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Nain, Caroline Waingeh, Eric Mignolet, Marie-France Herent, et al. "The Catechins Profile of Green Tea Extracts Affects the Antioxidant Activity and Degradation of Catechins in DHA-Rich Oil." Antioxidants 11, no. 9 (2022): 1844. http://dx.doi.org/10.3390/antiox11091844.
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This study investigated the effect of the catechins profile on the antioxidant activity of green tea extracts (GTEs) by comparing the antioxidant activity of an EGC-rich GTE (GTE1, catechin content: 58% EGC, 30.1% EGCG, 7.9% EC, and 3.9% ECG) and an EGCG-rich GTE (GTE2, catechin content: 60.6% EGCG, 17.7% EGC, 11.8% ECG, and 9.8% EC) in a DHA-rich oil. The effects of the individual catechins (EGC, EC, EGCG, and ECG) and reconstituted catechins mixtures (CatMix), prepared to contain the same amount of major catechins as in the GTEs, were also measured. All treatments (GTE1, CatMix1, GTE2, CatMix2, EGC250, EC250, EGCG250, and ECG250), each containing epistructured catechins at a concentration of 250 ppm, as well as the control (oil with no added antioxidant), were stored at 30 °C for 21 days with sampling intervals of 7 days. The antioxidant activity was assessed by measuring the peroxide value (PV) and p-anisidine value (p-AV) of oils. Changes in fatty acid content and catechins content were also monitored. Both GTEs enhanced the oxidative stability of the DHA-rich oil, but GTE1 demonstrated a stronger antioxidant activity than GTE2. No significant difference was observed between the PV of treatments with GTE1 and CatMix1 during storage, whereas the PV of oil with GTE2 was significantly higher than that with CatMix2 after 21 days. Among the individual catechins, EGC was the strongest antioxidant. Overall, the antioxidant activities of the extracts and catechins were observed in the decreasing order GTE1 ≈ EGC250 ≈ CatMix1 > GTE2 > EGCG250 ≈ CatMix2 > ECG250 > EC250. A significant change in fatty acid content was observed for the control and EC250 samples, and the catechins were most stable in GTE1-supplemented oil. Our results indicate that the EGC-rich GTE is a more potent antioxidant in DHA-rich oil than the EGCG-rich GTE.
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Onishi, Meguro, Pervin, et al. "Green Tea Extracts Attenuate Brain Dysfunction in High-Fat-Diet-Fed SAMP8 Mice." Nutrients 11, no. 4 (2019): 821. http://dx.doi.org/10.3390/nu11040821.
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Unhealthy diet promotes progression of metabolic disorders and brain dysfunction with aging. Green tea extracts (GTEs) have various beneficial effects and alleviate metabolic disorders. GTEs have neuroprotective effects in rodent models, but their effects against brain dysfunction in models of aging fed unhealthy diets are still unclear. Here, we showed that GTEs attenuate high-fat (HF) diet-induced brain dysfunction in senescence-accelerated mouse prone-8 (SAMP8), a murine model of senescence. SAMP8 mice were fed a control diet, HF diet, or HF diet with 0.5% GTEs (HFGT) for four months. The HF diet reduced memory retention and induced amyloid β1–42 accumulation, whereas GTEs attenuated these changes. In HF diet-fed mice, lipid oxidative stress, assessed by malondialdehyde levels, was increased. The levels of proteins that promote synaptic plasticity, such as brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95), were reduced. These alterations related to brain dysfunction were not observed in HFGT diet-fed mice. Overall, our data suggest that GTEs intake might attenuate brain dysfunction in HF diet-fed SAMP8 mice by protecting synaptic plasticity as well as via anti-oxidative effects. In conclusion, GTEs might ameliorate unhealthy diet-induced brain dysfunction that develops with aging.
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Aleya, Amina, Emőke Mihok, Bence Pecsenye, et al. "Phytoconstituent Profiles Associated with Relevant Antioxidant Potential and Variable Nutritive Effects of the Olive, Sweet Almond, and Black Mulberry Gemmotherapy Extracts." Antioxidants 12, no. 9 (2023): 1717. http://dx.doi.org/10.3390/antiox12091717.
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The extracts of whole plants or specific organs from different plant species are gaining increasing attention for their phytotherapy applications. Accordingly, we prepared standardized gemmotherapy extracts (GTEs) from young shoots/buds of olive (Olea europaea), sweet almond (Prunus amygdalus), and black mulberry (Morus nigra), and analyzed the corresponding phytonutrient profiles. We identified 42, 103, and 109 phytonutrients in the olive, almond, and black mulberry GTEs, respectively, containing amino acids, vitamins, polyphenols, flavonoids, coumarins, alkaloids, iridoids, carboxylic acids, lignans, terpenoids, and others. In order to assess the physiological effects generated by the GTEs, we developed a translational nutrition model based on Drosophila melanogaster and Cyprinus carpio. The results indicate that GTEs could influence, to a variable extent, viability and ATP synthesis, even though both are dependent on the specific carbohydrate load of the applied diet and the amino acid and polyphenol pools provided by the GTEs. It seems, therefore, likely that the complex chemical composition of the GTEs offers nutritional properties that cannot be separated from the health-promoting mechanisms that ultimately increase viability and survival. Such an approach sets the paves the way for the nutritional genomic descriptions regarding GTE-associated health-promoting effects.
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Bezerra, Merielly Mariano, and Katia Rejane de Medeiros. "Limites do Programa de Melhoria do Acesso e da Qualidade da Atenção Básica (PMAQ-AB): em foco, a gestão do trabalho e a educação na saúde." Saúde em Debate 42, spe2 (2018): 188–202. http://dx.doi.org/10.1590/0103-11042018s213.
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RESUMO O artigo analisa os limites das subdimensões propostas pelo Programa Nacional de Melhoria do Acesso e da Qualidade da Atenção Básica (PMAQ-AB) para avaliação externa das equipes de Atenção Básica, a partir das diretrizes e dos princípios do campo Gestão do Trabalho e da Educação em Saúde (GTES). Realizou-se um estudo descritivo, com abordagem qualitativa e análise documental sobre o PMAQ-AB, elegendo-se o instrumento de avaliação externa e publicações do Ministério da Saúde relacionadas à política de GTES, no período de 2011 a 2014. Constatou-se que o instrumento de avaliação do PMAQ-AB converge com a política de GTES nos aspectos da precarização do trabalho e da valorização do trabalhador, porém, o instrumento não explora a negociação do trabalho e a saúde do trabalhador. Sua concepção de Educação Permanente em Saúde (EPS) é limitada, embora apresente potencialidades quando investiga a relação das ações de EPS ofertadas e as necessidades das equipes e ao retratar a integração ensino-serviço como um padrão de qualidade. Afirma-se que há necessidade de aprimoramento dos instrumentos do PMAQ-AB para o fortalecimento das diretrizes e dos princípios das políticas do GTES para o Sistema Único de Saúde (SUS), contudo, assume-se que o Programa tem potencial de geração de informações para o sistema de saúde.
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Suryawijaya, Anita Natalia, Tutiek Purwanti, Djoko Agus Purwanto, and Widji Soeratri. "Characteristic and Physical Stability of Anti-Aging Green Tea Extract (GTE) on NLC with Argan Oil as Liquid Lipid." JURNAL FARMASI DAN ILMU KEFARMASIAN INDONESIA 9, no. 2 (2022): 115–24. http://dx.doi.org/10.20473/jfiki.v9i22022.115-124.
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Background: Green tea extract is a hydrophilic antioxidant that is difficult to penetrate. A nanostructured lipid carrier (NLC) delivers a system consisting of solid-liquid lipids that can improve penetration. Argan oil is a vegetable oil that can be used as a liquid lipid in NLC, reducing particle size and increasing penetration by hydrating the skin. Objective: To determine the formula of NLC green tea extract (NLC-GTE) with liquid lipid argan oil, which has good characteristics and is stable. Methods: Preparation of NLC-GTE used the High Shear Homogenization with solid lipids (cetyl palmitate-glyceryl stearate) - liquid lipids (argan oil) NLC-GTE1 (50:50), NLC-GTE2 (70:30), and NLC-GTE3 (90:10). Characteristic tests included organoleptic, pH, particle size (PS), and polydispersity index (PI). The physical stability test (organoleptic, pH, PS, and PI) used the thermal cycling method (3 cycles six days). Result: NLC-GTE1 – NLC-GTE2 has an odor of argan oil. NLC-GTE3 has odorless. NLC-GTE1 – NLC-GTE3 has a pH scale from 5.782-5.784; PS ranges from 359.73–432.56 nm; PI ranges from 0.175-0.257. The statistical analysis results showed no significant difference between NLC-GTE1 – NLC-GTE3 in pH and PI, there was a significant difference in PS NLC-GTE1; NLC-GTE2 against NLC-GTE3. Physical stability test NLC-GTE2 – NLC-GTE3 phase separation occurs. The statistical analysis results showed no significant difference in pH values NLC-GTE1 – NLC-GTE3 before and after storage; there was a significant difference in NLC-GTE3 before and after storage. Conclusion: NLC-GTE1 was a formula with good characteristics and stability.
