检索结果-南通市图书馆

Output feedback adaptive super twisting sliding mode control for quadrotor UAVs

在线全文

学校读者我要写书评

暂无评论

Control Theory and Technology 2024年第1期22卷 92-105页

作者： Oscar Salas-Peña Jesus DeLeón-Morales Susana V.gutiérrez-Martínez École Centrale de Nantes-LS2N UMR 6004 CNRS44300NantesFrance Facultad de Ingeniería Mecánica y Eléctrica Universidad Autónoma de Nuevo León66451San Nicolás de Los GarzaMexico

In this paper, a sliding mode control with adaptive gain combined with a high-order sliding mode observer to solve the tracking problem for a quadrotor UAV is addressed, in presence of bounded external disturbances and parametric uncertainties. The high order sliding mode observer is designed for estimating the linear and angular speed in order to implement the proposed scheme. Furthermore, a Lyapunov function is introduced to design the controller with the adaptation law, whereas an analysis of finite time convergence towards to zero is provided, where sufficient conditions are obtained. Regarding previous works from literature, one important advantage of proposed strategy is that the gains of control are parameterized in terms of only one adaptive parameter, which reduces the control effort by avoiding gain overestimation. Numerical simulations for tracking control of the quadrotor are given to show the performance of proposed adaptive control–observer scheme.

关键词： Adaptive super twisting controller High-order sliding modes observer UAV

Experimental and computational study of smoke dynamics from multiple fire sources inside a large-volume building

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Building Simulation 2021年第4期14卷 1147-1161页

作者： Gabriele Vigne Wojciech Węgrzyński Alexis Cantizano Pablo Ayala Guillermo Rein Cándido gutiérrez-Montes Fluid Dynamics Division of the Department of Mining and Mechanical Engineering Universidad de JaénJaénSpain Institute for Research in Technology ICAIUniversidad Pontificia ComillasMadridSpain Building Research Institute(ITB) WarsawPoland Imperial College London LondonUK JVVA Fire&Risk MadridSpain

Fire in large-volume buildings poses separate and distinct challenges from compartmented *** particular,the risk it poses on life safety is mostly due to the smoke it produces,its effects on the evacuation process,and how it can affect the firefighters when they approach the building to fight the fire and rescue the *** is why smoke control in large-volume enclosures is of utter importance for life safety,property protection and business *** research presents an experimental and numerical study of the smoke dynamics from four fire sources(combined heat release rate of 5.2 MW)with different ignition times and under transient ventilation conditions,inside a 20 m high cubic *** measurements in the plume and close to the walls have been recorded using 59 *** data was used in the determination of the smoke layer interface height,with the least-square and the N-Percent *** show that significantly worse conditions are induced by multiple sources than those in a single fire of equal *** results have been obtained using the computational fluid dynamics code FDS(Fire Dynamics Simulator,v6.7.1).The comparison shows that in the far field the temperature predictions are accurate inside the smoke layer(10 m and 15 m)with discrepancies lower than 10%,whereas higher significant discrepancies were observed at the smoke layer interface,i.e.5 m high,with discrepancies up to 20%.Furthermore,a grid analysis has been performed showing that grid resolutions,D*/δ,based on the global HRR of the fire might be sufficient to predict the fire induced conditions far from the *** analysis confirmed the applicability of FDS to the assessment of the smoke dynamics under complex fire conditions away from ***,the present work shows the importance of considering fires with multiple sources due to the faster smoke production compared with single fires.

