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Статті в журналах з теми "Bats – Losses"
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Zhao, Huabin, Dong Xu, Shuyi Zhang, and Jianzhi Zhang. "Widespread Losses of Vomeronasal Signal Transduction in Bats." Molecular Biology and Evolution 28, no. 1 (August 6, 2010): 7–12. http://dx.doi.org/10.1093/molbev/msq207.
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Kurta, Allen, Gary P. Bell, Kenneth A. Nagy, and Thomas H. Kunz. "Water balance of free-ranging little brown bats (Myotis lucifugus) during pregnancy and lactation." Canadian Journal of Zoology 67, no. 10 (October 1, 1989): 2468–72. http://dx.doi.org/10.1139/z89-348.
Повний текст джерелаАнотація:
This study provides the first measurements of daily water flux in free-ranging bats during pregnancy and lactation. We used the wash-out rate of tritiated water from the body water pool to calculate daily water flux in 10 pregnant and 14 lactating little brown bats (Myotis lucifugus). Average water influx was 6.16 ± 0.47 (SE) mL/day during pregnancy and 6.91 ± 0.37 mL/day during lactation; average efflux was 6.27 ± 0.44 and 7.07 ± 0.36 mL/day during pregnancy and lactation, respectively. Using data from the literature, we partitioned daily flux into major components. Our calculations indicated that most (> 62%) water influx was preformed water in the insect diet. Drinking water represented 23–26% of daily influx. Although previous studies indicated that evaporative losses greatly exceeded urinary losses in laboratory-maintained M. lucifugus, urinary and evaporative losses were comparable in our free-ranging bats. Urinary losses represented 46% of water efflux during pregnancy and 35% during lactation. Over 80% of all water efflux occurs during the 8-h night.
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da Silva Schreiber, Maicon, and Juliana Fachinetto. "PHYLOGENETIC RELATIONSHIP BETWEEN RABIES VIRUS (RABIES LYSSAVIRUS) VARIANTS FROM TWO DIFFERENT HOST SPECIES." Veterinária e Zootecnia 31 (January 13, 2024): 1–7. http://dx.doi.org/10.35172/rvz.2024.v31.1537.
Повний текст джерелаАнотація:
Rabies is a fatal zoonotic disease that affects several mammals. Bats are recognized hosts of the rabies virus, and their main food source is the blood of other mammals, particularly cattle. During feeding, bats transmit the virus to cattle, which are victims of the disease, contributing to economic losses and increasing the risk of infection for humans. Based on this affinity in the rabies cycle between bats and cattle, the objective of this study was to analyze the phylogenetic relationships of rabies virus samples in cattle and bats. The G gene of the rabies virus was chosen for this study because it is directly related to the infection process. Nucleotide sequences of the viral G gene were selected from GenBank for samples obtained from infected cattle and bats. Maximum parsimony analyses were conducted using the Molecular Evolutionary Genetics Analysis software. The Maxima Parsimony tree indicated a phylogenetic relationship between the G genes of both hosts, indicating that the virus evolved from bats to cattle. Analysis of parsimoniously informative sites revealed that the viral G gene carried specific mutations in each host. Knowledge of the evolutionary relationships between the rabies virus and its hosts is critical for identifying potential new hosts and the possible routes of infection for humans.
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Zhu, Dan, Yingying Liu, Lixin Gong, Man Si, Qiuya Wang, Jiang Feng, and Tinglei Jiang. "The Consumption and Diversity Variation Responses of Agricultural Pests and Their Dietary Niche Differentiation in Insectivorous Bats." Animals 14, no. 5 (March 6, 2024): 815. http://dx.doi.org/10.3390/ani14050815.
Повний текст джерелаАнотація:
Insectivorous bats are generalist predators and can flexibly respond to fluctuations in the distribution and abundance of insect prey. To better understand the effects of bats on arthropod pests, the types of pests eaten by bats and the response of bats to insect prey need to be determined. In this study, we performed DNA metabarcoding to examine prey composition and pest diversity in the diets of four insectivorous species of bats (Hipposideros armiger, Taphozous melanopogon, Aselliscus stoliczkanus, and Miniopterus fuliginosus). We evaluated the correlation between bat activity and insect resources and assessed dietary niche similarity and niche breadth among species and factors that influence prey consumption in bats. We found that the diets of these bats included arthropods from 23 orders and 200 families, dominated by Lepidoptera, Coleoptera, and Diptera. The proportion of agricultural pests in the diet of each of the four species of bats exceeded 40% and comprised 713 agricultural pests, including those that caused severe economic losses. Bats responded to the availability of insects. For example, a higher abundance of insects, especially Lepidoptera, and a higher insect diversity led to an increase in the duration of bat activity. In areas with more abundant insects, the number of bat passes also increased. The dietary composition, diversity, and niches differed among species and were particularly significant between H. armiger and T. melanopogon; the dietary niche width was the greatest in A. stoliczkanus and the narrowest in H. armiger. The diet of bats was correlated with their morphological and echolocation traits. Larger bats preyed more on insects in the order Coleoptera, whereas the proportion of bats consuming insects in the order Lepidoptera increased as the body size decreased. Bats that emitted echolocation calls with a high peak frequency and duration preyed more on insects in the order Mantodea. Our results suggest that dietary niche differentiation promotes the coexistence of different bat species and increases the ability of bats to consume insect prey and agricultural pests. Our findings provide greater insights into the role of bats that prey on agricultural pests and highlight the importance of combining bat conservation with integrated pest management.
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Jiao, Hengwu, Libiao Zhang, Huan-Wang Xie, Nancy B. Simmons, Hui Liu, and Huabin Zhao. "Trehalase Gene as a Molecular Signature of Dietary Diversification in Mammals." Molecular Biology and Evolution 36, no. 10 (July 16, 2019): 2171–83. http://dx.doi.org/10.1093/molbev/msz127.
Повний текст джерелаАнотація:
Abstract Diet is a key factor in determining and structuring animal diversity and adaptive radiations. The mammalian fossil record preserves phenotypic evidence of many dietary shifts, whereas genetic changes followed by dietary diversification in mammals remain largely unknown. To test whether living mammals preserve molecular evidence of dietary shifts, we examined the trehalase gene (Treh), which encodes an enzyme capable of digesting trehalose from insect blood, in bats and other mammals with diverse diets. Bats represent the largest dietary radiation among all mammalian orders, with independent origins of frugivory, nectarivory, carnivory, omnivory, and even sanguivory in an otherwise insectivorous clade. We found that Treh has been inactivated in unrelated bat lineages that independently radiated into noninsectivorous niches. Consistently, purifying selection has been markedly relaxed in noninsectivorous bats compared with their insectivorous relatives. Enzymatic assays of intestinal trehalase in bats suggest that trehalase activity tends to be lost or markedly reduced in noninsectivorous bats compared with their insectivorous relatives. Furthermore, our survey of Treh in 119 mammal species, which represent a deeper evolutionary timeframe, additionally identified a number of other independent losses of Treh in noninsectivorous species, recapitulating the evolutionary pattern that we found in bats. These results document a molecular record of dietary diversification in mammals, and suggest that such molecular signatures of dietary shifts would help us understand both historical and modern changes of animal diets.
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Carvalho, William D., Elizabete C. Lourenço, Júlia L. Luz, Bruna S. Xavier, Angélica V. Yantén, and Luciana M. Costa. "Giving Wings to Sustainability: Brazil Needs to Consider Bats as Suppressors of Agricultural Pests and Tropical Disease Vectors." Sustainability 16, no. 14 (July 9, 2024): 5858. http://dx.doi.org/10.3390/su16145858.
Повний текст джерелаАнотація:
Insect-eating bats play a crucial role in agriculture and public health by suppressing populations of agricultural pests and disease vectors. These ecosystem services promoted by insect-eating bats are essential in a world that seeks sustainability in agricultural production and the management of urban areas. Despite Brazil’s status as one of the largest agricultural producers globally, research using insect-eating bats for pest control is lacking. This review underscores the importance of filling this knowledge gap and provides guidelines for future research. Bats exhibit diverse feeding habits and consume significant quantities of insects, including agricultural pests. While studies in the USA and Europe have highlighted insect-eating bats’ role in reducing agricultural losses, research in Brazil is limited. Challenges include the need for more advanced diet analysis techniques, such as DNA metabarcoding, and understanding bat habitat use in agricultural and urban landscapes. Research on natural and artificial roosts’ effectiveness and population dynamics is also essential. Integrating bat conservation into agricultural sustainability requires investment in technological methods, valuation of ecosystem services, population monitoring, habitat use studies and environmental education. Financial incentives and collaboration between sectors are crucial for advancing research and implementing bat-friendly practices in agriculture, ultimately enhancing biodiversity conservation and production sustainability in Brazil.
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Liu, Yang, Huihui Xu, Xinpu Yuan, Stephen J. Rossiter, and Shuyi Zhang. "Multiple Adaptive Losses of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Fruit-Eating Bats." Molecular Biology and Evolution 29, no. 6 (January 19, 2012): 1507–11. http://dx.doi.org/10.1093/molbev/mss013.
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Miková, Edita, Katarína Varcholová, Sándor Boldogh, and Marcel Uhrin. "Winter diet analysis in Rhinolophus euryale (Chiroptera)." Open Life Sciences 8, no. 9 (September 1, 2013): 848–53. http://dx.doi.org/10.2478/s11535-013-0199-9.
