Thermal Performance Evaluation of a Residential Solar/Gas Hybrid Water Heating System

In climate regions with lower average daily solar radiation, such as the Pacific Northwest, a solar energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas water heater. Previous studies of such hybrid systems have shown that the efficiencies achieved while running in combined solar/gas mode was lower than expected. This inefficiency was attributed to a reduction in gas burner efficiency when the process fluid was partially pre-heated by the solar input. To predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. In this work, the performance of a commercial hybrid solar/gas system is experimentally characterized to evaluate individual component and overall system efficiency. The hybrid water heating system consisted of three flat plate collectors arranged in series (total area = 6.44 m2), and a 22.3 kW natural gas burner. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. Efficiency value for each mode was calculated. Based on the experimental efficiency results, a configuration that would provide higher efficiency for combined solar/gas heating is suggested

Paikkatietoaiheinen vuorovaikutukseen ja ryhmätyöhön kannustava oppimispeli Oulun yliopiston kasvitieteellisellä puutarhalla

Tiivistelmä. Teknologian kehitys on tarjonnut opettajille uusia mahdollisuuksia suunnitella opetustaan. Perusopetuksen opetussuunnitelmassa painotetaan osallistavaa ja toiminnallista oppimista, jotka tässä tutkielmassa ovat otettu huomioon ryhmätyöskentelyn, vuorovaikutuksen ja pelin tehtävien osalta. Digitaalisia opetuspelejä on tutkittu paljon etenkin motivointikyvyn ja flow-tilan herättämisen osalta, mutta opetuspelien mahdollistama informaaleissa tiloissa tapahtuva työskentely, sekä opetuspelien tehokkuus ryhmätyöskentelyn työkaluna, on jäänyt vähemmälle. Kolme vuotta sitten Oulun yliopiston kasvitieteelliselle sisäpuutarhalle tehtiin digitaalinen opetuspeli osana laajempaa hanketta. Osana tätä tutkielmaa valmistui opetuspeli myös ulkopuutarhalle. Tutkielmaa varten suunnitellun opetuspelin tehtävissä korostuu kartta- ja paikkatieto. Pelaamisessa suuressa osassa on myös digitaalisten karttojen avulla suunnistaminen seuraavalle tehtäväpaikalle. Toukokuussa 2020 kuusi oppilasryhmää kävi pelaamassa digitaalista opetuspeliä kasvitieteellisellä ulkopuutarhalla. Aineisto kerättiin kahdella sähköisesti täytettävällä kyselylomakkeella, jotka kerättiin ennen pelaamista ja pelaamisen jälkeen. Kyselyiden avulla selvitettiin, miten oppilaat kokivat ryhmätyöskentelyn ja vuorovaikutuksen pelaamisen aikana, mitä oppilaat oppivat pelatessaan ja miten oppilaat kokivat ulkopuutarhan oppimisympäristönä. Tuloksia analysoitiin kvantitatiivisesti taulukoiden ja kaavioiden perusteella, sekä kvalitatiivisesti sisällönanalyysiä hyödyntäen. Tuloksissa korostui oppilaiden myönteiset kokemukset ryhmätyöskentelystä ja vuorovaikutuksesta pelaamisen aikana. Lisäksi oppilaat kokivat ulkona liikkumisen ja työskentelyn mielekkääksi. Opetuspeli ei saanut niin selkeää suosiota tutkielman muihin tarkasteltaviin osa-alueisiin verrattuna, mutta huomattava enemmistö oppilaista koki oppineensa pelaamisen aikana. Aineisto kerättiin nopealla aikataululla keväällä 2020 Covid-19-viruksen tuomien rajoitteiden vuoksi ja rajoitteet toivat muutoksia pelaamisjärjestelyihin. Kevät oli ollut normaalia kylmempi ja kasvukausi ei ollut kunnolla alkanut, jonka vuoksi ulkopuutarhalla ei ollut juuri vihreyttä nähtävissä. Kokonaisuus huomioiden tulokset olivat myönteiset etenkin informaalien oppimisympäristöjen ja oppimisen kannalta. Opetuspelit näyttävät olevan tehokas työkalu ryhmätyöskentelyssä, mutta digitaaliset opetuspelit tarvitsevat edelleen lisää tutkimustietoa ja käytännöllisyyttä, jotta ne voivat tulevaisuudessa löytää paikkansa helposti lähestyttävänä opetus- ja oppimismenetelmänä

An enhanced sea-ice thermodynamic model applied to the Baltic sea

A refined Semtner 0-layer sea-ice model (ESIM1) is presented and applied to the Baltic landfast sea-ice. The physical model is capable of simulating seasonal changes of snow and ice thickness. Particular attention is paid to reproducing the snow-ice and the super-imposed-ice formation which play important roles in the total mass balance of the Baltic sea-ice. The model prognostic variables include all kinds of ice and snow layers that may be present during a Baltic landfast ice season and, in general, in every coastal area of an ice-covered ocean. The assessment of the model capabilities was done for 1979–1993 for four different stations in the Baltic Sea. A sensitivity test stresses the relevant role of some of the physical parameters, such as the oceanic heat flux, while a scenario analysis highlights the robustness of the model to perturbed physical forcing. Our results show that one of the key variables in modelling sea-ice thermodynamics is the snow layer and its metamorphism, and including the meteoric ice dynamics into a sea ice model is relevant to properly simulate any ice season, also in view of climate change scenario

