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Development of experimental equipment for vegetable oil fuel research Полный текст
2011
Birkavs, A., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dukulis, I., Latvia Univ. of Agriculture, Jelgava (Latvia)
The European Parliament and Council Directive 2003/30/EK ‘On the promotion of the use of biofuels and other renewable fuels for transport’ determines that pure or straight vegetable oil, produced from oil plants by pressing, extracting or comparable procedures, crude or refined but chemically unmodified, compatible with common engines, and corresponding to emission requirements, is also considered as biofuel. The biggest problems imposed by these conditions are directly associated with the carrying-out of the emission requirements, because when using vegetable oil as a fuel, usually increases the composition of the solid particles and nitrogen oxides in exhaust gases, that not only adversely affect the environment, but also is a serious threat to human health, and as a result trying to save the world from the global warming, human health continues to deteriorate. It is therefore necessary to carry out studies and find solutions to reduce harmful emissions from diesel engines when using vegetable oil fuel. For more qualitative and effective research on vegetable oil fuel emissions, the equipment for vegetable oil fuel testing has been developed. This equipment allows fast checking of theoretically proposed hypotheses and detailed calculations for vegetable oil fuel combustion processes and objective data acquisition. The equipment consists of the classic diesel engine adapted for work with vegetable oil and is equipped with several high-precision devices to get and store the measuring data. During pilot tests the optimal measuring modes (engine rotation frequencies, number and duration of repetitions) for further research are estimated.
Показать больше [+] Меньше [-]Evaluation of study programme external quality Полный текст
2011
Sproge, S., Latvia Univ. of Agriculture, Jelgava (Latvia)
Quality assessment of a study programme is a topical issue in the single education area. Quality is not a unequivocal term in higher education area, which lends itself to many understandings and interpretations according to different criteria. The best practice of software engineering may be applied for the study programme evaluation if by analogy it is viewed as software product. Study programme similar to software product has internal and external quality. Students as direct users of the study programme may be engaged in the evaluation of its external quality, in case the evaluation of internal quality of the study programme is mainly based on internal resources of a higher education institution. The paper provides the methodology for evaluation of external quality of a study programme based on software product quality model and quality assurance standards. Approbation of the methodology was started in 2009 at the Faculty of Information Technologies, where students evaluated external quality of undergraduate study programmes. Results obtained during the approbation lead to the conclusion that the chosen methodology ensures significant information for the enhancement of quality of a study course and simultaneously the entire study programme.
Показать больше [+] Меньше [-]The use of black-box modelling in bioprocess scale-up Полный текст
2011
Mednis, M., Latvia Univ. of Agriculture, Jelgava (Latvia)
Computer models of bioprocesses have become an essential tool in biotechnology. This paper describes various bioprocess scaleup releated problems. The problems at different scales are explained. In this paper the use of computer model in E.coli fermentation scale-up from shake flask to laboratory scale bioreactor is discussed. A black box modelling approach was used. Fermentation results have been visualized and discussed. The computer model created in Matlab environment was used for bioprocess behaviour prediction. Possible bioprocess scale-up software improvements and bioprocess optimization are discussed.
Показать больше [+] Меньше [-]Low-cost electrical energy monitoring method with wireless ICT Полный текст
2011
Apse-Apsitis, P., Riga Technical Univ. (Latvia) | Avotins, A., Riga Technical Univ. (Latvia | Ribickis, L., Riga Technical Univ. (Latvia
The electricity consuming end-user profile has changed in latest years, due to development of new electrical devices with increased functionality and complexity. Also increasing number of electricity consuming equipment that is available to end-user, makes very hard to identify real electricity consumption of each device. The existing wall plug digital power meters are too expensive for long-term power metering of each consuming device. The article describes a different approach of power metering system that lowers the costs and price of needed metering equipment. A new concept of low-cost energy monitoring system with wireless communication is developed.
Показать больше [+] Меньше [-]Growth, reproductive performance and survival rate of Bonga sheep and their crossbreds in southern Ethiopia Полный текст
2020
Abate, Z. | Kirmani, M. | Getachew, T. | Haile, Aynalem
Gender aspects in the dairy value chain in Tanzania: A review of literature Полный текст
2018
Sikira, A.N. | Waithanji, Elizabeth M. | Galiè, Alessandra | Baltenweck, Isabelle
The potential influence of social networks on the adoption of breeding strategies Полный текст
2013
Pali, Pamela N. | Zaibet, L. | Mburu, S.K. | Ndiwa, Nicholas N. | Rware, H.I.
Smallholder livestock farmers face challenges such as lack of appropriate fora and networks which can motivate and influence the adoption of breeding strategies in West Africa. Efforts to ensure participation of livestock owners in breeding programs such as performance recording, the use of village herd stocks for breeding programs have been documented as has the creation of livestock producer organizations to enhance effective participation of farmers in breeding programs. The study was conducted in southern Mali where livestock such as the N’dama cattle are endemic. We explored baseline characteristics from a household and community survey to determine the potential effects of individual, household and network characteristics on the knowledge and use of livestock breeding strategies. We assume that interaction amongst stakeholders results in transfer of knowledge between stakeholders. Results from the stakeholder analysis of the types of stakeholders present at the site level were used in the Probit and Seemingly Unrelated Regression (SUR) models. Farmers’ organisations were commonly found at the village level. However, despite the presence of these organizations across sites, they do not interact with the technical organisations as often as they should hence a lower incidence of use of livestock breeding technologies across sites. Results from the models confirm the importance of networks as key determinants to improve the adoption of breeding technologies.