Повний текст джерелаАнотація:
AbstractWe investigated the winter food of Mediterranean horseshoe bats (Rhinolophus euryale) in four winter cave roosts in southern Slovakia and northern Hungary and investigated the relationship between food and ambient temperature. The bats were active during the whole winter period and they produced excrement throughout the entire hibernation period, even when outside temperatures dropped below zero. The guano was in two forms, containing (1) prey items and (2) non-prey items. The identifiable items belonged to lepidopteran species, but only one was identified, on the basis of the genital fragments, the moth Colotois pennaria, which was the main prey species in autumn and early winter. Our results shed light on the extraordinarily high level of activity in this bat species during winter hibernation, which in temperate regions is a strategy that enables bats to survive when prey is reduced or absent. In R. euryale, the torpor in the course of hibernation is not continuous and our results help to explain how energy losses caused by bat movements are covered.
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Shen, Bin, Tao Fang, Mengyao Dai, Gareth Jones, and Shuyi Zhang. "Independent Losses of Visual Perception Genes Gja10 and Rbp3 in Echolocating Bats (Order: Chiroptera)." PLoS ONE 8, no. 7 (July 18, 2013): e68867. http://dx.doi.org/10.1371/journal.pone.0068867.
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Kłys, Grzegorz, and Joanna Makuchowska-Fryc. "Wintering Conditions and Heat Loss during Hibernation in the Brown Long-Eared Bat." Applied Sciences 14, no. 2 (January 15, 2024): 716. http://dx.doi.org/10.3390/app14020716.
Повний текст джерелаАнотація:
The aim of this study was to estimate heat loss in the brown long-eared bat during hibernation depending on the refugioclimate conditions. The measured values of refugioclimate parameters were: ambient temperature (Ta) 3–10 °C, relative humidity (Rh) 74–98% and air velocity (v) 0.06–0.95 m/s. Heat loss was calculated using convective heat transfer equations. Mean heat loss amounted to 4 W/m2. The results were compared to the heat loss calculated based on the fat burned during hibernation. Bats flying into underground systems during the hibernation period were captured and their body mass was measured. A loss of body mass of 2.6 g over the 126 days of hibernation was observed. Heat loss equalled 3.115 W/m2K.The presented method of calculating energy expenditure allows for non-invasive monitoring of the heat and fat losses of bats during hibernation. Such research may find application in designing artificial wintering sites.
Дисертації з теми "Bats – Losses"
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Carey, Charleve. "IS DISRUPTION TO PASSIVE GAS-EXCHANGE A MECHANISM OF DEHYDRATION FOR WNS-INFECTED HIBERNATING BATS?" OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1532.
Повний текст джерелаАнотація:
Emergent epizootics are responsible for dramatic declines in wildlife populations over the past few years. An emerging fungal-borne epizootic, called white-nose syndrome (WNS), is responsible for a catastrophic decline of hibernating bats in North America The fungus, Pseudogymnoascus destructans (Pd), is the causative agent of WNS, but to date, we have limited understanding of how an infection with Pd can lead to mortality in hibernating bats. Evidence suggests dehydration is an important part of the pathogenesis of WNS. Cryan et al. (2010) proposed four possible mechanisms by which infection could lead to dehydration. In this study, I tested one of these hypotheses - Pd infection could cause disruption to passive gas-exchange pathways across the wing membranes, thereby causing a compensatory increase in water-intensive pulmonary respiration. I hypothesized total evaporative water loss would be greater when passive gas-exchange was inhibited, especially at low ambient temperatures. I found that bats did not lose more water when passive gas-exchange was retarded (at least within the resolution of my equipment). This study provides evidence against the proposed proximal mechanism that disruption to passive gas-exchange causes dehydration and ultimately death to WNS-infected bats.
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Huang, Jianhua. "Evaluation of heat loss models for predicting temperature ratings of sleeping bags /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Minnaar, I. A. (Ingrid Ane). "Seasonal metabolic adjustments and partitioning of evaporative water loss in Wahlberg’s epauletted fruit bat,Epomophorus Wahlbergi." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/41369.
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Summary
Seasonal metabolic adjustments and partitioning of evaporative water loss in Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi
Student: Ingrid A. Minnaar
Supervisor: Prof. A. E. McKechnie
Co-supervisors: Prof. N. C. Bennett, Prof. Christian T. Chimimba
Department: Zoology and Entomology, University of Pretoria
Degree: MSc: Zoology
The capacity to thermoregulate over a wide range of TaS is critical for maintaining homeostasis in endotherms. Several aspects of the thermoregulatory properties of bats remain poorly studied when compared to other mammals and birds. I examined two specific aspects of thermoregulation in bats: the seasonal variation of maximum metabolic heat production and the partitioning of total evaporative water loss (TEWL) into respiratory and cutaneous components. I measured basal metabolic rate (BMR) and summit metabolism (Msum) in captive and wild Wahlberg’s epauletted fruit bats, Epomophorus wahlbergi, during summer and winter. I measured metabolic rate using flow-through respirometry, and elicited Msum by exposing bats to low temperatures in a helox (21% O2, 79% He) atmosphere. BMR decreased by 22-25% during winter in both captive and wild bats, with the BMR of captive bats 9-13% lower than the wild individuals across seasons. Msum was approximately seasonally stable in both captive and wild bats, but Msum in captive individuals was 13-18% higher than their wild conspecifics during both seasons. The ratio between Msum and BMR (i.e., metabolic expansibility) was greater in winter than during summer for both captive and wild bats. One likely explanation for the greater resting thermogenic capacity of the bats in captive individuals concerns their reduced activity levels; compared to wild, free-ranging bats, heat produced as a by-product of activity probably contributed far less to thermoregulation, apparently leading to an increase in resting heat production capacity in captive individuals. 5
At the other end of the thermal scale, knowledge of heat tolerance and the evaporative cooling mechanisms employed by bats in hot weather remains rudimentary. At high air temperatures (Ta), endotherms avoid overheating by dissipating heat via evaporative water loss. TEWL may be partitioned into cutaneous evaporative water loss (CEWL) and respiratory evaporative water loss (REWL). I quantified CEWL and REWL in E. wahlbergi at Tas of 10-40 °C using a latex mask. When Ta exceeded normothermic Tb, bats drastically increased their TEWL, metabolic rate and Tb. The relative contribution of CEWL to TEWL was the greatest at moderate Tas where it represented up to 80% of TEWL. REWL was the major route of evaporative cooling at the highest Ta: at Ta = 40 ºC, REWL represented 45% of TEWL. To avoid hyperthermia, E. wahlbergi greatly increased metabolic rate at high TaS to avoid hyperthermia, further compounding the need to cool down. REWL is thought to be less efficient as than CEWL in offloading heat at high TaS as panting increases metabolic heat, whereas CEWL occurs passively. There is a need for further studies to be conducted on the thermoregulatory capabilities of bats in varying environmental conditions, both intra- and interspecifically.Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Zoology and Entomology
unrestricted
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Miguel, Pedro Henrique. "Efeito de fragmentação de habitat sobre a associação entre ectoparasitos e morcegos na Mata Atlântica /." Rio Claro, 2019. http://hdl.handle.net/11449/183643.
Повний текст джерелаАнотація:
Orientador: Ariovaldo Pereira da Cruz NetoResumo: A perda de habitat é vista como um dos principais efeitos decorrentes das perturbações da paisagem causada pelo homem aos ambientes naturais. Essa gera maior isolamento dos fragmentos e diminui as áreas de contato entre habitat e matriz, com efeitos negativos sobre a biodiversidade. Os efeitos da perda de habitat nos padrões de biodiversidade são geralmente analisados usando dados de distribuição de espécies e / ou abundância relativa. No entanto, eles não podem ser identificados em populações em que esses efeitos ainda não foram refletidos na abundância e incidência de espécies, e não nos informam sobre os mecanismos causais subjacentes às respostas diferenciais de espécies ou populações a essas perturbações. Uma opção para preencher esta lacuna é concentrar-se em quantificar a miríade de processos fisiológicos em que diferentes espécies lidam com ambientes em mudança. Os morcegos apresentam uma grande diversidade morfológica, fisiológica e comportamental, estando presentes em uma diversa variedade de nichos ecológicos, estabelecendo diversas relações críticas para a manutenção dos ecossistemas onde ocorrem. Os morcegos frugívoros estão entre os mais importantes dispersores de sementes do Neotrópico. Juntamente com os morcegos, investigações com seus ectoparasitas específicos são de grande relevância, visto que, os ectoparasitas exercem pressões seletivas importantes sobre a evolução dos seus hospedeiros. Assim, perda de habitat pode trazer importantes mudanças para as popul... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Habitat loss is seen as one of the main effects of man-made landscape disturbances on natural environments. This generates greater isolation of the fragments and reduces the contact areas between habitat and matrix, with negative effects on biodiversity. The effects of habitat loss on biodiversity patterns are generally analyzed using species distribution and / or relative abundance data. However, they cannot be identified in populations where these effects have not yet been reflected in species abundance and incidence, and do not inform us of the causal mechanisms underlying the differential responses of species or populations to these disturbances. One option to bridge this gap is to focus on quantifying the myriad physiological processes in which different species deal with changing environments. Bats have a great morphological, physiological and behavioral diversity, being present in a diverse variety of ecological niches, establishing several critical relationships for the maintenance of the ecosystems where they occur. Fruit bats are among the most important seed dispersers of the Neotropic. Together with bats, investigations with their specific ectoparasites are of great relevance, as ectoparasites exert important selective pressures on their host evolution. Thus, habitat loss can bring about major changes to bat populations and in some biotic interactions such as parasitism. In this context, we use some physiological analysis to (1) evaluate the impacts of habitat los... (Complete abstract click electronic access below)
Mestre
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Palsovics, Norbert. "Vliv počtu rotorových tyčí na ztráty malého asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-317075.