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Ding, Xiaohu, Wei Wang, Jane Scheetz, and Mingguang He. "The Guangzhou Twin Eye Study: 2019 Update." Twin Research and Human Genetics 22, no. 6 (2019): 492–98. http://dx.doi.org/10.1017/thg.2019.118.
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AbstractThe primary aim of the Guangzhou Twin Eye Study (GTES) is to explore the impact that genes and environmental influences have on common eye diseases. Since 2006, approximately 1300 pairs of twins, aged 7–15 years, were enrolled at baseline. Progressive phenotypes, such as cycloplegic refraction, axial length, height and weight, have been collected annually. Nonprogressive phenotypes such as parental refraction, corneal thickness, fundus photo, intraocular pressure and DNA were collected once at baseline. We are collaborating with fellow international twin researchers and psychologists to further explore links with general medical conditions. In this article, we review the history, major findings and future research directions for the GTES.
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Alqallaf, Jasem, Naser Ali, Joao A. Teixeira, and Abdulmajid Addali. "Solid Particle Erosion Behaviour and Protective Coatings for Gas Turbine Compressor Blades—A Review." Processes 8, no. 8 (2020): 984. http://dx.doi.org/10.3390/pr8080984.
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Gas turbines (GTEs) are often utilised in harsh environments where the GT components, including compressor vanes and rotor blades, are subject to erosion damage by sand and dust particles. For instance, in a desert environment, the rate of damage made by solid particles erosion (SPE) becomes severe, and therefore results in degradation to the GTE parts, lowering the cycle efficiency, reducing the device lifetime, and increasing the overall cost of the operation. As such, understanding the erosion mechanism caused by solid particles and the effects associated with it is crucial for selecting the appropriate countermeasures and maintaining the system performance. This review paper provides a survey of the available studies on SPE effects on GTEs and surface protective coatings. Firstly, the ductile and brittle SPE mechanism is presented, as well as the ductile-brittle transition region. Then, an in-depth focus on the parameters associated with the SPE, such as particles properties and impingement conditions, is introduced. Furthermore, the existing theoretical models are shown and discussed. Afterwards, erosion resistant coating materials for surface protection and their selection criteria are covered in the review. Finally, the gap in knowledge and future research direction in the field of SPE on GTEs are provided.
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Simion, S. "On the Computation of the Attenuation Constant by Using the Generalized Telegraphist’s Equations Based Electromagnetic Analysis Method." Advanced Electromagnetics 12, no. 1 (2023): 17–27. http://dx.doi.org/10.7716/aem.v12i1.2086.
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Numerical results for the attenuation constant obtained by using the generalized telegraphist’s equations (GTEs) based electromagnetic analysis method and comparison with the HFSS (High Frequency Structure Simulator) results are reported. To calculate the attenuation constant with the GTEs method, not only the amplitudes of the voltage modes but also the amplitudes of the current modes must be found. In this paper, it is demonstrated that the relationships reported by other authors for the amplitudes of the current modes are not correct and new ones are proposed. To validate these relationships, the attenuation constants for homogeneous and different partially dielectric-filled rectangular waveguides are computed for the fundamental propagation mode by using the GTEs based analysis method and the results are compared with those obtained with HFSS. It is shown that using the revised relationships for the amplitudes of the current modes, the GTE method can be used to compute accurately the propagation and attenuation constant, but only for propagation modes in which the components of the electric field are not oriented perpendicular to the interface between different dielectrics. This limitation is not due to the proposed current mode relationships, but is due to the GTE method which cannot highlight the electric field discontinuities.
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Héjja, Melinda, Emőke Mihok, Amina Alaya, et al. "Specific Antimicrobial Activities Revealed by Comparative Evaluation of Selected Gemmotherapy Extracts." Antibiotics 13, no. 2 (2024): 181. http://dx.doi.org/10.3390/antibiotics13020181.
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Nowadays, unprecedented health challenges are urging novel solutions to address antimicrobial resistance as multidrug-resistant strains of bacteria, yeasts and moulds are emerging. Such microorganisms can cause food and feed spoilage, food poisoning and even more severe diseases, resulting in human death. In order to overcome this phenomenon, it is essential to identify novel antimicrobials that are naturally occurring, biologically effective and increasingly safe for human use. The development of gemmotherapy extracts (GTEs) using plant parts such as buds and young shoots has emerged as a novel approach to treat/prevent human conditions due to their associated antidiabetic, anti-inflammatory and/or antimicrobial properties that all require careful evaluations. Seven GTEs obtained from plant species like the olive (Olea europaea L.), almond (Prunus amygdalus L.), black mulberry (Morus nigra L.), walnut (Juglans regia L.), blackberry (Rubus fruticosus L.), blackcurrant (Ribes nigrum L.) and bilberry (Vaccinium myrtillus L.) were tested for their antimicrobial efficiency via agar diffusion and microbroth dilution methods. The antimicrobial activity was assessed for eight bacterial (Bacillus cereus, Staphylococcus aureus, Salmonella enterica subsp. enterica, Proteus vulgaris, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Listeria monocytogenes), five moulds (Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum) and one yeast strain (Saccharomyces cerevisiae). The agar diffusion method revealed the blackberry GTE as the most effective since it inhibited the growth of three bacterial, four moulds and one yeast species, having considered the total number of affected microorganism species. Next to the blackberry, the olive GTE appeared to be the second most efficient, suppressing five bacterial strains but no moulds or yeasts. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were then determined for each GTE and the microorganisms tested. Noticeably, the olive GTE appeared to feature the strongest bacteriostatic and bactericidal outcome, displaying specificity for S. aureus, E. faecalis and L. monocytogenes. The other GTEs, such as blueberry, walnut, black mulberry and almond (the list indicates relative strength), were more effective at suppressing microbial growth than inducing microbial death. However, some species specificities were also evident, while the blackcurrant GTE had no significant antimicrobial activity. Having seen the antimicrobial properties of the analysed GTEs, especially the olive and black mulberry GTEs, these could be envisioned as potential antimicrobials that might enhance antibiotic therapies efficiency, while the blackberry GTE would act as an antifungal agent. Some of the GTE mixtures analysed have shown interesting antimicrobial synergies, and all the antimicrobial effects observed argue for extending these studies to include pathological microorganisms.
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Koskinen Holm, Cecilia, and Chengjuan Qu. "Engineering a 3D In Vitro Model of Human Gingival Tissue Equivalent with Genipin/Cytochalasin D." International Journal of Molecular Sciences 23, no. 13 (2022): 7401. http://dx.doi.org/10.3390/ijms23137401.
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Although three-dimensional (3D) co-culture of gingival keratinocytes and fibroblasts-populated collagen gel can mimic 3D structure of in vivo tissue, the uncontrolled contraction of collagen gel restricts its application in clinical and experimental practices. We here established a stable 3D gingival tissue equivalent (GTE) using hTERT-immortalized gingival fibroblasts (hGFBs)-populated collagen gel directly crosslinked with genipin/cytochalasin D and seeding hTERT-immortalized gingival keratinocytes (TIGKs) on the upper surface for a 2-week air–liquid interface co-culture. MTT assay was used to measure the cell viability of GTEs. GTE size was monitored following culture period, and the contraction was analyzed. Immunohistochemical assay was used to analyze GTE structure. qRT-PCR was conducted to examine the mRNA expression of keratinocyte-specific genes. Fifty µM genipin (G50) or combination (G + C) of G50 and 100 nM cytochalasin D significantly inhibited GTE contraction. Additionally, a higher cell viability appeared in GTEs crosslinked with G50 or G + C. GTEs crosslinked with genipin/cytochalasin D showed a distinct multilayered stratified epithelium that expressed keratinocyte-specific genes similar to native gingiva. Collagen directly crosslinked with G50 or G + C significantly reduced GTE contraction without damaging the epithelium. In summary, the TIGKs and hGFBs can successfully form organotypic multilayered cultures, which can be a valuable tool in the research regarding periodontal disease as well as oral mucosa disease. We conclude that genipin is a promising crosslinker with the ability to reduce collagen contraction while maintaining normal cell function in collagen-based oral tissue engineering.
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Orita, Tsukasa, Satoshi Chogahara, Mayuko Okuda, Kozue Sakao, Takeshi Miyata, and De-Xing Hou. "Extraction Efficiency and Alpha-Glucosidase Inhibitory Activities of Green Tea Catechins by Different Infusion Methods." Foods 12, no. 13 (2023): 2611. http://dx.doi.org/10.3390/foods12132611.
