3,099 research outputs found
Дослідження розробки програмного забезпечення для платформи Android
Föreliggande projekt syftar till att utvärdera funktionen på ett bergvärmepumpsbaserat uppvärmningssystem för småhus med korta borrhål. För att kompensera för det korta borrhålet när en ny större och effektivare värmepump installeras har kollektorsystemet (dvs. borrhålssystemet) kompletterats med en solfångare kombinerad luftkonvektor, ”energikollektor”. Energikollektorns syfte är att tillföra energi till värmepumpens kalla sida, så att energiuttaget ur borrhålet inte ökar mot tidigare med den ersatta värmepumpen. Systemet har utrustats med flertalet energimätare samt en värmepumpsanalysator som samlar in och lagrar driftdata för systemet. Dessa driftdata visar för en dag i april, 2016, att energiuttaget ur kollektorsystemet via värmepumpen helt har kompensats av tillförd energi från energikollektorn. Dygnets medeltemperatur för detta dygn var 8.6 °C. Detta tyder på att syftet med systemet är uppfyllt och funktionen är den som initialt efterfrågades. Långtidsmätningar har inte gått att genomföra än, då installation av själva energisystemet, dvs. Värmestugan, försenats. Det intressantaste för en framtida studie är att se hur mycket energi, på årsbasis, som energikollektorn tillför kollektorsystemet, i förhållande till bortförd energi via värmepumpen. Det kunde noteras för undersökt dygn att temperaturen av vätskan in i värmepumpen signifikant ökade då energikollektorn tillförde energi. Kan detta även noteras sett över en årscykel? Solenergi som tillförs under varma tiden på året måste finnas kvar under uppvärmningssäsongen (dvs. ge en höge kollektorsystemtemperatur).QC 20160524</p
Digital mapping of soil properties using multivariate statistical analysis and ASTER data in an Arid Region
Modeling and mapping of soil properties has been identified as key for effective land degradation management and mitigation. The ability to model and map soil properties at sufficient accuracy for a large agriculture area is demonstrated using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. Soil samples were collected in the El-Tina Plain, Sinai, Egypt, concurrently with the acquisition of ASTER imagery, and measured for soil electrical conductivity (EC_e), clay content and soil organic matter (OM). An ASTER image covering the study area was preprocessed, and two predictive models, multivariate adaptive regression splines (MARS) and the partial least squares regression (PLSR), were constructed based on the ASTER spectra. For all three soil properties, the results of MARS models were better than those of the respective PLSR models, with cross-validation estimated R^2 of 0.85 and 0.80 for EC_e, 0.94 and 0.90 for clay content and 0.79 and 0.73 for OM. Independent validation of EC_e, clay content and OM maps with 32 soil samples showed the better performance of the MARS models, with R^2 = 0.81, 0.89 and 0.73, respectively, compared to R^2 = 0.78, 0.87 and 0.71 for the PLSR models. The results indicated that MARS is a more suitable and superior modeling technique than PLSR for the estimation and mapping of soil salinity (EC_e), clay content and OM. The method developed in this paper was found to be reliable and accurate for digital soil mapping in arid and semi-arid environments
Optimized Basis Sets for the Environment in the Domain-Specific Basis Set Approach of the Incremental Scheme
Minimal basis sets, denoted DSBSenv, have been developed based on the segmented basis sets of Ahlrichs and co-workers for use as environmental basis set for the domain-specific basis set incremental scheme with the aim of decreasing the CPU requirements of the incremental scheme. The use of this minimal basis within explicitly correlated (F12) methods has been enabled by the optimization of matching auxiliary basis sets for use in density fitting of two-electron integrals and the resolution-of-the-identity. The accuracy of these auxiliary sets has been validated by calculations on a test set containing small- to medium-sized molecules. The errors due to density fitting are about two to four orders of magnitude smaller than the basis set incompleteness error of the DSBSenv orbital basis sets. Additional reductions in computational cost are tested with the reduced DSBSenv basis sets, where the highest angular momentum functions of the DSBSenv auxiliary basis sets have been removed. The optimized and reduced basis sets are used in the framework of the domain-specific basis set of the incremental scheme to decrease the computation time without significant loss of accuracy. The computation times and accuracy of the previously used environmental basis and that optimized in this work is validated with a test set of medium- to large-sized systems. The optimized and reduced DSBSenv basis sets decrease the CPU-time by about 15.4% and 19.4% compared to the old environmental basis and retains the accuracy in the absolute energy with a standard deviation of 0.99 and 1.06 kJ/mol, respectively