Повний текст джерелаАнотація:
The aim of this semester work is to analyze the losses of induction motor, according to their measure, use programs using the finite element method for the detection of the motor and the subsequent evaluation and comparison of the results obtained. The first part deals with the general AM, losses and measure their losses. The next section is very Lossmeasurement submitted asynchronous motors. The measured two machines have different characteristics in the sheet. The following section is calculating the losses using the finite element method using ANSYS Maxwell and RMXprt.The next part is the analysis of motor losses with a different number of rotor bars. This section is addressed to the models developed and validated by measuring the actual machine.
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Lamb, Christopher. "Blueline Concerto: Critical Essay." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc283800/.
Повний текст джерелаАнотація:
The purpose of this critical essay is two-fold. First, the essay presents a detailed critical analysis of my original composition, Blueline Concerto for bass trombone and wind ensemble. Second, using Blueline Concerto, the essay presents preliminary findings of my study to develop an approach to composing that takes into account the musicians' health, specifically regarding noise induced hearing loss (NIHL). Through various hypothesized composition- and orchestral-based approaches, I test effectiveness on changes in NIHL risk while also noting that artistic merit and compositional integrity is preserved.
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Berbic, Almir, and Barès Markus de. "Redovisning av goodwill under IAS 36 : Bestämmande faktorer som påverkar aktualisering av goodwillnedskrivning hos företag på Nasdaq Stockholm." Thesis, Södertörns högskola, Företagsekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-41225.
Повний текст джерелаАнотація:
Denna studie undersöker företagsspecifika ekonomiska faktorer och opportunistiska incitamentrelaterade faktorer hos företagsledare som är bestämmande för aktualisering av goodwillnedskrivning i den svenska kontexten. År 2005 implementerade International Accounting Standard Board principbaserade riktlinjer avseende redovisning av goodwill enligt IAS 36 mot tidigare systematiska avskrivningar av goodwill. Implementeringen avsåg att förbättra redovisning av goodwill genom att förse användarna av finansiella rapporter med mer värderelevant information avseende tillgångens underliggande prestation. Dock har det nya principbaserade reglementet kritiserats av forskare mot bakgrund av diskretionen som medföljer av IAS 36 vid nedskrivningsprövningar som kan ge upphov till opportunistiska incitament hos företagsledare. Undersökningen avgränsas till Nasdaq Stockholm i betraktande av att tidigare forskning visat inkonsekventa forskningsresultat avseende vilka faktorer som är bestämmande för goodwill nedskrivning samt att det föreligger få empiriska belägg och olika argument inom redovisningslitteraturen. Undersökningen utgörs av totalt 285 företag på Nasdaq Stockholm över fem undersökningsår, vilket efter täckningsfel och bortfall resulterar i 1090 företagsobservationer. Det empiriska resultatet tyder att företagsledare i den svenska kontexten under diskretionen som medföljer av IAS 36 agerar opportunistiskt för att uppnå eftertraktade resultat vid nedskrivningsprövningar, specifikt vid positionsbyte av den verkställande direktören och resultatutjämning vid abnormt höga resultat, och inte fullständigt följer företagsspecifika ekonomiska kriterier som följer av IAS 36 vid bedömning av kassagenererande enheters återvinningsvärde. Det subjektiva utrymmet vid nedskrivningsprövningar medför praktiska och teoretiska implikationer för användare av finansiella rapporter, utövare och normgivare.This study examines factors associated to business specific characteristics and factors associated to opportunistic incentives by executives that are determining for actualization of goodwill impairment losses in the Swedish context. In 2005, the International Accounting Standard Board implemented principle-based guidelines regarding the recognition of goodwill in accordance with IAS 36 against previously systematic amortization of goodwill. The implementation was issued to improve the recognition of goodwill by providing users of financial reports with more value-relevant information regarding the asset's underlying performance. However, the new principle-based regulations have been criticized by researchers considering the discretion that follows with IAS 36 in impairment tests that may give rise to opportunistic incentives on the part of executives. The study is limited to Nasdaq Stockholm, owing to previous research showing inconsistent results regarding the factors that determine goodwill impairment losses and that there are few empirical evidence and different arguments in the accounting literature. The survey consists of a total of 285 companies on Nasdaq Stockholm over five examination years, which after coverage errors and omissions results in 1090 observations. The empirical result indicates that executives in Sweden under the discretion that are incorporated with IAS 36 act opportunistically to achieve coveted results in impairment tests, specifically in the change of position of the CEO and in managing of earnings by equalizing results in periods of abnormally high results, and do not fully follow business specific financials criteria that follows from IAS 36 when assessing the recoverable amount of cash generating units. The subjective scope of impairment tests entails practical and theoretical implications for users of financial reports, practitioners and normsetters.
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Riedel, Ismaël. "Analyse de la vulnérabilité du bati existant. Estimation et réduction des incertitudes dans l'estimation des dommages et des pertes pour un scénario sismique donné." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAU016/document.
Повний текст джерелаАнотація:
Parmi les risques naturels et les catastrophes majeures, les tremblements de terre sont l'un des plus meurtriers, préjudiciables et imprévisibles de tous. Avec une constante augmentation de l'impact dans les économies des pays et dans le nombre de victimes, les tremblements de terre modernes coûtent des dizaines de milliards de dollars et tuent en moyenne 35000 personnes par an dans le monde.Avec l'étendue des dommages observés après les tremblements de terre d'intensité modérée à forte de ces dernières décennies, la sensibilisation auprès des catastrophes naturelles a considérablement augmenté. Il y a donc une demande croissante d'analyses détaillées des risques sismiques pour renforcer la préparation en amont et mieux planifier la réponse après les séismes. Cette évaluation des risques nécessite non seulement l'estimation de l'aléa sismique, mais aussi la représentation de la capacité des structures à résister face au mouvement du sol: tel est l'objectif des évaluations de la vulnérabilité sismique. En raison de la complexité inhérente à l'estimation de l'aléa, des vulnérabilités et leur interaction, la quantification du risque sismique est une tâche ardue, et estimer des impacts réalistes dus aux grands tremblements de terre ne peut se faire qu'approximativement.L'estimation de la vulnérabilité sismique des bâtiments à l'échelle urbaine, étant un élément crucial dans l'évaluation des risques, est elle-même une tâche longue, coûteuse et compliquée, en particulier dans les régions où l'aléa sismique est modéré à faible et où la mobilisation des ressources pour l'évaluation sismique est réduite même si le risque est non négligeable.Nous proposons dans la première partie de cette étude un moyen d'effectuer une estimation rapide à l'aide des données fiables du bâtiment. Ces données sont plus facilement disponibles au niveau régional que l'information habituellement exigée par les méthodes traditionnelles. Avec l'utilisation d'un ensemble de données du bâtiment existant à Grenoble (France), avec une classification EMS98 de la vulnérabilité, et en employant deux techniques de fouille de données différentes - Association Rule Learning et Support Vector Machine - nous avons développé des proxies de la vulnérabilité sismique. Ceux-ci ont été appliqués à la France entière en utilisant des informations de base à partir de bases de données nationales (information de recensement) et les données issues du traitement des images satellites et des photographies aériennes pour produire une carte de la vulnérabilité à l'échelle nationale. Cette méthode macroscopique pour évaluer la vulnérabilité est facilement applicable dans le cas d'un manque d'informations concernant les caractéristiques structurelles du parc immobilier.La partie qui clôture ce travail est préconisée pour le calcul des pertes liées aux tremblements de terre et à l'analyse et la réduction des incertitudes. L'estimation complète des scénarios de tremblement de terre avec un nombre probable de bâtiments endommagés dans une ville européenne typique est présentée par la suite. Une analyse complète des incertitudes est réalisée à chaque étape, et l'incertitude combinée finale est calculée. Les principales sources de variabilité sont représentées. Dans la dernière partie, l'évolution des dommages et des risques lorsque des améliorations structurelles sont affectées aux bâtiments est examinée. Des évaluations des pertes économiques sont effectuées pour la France en utilisant des cartes de risques réglementaires pour des différentes périodes de retour. En particulier, pour cinq villes françaises, le modèle de perte proposé est utilisé pour concevoir un plan de réaménagement et de modernisation du parc immobilier en réalisant des études coûts-bénéfices pour les différents types de plans d'intervention structurelle. Des scénarios d'investissements optimaux sont calculés, qui peuvent servir d'appui aux décisions stratégiques concernant l'atténuation du risque sismique en FranceAmong the natural hazards and major catastrophes, earthquakes are one of the most deadly, damaging and unpredictable of all. With increasing impacts in countries' economies and casualties, modern earthquakes cost in average tens of billons of dollars and kill 35,000 people per year worldwide (USGS). The planet is experiencing the consequences of the large urban population growth of the last century.With the extensive damage observed after the moderate-to-strong earthquakes of the last decades, awareness of natural catastrophes has considerably increased. There is therefore, a growing demand for detailed seismic risk analysis to strengthen disaster risk mitigation and response. This risk assessment requires not only the estimation of the seismic hazard, but also the representation of the structures' capacity to withstand the seismic ground motion: this is the objective of seismic vulnerability assessments.Due to the inherent complexity of estimating hazard, vulnerabilities and their interaction, seismic risk quantification is a daunting task and estimating realistic impacts due to large earthquakes may only be done approximately.The estimation of the seismic vulnerability of buildings at an urban scale, while a crucial element in any risk assessment, is itself an expensive, time-consuming, and complicated assignment, especially in moderate-to-low seismic hazard regions where the mobilization of resources for the seismic evaluation is reduced, even if the hazard is not negligible. We propose in the first part of this study a way to perform a quick estimation using convenient, reliable building data that are readily available regionally instead of the information usually required by traditional methods. Using a dataset of existing buildings in Grenoble (France) with an EMS98 vulnerability classification and by means of two different data mining techniques - association rule learning and support vector machine - we developed seismic vulnerability proxies. These were applied to the whole France using basic information from national databases (census information) and data derived from the processing of satellite images and aerial photographs to produce a nationwide vulnerability map. This macroscale method to assess vulnerability is easily applicable in case of a paucity of information regarding the structural characteristics and constructional details of the building stock.The closing part of this work is advocated to the calculation of earthquake losses and to the analysis and reduction of uncertainties. A comparison between predicted and observed ground motions and intensities in France is presented, and prediction equations producing the smallest residuals are highlighted. The full estimation from earthquakes scenarios to probable number of damaged buildings in a typical European city is presented afterwards. A comprehensive analysis of uncertainties is carried on at every step, and the final combined uncertainty is calculated. The major sources of variability are depicted and recommendations on how to efficiently reduce them are proposed. In the last part, the evolution of damage and risk when structural improvements are performed to buildings is reviewed. Economic loss assessments are performed for France using regulatory hazard maps for different time horizons. In particular, for five French cities the proposed loss model is used to design retrofitting schemes by carrying out cost-benefit studies for different types of structural intervention plans. Optimal investment scenarios are calculated, which may support strategic decisions regarding the risk mitigation in France
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Tabaková, Eva. "Rozklad a stabilita organické hmoty v půdě." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316457.