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Alpha-glucosidase is an important target for glycemic control with the aim of reducing the risk of type 2 diabetes (T2D). Green tea catechins have been reported to inhibit alpha-glucosidase activity as a potential beverage to control blood glucose levels. However, the effects of the daily infusion style of green tea on tea catechins and their activity remain unclear. In this study, the extraction efficiency of catechins was investigated for 12 green tea extracts (GTEs) infused with 70% ethanol (70% EtOH for 24 h, a favored solvent for catechin extraction), room temperature water infusion (RT H2O for 24 h, an easy way to drink tea), and hot water infusion (Hot H2O for 90 s, a standard way to drink tea). Eight catechins were quantified by HPLC, and the inhibitory effect of GTEs and their catechins on alpha-glucosidase was measured with both rat intestinal enzymes and human Caco-2 cells. The inhibitory mechanism was further analyzed in silico by docking catechins to human alpha-glucosidase using Molecular Operating Environment software. The results showed that total catechins and gallate catechins were efficiently extracted in the order of 70% EtOH, RT H2O, and Hot H2O, and the inhibitory activity against alpha-glucosidase also followed a similar order. Pearson correlation analysis indicated that the alpha-glucosidase inhibitory activity of GTEs was significantly positively correlated with the contents of total catechins, especially gallate catechins. Gallate catechins, such as EGCg and ECg, showed lower IC50 values than free catechins for the enzyme in both rats and humans. In silico simulation revealed that gallate catechins were bound to the different sites with free catechins, and the docking energy of gallate catechins was lower than that of free catechins. Taken together, our data indicated that the daily infusion style of green tea significantly impacted the extraction efficiency and alpha-glucosidase inhibitory activities of catechins, which will give us insight into the use of green tea catechins for glycemic control through efficient infusion.
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Kablov, E. N., and S. A. Muboyadzhyan. "Heat-resistant coatings for the high-pressure turbine blades of promising GTEs." Russian Metallurgy (Metally) 2012, no. 1 (2012): 1–7. http://dx.doi.org/10.1134/s0036029512010089.
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Fadlullah, Zubair Md, Duong Minh Quan, Nei Kato, and Ivan Stojmenovic. "GTES: An Optimized Game-Theoretic Demand-Side Management Scheme for Smart Grid." IEEE Systems Journal 8, no. 2 (2014): 588–97. http://dx.doi.org/10.1109/jsyst.2013.2260934.
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Brod, Corinna, Wilfried Schippert, and Helmut Breuninger. "Ausgeprägtes dysplastisches Nävussyndrom mit Entwicklung multipler Melanome. Operatives Konzept zur Prophylaxe." Journal der Deutschen Dermatologischen Gesellschaft 7, no. 9 (2009): 773–75. http://dx.doi.org/10.1111/j.1610-0387.2009.07095_supp.x.
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Caseau, Y. "GTES : une méthode de simulation par jeux et apprentissage pour l'analyse des systèmes d'acteurs." RAIRO - Operations Research 43, no. 4 (2009): 437–62. http://dx.doi.org/10.1051/ro/2009028.
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Kortubash, Igor, Laura Ewing, Charles Skinner, et al. "Green Tea Extract as a Safe and Effective Dietary Supplement: Lessons Learned from Mice." Current Developments in Nutrition 4, Supplement_2 (2020): 419. http://dx.doi.org/10.1093/cdn/nzaa045_052.
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Abstract Objectives Green tea extracts (GTEs) are common ingredients among dietary supplements marketed for weight loss and weight management. However, GTEs and their various catechin polyphenols have also been linked to a number of hepatotoxicity cases. Methods The purpose of this study was to investigate, using various mouse models, the hepato- and cardiotoxic potential of a well-characterized GTE; its ability to promote weight loss; and its effect on the gut microbiome. Results Gavaging GTE over a range of 1X–10X mouse equivalent doses (MED) for up to 2 weeks did not elicit significant histomorphological, physiological, biochemical or molecular alterations in the livers of lean B6C3F1 mice. Similarly, no evidence of hepato- or cardiotoxicity was noted when GTE was administered to obese NZO/HlLtJ mice for 8 weeks, either alone or in combination with caffeine (CAF) and/or exercise (EX). Eight weeks of GTE administration in combination with CAF resulted in significant body weight reduction in obese mice, which was further enhanced by EX. Furthermore, GTE/CAF combinations partially mitigated obesity-associated small and large droplet steatosis and decreased both portal and lobular inflammation, demonstrating hepatoprotective capabilities. Administration of GTE at MEDs comparable to those consumed by humans resulted in significant modulation of gut microflora, with increases in beneficial Akkermansia spp. among lean mouse phenotypes being most pronounced. This favorable change in the gut microbiome may provide a mechanistic link to weight loss management. Conclusions Results of this study demonstrate that appropriate doses of caffeinated GTE can serve as a useful adjunct in weight management strategies. Furthermore, clinically relevant doses of GTE/CAF combinations did not produce hepato- or cardiotoxicity, but rather show significant potential to promote liver health by reversing early signs of non-alcoholic fatty liver disease and hepatosteatosis. Funding Sources NIGMS 1P20 GM109005.
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Johnstone, D. J., and M. J. R. Gaffikin. "Review of the Asset Valuation Guidelines of the Steering Committee on National Performance Monitoring of GTEs." Australian Accounting Review 6, no. 11 (1996): 50–65. http://dx.doi.org/10.1111/j.1835-2561.1996.tb00007.x.
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Alqallaf, Jasem, and Joao A. Teixeira. "Quantifying the Economic Benefits of Using Erosion Protective Coatings in a Low-Pressure Compressor (Aero-Engine): A Case Study Evaluation." Processes 10, no. 2 (2022): 385. http://dx.doi.org/10.3390/pr10020385.
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Gas turbine engines (GTEs) frequently operate in desert environments where the main components are exposed to erosive media such as sand and dust. In these circumstances, a crucial problem, particularly with compressor blades, is solid particle erosion (SPE). Positioned in the front of the GTE, the compressors suffer most from SPE in terms of inflicting damage on compressor hardware such as blades, decreasing the GTE’s working life and increasing fuel consumption, energy losses, and efficiency losses. Results obtained from Turbomatch, an in-house performance tool, showed that degraded compressors can experience increased turbine entry temperature (TET) and specific fuel consumption (SFC), which leads to a significant increase in the operating, maintenance and component replacement costs, in addition to fuel costs. Fitting erosion protective coatings (EPCs) is a conventional approach to reduce SPE of the compressor blades of aeroengines. Titanium nitride (TiN), applied via physical vapour deposition (PVD) techniques, is often used to extend the life of compressor blades in erosive conditions. This paper reports the outcomes of a cost benefit analysis (CBA) of whether applying an EPC to the booster blades of an aeroengine is economically beneficial. The case study takes into account the available coatings potential of the market, in addition to all of the available technical data in the public domain regarding the compressor of the research engine. To identify the economic consequences of employing an EPC over the blades of a compressor, a CBA study was carried out by investigating consequent benefits and costs. The results indicate that under certain conditions the application of an EPC can be profitable.
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García Sandoval, Francisco, Ramón Hernández Salgado, Joel Hernández Cerón, Carlos Elizondo Vázquez, and Ilda Graciela Fernández García. "Tasas de concepción en respuesta a dosis reducidas de somatotropina en vacas holstein, durante la sincronización del estro." Revista Agraria 7, no. 1-2-3 (2010): 49–54. http://dx.doi.org/10.59741/agraria.v7i1-2-3.439.
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El objetivo de esta investigación fue determinar el efecto sobre las tasas de concepción en vacas Holstein, al administrarles 2 dosis reducidas de somatropina bovina recombinante (STbr) (250 mg, cada una, sc) en el día 56 posparto, y al momento de la inseminación artificial. El experimento se realizó en un establo de la Comarca Lagunera, México, de agosto de 2004 a abril de 2005. Se utilizaron vacas multíparas de primer servicio (n=264), con condición corporal de 3. Todas fueron sometidas al protocolo de sincronización del estro con prostaglandina F2á (días 28 y 42 PP) y GnRH (día 56 PP). Fueron divididas en dos grupos; Grupo Testigo (GTES, n=156) con vacas a las que se les administró un placebo; y Grupo STbr (GSTbr, n=108), con vacas a las que se les inyectó una primera dosis de 250 mg de STbr en el día 56 postparto. La segunda dosis de 250 mg a STbr se aplicó al momento de la inseminación artificial (67 ± 2 días postparto). Se tomaron muestras de sangre en 10 vacas de cada grupo, cada dos días, durante 12 días. Se determinaron las concentraciones de IGF-I mediante un ensayo inmunoradiométrico. El diagnóstico de gestación se realizó mediante palpación rectal a los 45 ± 3 días postinseminación. Las tasas de concepción se compararon, entre grupos, mediante análisis de regresión logística y las concentraciones de IGF-I. Se utilizó un diseño experimental completamente al azar con mediciones repetidas. Las tasas de concepción fueron más elevadas (P<0.05) en el grupo de vacas tratadas con STbr (65.77 ± 4.57 %) que en las del grupo testigo (56.49 ± 3.97 %). Las concentraciones de IGF-I fueron más altas (P<0.05) en GSTbr que en GTES en los días 58 y 66 postparto. Los resultados de este estudio permiten concluir que en la administración de 2 dosis reducidas de STbr, en el día 56 postparto, y al momento de la inseminación artificial, se incrementaron las tasas de concepción de vacas Holstein de primer servicio.
