خيارات البحث
النتائج 861 - 870 من 2,185
Evaluation of compliance of existing forest machine information systems for the implementation of the standard StanForD 2010 النص الكامل
2020
Strubergs, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Sisenis, L., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
The aim of the study is to clarify the compliance of machinery information systems used by Latvian logging service providers with the requirements of the Forest Machine Data and Communications Standard StanForD 2010. For determining the number of logging machines and structure registered in Latvia, data from the State Technical Control Agency of Latvia (VTUA) has been used. This dataset includes 2094 registered machinery units from which 1663 units recorded as harvesters and forwarders are distributed for data processing. Using the national AS Latvian State Forests (LSF) database, where 541 machinery units have been recorded, of which 239 harvesters and 302 forwarders, it is determined what and how many machines already use the standard StanForD 2010, how many machines can implement it and which machines are not suitable for the implementation of StanForD 2010. The study showed that the VTUA register does not fully reflect the true quantity of harvesting machines in Latvia and does not provide information about the use of machines. The LSF data provide reliable information on the possibilities of using StanForD 2010 in harvesters in national forests. From the harvesters working in the country’s forests, 52% of the machines use the StanForD 2010 standard. Work should be continued to clarify the possible use of the standard in the machines working in private forests. Similarly, work should be continued with dealers of harvesting machines to identify models for which it is possible to adjust the StanForD 2010 standard and what the cost of adapting the indicative information systems is.
اظهر المزيد [+] اقل [-]Organosolv delignification of residual plantation willow bark after extractive removal النص الكامل
2020
Pals, M., Latvian State Inst. of Wood Chemistry, Riga (Latvia);University of Latvia, Riga (Latvia) | Lauberte, L., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Arshanitsa, A., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Vevere, L., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Jurkjane, V., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Telysheva, G., Latvian State Inst. of Wood Chemistry, Riga (Latvia)
Plantation willows are commonly grown plants which are widely used for energetic purposes that does not correspond completely to its potential. To fully integrate this resource into biorefinery scheme, it is necessary to study optimal conditions of willow bark processing, aimed for separation of bark components, their comprehensive characterization and profitable practical application. Extraction of secondary metabolites is well known approach for bark processing. But the separation of the main cell wall components including lignin from the residual biomass is less studied. In this work plantation residual willow bark after extractives separation by two different solvents (acetone and ethanolwater) was used as a feedstock for Organosolv delignification. Effect of temperature and catalyst used on the yield and properties of lignin isolated from residual bark by ethanol-water treatment was studied. It was possible to obtain pure lignin with high yields (up to 41%) that has the potential to be used for bio-plastic producing. Insoluble residue after delignification was carbohydrate rich (up to 80%) feedstock allowing its practical use for bioethanol producing.
اظهر المزيد [+] اقل [-]Pyrolysis and acid hydrolysis of lignocellulosic biomass as a tool for monosaccharide obtaining النص الكامل
2020
Godina, D., Latvian State Inst. of Wood Chemistry, Riga (Latvia);University of Latvia, Riga (Latvia) | Pomilovskis, R., Latvian State Inst. of Wood Chemistry, Riga (Latvia) | Iljina, N., Latvian State Inst. of Wood Chemistry, Riga (Latvia));University of Latvia, Riga (Latvia) | Meile, K., Latvian State Inst. of Wood Chemistry, Riga (Latvia
Due to the ever increasing demand for energy resources, more and more attention is being paid to renewable energy resources. One such potential resource is lignocellulosic biomass that can be treated to acquire a carbohydrate rich substrate for further use in producing biofuels such as bioethanol or biobutanol. In this study, birch (Betula pendula) chips were used in fast pyrolysis to acquire bio-oil. This bio-oil was further hydrolyzed in pressurized reactor Parr 4554 to produce a carbohydrate rich feedstock. Hydrolysis conditions were optimized. Several conditions − three different temperatures (111, 121, 131 °C) and four different sulfuric acid concentrations (0.05, 0.1, 0.2, 0.5 M) were tested. The optimal conditions were 121 °C with 0.2 M sulfuric acid as a catalyst that allowed to acquire a solution with the total glucose concentration being 6.6% that can be further used as a feedstock for biofuel acquiring.