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In the soil, the plant material is decomposed by several factors. In the process, one part of the carbon returns to the atmosphere as carbon dioxide, whereas another part is stabilised in the soil. The aim of this study is decomposition and stability of organic matter in soil using a simple and innovative TBI method. Through this method, we examined the weight change after the incubation period of 90 days, where biomass of green tea was degraded in cambodia soil. Tea bags have provided us with valuable information on the decomposition and amount of carbon in the soil, because the biomass itself is of organic origin. This information is based on the fact that the soil and the decomposition processes have a direct impact on the change in climatic conditions. Thanks to further analytical methods, elemental analysis, thermogravimetric analysis and infrared spectroscopy with Furier transformation, was found indispensable information about tea composition.
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Coelho, Francisco Carlos Rodrigues. "Alocação de geração distribuída em sistemas de distribuição de energia elétrica via otimização bioinspirada na ecolocalização de morcegos." Universidade Federal de Juiz de Fora, 2013. https://repositorio.ufjf.br/jspui/handle/ufjf/1203.
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A alocação de geração distribuída em sistemas de distribuição de energia elétrica consiste em definir a localização ótima para instalação de centrais geradoras distribuídas no sistema e a quantidade de potência que deverá ser injetada por estas centrais, de modo a minimizar as perdas técnicas inerentes aos sistemas de distribuição. Este é um problema de otimização de difícil solução e que apresenta implicações ambientais e econômicas. A técnica de otimização empregada nesta pesquisa para determinar a alocação dos geradores distribuídos é recente, sendo a mesma bioinspirada. Ela se baseia na ecolocalização de morcegos e foi desenvolvida em 2010 pelo pesquisador Xin-She Yang. Esta técnica de otimização agrega em sua constituição conhecimento prévio adquirido por outras técnicas de otimização, como enxame de partículas e busca harmônica, utilizando assim, as vantagens inerentes a cada uma destas ferramentas. Esta característica confere à otimização via ecolocalização uma expectativa de sucesso em problemas de difícil solução, com características combinatórias, que é o caso do problema em estudo. Com o intuito de melhorar o desempenho da técnica de otimização em questão, foi proposta uma etapa adicional em sua constituição. Esta alteração no algoritmo original se mostrou eficiente nas simulações realizadas, pois o mecanismo de busca modificado alcançou resultados de melhor qualidade com maior frequência, tanto em sua validação, onde foram utilizadas funções matemáticas não convexas, como na aplicação do método ao problema referente à alocação de geração distribuída em sistemas de distribuição de energia elétrica. Utilizando-se três sistemas teste, de trinta e três, de cinquenta e de sessenta e nove barras, foram realizados testes com alocação exclusiva de potência ativa e reativa, e também alocação simultânea destes dois tipos de potência, sendo que os resultados obtidos foram comparados com resultados presentes na literatura especializada. Além das perdas, fatores como perfil de tensão resultante nas barras e trajetória de convergência do algoritmo inspirado na ecolocalização de morcegos foram analisados para a avaliação da metodologia de otimização empregada nesta pesquisa.
The optimal distributed generation placement in electrical power systems is a complex problem involving environmental and economical issues. The solution to this problem consists of choosing the optimum location of distributed power plants, and to define the amount of power that must be injected by these plants in order to minimize technical losses in electrical distribution systems. The optimization technique utilized in this work to determine the placement of distributed generators is recent. It was developed in 2010 by Xin-She Yang. The optimization procedure is inspired by the echolocation of bats phenomenon, and uses some previous knowledge from others techniques, like Particle Swarm Optimization and Harmony Search, combining their advantages. This feature gives the Bat-Inspired Algorithm an expectation of success on difficult problems, such as the combinatorial problem under study. In order to improve the performance of the optimization technique an additional step was proposed in its search engine. Endowed with this change, the algorithm has achieved better results more frequently. Nonconvex benchmark mathematical functions were used, as well as in its application on distributed generation placement. Using three different bus systems (33, 50 and 69 busses), simulations were performed placing real and reactive Power separately, and those two kind of Power together. The produced results were compared to specialized literature. Real power losses, bus voltage and convergence trajectory indicates the level of success reached by the optimization technique utilized in this research work.
Книги з теми "Bats – Losses"
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Colin, Harrison. The Havana room. New York, NY: St. Martin's Paperbacks, 2005.
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Harrison, Colin. Kubinskiĭ zal. Moskva: Inostranka, 2004.
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Colin, Harrison. The Havana room. New York: Farrar, Straus and Giroux, 2004.
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The Havana room. New York: Farrar, Straus and Giroux, 2004.
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Colin, Harrison. The Havana room: Please keep door closed. Waterville, Me: Thorndike Press, 2004.
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Inc, Game Counselor. Game Counselor's Answer Book for Nintendo Players. Redmond, USA: Microsoft Pr, 1991.
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Inc, Game Counsellor, ed. The Game Counsellor's answer book for Nintendo Game players: Hundredsof questions -and answers - about more than 250 popular Nintendo Games. Redmond, Washington: Microsoft Press, 1991.
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Bat Count: A Citizen Science Story. Mt. Pleasant, SC, USA: Arbordale Publishing, 2017.
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Forrester, Anna. Bat Count: A Citizen Science Story. Arbordale Publishing, 2017.
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Detwiler, Susan, and Anna Forrester. Contando los murciélagos : Una historia de ciencias cívicas [Bat Count: A Citizen Science Story]. Arbordale Publishing, 2017.
Знайти повний текст джерелаЧастини книг з теми "Bats – Losses"
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Silvis, Alexander, Nicole Abaid, W. Mark Ford, and Eric R. Britzke. "Responses of Bat Social Groups to Roost Loss: More Questions Than Answers." In Sociality in Bats, 261–80. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-38953-0_13.
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Propper, Catherine R., Grant Robert Singleton, Jodi L. Sedlock, Richard E. Smedley, Oliver B. Frith, Molly E. Shuman-Goodier, Renee P. Lorica, et al. "Faunal Biodiversity in Rice-Dominated Wetlands—An Essential Component of Sustainable Rice Production." In Closing Rice Yield Gaps in Asia, 93–120. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37947-5_3.
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AbstractRice agriculture provides wetlands and complex habitats supporting biodiversity. Wetlands associated with rice agriculture since the 1960s have increased by 32% and now form nearly 12% of wetlands globally at a time when vast areas of natural wetlands are being lost. In this chapter, we set our sights beyond Sustainable Development Goal (SDG) 2 that focuses on ending hunger and achieving food security via the promotion of sustainable agriculture. Often, agricultural scientists are so motivated to achieve food security that they pay insufficient attention to the need to have a healthy and dynamic agroecosystem that promotes floral and faunal biodiversity, which may also provide ecosystem services including support for food security of smallholder families. Because of their aquatic, semi-aquatic, and terrestrial ecological phases, rice fields represent a changing mosaic of ecological niches and have the potential to sustain a broad diversity of wildlife. In addition, a multitude of studies have investigated how modifications to rice cultivation have the potential to support a greater diversity of species across biological scales while often maintaining or increasing yield. SDG 15 emphasizes the need to promote sustainable use of terrestrial ecosystems and halt biodiversity loss. Given the high losses in global biodiversity, especially in tropical zones where most of the world’s rice is grown, we set our sights on achieving both SDGs 2 and 15. We provide case studies on amphibians, bats, birds, and rodents living in and around irrigated rice-cropping systems. We report on transdisciplinary studies supported by CORIGAP that include agronomic, sociological, ecological, biochemical, environmental physiological, and genomic studies. Most of these studies identify potential positive ecosystem services provided by wildlife, which can lead to more sustainable and healthier rice production landscapes. We conclude that our current management of rice landscapes contributes to the biodiversity crisis. Rice production often overuses pesticides and fertilizers and applies unsustainable intensification practices and land modifications, which result in biodiversity loss. Finding a balance, where human population requirements for food are met without degrading the natural environment, is critical to the health of smallholder agricultural communities. We propose that future research and development projects need to: build capacity of countries to scale-up use of proven practices that reduce rice farming’s ecological footprint and conserve biodiversity, increase investment in biodiversity research in rice production landscapes, promote Green “Rice Value Chains” and “Agri-input Markets,” and monitor and evaluate the ecological benefits to biodiversity of broadscale promotion of sustainable rice production.