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Lozhkova, D. S., and I. S. Krasnov. "Experimental studies on the evaluation of the defectiveness of weld joints of the main parts of GTEs." Russian Journal of Nondestructive Testing 51, no. 2 (2015): 65–69. http://dx.doi.org/10.1134/s1061830915020060.
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Schumacher, S., and R. Schulz. "Effectiveness of acidizing geothermal wells in the South German Molasse Basin." Geothermal Energy Science 1, no. 1 (2013): 1–11. http://dx.doi.org/10.5194/gtes-1-1-2013.
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<p><strong>Abstract.</strong> In Germany, many hydro-geothermal plants have been constructed in recent years, primarily in the region of Munich. As the host formation here mainly consists of carbonates, nearly all recently drilled wells have been acidized in order to improve the well yield. In this study, the effectiveness of these acid treatments is analyzed with respect to the amount of acid used and the number of acid treatments carried out per well. The results show that the first acid treatment has the largest effect, while subsequent acidizing improves the well only marginally. Data also indicate that continued acidizing can lead to degradation of the well. These findings may not only be important for geothermal installations in Germany but also for projects, for example, in Austria, France or China where geothermal energy is produced from carbonate formations as well.</p>
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Cherubini, Y., M. Cacace, M. Scheck-Wenderoth, and V. Noack. "Influence of major fault zones on 3-D coupled fluid and heat transport for the Brandenburg region (NE German Basin)." Geothermal Energy Science 2, no. 1 (2014): 1–20. http://dx.doi.org/10.5194/gtes-2-1-2014.
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<p><strong>Abstract.</strong> To quantify the influence of major fault zones on the groundwater and thermal field, 3-D finite-element simulations are carried out. Two fault zones – the Gardelegen and Lausitz escarpments – have been integrated into an existing 3-D structure of the Brandenburg region in northeastern Germany. Different geological scenarios in terms of modelled fault permeability have been considered, of which two end-member models are discussed in detail. In addition, results from these end-member simulations are compared to a reference case in which no faults are considered. <br><br> The study provides interesting results with respect to the interaction between faults and surrounding sediments and how it affects the regional groundwater circulation system and thermal field. <br><br> Impermeable fault zones seem to induce no remarkable effects on the temperature distribution; that is, the thermal field is similar to the no-fault model. In addition, tight faults have only a local impact on the fluid circulation within a domain of limited spatial extent centred on the fault zone. Fluid flow from the surrounding aquifers is deviated in close proximity of the fault zones acting as hydraulic barriers that prevent lateral fluid inflow into the fault zones. <br><br> Permeable fault zones induce a pronounced thermal signature with alternating up- and downward flow along the same structures. Fluid flow along the plane of the faults is principally driven by existing hydraulic head gradients, but may be further enhanced by buoyancy forces. Within recharge domains, fluid advection induces a strong cooling in the fault zones. Discharge domains at shallow depth levels (~<−450 m) are instead characterized by the presence of rising warm fluids, which results in a local increase of temperatures which are up to 15 °C higher than in the no-fault case. <br><br> This study is the first attempt to investigate the impact of major fault zones on a 3-D basin scale for the coupled fluid and heat transport in the Brandenburg region. The approach enables a quantification of mechanisms controlling fluid flow and temperature distribution both within surrounding sediments and fault zones as well as how they dynamically interact. Therefore, the results from the modelling provide useful indications for geothermal energy exploration.</p>
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Reyer, D., and S. L. Philipp. "Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling." Geothermal Energy Science 2, no. 1 (2014): 21–37. http://dx.doi.org/10.5194/gtes-2-21-2014.
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<p><strong>Abstract.</strong> Information about geomechanical and physical rock properties, particularly uniaxial compressive strength (UCS), are needed for geomechanical model development and updating with logging-while-drilling methods to minimise costs and risks of the drilling process. The following parameters with importance at different stages of geothermal exploitation and drilling are presented for typical sedimentary and volcanic rocks of the Northwest German Basin (NWGB): physical (<i>P</i> wave velocities, porosity, and bulk and grain density) and geomechanical parameters (UCS, static Young's modulus, destruction work and indirect tensile strength both perpendicular and parallel to bedding) for 35 rock samples from quarries and 14 core samples of sandstones and carbonate rocks. <br><br> With regression analyses (linear- and non-linear) empirical relations are developed to predict UCS values from all other parameters. Analyses focus on sedimentary rocks and were repeated separately for clastic rock samples or carbonate rock samples as well as for outcrop samples or core samples. Empirical relations have high statistical significance for Young's modulus, tensile strength and destruction work; for physical properties, there is a wider scatter of data and prediction of UCS is less precise. For most relations, properties of core samples plot within the scatter of outcrop samples and lie within the 90% prediction bands of developed regression functions. The results indicate the applicability of empirical relations that are based on outcrop data on questions related to drilling operations when the database contains a sufficient number of samples with varying rock properties. The presented equations may help to predict UCS values for sedimentary rocks at depth, and thus develop suitable geomechanical models for the adaptation of the drilling strategy on rock mechanical conditions in the NWGB.</p>
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Ziefle, G. "Rearrangement of stresses in fault zones – detecting major issues of coupled hydraulic–mechanical processes with relevance to geothermal applications." Geothermal Energy Science 2, no. 1 (2014): 39–48. http://dx.doi.org/10.5194/gtes-2-39-2014.
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<p><strong>Abstract.</strong> The South German Molasse Basin provides favourable conditions for geothermal plants. Nevertheless, micro-seismic events occur in the vicinity of the geothermal Unterhaching Gt2 well and seem to be caused by the geothermal plant. <br><br> The injection and production are located in an existing fault system. The majority of seismic events takes place at a horizontal distance of 500 m or less of the borehole. However, none of the seismic events are located in the injection reservoir but in fact at a significantly greater depth. A deeper process understanding of the interacting thermal–hydraulic–mechanical effects in the vicinity of the well is desired. <br><br> This article presents a significantly simplified 2-D model, investigating interactions of the stress field in the vicinity of the geothermal well and movements in the fault system. This might be of special interest, as the operation of the geothermal plant might lead to changes in the material and fracture properties on the one hand and in the equilibrium state on the other. A detailed description of the model, as well as various parameter studies, is presented. It can be seen that boundary conditions such as direction of the stress field in relation to the fault system, geometry of the fault system and parameters of the fractures have a significant influence on stresses in the proximity of the geothermal well. A variation in the spatial stress field in some parts of the fault system is to be expected. For the chosen assumptions the dimension of this variation is about 25% of the assumed stresses. Future work on this model might focus on the characteristics of the fault system, as well as on the influence of the coupled thermal–hydraulic–mechanical effects.</p>
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Grant, M. A. "Stored-heat assessments: a review in the light of field experience." Geothermal Energy Science 2, no. 1 (2014): 49–54. http://dx.doi.org/10.5194/gtes-2-49-2014.
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<p><strong>Abstract.</strong> Stored-heat or volumetric assessments of geothermal resources are appealingly simple: the resource being exploited is heat. A stored-heat calculation simply computes the amount of heat in the resource, similarly to computing the amount of ore in an ore body. The method has theoretical support in numerical simulations of resource production. While there are significant unknowns in any resource, some of these can be covered by probabilistic approaches, notably a Monte Carlo method. The Australian Geothermal Reporting Code represents one specification of such stored-heat assessments. <br><br> However the experience of recent decades, with the development of significant numbers of geothermal resources, has shown that the method is highly unreliable and usually biased high. The tendency to overestimates, in particular, has led to the reduced credibility of the method. An example is quoted where simple application of the apparently simple rules gives a ridiculous result. Much of the problem lies in the "recovery factor", the proportion of the resource that can actually be exploited, where comparison with actual performance shows past values have been in all cases too high, as is the current version of the Australian code. <br><br> There are further problems, usually overlooked, in the way that the reservoir volume and "cutoff temperature" are defined. Differing approaches mean that results between different reports are not comparable. The different approaches also imply unrecognised assumptions about the physical processes controlling reservoir depletion. The failure of Monte Carlo methods is similarly due to unrecognised violation of logical consistency in the use of probabilities. <br><br> The net effect of these problems is that the method is not a simple means to generate a rough resource estimate, and it often generates faulty results. Usually, such results are overestimates. Monte Carlo methods do not provide a protection against these errors. <br><br> The Australian Geothermal Reporting Code should be used for hydrothermal systems with an average recovery factor of 10%. With this average, results are subject to an error of ±70%. For enhanced geothermal systems (EGS), the recovery factor should be a few percent.</p>
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Limberger, J., P. Calcagno, A. Manzella, et al. "Assessing the prospective resource base for enhanced geothermal systems in Europe." Geothermal Energy Science 2, no. 1 (2014): 55–71. http://dx.doi.org/10.5194/gtes-2-55-2014.