关键词： experiments simulation fire buildings FDS CFD

The reaction electronic flux in chemical reactions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第12期54卷 1982-1988页

作者： CERON María Luisa ECHEGARAY Eleonora gutirrez-OLIVA Soledad HERRERA Barbara TORO-LABB Alejandro Laboratorio de Química Teorica Computacional(QTC) Facultad de Química Pontificia Universidad Catolica de Chile

The mechanism of a chemical reaction can be characterized in terms of chemical events that take place during the *** events are bond weakening/breaking and/or bond strengthening/*** reaction electronic flux(REF),a concept that identifies and rationalizes the electronic activity taking place along the reaction coordinate,has emerged recently as a powerful tool for characterizing the mechanism of chemical reactions.A quantitative theory introducing new descriptors for characterizing reaction mechanisms is presented in detail and three illustrative examples are *** nucleophilic substitution reactions the REF indicates that bond breaking or forming events may be leading the electronic activity whereas in the methanol decomposition reaction by copper oxide,the REF allows to discover that consecutive electronic reductions of copper together with bond breaking processes control the course of the reaction.

关键词： reaction mechanisms chemical potential conceptual DFT reaction electronic flux (REF)

A review of feed efficiency in swine:biology and application

在线全文

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2015年第4期6卷 369-377页

作者： John F.Patience Mariana C.Rossoni-Seräo Nestor A.gutiérrez Department of Animal Science Iowa State University

Feed efficiency represents the cumulative efficiency with which the pig utilizes dietary nutrients for maintenance, lean gain and lipid accretion. It is closely linked with energy metabolism, as the oxidation of carbon-containing components in the feed drive all metabolic processes. While much is known about nutrient utilization and tissue metabolism, blending these subjects into a discussion on feed efficiency has proven to be difficult. For example, while increasing dietary energy concentration will almost certainly increase feed efficiency, the correlation between dietary energy concentration and feed efficiency is surprisingly low. This is likely due to the plethora of non-dietary factors that impact feed efficiency, such as the environment and health as well as individual variation in maintenance requirements, body composition and body weight. Nonetheless, a deeper understanding of feed efficiency is critical at many levels. To individual farms, it impacts profitability. To the pork industry, it represents its competitive position against other protein sources. To food economists, it means less demand on global feed resources. There are environmental and other societal implications as well. Interestingly, feed efficiency is not always reported simply as a ratio of body weight gain to feed consumed. This review will explain why this arithmetic calculation, as simple as it initially seems, and as universally applied as it is in science and commerce, can often be misleading due to errors inherent in recording of both weight gain and feed intake. This review discusses the importance of feed efficiency, the manner in which it can be measured and reported, its basis in biology and approaches to its improvement. It concludes with a summary of findings and recommendations for future efforts.

关键词： Caloric efficiency Energy Feed efficiency Residual feed intake Swine

Targeting harmful effects of non-excitatory amino acids as an alternative therapeutic strategy to reduce ischemic damage

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第9期20卷 2454-2463页

作者： Victoria Jiménez Carretero IrisÁlvarez-Merz jorge Hernández-Campano Sergei A.Kirov Jesús M.Hernández-Guijo Department of Pharmacology and Therapeutic School of MedicineUniv.Autónoma de MadridMadridSpain Ramón y Cajal Institute for Health Research(IRYCIS) Neurobiology-Research ServiceHospital Ramón y CajalMadridSpain Institute of Neurobiology Faculty of Mathematics and Natural SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany Department of Neuroscience and Regenerative Medicine&Department of Neurosurgery Medical College of Georgia at Augusta UniversityAugustaGAUSA

The involvement of the excitatory amino acids glutamate and aspartate in ce rebral ischemia and excitotoxicity is ***,the role of non-excitatory amino acids in brain damage following a stroke or brain trauma remains largely *** release of amino acids by necrotic cells in the ischemic core may contribute to the expansion of the *** findings indicated that the reversible loss of field excitato ry postsynaptic potentials caused by transient hypoxia became irreversible when exposed to a mixture of just four non-excitatory amino acids(L-alanine,glycine,L-glutamine,and L-serine)at their plasma *** amino acids induce swelling in the somas of neurons and astrocytes during hypoxia,along with permanent dendritic damage mediated by N-methyl-D-aspartate *** N-methyl-D-aspartate receptors prevented neuronal damage in the presence of these amino acids during *** is likely that astroglial swelling caused by the accumulation of these amino acids via the alanine-serine-cysteine transporter 2 exchanger and system N transporters activates volume-regulated anion channels,leading to the release of excitotoxins and subsequent neuronal damage through N-methyl-D-aspartate receptor ***,previously unrecognized mechanisms involving non-excitatory amino acids may contribute to the progression and expansion of brain injury in neurological emergencies such as stroke and traumatic brain *** these pathways co uld highlight new therapeutic targets to mitigate brain injury.