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Boyd-Weetman, B., P. Thomas, P. DeSilva, and V. Sirivivatnanon. "Accelerated Mortar Bar Test to Assess the Effect of Alkali Concentration on the Alkali–Silica Reaction." In Lecture Notes in Civil Engineering, 233–39. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_24.
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AbstractWe report the outcomes of a study into the influence of alkali concentration on expansion induced by the alkali–silica reaction (ASR), a deleterious reaction that causes cracking and durability loss in concrete structures. We assessed the effect of alkali concentration on mortar bar expansion using a modified form of AS1141.60.1, the accelerated mortar bar test (AMBT). Mortar prisms were prepared with a reactive aggregate and immersed in alkali solutions of varying concentrations (from 0.4 to 1.0 M NaOH) and saturated limewater at 80 °C. Expansion was monitored for 28 days. The degree of expansion was observed to increase with increasing alkali concentration and an induction period prior to expansion was observed for the 0.4 M NaOH. No expansion was observed for mortar bars immersed in the control saturated lime water bath. Additionally, no expansion was observed for mortars using blended cements containing fly ash (FA) and ground granulated blast furnace slag, suggesting the AMBT is a viable technique for demonstrating the efficacy of mitigation strategies.
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Sulistyowati, Lilik, Firman Afrianto, Abdul Rais, Muhammad Fauzi Hafa Darwiyanti, and Andi Lopa Ginting. "Spatial Multi-Criteria Analysis for Sustainability Assessment Based on Disaster Losses in Batu City." In Lecture Notes in Civil Engineering, 267–81. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1403-6_20.
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Weier, Sina M., Thomas Bringhenti, Mina Anders, Issaka Abdulai, Stefan Foord, Ingo Grass, Quang D. Lam, et al. "Management Options for Macadamia Orchards with Special Focus on Water Management and Ecosystem Services." In Sustainability of Southern African Ecosystems under Global Change, 625–52. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-10948-5_22.
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AbstractSouth Africa is the World’s largest producers of macadamia nuts, with about 51,000 ha of land covered by macadamia. This leads to major farming challenges, as the expansion of orchards is associated with the loss of habitat and biodiversity, the excessive use of and resistance to insecticides, and an increased pressure on water resources. More frequent and severe droughts and heat waves are projected to worsen the situation and have already negatively affected harvests. Here we review current literature and recent work conducted in the subtropical fruit growing area of Levubu, South Africa, which include catchment-scale assessments of ground water, landscape-scale studies on pest control and pollination services, through to evaluations of tree-level water use. Several biological control options are being developed to replace pesticides. Results suggest that bats and birds provide large and financially measurable pest control services, and interventions should therefore focus on maintaining functional landscapes that would be resilient in the face of global climate change. This would include a landscape matrix that includes natural vegetation and minimize water consumption by optimizing irrigation schedules.
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Smit, Martijn, Veronique Schutjens, and Aleid Brouwer. "Not Going Back to the Office any Time Soon: Coworking Spaces in The Netherlands." In SpringerBriefs in Applied Sciences and Technology, 63–72. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-26018-6_7.
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AbstractIn the Netherlands traditionally many employees often did not work not at the office. The Dutch workforce was a large user of third spaces, especially in libraries and coffee bars and in coworking spaces. This meant that for most Dutch workers the switch to working from home during the pandemic was less substantial than in some other countries. These third spaces did suffer from the loss of working clientele during the pandemic and some (non)commercial third spaces had to close. Dutch coworking spaces are mostly found in densely populated areas and are either located in the inner city or at industrial sites.
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Young, P. C. "Recruitment variability in scallops: Potential causes for the loss of bass strait populations." In Coastal and Estuarine Studies, 327–42. Washington, D. C.: American Geophysical Union, 1994. http://dx.doi.org/10.1029/ce045p0327.
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Adelabu, Dolapo Bola, and Angelinus C. Franke. "Beneficial Role of Pollination and Soil Fertility for Soybean Production in Mountainous Farming Conditions." In Sustainable Development Goals Series, 53–73. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-15773-8_5.
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AbstractThe synergetic potentials of essential ecosystem services have not been well explored under mountainous farming conditions in southern Africa. Cropping practices that maximize beneficial pollinators and reduce dependency on chemical inputs through efficient crop management in the mountainous environment are needed. The synergetic potentials of insect pollination on soybeans under varying soil fertility during two seasons in Phuthaditjhaba, the Free State, South Africa was examined. We manipulated soil fertility with fertilizer treatments and used exclusion bags to manipulate pollination intensity. High intensity of pollination services increased the seed yield by approximately 0.5 tons per hectare on optimally fertilized soil and 0.3 tons per hectare on minimally fertilized soil. This study found complementary benefits of using appropriate fertilizer rates on crop pollination. It is an efficient way to minimize losses in crop production and improve yields. However, minimal fertilizer application that is common among smallholder farmers still gave substantial yield in insect pollinator-rich environments such as Phuthaditjhaba. This finding gives an immense advantage to farmers in Phuthaditjhaba who tend to minimize the use of fertilizer due to financial issues. Harnessing the prospects from these ecosystem service benefits would help local communities to attain sustainable food production (SDGs 2 and 15).
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Dritsos, Stephanos, and Dimitrios Baros. "Modification and Strengthening of a Characteristic Reinforced Concrete Building in Patras, Greece." In Case Studies on Conservation and Seismic Strengthening/Retrofitting of Existing Structures, 21–41. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2020. http://dx.doi.org/10.2749/cs002.021.
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<p>The design and application of strengthening measures aiming to effectively counter possible weaknesses related to the extensive architectural modification of a characteristic reinforced concrete building is discussed in this chapter. Several balconies were removed as part of the architectural interventions. Externally bonded reinforcement consisting of steel and fibre reinforced polymer laminates was applied as an “answer” to possible changes in flexural stress of selected structural elements in the immediate area of the demolitions. A unique anchorage system was also designed and applied as an answer to the loss of development length of the main reinforcement bars of selected beams due to the removal of their cantilever parts.</p>
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Lv, Liugen, Tao Jia, Wenlian Zhang, Qianqian Jia, Jin Lv, and Zhenzhen Jia. "Study on Bath Water Energy Loss of Campus Dormitory Air-Source Heat-Pump Water Heater." In Environmental Science and Engineering, 1207–14. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-13-9528-4_122.
Повний текст джерелаТези доповідей конференцій з теми "Bats – Losses"
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Yudell, Alexander C., and James D. Van de Ven. "Soft Switching in Switched Inertance Hydraulic Circuits." In BATH/ASME 2016 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fpmc2016-1779.
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Switched Inertance Hydraulic Systems (SIHS) use inductive, capacitive, and switching elements to boost or buck a pressure from a source to a load in an ideally lossless manner. Real SIHS circuits suffer a variety of energy losses, with throttling of flow during transitions of the high-speed valve resulting in 44% of overall losses. These throttling energy losses can be mitigated by applying the analog of zero-voltage-switching, a soft switching strategy, adopted from power electronics. In the soft switching circuit, the flow that would otherwise be throttled across the transitioning valve is stored in a capacitive element and bypassed through check valves in parallel with the switching valves. To evaluate the effectiveness of soft switching in a boost converter SIHS, a lumped parameter model was constructed. The model demonstrates that soft switching can improve the efficiency of the circuit up to 42% and extend the power delivery capabilities of the circuit by 76%.
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Shinn, Tyler, Richard Carpenter, and Roger C. Fales. "Pump Efficiency Parameter Estimation." In BATH/ASME 2016 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fpmc2016-1765.
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Hydraulic pump health monitoring can give early notice of a catastrophic failure occurring within the pump, saving time and money on repairs. This work focuses on developing a system to monitor an axial piston pump’s volumetric efficiency, using state and parameter estimation techniques. A high order, nonlinear model has been utilized for the axial piston pump. Pressure measurements of the pump are used for a linear Kalman filter (KF) as well as an extended Kalman filter (EKF) to estimate the remaining states of pump model. Volumetric efficiency losses are tracked by the filters via estimation of two flow loss coefficients, low Reynolds and high Reynolds flow loss, which are allowed to vary within the model to track the changes. In a separate analysis, a third parameter, a disturbance torque, was applied to the load and its estimation in a similar process to the flow loss coefficients. Both filters are able to estimate a single flow loss or load. However, the KF was unable to distinguish between two flow losses. The EKF is able to distinguish between low and high Reynolds number flows since it takes into account the nonlinearities in the system including the flow loss characteristics. The EKF shows promise in being able to estimate both flow losses and a load disturbance simultaneously. Both types of filters are found to have fast run times suggesting that the filters could be implemented using typical microcontroller hardware found on industrial and mobile hydraulic machinery.
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Mirnazari, Mir T., and Henning M. Norup. "Air Bags and Their Impact on Collision Insurance Losses." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1999. http://dx.doi.org/10.4271/1999-01-1063.
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Khandekar, Aditya, Jackson Wills, Meng (Rachel) Wang, and Perry Y. Li. "Incorporating Valve Switching Losses Into a Static Optimal Control Algorithm for the Hybrid Hydraulic-Electric Architecture (HHEA)." In ASME/BATH 2021 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fpmc2021-69045.