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<p><strong>Abstract.</strong> In this study the resource base for EGS (enhanced geothermal systems) in Europe was quantified and economically constrained, applying a discounted cash-flow model to different techno-economic scenarios for future EGS in 2020, 2030, and 2050. Temperature is a critical parameter that controls the amount of thermal energy available in the subsurface. Therefore, the first step in assessing the European resource base for EGS is the construction of a subsurface temperature model of onshore Europe. Subsurface temperatures were computed to a depth of 10 km below ground level for a regular 3-D hexahedral grid with a horizontal resolution of 10 km and a vertical resolution of 250 m. Vertical conductive heat transport was considered as the main heat transfer mechanism. Surface temperature and basal heat flow were used as boundary conditions for the top and bottom of the model, respectively. If publicly available, the most recent and comprehensive regional temperature models, based on data from wells, were incorporated. <br><br> With the modeled subsurface temperatures and future technical and economic scenarios, the technical potential and minimum levelized cost of energy (LCOE) were calculated for each grid cell of the temperature model. Calculations for a typical EGS scenario yield costs of EUR 215 MWh<sup>−1</sup> in 2020, EUR 127 MWh<sup>−1</sup> in 2030, and EUR 70 MWh<sup>−1</sup> in 2050. Cutoff values of EUR 200 MWh<sup>−1</sup> in 2020, EUR 150 MWh<sup>−1</sup> in 2030, and EUR 100 MWh<sup>−1</sup> in 2050 are imposed to the calculated LCOE values in each grid cell to limit the technical potential, resulting in an economic potential for Europe of 19 GW<sub>e</sub> in 2020, 22 GW<sub>e</sub> in 2030, and 522 GW<sub>e</sub> in 2050. The results of our approach do not only provide an indication of prospective areas for future EGS in Europe, but also show a more realistic cost determined and depth-dependent distribution of the technical potential by applying different well cost models for 2020, 2030, and 2050.</p>
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Fauzi, A. "Geothermal resources and reserves in Indonesia: an updated revision." Geothermal Energy Science 3, no. 1 (2015): 1–6. http://dx.doi.org/10.5194/gtes-3-1-2015.
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<p><strong>Abstract.</strong> More than 300 high- to low-enthalpy geothermal sources have been identified throughout Indonesia. From the early 1980s until the late 1990s, the geothermal potential for power production in Indonesia was estimated to be about 20 000 MWe. The most recent estimate exceeds 29 000 MWe derived from the 300 sites (Geological Agency, December 2013). <br><br> This resource estimate has been obtained by adding all of the estimated geothermal potential resources and reserves classified as "speculative", "hypothetical", "possible", "probable", and "proven" from all sites where such information is available. However, this approach to estimating the geothermal potential is flawed because it includes double counting of some reserve estimates as resource estimates, thus giving an inflated figure for the total national geothermal potential. <br><br> This paper describes an updated revision of the geothermal resource estimate in Indonesia using a more realistic methodology. The methodology proposes that the preliminary "Speculative Resource" category should cover the full potential of a geothermal area and form the base reference figure for the resource of the area. Further investigation of this resource may improve the level of confidence of the category of reserves but will not necessarily increase the figure of the "preliminary resource estimate" as a whole, unless the result of the investigation is higher. A previous paper (Fauzi, 2013a, b) redefined and revised the geothermal resource estimate for Indonesia. The methodology, adopted from Fauzi (2013a, b), will be fully described in this paper. As a result of using the revised methodology, the potential geothermal resources and reserves for Indonesia are estimated to be about 24 000 MWe, some 5000 MWe less than the 2013 national estimate.</p>
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Rybach, L. "Classification of geothermal resources by potential." Geothermal Energy Science 3, no. 1 (2015): 13–17. http://dx.doi.org/10.5194/gtes-3-13-2015.
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<p><strong>Abstract.</strong> When considering and reporting resources, the term "geothermal potential" is often used without clearly stating what kind of potential is meant. For renewable energy resources it is nowadays common to use different potentials: theoretical, technical, economic, sustainable, developable – decreasing successively in size. In such a sequence, the potentials are progressively realizable and more and more rewarding financially. The theoretical potential describes the physically present energy, the technical potential the fraction of this energy that can be used by currently available technology and the economic potential the time- and location-dependent fraction of the previous category; the sustainable potential constrains the fraction of the economic potential that can be utilized in the long term; the developable potential is the fraction of the economic resource which can be developed under realistic conditions. In converting theoretical to technical potential, the recovery factor (the ratio extractable heat/heat present at depth) is of key importance. An example (global geothermal resources) is given, with numerical values of the various potentials. The proposed classification could and should be used as a kind of general template for future geothermal energy resources reporting.</p>
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Breede, K., K. Dzebisashvili, and G. Falcone. "Overcoming challenges in the classification of deep geothermal potential." Geothermal Energy Science 3, no. 1 (2015): 19–39. http://dx.doi.org/10.5194/gtes-3-19-2015.
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<p><strong>Abstract.</strong> The geothermal community lacks a universal definition of deep geothermal systems. A minimum depth of 400 m is often assumed, with a further sub-classification into middle-deep geothermal systems for reservoirs found between 400 and 1000 m. Yet, the simplistic use of a depth cut-off is insufficient to uniquely determine the type of resource and its associated potential. Different definitions and criteria have been proposed in the past to frame deep geothermal systems. However, although they have valid assumptions, these frameworks lack systematic integration of correlated factors. To further complicate matters, new definitions such as hot dry rock (HDR), enhanced or engineered geothermal systems (EGSs) or deep heat mining have been introduced over the years. A clear and transparent approach is needed to estimate the potential of deep geothermal systems and be capable of distinguishing between resources of a different nature. In order to overcome the ambiguity associated with some past definitions such as EGS, this paper proposes the return to a more rigorous petrothermal versus hydrothermal classification. This would be superimposed with numerical criteria for the following: depth and temperature; predominance of conduction, convection or advection; formation type; rock properties; heat source type; requirement for formation stimulation and corresponding efficiency; requirement to provide the carrier fluid; well productivity (or injectivity); production (or circulation) flow rate; and heat recharge mode. Using the results from data mining of past and present deep geothermal projects worldwide, a classification of the same, according to the aforementioned criteria is proposed.</p>
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Homuth, S., A. E. Götz, and I. Sass. "Reservoir characterization of the Upper Jurassic geothermal target formations (Molasse Basin, Germany): role of thermofacies as exploration tool." Geothermal Energy Science 3, no. 1 (2015): 41–49. http://dx.doi.org/10.5194/gtes-3-41-2015.
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<p><strong>Abstract.</strong> The Upper Jurassic carbonates of the southern German Molasse Basin are the target of numerous geothermal combined heat and power production projects since the year 2000. A production-orientated reservoir characterization is therefore of high economic interest. Outcrop analogue studies enable reservoir property prediction by determination and correlation of lithofacies-related thermo- and petrophysical parameters. A thermofacies classification of the carbonate formations serves to identify heterogeneities and production zones. The hydraulic conductivity is mainly controlled by tectonic structures and karstification, whilst the type and grade of karstification is facies related. The rock permeability has only a minor effect on the reservoir's sustainability. Physical parameters determined on oven-dried samples have to be corrected, applying reservoir transfer models to water-saturated reservoir conditions. To validate these calculated parameters, a Thermo-Triaxial-Cell simulating the temperature and pressure conditions of the reservoir is used and calorimetric and thermal conductivity measurements under elevated temperature conditions are performed. Additionally, core and cutting material from a 1600 m deep research drilling and a 4850 m (total vertical depth, measured depth: 6020 m) deep well is used to validate the reservoir property predictions. Under reservoir conditions a decrease in permeability of 2–3 magnitudes is observed due to the thermal expansion of the rock matrix. For tight carbonates the matrix permeability is temperature-controlled; the thermophysical matrix parameters are density-controlled. Density increases typically with depth and especially with higher dolomite content. Therefore, thermal conductivity increases; however the dominant factor temperature also decreases the thermal conductivity. Specific heat capacity typically increases with increasing depth and temperature. The lithofacies-related characterization and prediction of reservoir properties based on outcrop and drilling data demonstrates that this approach is a powerful tool for exploration and operation of geothermal reservoirs.</p>
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Santilano, A., A. Manzella, G. Gianelli, et al. "Convective, intrusive geothermal plays: what about tectonics?" Geothermal Energy Science 3, no. 1 (2015): 51–59. http://dx.doi.org/10.5194/gtes-3-51-2015.