اظهر المزيد [+] اقل [-]Cattle (Bos taurus) endometrium morphology on the seventh day of the estrous cycle النص الكامل
2020
Ponomarjova, O., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Sematovica, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Piginka-Vjaceslavova, I., Institute of Food Safety, Animal Health and Environment “BIORˮ, Riga (Latvia) | Vanaga, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
The aim of our study was to describe the histopathological and cytological characteristic of the cow endometrium on the seventh day of the oestrous cycle. In this study, 11 different breeds’ dairy cows (78.18 ± 37.46 months old, in 3.6 ± 2.17 lactation, the mean body condition score 3.4 ± 0.72 (5 points scale)) from Research and Study farm ‘Vecauce’ were selected. All cows were more than 210 days postpartum. Overall health and reproductive tract examination was performed, progesterone (P4) and estradiol (E2) concentration in blood serum were established and the biopsy and cytology samples of endometrium were taken. Mean E2 concentration was 14.92 ± 7.92 pg mLE−1, mean P4 concentration was 13.64 ± 9.44 nmol LE−1. The mean percentage in the cytology slides was established: epithelial cells 89 ± 9%, polimorphonuclear leukocytes (PMN) 6 ± 5%. Cytological subclinical endometritis (SE) was confirmed in 5 cows. Histopathological findings (out of 22 samples): endometrium stromal edema in 14, hemosiderin and hemosiderophages in 8, supranuclear vacuolization in 12, pseudodecidual reaction in 12 samples. No subnuclear vacuolization and mitosis in the glandular epithelium were detected. Histopathological examination did not reveal SE. Morphology between the uterine horns with and without corpus luteum (CL) and between cows with serum P4 level higher than 15 nmol LE−1 and lower than 15 nmol LE−1 were not statistically different (p is greater than 0.05). In conclusion, histopatological examination is more reliable diagnostic method for SE. Future investigation should be performed to establish cut-off values for the diagnosis of SE in cows more than 210 days postpartum.
اظهر المزيد [+] اقل [-]Development of ecosystem service opportunities in the Nemunas Delta in the context of global climate change النص الكامل
2020
Pilipavicius, V., Vytautas Magnus Univ., Kaunas (Lithuania) | Zukovskis, J., Klaipeda Univ. (Lithuania)
The second half of the 20th century brought to light the consequences of human activity, when Humanity was confronted with demiurgical complexes and realized that the planet Earth was not only nature, but a complex system that today could no longer be operated by traditional methods and logic. While until the middle of the 20th century man used natural resources only to meet his needs, the 21st century poses new challenges for mankind to manage the consequences of human activities and to use them rationally and sustainably. The paper presents a study aimed at assessing the potential of ecosystem services development in the Nemunas Delta and anticipating their development directions. As a result of the research, the possible development directions of the Elderships were presented. It was done in two scenarios. The research was carried out in six municipality subdivisions (elderships) of the Nemunas Delta area in the framework of the Lithuanian Science Council project ‘Interaction of ecosystem services and human activities in the context of climate change’. Preparation of this paper was supported by funding from European Social Fund (project No 09.3.3-LMT-K-712-01-0178) under the grant agreement with the Research Council of Lithuania (LMTLT).
اظهر المزيد [+] اقل [-]Challenges in human resource management in the culture industry in Latvia النص الكامل
2020
Bethere, S., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Licite-Kurbe, L., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
The culture industry and its human resources have been little researched in Latvia, yet research on the culture industry is important, because the industry makes a significant contribution to economic growth by promoting employment and the development of competitive regions. The culture industry encompasses libraries, folk art, theatre, music, museums, the creative industry and other sub-industries, yet in recent years those working in all the culture subindustries faced various challenges, including: a low remuneration and insufficient monetary and non-monetary bonuses, resulting in lower job satisfaction and a high personnel turnover. Accordingly, the aim of the research is to develop recommendations for hiring and retaining human resources by examining challenges in managing human resources in the culture industry. The authors conducted a survey among the personnel of the Board of Culture of Jelgava municipality. The survey found that the main challenges faced by the administration of the Board of Culture were an uncompetitive remuneration, the aging of the personnel and generational change as well as inefficient and insufficient motivation for working. The research has developed two scenarios for recruiting: ‘promotion of creativity and non-monetary motivation’ that aim to publicly appreciate human resources, so that they would feel important and significant as well as facilitate creativity, innovation and collective solidarity, while for the purpose of retaining human resources in a long-term and decreasing their turnover, the second scenario ‘competitive remuneration and the differentiation by position category’ aims to gradually raise the remuneration and differentiate it for all categories of personnel.
اظهر المزيد [+] اقل [-]Company capital structure’s theoretical framework: historical assessment and trends in the 21st century النص الكامل
2020
Pilvere-Javorska, A., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Pilvere, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Riva, B., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia)
Company capital is essential in running business and creating value added for the stakeholders, including economy. How the view on company’s capital structure has evolved from theoretical perspective in the 20th century is needed to be assessed, in order to determine what concepts and theories, if any are relevant in the 21st century. Many theories have competed their way and transformed during the 20th century, while some, i.e. trade-off, signalling and stakeholder theories are still relevant in the 21st century. There are also new trends in the 21st century, new terms and quests shifting from determining and analysing optimal company’s capital structure to sustainable finance, taxonomy and also sustainability in capital structure. Therefore, the aim of this research: to establish existing main theories impacting and analysing company’s capital structure and to examine the theoretical shift of the theories based on the needs in the 21st century. Authors defined company’s capital structure and determined that during the years 1989–2020, number of research publications has grown significantly, thus validating the need to reassess theoretical background of capital structure theories in the 20th century, as well as to help to determine the trends still relative and emerging from the theoretical and practical aspects to company’s capital structure in the 21st century.