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Abstract The Hybrid Hydraulic-Electric Architecture (HHEA) has, in recent years, been proposed as an energy efficient alternative to conventional load-sensing architectures in mobile machines such as excavators and wheel-loaders. HHEA leverages the advantages of hydraulic power and electric power to eliminate throttling valves while also improving the energy and control performance of the system. The architecture utilizes a set of common pressure rails to provide a majority of power and and a small electric motor driven pump to modulate this power to meet the exact demand. Previous work has developed a computationally efficient Lagrange Multiplier approach for determining the optimal pressure rail selections that minimizes the energy losses in the system. The static model used considers only the energy use for each pressure rail selection but not the losses associated with the valves during the transition. This paper presents an approach to include the switching losses in the model and in the optimization procedure. To capture the switching losses, switching events between different rails and at various input and output flow rates were simulated with consideration of valve spool dynamics. A parameterized model that summarizes the losses is then obtained, allowing switching losses to be added to the previous energy analysis. The performance of the switching loss model was compared with reference data obtained from a high-fidelity simulation model. To incorporate the switching losses into optimal control algorithm, an efficient dynamic programming approach that prevents frequent switching is adopted in place of the Lagrange multiplier approach. The overall effect of switching losses on the energy consumption and optimal control decisions is presented. In general, switching losses contribute to about 9–10% of input energy.
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Wiens, Travis K. "Analysis and Mitigation of Valve Switching Losses in Switched Inertance Converters." In ASME/BATH 2015 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fpmc2015-9600.
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Switched inertance converters use digital valves to exploit the inertia of a flow in order to trade flow for pressure or vice versa. These components can be used to efficiently match load and supply pressures, avoiding the energy wasted by using resistive valves. While theoretical switched inertance converters can be highly efficient, practical implementations suffer from a number of energy losses. One of these losses is the valve switching loss: the energy wasted due to the flow experiencing a pressure drop across the partially open valve as the digital valve shifts from one position to the other. This paper quantifies the effect of this loss on the valve’s overall performance. Two novel strategies for mitigating this effect are introduced: a shaped inertance tube design and positioning of the tank-flow valve along the length of the inertance tube.
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Achten, Peter, Robin Mommers, Takao Nishiumi, Hubertus Murrenhoff, Nariman Sepehri, Kim Stelson, Jan-Ove Palmberg, and Katharina Schmitz. "Measuring the Losses of Hydrostatic Pumps and Motors: A Critical Review of ISO4409:2007." In ASME/BATH 2019 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/fpmc2019-1615.
Повний текст джерелаАнотація:
Abstract ISO 4409 is the most important international standard for measuring the efficiency of hydraulic pumps and motors, the latest edition being 4409:2007. The standard describes methods for determining the steady-state performance in terms of overall efficiency. It also defines equations for calculating the volumetric efficiency of pumps and motors. The hydro-mechanical efficiency is only defined for motors, not for pumps. This paper analyses the efficiency and losses of pumps and motors in an alternative way. The preference is on loss analysis instead of efficiencies. Especially the effects of the bulk modulus are considered in a different and more inclusive manner. The new methodology results in a higher total loss for motor and a lower total loss for pumps than the current ISO 4409 standard. Furthermore, it results in significant changes of the hydro-mechanical and volumetric losses. The differences between the new methodology and ISO 4409 become larger for high load pressures. The new methodology demands knowledge about the minimum volume of the displacement chamber. The ratio between this volume and the full displacement of a single displacement chamber strongly influences the hydro-mechanical and volumetric losses of the pump or motor. The new methodology is valid for all positive displacement hydrostatic pumps and motors. The volumetric efficiency, as defined in ISO 4409, can still be used as a flow rate factor, but should not be regarded as an energy conversion efficiency. The importance of adopting the proposed methodology is further demonstrated by analyzing and comparing the measurement data about a fixed displacement pump and motor, showing the differences in the loss analysis by means of ISO 4409 and the new equations. The methodology, observations and validation results presented in this paper are significant and can pave the road for improving the current ISO 4409:2007 standard, which would ultimately benefit the industry.
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Pan, Dinghao, and Andrea Vacca. "Total Efficiency Prediction of Crescent-Type Internal Gear Pump Considering Floating Balancing Components." In ASME/BATH 2023 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/fpmc2023-111553.
Повний текст джерелаАнотація:
Abstract This work presents a model-based study of crescent-type internal gear pump total efficiency, the measure between the output and input energy of the machine. The proposed numerical approach couples a lumped parameter simulation of the fluid pressure within the inter-teeth volumes, a CFD simulation of the lubricating interfaces, and a simulation of the micromotions of the pressure-compensating components. This paper’s simulation tool developed in C++ constitutes the software Multics’ simulation core for internal gear pumps. The total efficiency predictions from the model show consistency with the measurements performed on a reference commercial unit. Minor discrepancies can be explained with an underprediction of the contact friction within the lateral films. The study also provides a breakdown of the sources of energy loss within the reference internal gear pump, from where the lateral lubricating films exhibit the most power losses. The ring gear bearing film also presents substantial mechanical losses, and the volumetric losses become increasingly important with a higher temperature.
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Mettakadapa, Shreya, Scott Bair, Shinji Aoki, Masahiro Kobessho, Laura Carter, Hideto Kamimura, and Paul W. Michael. "A Fluid Property Model for Piston Pump Case Drain and Pressure Compensator Flow Losses." In ASME/BATH 2015 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fpmc2015-9515.
Повний текст джерелаАнотація:
This paper describes an investigation into the effects of fluid properties on piston pump flow losses through experimentation and modeling. The case drain and pressure compensator control flow rates of a variable-displacement axial piston pump were measured under a wide range of conditions. Synthetic ester, high bulk modulus, VI-improved and single grade mineral oils were evaluated. The high bulk modulus fluid exhibited 20% lower flow losses than a conventional mineral oil of the same viscosity grade. The modeling effort extended the flow loss analysis of Jeong to account for compensator control of the pump displacement. Comparisons between model predictions and measured flow losses showed good agreement. Stepwise regression analysis of the model parameters disclosed that the compressible flow term had a greater coefficient of determination than the turbulent or laminar flow terms. These findings demonstrate the potential of combining comprehensive fluid analysis with modeling to optimize fluids for the efficient transmission of power.
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Larson, Jacob, Jonatan Pozo-Palacios, Grey Boyce-Erickson, Nathaniel Fulbright, Jaichen Dai, John Voth, Ninaad Gajghate, et al. "Experimental Validation of Subsystem Models for a Novel Variable Displacement Hydraulic Motor." In ASME/BATH 2021 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fpmc2021-68604.
Повний текст джерелаАнотація:
Abstract A novel, variable displacement, low-speed high-torque hydraulic motor is being developed that is expected to be highly efficient across a broad operating range. To ensure the final hardware achieves the expected performance, the models used in the development of the motor must be experimentally validated and revised. The focus of this work is on mechanical energy loss models that were used to guide the design of a single-cylinder motor prototype and then experimental tests used for validation. Losses were modeled and organized into five primary groups: main shaft bearings, main shaft seal, case windage, valve actuation, and linkage losses. The single-cylinder prototype was fabricated, and test parameters were defined. Two test rigs were designed and built to capture losses of the motor experimentally; one was used to collect low torque, zero/low-pressure differential results, and the other used to collect high torque, high-pressure differential results. A staged assembly procedure was developed to capture the independent contributions of each loss. By reviewing the quality of correlation between test observations and model predictions and revising the model when necessary, the models were validated. The correlation was improved by reviewing and modifying model inputs. This allows future solutions to be more accurately predicted in the design phase to drive the design of better machines. The validated model package was able to predict the motor performance within an acceptable range of error.
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Merrill, Kyle J., Farid Y. Breidi, and John Lumkes. "Simulation Based Design and Optimization of Digital Pump/Motors." In ASME/BATH 2013 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fpmc2013-4475.
Повний текст джерелаАнотація:
Current state of the art variable displacement pump/motors have high efficiencies when operating at high displacements. However, as the displacement of the pump/motor is reduced, the efficiency significantly decreases. Digital pump/motors aim to increase the efficiency and range of operation of the fluid power system by minimizing leakages, friction losses and compressibility losses. It is based on the concept of actively controlling high speed on/off valves connected to each piston cylinder displacement chamber. This work involves the development of a coupled dynamic model of a digital hydraulic pump/motor that is crucial for understanding the design tradeoffs and operating characteristics of the digital pump/motor. This simulation model can be used to characterize and predict the efficiency, define the dynamic response and flow requirements of on/off valves required to provide significant improvements in efficiency and dynamic response over traditional pump/motors, and perform design optimization studies. The model can analyze different operating strategies (flow limiting and flow diverting) and characterize the effects on pump/motor efficiency and flow ripple. The simulation analysis shows that the sequential flow limiting strategy yields the lowest power loss in both pumping and motoring and that small variances in the valve response would cause a significant loss of power.
Звіти організацій з теми "Bats – Losses"
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Andrawes, Bassem, Ernesto Perez Claros, and Zige Zhang. Bond Characteristics and Experimental Behavior of Textured Epoxy-coated Rebars Used in Concrete Bridge Decks. Illinois Center for Transportation, January 2022. http://dx.doi.org/10.36501/0197-9191/22-001.