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<p><strong>Abstract.</strong> We revised the concept of convective, intrusive geothermal plays, considering that the tectonic setting is not, in our opinion, a discriminant parameter suitable for a classification. We analysed and compared four case studies: (i) Larderello (Italy), (ii) Mt Amiata (Italy), (iii) The Geysers (USA) and (iv) Kizildere (Turkey). The tectonic settings of these geothermal systems are different and a matter of debate, so it is hard to use this parameter, and the results of classification are ambiguous. We suggest a classification based on the age and nature of the heat source and the related hydrothermal circulation. Finally we propose to distinguish the convective geothermal plays as volcanic, young intrusive and amagmatic.</p>
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Lahan, M. M., R. T. Verave, and P. Y. Irarue. "Geochemical study on hot-spring water in West New Britain Province, Papua New Guinea." Geothermal Energy Science 3, no. 1 (2015): 61–67. http://dx.doi.org/10.5194/gtes-3-61-2015.
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<p><strong>Abstract.</strong> West New Britain Province, which occupies the western part of New Britain Island in Papua New Guinea, is ideally located within an active tectonic region that influences volcanism creating an environment favourable for geothermal activity. Geothermal mapping of surface manifestations reveals high temperature geothermal prospects along the northern coastline of West New Britain Province that are further confirmed by geochemical analysis. The occurrence of geothermal features is confined to the Quaternary Kimbe Volcanics and alluvium in the lowland areas. The features in Talasea appear to be controlled by deep-seated northerly trending faults while structures in Hoskins also appear to be deep seated but have not been identified. The geothermal systems in West New Britain Province have not been drilled, but preliminary reconnaissance geothermal mapping and geochemical analysis reveals four high temperature geothermal prospects suitable for further investigation and development of geothermal energy. These are the Pangalu (Rabili) and Talasea Station geothermal prospects in Talasea and Kasiloli (Magouru) and Silanga (Bakama and Sakalu) geothermal prospects in Hoskins. The calculated reservoir temperatures for these fields are in the range of 245–310 °C. Recommendations are made for further follow-up exploratory investigations.</p>
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Chauhan, V., and Á. Ragnarsson. "Thermodynamic and thermoeconomic analysis of combined geothermal space heating and thermal storage using phase change materials." Geothermal Energy Science 3, no. 1 (2015): 69–80. http://dx.doi.org/10.5194/gtes-3-69-2015.
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<p><strong>Abstract.</strong> The present work discusses the utilization of phase change materials for energy storage in geothermal space heating systems. Thermodynamics and thermoeconomics of the combined heating and thermal storing system were studied to show the scope of energy storage and cost savings. A computational model of the combined space heating and thermal storage system was developed and used to perform thermodynamic studies of the heat storage process and heating system efficiency at different times and ambient temperatures. The basis for these studies is daily variations in heating demand that is higher during the night than during the day. The results show the scope of the utilization of phase change material for low ambient temperature conditions. Under proper conditions a sufficient amount of exergy is stored during the charging period at a low ambient temperature to fulfill the daytime heat load requirement. Under these conditions the cost flow rate of exergy storage is found to be lower than the radiator heating cost flow rate. Thus, the use of exergy storage at low ambient temperatures for heating at higher ambient temperatures makes a significant contribution to cost savings.</p>
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Falcone, G. "Proposal of a consistent framework to integrate geothermal potential classification with energy extraction." Geothermal Energy Science 3, no. 1 (2015): 7–11. http://dx.doi.org/10.5194/gtes-3-7-2015.
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<p><strong>Abstract.</strong> The classification of geothermal resources is dependent on the estimate of their corresponding geothermal potential, so adopting a common assessment methodology would greatly benefit operators, investors, government regulators and consumers. <br><br> Several geothermal classification schemes have been proposed, but, to date, no universally recognised standard exists. This is due to the difficulty in standardising fundamentally different geothermal source and product types. The situation is not helped by the accepted use of inconsistent jargon among the geothermal community. In fact, the term "geothermal potential" is often interpreted differently by different geothermal practitioners. <br><br> This paper highlights the importance of integrating the classification of geothermal potential with that of geothermal energy extraction from well-defined development projects. A structured progression, from estimates of in situ quantities for a given prospect to actual production, is needed. Employing a unique, unambiguous framework would ensure that the same resource cannot exist simultaneously under different levels of maturity of the estimate (as in double bookings of resources), which would let stakeholders better assess the level of risk involved and the steps needed for a geothermal potential to achieve commercial extraction.</p>
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Nakagawa, M., and Y. Koizumi. "Geothermal heat pump system assisted by geothermal hot spring." Geothermal Energy Science 4, no. 1 (2016): 1–10. http://dx.doi.org/10.5194/gtes-4-1-2016.
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<p><strong>Abstract.</strong> The authors propose a hybrid geothermal heat pump system that could cool buildings in summer and melt snow on the pedestrian sidewalks in winter, utilizing cold mine water and hot spring water. In the proposed system, mine water would be used as cold thermal energy storage, and the heat from the hot spring after its commercial use would be used to melt snow for a certain section of sidewalks. Neither of these sources is viable for direct use application of geothermal resources, however, they become contributing energy factors without producing any greenhouse gases. To assess the feasibility of the proposed system, a series of temperature measurements in the Edgar Mine (Colorado School of Mines' experimental mine) in Idaho Springs, Colorado, were first conducted, and heat/mass transfer analyses of geothermal hot spring water was carried out. The result of the temperature measurements proved that the temperature of Edgar Mine would be low enough to store cold groundwater for use in summer. The heat loss of the hot spring water during its transportation was also calculated, and the heat requirement for snow melt was compared with the heat available from the hot spring water. It was concluded that the heat supply in the proposed usage of hot spring water was insufficient to melt the snow for the entire area that was initially proposed. This feasibility study should serve as an example of "local consumption of locally available energy". If communities start harnessing economically viable local energy in a responsible manner, there will be a foundation upon which to build a sustainable community.</p>
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Neupane, G., E. D. Mattson, T. L. McLing, et al. "Geothermometric evaluation of geothermal resources in southeastern Idaho." Geothermal Energy Science 4, no. 1 (2016): 11–22. http://dx.doi.org/10.5194/gtes-4-11-2016.
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<p><strong>Abstract.</strong> Southeastern Idaho exhibits numerous warm springs, warm water from shallow wells, and hot water from oil and gas test wells that indicate a potential for geothermal development in the area. We have estimated reservoir temperatures from chemical composition of thermal waters in southeastern Idaho using an inverse geochemical modeling technique (Reservoir Temperature Estimator, RTEst) that calculates the temperature at which multiple minerals are simultaneously at equilibrium while explicitly accounting for the possible loss of volatile constituents (e.g., CO<sub>2</sub>), boiling and/or water mixing. The temperature estimates in the region varied from moderately warm (59<span class="thinspace"></span>°C) to over 175<span class="thinspace"></span>°C. Specifically, hot springs near Preston, Idaho, resulted in the highest reservoir temperature estimates in the region.</p>
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Skapare, I., A. Kreslins, and A. Cers. "The role of the legislative and regulatory branches in promoting the use of geothermal energy in Latvia." Geothermal Energy Science 4, no. 2 (2016): 23–27. http://dx.doi.org/10.5194/gtes-4-23-2016.
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<p><strong>Abstract.</strong> Latvia currently is self-sufficient in energy resources up to approximately 35<span class="thinspace"></span>%. Annual fossil energy prices rise and risks of security of energy supply promote the development legislation in the matter of renewable resources. One of the Latvian Ministry of Economics' recent products is a new draft law called the "Renewable Energy Law", which has been created due to one of the European Union and Latvian national energy policy objectives: to increase the share of renewable energy up to 40<span class="thinspace"></span>% by 2020 (Moore and Vanags, 2012). Currently, geothermal energy potential is assessed at 1 × 1013<span class="thinspace"></span>kWh; nevertheless, it is difficult for geothermal energy to compete with other renewable energy resources in the Latvian energy market. A great job has been done in recent years at the legislative branch to choose the right methods for supporting the use of renewable energy resources. This paper aims is analysis of current situation and assessment of Latvian legislation possibilities to promote the use of geothermal energy.</p>
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Nwankwo, Levi I., and Abayomi J. Sunday. "Regional estimation of Curie-point depths and succeeding geothermal parameters from recently acquired high-resolution aeromagnetic data of the entire Bida Basin, north-central Nigeria." Geothermal Energy Science 5, no. 1 (2017): 1–9. http://dx.doi.org/10.5194/gtes-5-1-2017.
