift between the time series for the concentration of the standard isotopologue C^16O^16O and C^16O^18O at Waliguan, China (36°17'N, 100° 54'E, 3816 m) and several other places. Previous attempts to explain the shift have not been satisfactory. Here we show that the phase shift could be explained by the downwelling air from the stratosphere, and demonstrate that this source of CO_2 provides a useful tool for constraining the carbon cycle. Using O_3 as a proxy of stratosphere-troposphere exchange, we find excellent correlation between O_3 and C^16O^18O observed at the Waliguan Observatory. The observed variability of C^16O^18O is consistent with model predictions, thus supporting that the surface air has significant contributions from the stratosphere. Quantitative modeling may provide a powerful tool for constraining the sources and sinks of CO_2 using the isotopically enriched CO_2 from the stratosphere as a tracer

The State of the Art of Information Integration in Space Applications

This paper aims to present a comprehensive survey on information integration (II) in space informatics. With an ever-increasing scale and dynamics of complex space systems, II has become essential in dealing with the complexity, changes, dynamics, and uncertainties of space systems. The applications of space II (SII) require addressing some distinctive functional requirements (FRs) of heterogeneity, networking, communication, security, latency, and resilience; while limited works are available to examine recent advances of SII thoroughly. This survey helps to gain the understanding of the state of the art of SII in sense that (1) technical drivers for SII are discussed and classified; (2) existing works in space system development are analyzed in terms of their contributions to space economy, divisions, activities, and missions; (3) enabling space information technologies are explored at aspects of sensing, communication, networking, data analysis, and system integration; (4) the importance of first-time right (FTR) for implementation of a space system is emphasized, the limitations of digital twin (DT-I) as technological enablers are discussed, and a concept digital-triad (DT-II) is introduced as an information platform to overcome these limitations with a list of fundamental design principles; (5) the research challenges and opportunities are discussed to promote SII and advance space informatics in future

大時代的文化研究 : 馬照跑，舞照跳? = Will horse racing and dancing go on in the Great Era of Cultural Studies?

研討會分為二部分。第一部分的主題是「大時代的文化研究：馬照跑，舞照跳？」，以MCSian的論文為引旨，透過對話去思考在當前處境如何尋找出路，由鄧芝珊主持，分別由廖可兒主講〈從聯合國氣候變化大會到黃背心運動–反思「環境 vs 發展與生計」的二元對立〉，馮羚主講〈從台灣電音三太子看傳統文化的傳承與挑戰〉，譚家浚主講〈賽馬作為統治殖民手段 - 由被統治者的接受與反抗所演變成的香港賽馬文化〉，並由李小良評論及與講者進行討論