Повний текст джерелаАнотація:
The deterioration of bridge decks is a problem typically associated with the corrosion of the reinforcing steel. This issue was partially controlled during the 1970s with the incorporation of the epoxy-coating protection system. However, research later demonstrated that the smooth surface resulting from the epoxy-coating application reduces most of the friction between the rebar and the surrounding concrete. Consequently, forces acting on the rib faces are reconfigured in such a way that the radial components increase, triggering the early development of cracks. To mitigate both the reduction of bonding and the formation of cracks, the Illinois Department of Transportation proposed a new type of coated bars: textured epoxy-coated (TEC) bars. Over the last few years, different projects have been executed to understand and improve the characteristics of TEC rebars. This report is a continuation of research performed at the University of Illinois Urbana-Champaign to evaluate the bond behavior of TEC bars. The experimental program starts by characterizing, qualitatively and quantitatively, the roughness of the TEC rebars. Next, their bond-slip interaction embedded in concrete is evaluated through pull-out tests. Finite element models of these tests are developed to validate the behavior observed as the textured reinforcement loses anchorage with concrete. Based on these results, the experimental program then aims to study the impact of the drying shrinkage, temperature change, and flexural demands on two large-scale bridge deck specimens reinforced, individually, with TEC and standard epoxy-coated bars. The results collected from both specimens using digital image correlation and strain gauges are compared to explore the differences exhibited by the traditional and the new type of reinforcement coatings in terms of stress distribution in bridge decks. Finally, given the specialized equipment and time-consuming procedure needed to calculate the roughness parameters of TEC bars, an empirical, weight-based approach is developed as a rapid method for assessing the rebars’ roughness on-site.
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Noga, Edward J., Angelo Colorni, Michael G. Levy, and Ramy Avtalion. Importance of Endobiotics in Defense against Protozoan Ectoparasites of Fish. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7586463.bard.
Повний текст джерелаАнотація:
Infectious disease is one of the most serious causes of economic loss in all sectors of aquaculture. There is a critical need to understand the molecular basis for protection against infectious disease so that safer, more reliable and more cost-effective strategies can be designed for their control. As part of this effort, the major goal of our BARD project was to determine the importance of endobiotics as a defense against protozoan ectoparasites in fish. Endobiotics, or antimicrobial polypeptides, are peptides and small proteins that are increasingly recognized as having a vital role in the innate defense of virtually all animals. One objective of our BARD project was to determine the antiparasitic potency of one specific group of endobiotics that were isolated from hybrid striped bass (Morone saxatilis x M chrysops). We found that these endobiotics, which we had previously named histone-like proteins (HLPs), exhibited potent activity against Amyloodinium and that the putative levels of HLPs in the skin were well within the levels that we found to be lethal to the parasite in vitro. We also found evidence for the presence of similar antibiotics in sea bream (Sparus aurata) and Mediterranean sea bass (Dicentrarchus labrax). We also examined the effect of chronic stress on the expression of HLP in fish and found that HLP levels were dramatically decreased after only one week of a crowding/high ammonia sublethal stress. We also began to explore the feasibility of upregulating endobiotics via immunostimulation. However, we did not pursue this objective as fully as we originally intended because we spent a much larger effort than originally anticipated on the last objective, the attempted isolation of novel endobiotics from hybrid striped bass. In this regard, we purified and identified four new peptide endobiotics. These endobiotics, which we have named piscidins (from "Pisces" meaning fish), have potent, broad-spectrum activity against a number of both fish and human pathogens. This includes not only parasites but also bacteria. We also demonstrated that these peptides are present in the mast cell. This was the first time that the mast cell, the most common tissue granulocyte in vertebrates, was shown to possess any type of endobiotic. This finding has important implications in explaining the possible function of mast cells in the immune response of vertebrates. In summary, the research we have accomplished in this BARD project has demonstrated that endobiotics in fish have potent activity against many serious pathogens in aquaculture and that there is considerable potential to use these compounds as stress indicators in aquaculture. There is also considerable potential to use some of these compounds in other areas of medicine, including treatment of serious infectious diseases of humans and animals.
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Poverenov, Elena, Tara McHugh, and Victor Rodov. Waste to Worth: Active antimicrobial and health-beneficial food coating from byproducts of mushroom industry. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600015.bard.
Повний текст джерелаАнотація:
Background. In this proposal we suggest developing a common solution for three seemingly unrelated acute problems: (1) improving sustainability of fast-growing mushroom industry producing worldwide millions of tons of underutilized leftovers; (2) alleviating the epidemic of vitamin D deficiency adversely affecting the public health in both countries and in other regions; (3) reducing spoilage of perishable fruit and vegetable products leading to food wastage. Based on our previous experience we propose utilizing appropriately processed mushroom byproducts as a source of two valuable bioactive materials: antimicrobial and wholesome polysaccharide chitosan and health-strengthening nutrient ergocalciferol⁽ᵛⁱᵗᵃᵐⁱⁿ ᴰ2⁾. ᴬᵈᵈⁱᵗⁱᵒⁿᵃˡ ᵇᵉⁿᵉᶠⁱᵗ ᵒᶠ ᵗʰᵉˢᵉ ᵐᵃᵗᵉʳⁱᵃˡˢ ⁱˢ ᵗʰᵉⁱʳ ᵒʳⁱᵍⁱⁿ ᶠʳᵒᵐ ⁿᵒⁿ⁻ᵃⁿⁱᵐᵃˡ ᶠᵒᵒᵈ⁻ᵍʳᵃᵈᵉ source. We proposed using chitosan and vitamin D as ingredients in active edible coatings on two model foods: highly perishable fresh-cut melon and less perishable health bars. Objectives and work program. The general aim of the project is improving storability, safety and health value of foods by developing and applying a novel active edible coating based on utilization of mushroom industry leftovers. The work plan includes the following tasks: (a) optimizing the UV-B treatment of mushroom leftover stalks to enrich them with vitamin D without compromising chitosan quality - Done; (b) developing effective extraction procedures to yield chitosan and vitamin D from the stalks - Done; (c) utilizing LbL approach to prepare fungal chitosan-based edible coatings with optimal properties - Done; (d) enrichment of the coating matrix with fungal vitamin D utilizing molecular encapsulation and nano-encapsulation approaches - Done, it was found that no encapsulation methods are needed to enrich chitosan matrix with vitamin D; (e) testing the performance of the coating for controlling spoilage of fresh cut melons - Done; (f) testing the performance of the coating for nutritional enhancement and quality preservation of heath bars - Done. Achievements. In this study numerous results were achieved. Mushroom waste, leftover stalks, was treated ʷⁱᵗʰ ᵁⱽ⁻ᴮ ˡⁱᵍʰᵗ ᵃⁿᵈ ᵗʳᵉᵃᵗᵐᵉⁿᵗ ⁱⁿᵈᵘᶜᵉˢ ᵃ ᵛᵉʳʸ ʰⁱᵍʰ ᵃᶜᶜᵘᵐᵘˡᵃᵗⁱᵒⁿ ᵒᶠ ᵛⁱᵗᵃᵐⁱⁿ ᴰ2, ᶠᵃʳ ᵉˣᶜᵉᵉᵈⁱⁿᵍ any other dietary vitamin D source. The straightforward vitamin D extraction procedure and ᵃ ˢⁱᵐᵖˡⁱᶠⁱᵉᵈ ᵃⁿᵃˡʸᵗⁱᶜᵃˡ ᵖʳᵒᵗᵒᶜᵒˡ ᶠᵒʳ ᵗⁱᵐᵉ⁻ᵉᶠᶠⁱᶜⁱᵉⁿᵗ ᵈᵉᵗᵉʳᵐⁱⁿᵃᵗⁱᵒⁿ ᵒᶠ ᵗʰᵉ ᵛⁱᵗᵃᵐⁱⁿ ᴰ2 ᶜᵒⁿᵗᵉⁿᵗ suitable for routine product quality control were developed. Concerning the fungal chitosan extraction, new freeze-thawing protocol was developed, tested on three different mushroom sources and compared to the classic protocol. The new protocol resulted in up to 2-fold increase in the obtained chitosan yield, up to 3-fold increase in its deacetylation degree, high whitening index and good antimicrobial activity. The fungal chitosan films enriched with Vitamin D were prepared and compared to the films based on animal origin chitosan demonstrating similar density, porosity and water vapor permeability. Layer-by-layer chitosan-alginate electrostatic deposition was used to coat fruit bars. The coatings helped to preserve the quality and increase the shelf-life of fruit bars, delaying degradation of ascorbic acid and antioxidant capacity loss as well as reducing bar softening. Microbiological analyses also showed a delay in yeast and fungal growth when compared with single layer coatings of fungal or animal chitosan or alginate. Edible coatings were also applied on fresh-cut melons and provided significant improvement of physiological quality (firmness, weight ˡᵒˢˢ⁾, ᵐⁱᶜʳᵒᵇⁱᵃˡ ˢᵃᶠᵉᵗʸ ⁽ᵇᵃᶜᵗᵉʳⁱᵃ, ᵐᵒˡᵈ, ʸᵉᵃˢᵗ⁾, ⁿᵒʳᵐᵃˡ ʳᵉˢᵖⁱʳᵃᵗⁱᵒⁿ ᵖʳᵒᶜᵉˢˢ ⁽Cᴼ2, ᴼ²⁾ ᵃⁿᵈ ᵈⁱᵈ not cause off-flavor (EtOH). It was also found that the performance of edible coating from fungal stalk leftovers does not concede to the chitosan coatings sourced from animal or good quality mushrooms. Implications. The proposal helped attaining triple benefit: valorization of mushroom industry byproducts; improving public health by fortification of food products with vitamin D from natural non-animal source; and reducing food wastage by using shelf- life-extending antimicrobial edible coatings. New observations with scientific impact were found. The program resulted in 5 research papers. Several effective and straightforward procedures that can be adopted by mushroom growers and food industries were developed. BARD Report - Project 4784
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Bourdeau, J. E., and R. D. Dyer. Regional-scale lake-sediment sampling and analytical protocols with examples from the Geological Survey of Canada. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331911.