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<p><strong>Abstract.</strong> A regional estimation of Curie-point depths (CPDs) and succeeding geothermal gradients and subsurface crustal heat flow has been carried out from the spectral centroid analysis of the recently acquired high-resolution aeromagnetic (HRAM) data of the entire Bida Basin in north-central Nigeria. The HRAM data were divided into 28 overlapping blocks, and each block was analysed to obtain depths to the top, centroid, and bottom of the magnetic sources. The depth values were then used to assess the CPD, geothermal gradient, and subsurface crustal heat flow in the basin. The result shows that the CPD varies between 15.57 and 29.62<span class="thinspace"></span>km with an average of 21.65<span class="thinspace"></span>km, the geothermal gradient varies between 19.58 and 37.25<span class="thinspace"></span>°C<span class="thinspace"></span>km<sup>−1</sup> with an average of 27.25<span class="thinspace"></span>°C<span class="thinspace"></span>km<sup>−1</sup>, and the crustal heat flow varies between 48.41 and 93.12<span class="thinspace"></span>mW<span class="thinspace"></span>m<sup>−2</sup> with an average of 68.80<span class="thinspace"></span>mW<span class="thinspace"></span>m<sup>−2</sup>. Geodynamic processes are mainly controlled by the thermal structure of the Earth's crust; therefore this study is important for appraisal of the geo-processes, rheology, and understanding of the heat flow variations in the Bida Basin, north-central Nigeria.</p>
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Норин, А., A. Norin, Сергей Никитин, Sergey Nikitin, В. Макаров, and V. Makarov. "Quality and productivity increase at profile creep feed grinding of turbine blades." Science intensive technologies in mechanical engineering 1, no. 5 (2016): 17–24. http://dx.doi.org/10.12737/18710.
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A new concept of working quality assessment and cutting mode setting at profile creep feed grinding of some complex conjugate surfaces simultaneously on a multiaxes NC machine is presented. The analysis of dynamic and thermo-physical phenomena at machining each of the conjugate surfaces grinded simultaneously by one profile abrasive disk is carried out. The simulators for the definition of contact patch parameters of a grinding disk and a billet at a creep feed grinding of different conjugate profile surfaces of turbine and nozzle blades of GTEs allowing the prediction of material removal intensity, grinding disk wear, and roughness of every surface on the basis of changes in cutting modes, disk characteristics, dynamics of elastic, thermal and operation processes in a technological system are shown. This procedure allows controlling the process of profile creep feed grinding to achieve preset parameters of surface quality, dimension accuracy in blade profiles of gas turbine engines, productivity increase and decrease of machining prime cost.
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Mykhailenko, Taras, Oleksandr Goridko та Illia Petukhov. "Особливості теплогідравлічних процесів у маслорадіаторі авіаційного газотурбінного двигуна". Aerospace Technic and Technology, № 5 (3 жовтня 2023): 50–56. http://dx.doi.org/10.32620/aktt.2023.5.03.
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The modern gas turbine engines (GTEs) development is associated with an increase in the compressor pressure ratio and the gas temperature at the turbine inlet with a simultaneous reduction in the size and weight of the engine. The reliable operation of the GTE largely depends on the oil system excellence. In circulating oil systems, to ensure the lubrication and cooling of engine friction units, a high multiplicity of oil circulation is necessary. The preparation of oil for the next lubrication cycle is related to its cooling, cleaning of mechanical impurities formed during operation, and air separation. Oil coolers are used to cool the oil in GTEs. Air or fuel can be used as the cooling medium. Regardless of the cooling medium choice, a two-phase mixture (oil-air) and not a single-phase oil, as is considered when designing oil coolers, affects the course of thermo-hydraulic processes. Therefore, the subject of this paper is thermohydraulic processes in two-phase media. The goal of this study is to determine the specific aspects of thermohydraulic processes during the oil-air mixture cooling in an aviation gas turbine engine to further improve oil cooler design approaches. This paper aims to show the differences in the course of thermohydraulic processes in two-phase media from single-phase media and to emphasize the importance of considering them when designing oil coolers. The main results are as follows. For a two-phase flow, changes in temperature and pressure change not only the thermophysical properties of the phases but also the gas content, density, and speed of the mixture, which affects the course of thermohydraulic processes in the oil cooler. Under certain combinations of parameters, the structure of the two-phase flow may change. A low value of the equilibrium speed of sound can lead to unpredictable operation of the oil cooler and the oil system as a whole. In addition, the presence of an oil-air mixture reduces the heat transfer capacity of the oil cooler compared with the results of calculations using standard methods. In conclusion, it can be stated that to increase the efficiency of the oil system, it is extremely important to establish the regularities of thermo-hydraulic processes for the two-phase flow of the oil-air mixture and consider this during the design of oil coolers.
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Hussen, Hamed Ali, Essam Lauibi Esmail, and Rahman A. Hussen. "Power Flow Simulation for Two-Degree-of-Freedom Planetary Gear Transmissions with Experimental Validation." Modelling and Simulation in Engineering 2020 (November 6, 2020): 1–14. http://dx.doi.org/10.1155/2020/8837605.
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The basic relationships among gear ratios, velocity succession, torque directions, power ratios, energy losses, and efficiency are derived from first principles. The techniques presented here can be applied to ordinary, planetary, or mixed gear trains. Also, these techniques provide more insight into how power is flowing through the different parts of the mechanism. Power flow relationships are a helpful tool to study power amplification and power circulation in multipath transmissions. They also provide more insight into how the gear pair entities (GPEs) or gear train entities (GTEs) affect total power losses and allow immediate derivation of the overall efficiency. A representative two-input mechanism is analyzed to demonstrate the effectiveness of improved techniques. The theoretical results are compared with experimental data of previous work. The theoretical and experimental curves exhibit identical trends with a distinct jump in friction loss. The jump is explained by a change in the way of the power flow through the mechanism. The conditions under which power circulation occurs are determined. The results have important implications for understanding how to improve the efficiency of multipath power flow systems.
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Lukash, V. P. "Study of radiation heat transfer and the temperature state in the combustion chambers of small-size gas-turbine engines (GTEs)." Journal of Engineering Physics and Thermophysics 64, no. 3 (1993): 213–15. http://dx.doi.org/10.1007/bf00858580.
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Khan, Md Maruf, Hyun S. Lillehoj, Youngsub Lee, et al. "Use of Selected Plant Extracts in Controlling and Neutralizing Toxins and Sporozoites Associated with Necrotic Enteritis and Coccidiosis." Applied Sciences 14, no. 8 (2024): 3178. http://dx.doi.org/10.3390/app14083178.
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Due to increasing concerns about the contamination of animal food products with antibiotic-resistant bacteria and their byproducts, phytogenic feed additives in animal diets have been explored as antibiotic alternatives. In this study, we investigated the effect of ginger root extract (GRE), green tea extract (GTEC caffeinated and GTED decaffeinated), and onion peel combined (OPEC) on the activity of C. perfringens toxin genes and Eimeria tenella sporozoites. To this end, two Clostridium perfringens strains, CP19 and CP240 (Rollins Diagnostic Lab, Raleigh, NC, USA), were cultured (three replicates per treatment) as follows: without additives (Control), with Bacitracin Methylene Disalicylate (BMD), with GRE, with GTEC, with GTED, and, finally, with OPEC for 0, 2, 4, 6, 8, and 24 h. RNA was extracted to determine the expression of tpeL, alpha toxin (α-toxin), and NetB and we measured the protein concentration of NetB-positive C. perfringens toxin. Also, we evaluated the cytotoxic effect of green tea and ginger extracts on E. tenella sporozoites. Results show that phytogenic extracts, GRE, GTEC, and GTED, significantly reduced (p < 0.05) the level of expression of α-toxin gene compared to control; however, BMD treatment showed much less effect. Furthermore, NetB and tpeL encoding gene expression was significantly (p < 0.05) reduced by GRE and GTED, as well as BMD treatment, compared to the control. In contrast, GTEC treatment did not change the expression levels of these genes and was similar to control. With the CP240 strain, all the selected phytogenic extracts significantly reduced (p < 0.05) the expression of selected genes, except for OPEC, which was similar to control. GRE, GTEC, and GTED all reduced the viability of concentration of E. tenella sporozoites. Overall, our data show that these selected phytogenic extracts reduced the level of expression of toxin encoding genes associated with necrotic enteritis and decreased the viability of sporozoites which cause coccidiosis in broiler chicken.
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Burunsuz, К. S., V. V. Kuklinovsky, and S. I. Serbin. "Investigations of the emission characteristics of a gas turbine combustor with water steam injection." Refrigeration Engineering and Technology 55, no. 2 (2019): 77–83. http://dx.doi.org/10.15673/ret.v55i2.1356.
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The article is devoted to investigation of the possibilities of creating highly efficient and competitive Ukrainian gas turbine engines (GTEs), which correspond to modern environmental requirements for new generation energy modules. One of the most important directions of solving this problem is considered, namely, the possibility of realizing a complex thermal circuit of a gas turbine unit (GTU) - the scheme "Aquarius" with the utilization of exhaust gases heat and the injection of ecological and energy water steam into the flowing part of a combustor. The possibilities of reducing emission of harmful components, in particular, of nitrogen oxides, are analyzed, while organizing the process of a 25 MW gas turbine combustor with the supply of water steam to the primary and secondary chamber’s zones. Three-dimensional calculations of the aerodynamic structure of chemically reacting flows in a gas turbine combustor were performed with the help of methods of computational fluid dynamics (CFD). The results of theoretical investigations of gas turbine combustor’s emission characteristics at different ratios of the ecological and energy steam consumptions are presented, their rational values are revealed. The main results of the work can be used at power engineering enterprises for upgrading and modernizing existing and designing models of low-emission combustors of GTE.