اظهر المزيد [+] اقل [-]Customer-based brand equity creation for online grocery stores النص الكامل
2020
Sontaite-Petkeviciene, M., Vytautas Magnus Univ., Kaunas (Lithuania)
Given the growing worldwide tendencies of online shopping and increasing popularity of online grocery shopping, building customer-based brand equity for online grocery stores is gaining its popularity among business owners and marketers. Building good customer-based brand equity is considered to be one of the crucial goals for online businesses that lead to successful competition and good customer experience. The aim of this research is to determine customer-based brand equity dimensions for online grocery stores. To reach the aim, this paper adopts analysis and synthesis of scientific and practical literature in the field of customer-based brand equity and empirical research of three stages: field analysis, expert interviews and customer survey. 33 dimensions of customer-based brand equity for online grocery stores grouped in 8 dimension clusters were generated from the field analysis and expert interviews. Generated dimensions were provided for the evaluation during the customer survey. Empirical research proved 31 valid dimensions of customer-based brand equity for online grocery stores evaluated as very relevant, relevant and of average relevance. Main drivers of customer-based brand equity for online grocery stores that proved to be very relevant are: saving time, good price, fresh products, quality of service, and reputation of retail chain behind.
اظهر المزيد [+] اقل [-]Surface modelling of a unique heritage object: use of UAV combined with camera and LiDAR for mound inspection النص الكامل
2020
Jankauskiene, D., Klaipeda State Univ. of Applied Sciences (Lithuania);Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Kuklys, I., Klaipeda State Univ. of Applied Sciences (Lithuania) | Kukliene, L., Klaipeda State Univ. of Applied Sciences (Lithuania) | Ruzgiene, B., Klaipeda State Univ. of Applied Sciences (Lithuania)
Nowadays, the use of Unmanned Aerial Vehicle flying at a low altitude in conjunction with photogrammetric and LiDAR technologies allows to collect images of very high-resolution to generate dense points cloud and to simulate geospatial data of territories. The technology used in experimental research contains reconstruction of topography of surface with historical structure, observing the recreational infrastructure, obtaining geographic information for users who are involved in preservation and inspection of such unique cultural/ heritage object as are mounds in Lithuania. In order to get reliable aerial mapping products of preserved unique heritage object, such photogrammetric/ GIS procedures were performed: UAV flight for taking images with the camera; scanning surface by LiDAR simultaneously; processing of image data, 3D modelling and generation of orthophoto. Evaluation of images processing results shows that the accuracy of surface modelling by the use of UAV photogrammetry method satisfied requirements – mean RMSE equal to 0.031 m. The scanning surface by LiDAR from low altitude is advisable, relief representation of experimental area was obtained with mean accuracy up to 0.050 m. Aerial mapping by the use of UAV requires to specify appropriate ground sample distance (GSD) that is important for reducing number of images and time duration for modelling of area. Experiment shows that specified GSD of 1.7 cm is not reasonable; GSD size increased by 1.5 times would be applicable. The use of different software in addition for DSM visualization and analysis is redundant action.
اظهر المزيد [+] اقل [-]Clay minerals and humic substances as landfill closure covering material constituents: first studies النص الكامل
2020
Burlakovs, J., University of Latvia, Riga (Latvia) | Pilecka, J., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Grinfelde, I., Latvia Univ. of Life Sciences and Technologies, Jelgava (Latvia) | Ozola-Davidane, R., University of Latvia, Riga (Latvia)
Soil and groundwater as the leachate may contaminate surrounding watersheds, thus different pollutants from closed dumps and landfills pose significant risks to human health and ecology. Pollution may lead to soil and water degradation however it might be diminished through sustainable dump site closure projects and processual management. Several decades of clays and clay minerals studies lead to modified clay composites concept that is one of the potential promising solutions for building the landfill covering material and serve as capping biocover layer at the same time. As humic substances are constituents of soil organic matter, pollutants can be sorbed on the surfaces of complex molecules. These kind of humic acid-clay mineral composite materials thus might become as low cost building material component − covering material. Construction of such layer is to be performed as a combination of clay-humic composites and landfill mined fine fraction of waste with small amendment of natural soil. Several hypotheses that are already proven has to be mentioned: a) Clay minerals produce composites with humic substances; 2) Clay-humic complexes reduce through sorption both organic and inorganic pollutants; 3) Low risk of toxic by-products from landfill mined waste fine fraction can be the problem; 4) Such composites mostly would trap toxic contaminants (e.g., pharmaceuticals) found in reworked fine fraction of waste. The aim of the work is to provide alternative solution for landfill closure by giving theoretical considerations from multidisciplinary knowledge of environmental engineering, chemistry and waste management.
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