Toiminnallinen opetus tarkkaavaisuushäiriöisen lapsen oppimisen tukemisessa

Tiivistelmä. Tässä tutkielmassa tarkastelemme toiminnallista opetusta tarkkaavaisuushäiriöisten lasten oppimisen tukemisessa. Keskitymme tutkielmassamme ADHD-diagnoosin saaneisiin lapsiin. Suomessa ADHD diagnosoidaan International Classification of Diesaes — 10 -tautiluokituksen (ICD- 10) mukaan. Pohjaamme työmme konstruktivistiseen oppimiskäsitykseen sekä John Deweyn ja David Kolbin teorioihin tekemällä oppimisesta sekä kokemuksen merkityksestä oppimisprosessissa. Toiminnallinen opetus on ajankohtainen tutkimuskohde, sillä vuoden 2016 perusopetuksen opetussuunnitelma korostaa toiminnallisen opetuksen merkitystä opetusmenetelmänä. Tämän hetkinen oppimiskäsitys puoltaa oppilaan aktiivista roolia oppimisprosessissa. Tarkkaavaisuushäiriö on yksi lasten yleisimmistä neuropsykologisista ongelmista ja diagnoosien määrä on yhä nousussa. Tarkkaavaisuushäiriöiset lapset integroidaan usein yleisopetuksen luokkaan, joten luokanopettaja tulee työssään todennäköisesti kohtaamaan tarkkaavaisuushäiriöisiä lapsia. Toteutimme työmme kirjallisuuskatsauksena perehtymällä aikaisempiin tutkimuksiin sekä kirjallisuuteen aiheesta. Tarkkaavaisuushäiriöiset lapset, erityisesti pojat, tarvitsevat toiminnallisuutta. Heillä on tarve päästä purkamaan pakottavaa liikkumisen tarvetta. Toiminnallinen opetus on hyvä keino antaa liikkeelle tarkoitus. Toiminnallinen opetus on pääasiassa toimiva opetustapa ADHD-diagnoosin saaneille lapsille. Kuitenkin on syytä muistaa, että jokainen lapsi on yksilö, eikä yhtä oikeaa opetustapaa voida yleistää tarkkaavaisuushäiriöisille oppilaille

A miniaturised 3D printed polypropylene reactor for online reaction analysis by mass spectrometry

Correction: Reaction Chemistry & Engineering, vol. 2:5, p. 811 DOI: 81110.1039/C7RE90018JA miniaturised polypropylene reactor was fabricated by 3D printing using fused deposition modeling. A stainless steel nanoelectrospray ionisation capillary and a magnetic stir bar were integrated into the reactor during the printing process. The integrated nanoelectrospray ionisation capillary allows direct sampling of a reaction solution without external pumping. It also allows ionisation of the analytes. Therefore, very rapid online mass spectrometric chemical reaction monitoring is possible. Operation of the miniaturised reactor is shown by the online nanoelectrospray mass spectrometry characterisation of a Diels–Alder reaction and the subsequent retro Diels–Alder reaction.Peer reviewe

The effects of simultaneous large acidic and alkaline airborne pollutants on forest soil

http://www.elsevier.com/locate/issn/02697491The effects of air pollutants on soil were studied in Scots pine (Pinus sylvestris L.) forests near the boundary of Russia and Estonia. The study area is characterized by large amounts of acidic and basic pollutants, mainly sulphur dioxide (SO*) and calcium (Ca) . Several variables were measured in different horizons of the podzolic soil polluted by emissions from local sources in areas of several thousands of square kilometres. Alkalinization dominates the processes in the soil, since sulphur is absorbed only in small quantities and Ca is much better absorbed. Ca content in humus horizon may rise even to 100 000 mg kg-’ and the pH of originally very acidic soil may rise to 8.3. Total aluminum (Al) content was high in the heavily polluted plots, since emissions contain much Al. On the other hand, the exchangeable Al was very low in these alkaline sites. A larger quantity of exchangeable Al occurred farther from the pollutant sources, even though total Al in these plots was low. These plots had acidic soils in which Al is in exchangeable form. Due to the neutralizing effect of acidic and basic pollutants, forest damage in the study area was not as serious as might be supposed, Complicated pollutant situations must be taken into consideration when pollution-caused environmental protection measures are planned. It is not reasonable to reduce only SO2 emissions, but necessary to lower the basic emissions at the same time

Decline after immobilisation and recovery after remobilisation of synovial fluid IL1, TIMP, and chondroitin sulphate levels in young beagle dogs