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Suriya, Ponnambalam, Srikrishna Subramanian, Sivarajan Ganesan, and Manoharan Abirami. "Generation and transmission expansion management using grasshopper optimization algorithm." International Journal of Engineering Business Management 11 (January 1, 2019): 184797901881832. http://dx.doi.org/10.1177/1847979018818320.
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This article explores how generation and transmission expansion plans (GTEPs) vary and become better suited for the accessibility of smart grid technology (SGT), essentially comprising load shifting, environmental assets and cost rebates. Demand response (DR) resources in smart grids have emerged in debates on GTEP, especially with respect to compromising system security. The planned model is designed as an innovative GTEP solution with DR resources that minimize cost by decreasing the peak load of the basic plan. A chaotic grasshopper optimization algorithm (CGOA) is used to optimize the results of the proposed GTEP model.
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Kulikov, G. G., I. M. Goryunov, V. A. Shukalyuk, and A. V. Afanasyeva. "Calculation and analytical method for identifyingthe structure and parameters of the system of wave equations of GTEs as an object of control, monitoring and diagnostics." Vestnik UGATU 27, no. 4(102) (2023): 77–85. http://dx.doi.org/10.54708/19926502_2023_27410277.
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A system-semantic approach to the formation of an automated method for identifying the structure and thermogasdynamicparameters of a system of wave models of basic units in a gas turbine engine is considered, based on its 4d –1d computer models. It is shown that this approach makes it possible to provide the required level of expansion and formalization of knowledge inthe form of a variety of system models of digital twins (DT) of real and virtual objects and their processes while preserving their cause-and-effect relationships. The logic of representing elements of system models of gas turbine engine units in the spatial-temporal Minkowski basis based on their wave functions is expanded. The objective need for the formation and application of a subject-oriented formal (generative) metalanguage is shown. An example of the application of this approach to identifying the structure and parameters of the wave model of an axial compressor as part of a gas turbine engine as an object of control and diagnostics is considered
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Дологлонян, А. В., В. Т. Матвеенко, and А. Г. Клименко. "Efficiency of combined gas turbine plants at partial loads under different types of loading." MORSKIE INTELLEKTUAL`NYE TEHNOLOGII)</msg>, no. 2(60) (May 25, 2023): 104–15. http://dx.doi.org/10.37220/mit.2023.60.2.013.
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Комбинированные установки на базе газотурбинных двигателей (ГТД) и установок органического цикла Ренкина (ОЦР) наземного, морского и подводного базирования часто работают на переменных нагрузках в зависимости от условий эксплуатации. Поэтому необходимо оценить их энергоэффективность для различных схем ГТД, ОЦР и рабочих тел на частичных нагрузках при различных способах нагружения. Предметом рассмотрения в статье является исследование влияния схем микрогазотурбинных двигателей (МГТД), ОЦР и рода рабочего тела на эффективность комбинированных микрогазотурбинных установок. Показано, что наиболее эффективной комбинированной микрогазотурбинной установки для всех режимов нагружения и во всем диапазоне мощностей является комбинация МГТД на базе простого цикла с турбокомпрессорным утилизатором и регенерацией, а также регенеративной установки ОЦР. Установлено, что наиболее предпочтительным рабочим телом ОЦР для большинства схем ГТД является R-123. Combined units based on gas turbine engines (GTE) and Rankine organic cycle units (ROCU) of land, sea and submarine basing often operate at variable loads depending on the operating conditions. Therefore, it is necessary to evaluate their energy efficiency for different schemes of GTEs, ORC and working bodies at partial loads at different methods of loading. The subject of the article is a study of the influence of schemes of microgas turbine engines (MGTE), OTRs and the type of working body on the efficiency of combined microgasturbine plants. It is shown that the most efficient combined microgasturbine unit for all loading modes and in all power range is a combination of a simple cycle MGTE with a turbocharger utilizer and regeneration, as well as a regenerative ORC unit. It is established that the most preferable working body of the ORC for the majority of GTE schemes is R-123.
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Alqallaf, Jasem, and Joao A. Teixeira. "Blade Roughness Effects on Compressor and Engine Performance—A CFD and Thermodynamic Study." Aerospace 8, no. 11 (2021): 330. http://dx.doi.org/10.3390/aerospace8110330.
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Degradation of compressors is a common concern for operators of gas turbine engines (GTEs). Surface roughness, due to erosion or fouling, is considered one of the major factors of the degradation phenomenon in compressors that can negatively affect the designed pressure rise, efficiency, and, therefore, the engine aero/thermodynamic performance. The understanding of the aerodynamic implications of varying the blade surface roughness plays a significant role in establishing the magnitude of performance degradation. The present work investigates the implications due to the degradation of the compressor caused by the operation in eroding environments on the gas turbine cycle performance linking, thereby, the compressor aerodynamics with a thermodynamic cycle. At the core of the present study is the numerical assessment of the effect of surface roughness on compressor performance employing the Computational Fluid Dynamics (CFD) tools. The research engine test case employed in the study comprised a fan, bypass, and two stages of the low pressure compressor (booster). Three operating conditions on the 100% speed-line, including the design point, were investigated. Five roughness cases, in addition to the smooth case, with equivalent sand-grain roughness (ks) of 15, 30, 45, 60, and 150 µm were simulated. Turbomatch the Cranfield in-house gas turbine performance simulation software, was employed to model the degraded engine performance. The study showed that the increase in the uniform roughness is associated with sizable drops in efficiency, booster pressure ratio (PR), non-dimensional mass flow (NDMF), and overall engine pressure ratio (EPR) together with rises in turbine entry temperature (TET) and specific fuel consumption (SFC). The performance degradation evaluation employed variables such as isentropic efficiency (ηis), low pressure compressor (LPC) PR, NDMF, TET, SFC, andEPR. The variation in these quantities showed, for the maximum blade surface degradation case, drops of 7.68%, 2.62% and 3.53%, rises of 1.14% and 0.69%, and a drop of 0.86%, respectively.
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Дуаиссиа, Омар Хадж Аисcа, та Тарас Петрович Михайленко. "ОСОБЕННОСТИ ТЕПЛООБМЕНА В КАМЕРЕ ПОДШИПНИКА ГАЗОТУРБИННОГО ДВИГАТЕЛЯ". Aerospace technic and technology, № 6 (20 грудня 2018): 19–28. http://dx.doi.org/10.32620/aktt.2018.6.03.
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The issue of ensuring the thermal regime of the rotor support, which guarantees reliable operation of the power plant, is particularly important in designing oil systems of aviation gas turbine engines, as well as ground-based GTEs. The exact calculation of the heat flux from the engine to the GTE bearing chamber is necessary to determine the required oil pumping through the GTE rotor support. The complexity of the mathematical description of thermo-hydraulic processes is associated with the presence of a multiphase mixture in the bearing chamber, consisting of oil, which is applied to lubricate and cool the support elements, and the air applied to pressurize the seals. The current practice of designing oil systems is based on the experimental data and technology that has been established more than 20 years ago. The development trends of aircraft engines, aimed at reducing specific fuel consumption and harmful emissions, suggest higher loads and temperatures in the engine while reducing power take-off for reliable operation of its main systems. This adds demands for oil systems and leads to the need to improve their circuits and elements using modern methods of modeling and design, accumulated knowledge of work-flows. The article deals with the features of the heat exchange process between the walls of the bearing chamber and the multi-phase oil-air flow applying the developed three-dimensional CFD-model of the oil-air flow in the cavity of the rotor support of a gas turbine engine. The developed CFD model is verified and the results of a numerical study of thermal-hydraulic processes are presented by the example of a bearing chamber with simplified geometry applying experimental open access data. It is presented the effect of gravity and shear forces (shear stress) on the distribution of the flow and heat transfer in the bearing chamber, which is reflected in the nonuniform distribution of the oil film and the heat transfer coefficient around the circumference of the cavity. It is determined the influence of the size on oil droplets moving in the oil-air flow on the distribution of the oil film and the heat transfer coefficient in the bearing chamber
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Lee, Soon-Yong, Yeon-Choon Chung, and Jea-Hoon Choi. "The Propose of EMI Limits for GETM Cell Using Correlation Factor between OATS and GTEM Cell." Journal of Korean Institute of Electromagnetic Engineering and Science 22, no. 1 (2011): 1–8. http://dx.doi.org/10.5515/kjkiees.2011.22.1.001.
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