Повний текст джерелаАнотація:
Regional-scale lake sediment surveys have been successfully used since the 1970s as a means for reconnaissance geochemical exploration. Lake sediment sampling is typically performed in areas with a lack of streams and an overabundance of small-sized (=5 km across) lakes. Lake sediments are known to have major, minor and trace element concentrations that reflect the local geology. Overall, lake sediment surveys are planned and conducted following four distinct stages: 1) background research, 2) orientation survey, 3) regional survey, and 4) detailed survey. At the Geological Survey of Canada, samples are usually collected from a helicopter with floats. Sample density ranges from 1 sample per 6 - 13 km2. Samples are collected from the centre of the lake using a gravity torpedo sampler which corresponds to a hollow-pipe, butterfly bottom-valved sampler attached by a rope to the helicopter. Collected sediment samples are then placed in labelled bags and left to air dry. Detailed field notes and additional samples (field duplicates), for the purpose of an adequate quality assurance and quality control program, are also taken. Samples are then milled and sent to analytical laboratories for element determination. Commonly used analytical methods include: X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and -mass spectrometry (ICP-MS), instrumental neutron activation analysis (INAA), and/or determination of volatile compounds and organic carbon using Loss on Ignition (LOI). Analytical data is first evaluated for quality (contamination, accuracy and precision). Numerous options for the analysis of lake sediment data exist, ranging from simple basic element concentration maps and statistical graphical displays together with summary statistics, to employing multivariate methodologies, and, more recently, using machine learning algorithms. By adopting the set of guidelines and examples presented in this manual, scientific researchers, exploration geologists, geochemists and citizen scientists will be able to directly compare lake sediment datasets from anywhere in Canada.
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Allegheny woodrat and eastern small-footed bat inventory: White Rocks ? Cumberland Gap National Historical Park. National Park Service, 2024. http://dx.doi.org/10.36967/2302513.
Повний текст джерелаАнотація:
Surveys were conducted for the presence of Allegheny woodrats, eastern small-footed bats, and their habitat within Sample Units surrounding potential climbing routes on the White Rocks cliff of Cumberland Gap National Historical Park. White Rocks is a 200-300ft south facing cliff along the Virginia- Kentucky border that contains the typical habitat requirements of both species: rock ledges, outcrops, or a network of fissures and crevices surrounded by forested habitat. The eastern small-footed bat uses this type of habitat primarily during the summer months for roosting while the Allegheny woodrat is present year-round building nests within deep crevices. The eastern small-footed bat is listed as threatened in Kentucky and both are considered Species of Greatest Conservation Need in Virginia. The rock-climbing community has approached the National Park Service with interest in opening the cliff to recreational climbing. The results of this survey will be used to assess impacts to the species and aid in the studies required for the potential development of a formal climbing management plan. Surveys were conducted from August 24 to September 3, 2021, and included searches of the cliff face via rappelling, ground searches of suitable habitat surrounding the rim and base of the climbing routes, and noninvasive woodrat camera trap and bat acoustic surveys. Suitable eastern small-footed bat and Allegheny woodrat habitat was documented along all eleven potential climbing routes, and results of the acoustic and camera trap surveys confirmed the presence of both species. Surveyors did not observe roosting bats during visual encounter surveys, so we cannot confirm they are roosting along the specific climbing routes. It is likely they are using or could use the habitat at some point given their presence at the site. Surveyors did not observe obvious sign of woodrat presence, perhaps due to the complexity of the cliff habitat, but woodrats were captured at 32 of 37 (86%) camera sites. Video of woodrat activity at sites F3-C3, MF-C3, and CC-C1 confirm that these cameras were placed at crevices actively used by woodrats for caching food. Woodrat activity was captured on the first night at nearly half of the camera sites (40%) and within all Sample Units except SU-4. This suggests that the rim and/or base of most climbing routes are at or near core activity centers. Detection data was fitted to occupancy models to estimate probabilities of site occupancy and detection. Consistent with observations of woodrat activity detection probabilities and na?ve estimates of occupancy indicate woodrats are active at both the rim and base throughout the white rocks area. Design constraints, however, make it difficult to make strong inferences about factors affecting occupancy at the site or to predict occupancy at unsampled areas of the White Rocks cliff. Detection probabilities were high in all Sample Units especially after the first night of detection and were positively associated with habitat. However, these variables had little to do with site occupancy rates and are not very informative for predicting the influence of climbing activities on Allegheny woodrats. Research on the effects of rock climbing to roosting bats and Allegheny woodrats is lacking, but it has the potential to negatively impact these species both directly and indirectly. Directly through disturbance or harm to roosting bats or woodrats during climbing activities and indirectly through degradation of the cliff face and loss of suitable habitat. Whether climbing activities negatively affect the population of either species may depend on the amount of suitable habitat in areas where climbing does not occur and the extent of climbing activities. Suitable habitat does not appear to be a limiting factor at the site and the White Rocks cliff area extends beyond the potential climbing areas. These and other factors such as the presence of other species of concern should be considered when evaluating alternatives to continue climbing closures or consider opening the cliff to recreational climbing with protection measures. Measures that may reduce the impact of climbing activities on these species include additional surveys to determine exact roosting or nesting areas, restrictions on the amount and timing of climbing activities, restrictions on actions that degrade or remove vegetation from the rock surface, and education about the presence of these species at the site.
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Opportunities and drivers for SME agribusinesses to reduce food loss in Africa and Asia. Commercial Agriculture for Smallholders and Agribusiness (CASA), 2023. http://dx.doi.org/10.1079/20240191175.
Повний текст джерелаАнотація:
Climate change, conflict, and the COVID-19 pandemic and its aftermath have caused a sharp increase in food insecurity globally. Reducing food loss - a decrease in the quantity and/or quality of food that takes place from production through to processing - in places where food insecurity is most severe has the potential to be a win-win for food security, climate outcomes, and for commercially driven agribusinesses. This report reviews the common drivers of food loss in sub-Saharan Africa and South Asia, which include inadequate storage, lack of cold chain, and poor post-harvest and distribution practices. It then highlights five technologies or approaches which have the potential to address food loss, and which are appropriate for agricultural small and medium-sized enterprises (agri-SMEs) operating in much of sub-Saharan Africa and South Asia, which face particular challenges (e.g. an unreliable electrical grid and fragmented value chains). Finally, the report highlights the main barriers to adoption and scale for these technologies and approaches, and identifies opportunities for governments, development partners, investors, and technology manufacturers to improve their uptake among agri-SMEs. The five technologies and approaches covered in this report are as follows: Decentralization of processing using solar dryers: The decentralization of primary food processing, in which some portion of value addition is undertaken close to the farm gate by farmers or SMEs, can have multiple benefits, including reducing food loss, lowering transport costs, and increasing rural incomes. Solar drying technology can enable this model, particularly in areas where there is a tradition of sun drying fruits and vegetables and there is a viable domestic or regional market for these products. Successful models typically involve an agribusiness off-taker who works with farmers and SME producers, providing technology and services (e.g., guaranteed off-take, training etc.) that ensure the production of high-quality produce. Hermetic storage (e.g. bags and cocoons): This maturing technology is increasingly available in local markets and represents a potentially easy-to-implement solution which could help to substantially address food loss during storage - where most loss occurs - for key staple grains. Cost and usage remain challenges for smallholders, with greater potential for small- to medium-scale traders and aggregators in rural areas with limited storage infrastructure. By creating a hypoxic environment around the produce, these solutions can achieve 100% insect mortality and reduce the growth of mould and aflatoxins. Bags are more appropriate for agri-SMEs involved in distribution, whereas cocoons (i.e. storage containers consisting of two plastic halves joined together by an airtight zip) are more useful for those storing large volumes for periods of six months or longer. Off-grid cold storage (e.g. solar-powered cold rooms): Innovative technologies and delivery mechanisms are still being tested in markets in India, Nigeria, and Kenya. Despite the high upfront cost, there are several examples of agri-SMEs and co-operatives achieving payback periods of as little as two years across a range of fruit and vegetable value chains, with returns driven by reductions in food loss and improved pricing due to better quality of the produce. Cooling as a service business models also offer the potential to reach smaller agri-SMEs and micro-entrepreneurs operating in informal rural and peri-urban value chains, but their application is limited to high-value crops that are generally out of the reach of the rural poor. Agri-ecommerce platforms: Agri-ecommerce platforms are a well-developed technology that aims to reduce food loss by improving the availability of information on market demand for farmers. Technology providers can also engage in logistics, warehousing, and quality control, taking collection of the produce from rural-based hubs, combining it at a central packing house, and delivering to urban retailers. Models of this kind have scaled more effectively in South Asia than sub-Saharan Africa, where they are constrained by poor road and logistics infrastructure. Waste-to-value approaches: Waste-to-value or circular economy approaches have the potential to reduce food loss by utilizing bruised or damaged fruits and vegetables which are unable to be sold as intended as inputs into other food products. Although the application of these approaches to the production of products such as condiments and oils is popular, they are unlikely to have a material impact on food security. However, models such as using black soldier fly larvae (BSFL) to produce animal feed (after consuming the food waste) are more promising, with a range of related technologies and business models operating in markets in both Africa and Asia. The main barriers to the success and scaling up of these technologies and approaches include a lack of knowledge and awareness of their commercial benefits, a lack of finance for manufacturers and agri-SME customers, a need for further research and development (R&D) and business model innovation (e.g. to bring down cost), and a lack of supportive policies and regulatory frameworks. Policymakers, development partners, investors, and the private sector can all play important roles in addressing these barriers.