Estimating the soil clay content and organic matter by means of different calibration methods of vis-NIR diffuse reflectance spectroscopy
The selection of calibration method is one of the main factors influencing measurement accuracy of soil properties estimation in visible and near infrared reflectance spectroscopy. In this study, the performance of three regression techniques, namely, partial least-squares regression (PLSR), support vector regression (SVR), and multivariate adaptive regression splines (MARS) were compared to identify the best method to assess organic matter (OM) and clay content in the salt-affected soils. One hundred and two soil samples collected from Northern Sinai, Egypt, were used as the data set for the calibration and validation procedures. The dry samples were scanned using a FieldSpec Pro FR Portable Spectroradiometer (Analytical Spectral Devices, ASD) with a measurement range of 350–2500 nm. The spectra were subjected to seven pre-processed techniques, e.g., Savitzky–Golay (SG) smoothing, first derivative with SG smoothing (FD-SG), second derivative with SG smoothing (SD-SG), continuum removed reflectance (CR), standard normal variate and detrending (SNV-DT), multiplicative scatter correction (MSC) and extended MSC. The results of cross-validation showed that in most cases MARS models performed better than PLSR and SVR models. The best predictions were obtained using MARS calibration methods with CR prep-processing, yielding R2, root mean squared error (RMSE), and ratio of performance to deviation (RPD) values of 0.85, 0.19%, and 2.63, respectively, for OM; and 0.90, 5.32%, and 3.15, respectively, for clay content
Morphometric differences in the grasshopper Cornops aquaticum (Bruner, 1906) from South America and South Africa
The semi-aquatic grasshopper Cornops aquaticum is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay. It is host-specific to aquatic plants in the genera Eichhornia and Pontederia. A quarantine population has existed in South Africa for 10 y, and it is planned to release it there as a biological control agent of water hyacinth, E. crassipes. Various studies of C. aquaticum are coordinated under HICWA (www.mpil-ploen.mpg.de). This paper compares the morphometry of the release population and 11 native populations in South America. We tested four hypotheses: 1) South African and South American populations of C. aquaticum differ in morphology; 2) the South African laboratory population is more similar to other isolated populations in South America than to nonisolated populations; 3) morphology differs across sites; 4) morphology differs with host plant. South African populations differed from continental nonisolated populations, but not from continental isolated ones. Isolated populations presented smaller individuals than nonisolated, but there was also a change in male morphology: while in nonisolated populations male wing length was similar to their body length, in isolated populations, male wings were smaller than body length. Females were larger when on Eicchornia azurea than on E. crassipes, while males presented larger wings than their body on E. azurea, and similar lengths on E. crassipes. These morphological changes may have resulted from phenotypic plasticity, selection for small size, or because of a loss of genetic diversity in quantitative traits.Fil: Adis, Joachim. Institute for Limnology; AlemaniaFil: Sperber, Carlos F. Universidade Federal de Viçosa; BrasilFil: Brede, Edward G. Institute for Limnology; AlemaniaFil: Capello, Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Franceschini, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Hill, Martin. Rhodes University; SudáfricaFil: Lhano, Marcos G. Universidade Federal de Viçosa; BrasilFil: Marques, Marinê. A;z M.. Universidade Federal de Mato Grosso; BrasilFil: Nunes, Ana L.. Muséu Paraense Emílio Goeldi; BrasilFil: Polar, Perry. CAB International; Trinidad y Tobag
Using Annual Landsat Time Series for the Detection of Dry Forest Degradation Processes in South-Central Angola
Dry tropical forests undergo massive conversion and degradation processes.