Показать больше [+] Меньше [-]Comparison of spectrophotometric methods for assessment of oxidation of milk fat Полный текст
2010
Antone, U., Latvia Univ. of Agriculture, Jelgava (Latvia);Latvia Univ. of Agriculture, Sigulda (Latvia). Research Inst. of Biotechnology and Veterinary Medicine Sigra | Sterna, V., Latvia Univ. of Agriculture, Sigulda (Latvia). Research Inst. of Biotechnology and Veterinary Medicine Sigra | Zagorska, J., Latvia Univ. of Agriculture, Jelgava (Latvia)
Three spectrophotometric methods were compared for the assessment of milk fat oxidation: the AOCS (American Oil Chemists' Society) 2-thiobarbituric acid (TBA) value direct method, the TBA method of Aristova, and the modified method for the estimation of total carbonyl compounds in oils of Endo et al. Two cow milk fat samples – a fresh fat, obtained from fresh milk, and a rancid fat, obtained from a rancid commercial butter by means of high-speed centrifugation (15.871 × g, 30 minutes at 40 deg C) – were analyzed several times in a 22-day period after sample preparation. A positive linear correlation between absorbance and storage time was established in all used methods. The method of Aristova is appropriate for exact determination of oxidation products. This method had rather good R2 value (0.85) of the fresh fat sample results; however, the coefficient of variation (45.78%) showed rather large deviations between parallel analyses. The methods of AOCS and Endo et al. can be used for the assessment of the dynamics of fat oxidation by reporting absorbance values from the assay directly. By these methods rather high R2 values (0.86, 0.93) of the fresh fat sample results were obtained; the coefficients of variation also were satisfactory (10.13%, 11.12%). The last two methods are cheaper and require smaller sample amounts (less than 0.2 g), while the method of AOCS is the most time-consuming method.
Показать больше [+] Меньше [-]The evaluation of sensory physical and chemical properties of pears grown in Latvia Полный текст
2010
Krasnova, I., Latvian State Inst. of Fruit-Growing, Dobele (Latvia);Latvia Univ. of Agriculture, Jelgava (Latvia) | Karklina, D., Latvia Univ. of Agriculture, Jelgava (Latvia) | Seglina, D., Latvian State Inst. of Fruit-Growing, Dobele (Latvia) | Juhnevica, K., Latvian State Inst. of Fruit-Growing, Dobele (Latvia) | Heidemane, G., Latvian State Inst. of Fruit-Growing, Dobele (Latvia)
The pears (Pyrus communis) are one of most popular fruits that consumers willingly use as fresh produce. On the market place, consumer mainly pays attention to per's externals, size, colour, as well as to fruit taste, substantially influenced by degree of readiness, which in its turn has affect on the chemical composition of pears. The physical, chemical and sensory indices are significant when fruits have been used for fresh-cut fruit salad preparation. All tests have been carried out at Latvia State Institute of Fruit Growing, Dobele in year 2009-2010. The objective of this study was to evaluate the physical, chemical and organoleptical properties of winter cultivars of pears grown in Latvia. The object of the research was 13 cultivars of pears: 'Delta', 'Latgale', 'Tayushchaya', 'Talgarskaya', 'BP 8965', 'Elektra', 'Janvarskaya', 'Beta', 'Bere Kiyevskaya', 'Eckehard', 'Belorusskaya Pozdnaya', 'Erika', and 'Conference' and as a control commercial cultivar. The pears were analysed and their parameters were measured: average mass and diameter of fruits, flesh firmness, colour of flesh, titratable acid (TA) and soluble solids content (SSC) were determined. Sensory analyses were carried out by 9-point hedonic line scale method. Soluble solids content (degree Brix) of pear fruits grown in Latvia is within 9.6 - 14.5 degree Brix. The titratable acidity (TA) is insignificant (0.05-0.26%). The average mean mass of one fruit depending on a cultivar, is 174 g, the flesh firmness at the maturity stage is on average 10.7 to 26.5N. The fruits of cultivars 'Tayushchaya', 'Elktra', and 'Bere kiyevskaya' by their sensory indices were evaluated as the best.
Показать больше [+] Меньше [-]Detecting and measuring individual trees with laser scanning in Latvian forest conditions Полный текст
2010
Priedītis, G., Latvia Univ. of Agriculture, Jelgava (Latvia) | Smits, I., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dagis, S., Latvia Univ. of Agriculture, Jelgava (Latvia) | Dubrovskis, D., Latvia Univ. of Agriculture, Jelgava (Latvia)
Researching new remote sensing and data processing methods is very important subject in forestry. The objectives of research are to explore methods to determine single tree characteristics using LIDAR and adapt them for Latvian forest conditions. Different algorithms and mathematical relations for automatic calculation of tree species, coordinates, height and diameter at breast height are described. Within the project four different clustering methods for tree identification were evaluated. The first method's construction is based on reflection point count in certain height range. The second and third methods are searching for global and local maximums on height axis of LIDAR data collection. In the fourth method segmentation of aerial photography is done by using the user selected sample data. Tree tops were s discovered by searching similarly coloured regions. Field measurements were used for the calibration of LIDAR data and analysis. Sample plots were fitted in the study area with different species composition, age and density. The total number of measured trees in sample plots is 1844. Results show that height can be found mainly for I, II, III craft class trees with average error 2.5%. Stem diameter estimation error of pine is 28%, spruce 17%, birch 4.2% and second storey trees 5.4% using linear equations D = 0.6616*H + 4.6969 (for coniferous trees) and D = 0.7756*H + 3.7132 (for deciduous trees). Dividing trees in classes of coniferous and deciduous can be done by using near infra red photography. The total number of first storey trees identified by LIDAR is 91%, by aerial photographic method 94%.
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