OBJECTIVE: To monitor the concentration of markers of cartilage and synovium metabolism in the knee (stifle) joint synovial fluid of young beagles subjected to immobilisation and subsequent remobilisation.METHODS: The right hind limb of 17 dogs was immobilised in flexion for 11 weeks. Simultaneously, the contralateral left knee was exposed to increased weight bearing. The remobilisation period lasted 50 weeks. Litter mates served as controls. The concentration in joint lavage fluid of interleukin 1 (IL1) was measured by immunoassay, the activity of phospholipase A2 (PLA2) was determined by an extraction method, chondroitin sulphate (CS) concentration by precipitation with Alcian blue, hyaluronan (HA) by an ELISA-like assay using biotinylated HA-binding complexes, matrix metalloproteinase 3 (MMP-3), and tissue inhibitor of metalloproteinases 1 (TIMP-1) by sandwich ELISA, and synovitis was scored by light microscopy.RESULTS: Synovitis or effusion was absent in all experimental and control groups. Immobilisation decreased the joint lavage fluid levels of IL1 (p<0.05), TIMP (p< 0.05), and the concentration of CS down to 38 (p<0.05) in comparison with untreated litter mates with normal weight bearing. Immobilisation did not affect the activity of PLA2, or the concentration of MMP-3 or HA in synovial fluid. Joint remobilisation restored the decreased concentrations of markers to control levels. Increased weight bearing did not change the concentrations of markers in comparison with the control joints with normal weight bearing.CONCLUSIONS: 11 weeks joint immobilisation decreased the concentration of markers of cartilage and synovium metabolism in the synovial fluid, and remobilisation restored the concentrations to control levels. The changes in joint metabolism induced by immobilisation, as reflected by the markers, are thus different from those found in osteoarthritis, where increased levels of these markers are associated with enhanced degradation and synthesis. These findings suggest that the change induced in joint metabolism by immobilisation is reversible in its early stages

Investigation of the combined efficiency of a solar/gas hybrid water heating system

In climate regions with large seasonal variations in solar radiation, such as the Pacific Northwest of the United States, a solar thermal energy collector might not economically satisfy year-round domestic water heating demands, requiring an auxiliary unit, such as a natural gas-fired water heater. Previous studies have shown that the burner efficiency of a gas-fired water heater varies depending on the log-mean temperature difference between the cold fluid (water) and the hot fluid (combustion gases). In a solar/gas hybrid water heating system, where solar collectors are used in conjunction with a gas-fired heater, the partial heating of water provided by solar input reduces the log-mean temperature difference value for the gas heater, reducing the efficiency of the gas burner. Since this efficiency reduction varies depending on the amount of pre-heating provided by solar energy input, it is difficult to accurately predict the actual cost and energy savings offered by solar/gas hybrid water heaters in different climates and operation scenarios. Hence, to predict the actual energy and cost savings under various design conditions, the performance of solar/gas hybrid systems must be better understood. The objective of this work is to experimentally determine the thermal performance of a solar/gas water hybrid water heating system with a 6.44 m2 flat plate solar collector array and a 22.3 kW natural gas burner in Corvallis, Oregon, USA. Under different temperature lifts and solar insolation values, the system was operated at three different modes of heating: solar, gas, and combined solar/gas mode. The overall system thermal efficiency value for each mode is calculated. The efficiency of the solar collector heating system was found to be 41.97%, 39.82%, and 35.05% at initial water temperature of 20, 30, and 51.5 °C, respectively. For initial water temperatures of 20, 30, and 51.5 °C, the efficiency of the gas burner was found to be 69.2%, 66.4%, and 65.5% at the HHV, and 76.7%, 73.6%, and 72.6% at the LHV of natural gas, respectively. In the combined solar/gas heating mode, the efficiency of the gas burner decreased with increasing solar fraction. For solar fractions of 4.93%, 9.40%, 11.39%, and 14.27%, the efficiency of the gas burner in terms of the HHV of natural gas was found to be of 69.08%, 66.80%, 66.17%, and 65.18%, respectively. Based on the experimental results, a configuration that would provide higher overall system efficiency for combined solar/gas heating is suggested

Interannual sea ice thickness variability in the Bay of Bothnia

While variations of Baltic Sea ice extent and thickness have been extensively studied, there is little information about drift ice thickness, distribution, and its variability. In our study, we quantify the interannual variability of sea ice thickness in the Bay of Bothnia during the years 2003–2016. We use various different data sets: official ice charts, drilling data from the regular monitoring stations in the coastal fast ice zone, and helicopter and shipborne electromagnetic soundings. We analyze the different data sets and compare them to each other to characterize the interannual variability, to discuss the ratio of level and deformed ice, and to derive ice thickness distributions in the drift ice zone. In the fast ice zone the average ice thickness is 0.58±0.13&thinsp;m. Deformed ice increases the variability of ice conditions in the drift ice zone, where the average ice thickness is 0.92±0.33&thinsp;m. On average, the fraction of deformed ice is 50&thinsp;% to 70&thinsp;% of the total volume. In heavily ridged ice regions near the coast, mean ice thickness is approximately half a meter thicker than that of pure thermodynamically grown fast ice. Drift ice exhibits larger interannual variability than fast ice.</p