This also holds true for the extensive Miombo forests that cover large parts
of Southern Africa. While the largest proportional area can be found in
Angola, the country still struggles with food shortages, insufficient medical
and educational supplies, as well as the ongoing reconstruction of
infrastructure after 27 years of civil war. Especially in rural areas, the
local population is therefore still heavily dependent on the consumption of
natural resources, as well as subsistence agriculture. This leads, on one
hand, to large areas of Miombo forests being converted for cultivation
purposes, but on the other hand, to degradation processes due to the selective
use of forest resources. While forest conversion in south-central rural Angola
has already been quantitatively described, information about forest
degradation is not yet available. This is due to the history of conflicts and
the therewith connected research difficulties, as well as the remote location
of this area. We apply an annual time series approach using Landsat data in
south-central Angola not only to assess the current degradation status of the
Miombo forests, but also to derive past developments reaching back to times of
armed conflicts. We use the Disturbance Index based on tasseled cap
transformation to exclude external influences like inter-annual variation of
rainfall. Based on this time series, linear regression is calculated for
forest areas unaffected by conversion, but also for the pre-conversion period
of those areas that were used for cultivation purposes during the observation
time. Metrics derived from linear regression are used to classify the study
area according to their dominant modification processes. We compare our
results to MODIS latent integral trends and to further products to derive
information on underlying drivers. Around 13% of the Miombo forests are
affected by degradation processes, especially along streets, in villages, and
close to existing agriculture. However, areas in presumably remote and dense
forest areas are also affected to a significant extent. A comparison with
MODIS derived fire ignition data shows that they are most likely affected by
recurring fires and less by selective timber extraction. We confirm that areas
that are used for agriculture are more heavily disturbed by selective use
beforehand than those that remain unaffected by conversion. The results can be
substantiated by the MODIS latent integral trends and we also show that due to
extent and location, the assessment of forest conversion is most likely not
sufficient to provide good estimates for the loss of natural resources. View
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Perfectionism and training distress in junior athletes: A longitudinal investigation
Perfectionistic athletes may train harder and for longer than non-perfectionistic athletes, leaving them susceptible to elevated levels of training distress. So far, however, no study has investigated the relationships between perfectionism and training distress, a key indicator of overtraining syndrome. Furthermore, no study has determined psychological predictors of overtraining syndrome. Using a two-wave design, the present study examined perfectionistic strivings, perfectionistic concerns, and training distress in 141 junior athletes (mean age 17.3 years, range 16-19 years) over 3 months of active training. Multiple regression analyses were employed to test cross-sectional and longitudinal relationships between perfectionism and training distress. In all analyses, perfectionism emerged as a significant predictor, but strivings and concerns showed differential relationships. When the cross-sectional relationships were regarded, perfectionistic concerns positively predicted training distress (p .05). The findings suggest that sports scientists who wish to identify athletes at risk of overtraining syndrome may monitor athletes’ perfectionistic concerns as a possible risk factor
Validation of the German version of the STarT-Back Tool (STarT-G): a cohort study with patients from primary care practices
Background: Current research emphasizes the high prevalence and costs of low back pain (LBP). The STarT Back Tool was designed to support primary care decision making for treatment by helping to determine the treatment prognosis of patients with non-specific low back pain. The German version is the STarT-G. The cross-cultural translation of the tool followed a structured and widely accepted process but to date it was only partially validated with a small sample. The aim of the study was to test the psychometric properties construct validity, discriminative ability, internal consistency and test-retest-reliability of the STarT-G and to compare them with values given for the original English version. Methods: A consecutive cohort study with a two-week retest was conducted among patients with non-specific LBP, aged 18 to 60 years, from primary care practices. Questionnaires were collected before the first consultation, and two weeks later by post, using the following reference standards: the Roland and Morris disability questionnaire, the Tampa Scale of Kinesiophobia, the Pain Catastrophizing Scale and the Hospital Anxiety and Depression Scale. Psychometric properties examined included the tool’s discriminative abilities, whether the psychosocial subscale was one factor, internal consistency, item redundancy, test-retest reliability and floor and ceiling effects. Results: There were 228 patients recruited with a mean age of 42.2 (SD 11.0) years, and 53 % were female. The areas under the curve (AUC) for discriminative ability ranged from 0.70 (STarT-G Subscale - Pain Catastrophizing Scale; CI95 0.63, 0.78) to 0.77 (STarT-G Total - Composite reference standard, CI95 0.60, 0.94). Factor loadings ranged from 0.49 to 0.74. Cronbach’s alpha testing the internal consistency and redundancy for the total/subscale scores were α = 0.52/0.55 respectively. The STarT-G test-retest reliability Kappa values for the total/subscale scores were 0.67/0.68 respectively. No floor or ceiling effects were present. Conclusions: The STarT-G shows acceptable psychometric properties although not in exact agreement with the original English version. The items previously regarded as a psychosocial subscale may be better seen as an index of different individual psychosocial constructs. The relevance of using the tool at the point of consultation should be further examined
Perfectionism and exam performance: The mediating effect of task-approach goals
Perfectionistic strivings are positively correlated with students’ achievement goals and exam performance. However, so far no study has employed a prospective design investigating whether achievement goals mediate the positive relationship between perfectionistic strivings and exam performance. In the present study, 100 university students completed a measure of self-oriented perfectionism and socially prescribed perfectionism (Hewitt & Flett, 1991) and received a chapter from a textbook to study for 2-4 days. Then they returned to the lab to complete a measure of achievement goals following the 3 x 2 model (Elliot, Murayama, & Pekrun, 2011) and sit a mock exam testing their knowledge of the chapter. Multiple regressions showed that socially prescribed perfectionism negatively predicted exam performance when the overlap with self-oriented perfectionism was controlled for. In contrast, self-oriented perfectionism—a defining indicator of perfectionistic strivings—positively predicted exam performance. Moreover, task-approach goals mediated the positive relationship between self-oriented perfectionism and exam performance. The findings suggest that perfectionistic strivings make students adopt task-approach goals that help them achieve better results on exams
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