关键词： cell swelling N-methyl-D-aspartate receptor non-excitatory amino acids stroke synaptic transmission

Natural compounds and extracts from Mexican medicinal plants with anti-leishmaniasis activity: An update

在线全文

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Medicine 2017年第12期10卷 1105-1110页

作者： Gabriel Alfonso gutiérrez-Rebolledo Susan Drier-Jonas María Adelina Jiménez-Arellanes Unidad de Investigación Médica en Farmacología Hospital de EspecialidadesCentro Médico Nacional Siglo XXIInstituto Mexicano del Seguro SocialAv. Cuauhtémoc 330Col. DoctoresDelg. Cuauhtémoc06720 Ciudad de MéxicoMexico

Leishmaniasis is considered as an emerging, uncontrolled disease and is endemic in 98 countries. Annually, about 2 million cases of cutaneous and 500000 cases of visceraltype leishmaniasis are recorded and 60000 persons died from the disease. In Mexico,cutaneous leishmaniasis is known as chiclero's ulcer and is reported in 22 states, it is considered as a health problem. For its treatment, pentavalent antimonial drugs are administered. These drugs cause severe side effects, are costly. Drug-resistant cases have been reported and have been developing for over 70 years. One alternative to the drugs that are currently available is to find active molecules in medicinal plants. Dihydrocorynantheine, corynantheine and corynantheidine are active against Leishmania major,while harmane, pleiocarpin, buchtienin, luteolin and quercetin are active against Leishmania donovani. In Mexico, about 20 medicinal plants have been evaluated against Leishmania mexicana, among which the most active are Tridax procumbens, Lonchocarpus xuul and Pentalinon andrieuxii. From these plants, active compounds with IC_(50)≤30 mg/mL or m M have been isolated, such as 3(S)-16,17-didehydrofalcarinol or Oxylipin, cholestra-4,20,24-trien-3-one or pentalinosterol, 24-methylcholest-4-24(28)-dien-3-one, cholest-4-en-3-one, 6,7-dihydroneridie-none, neridienone, cholest-5,20,24-trien-3β-ol, and isocordoin. Today, only pentalinonsterol has been synthesized and assayed in the visceral leishmaniasis experimental model using BALB/c mice infected with Leishmania donovani. Liposome formulation of this compound administered by intravenous route at 2.5 mg/kg showed a significant reduction of parasite load in mouse liver and spleen.

关键词： Active extracts Leishmaniasis Antileishmanicidal activity Natural compounds Mexican medicinal plants

MgO-based adsorbents for CO2 adsorption:Influence of structural and textural properties on the CO_2 adsorption performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2017年第7期29卷 418-428页

作者： gutiérrez-Bonilla Elvira Granados-Correa Francisco Sánchez-Mendieta Víctor Morales-Luckie Raúl Alberto National Institute of Nuclear Research Department of ChemistryA.P.18-1027Col.EscandonMigud Hidalgo DelegationZip Code 1180 Mexico D.F.Mexico Autonomous University of Mexieo State Faculty of ChemistryColon avenueintersection with ride Tollocan s/n TolucaMexicoMexico

A series of MgO-based adsorbents were prepared through solution–combustion synthesis and ball-milling *** prepared MgO-based powders were characterized using X-ray diffraction,scanning electron microscopy,N_2 physisorption measurements,and employed as potential adsorbents for CO_2 *** influence of structural and textural properties of these adsorbents over the CO_2 adsorption behaviour was also *** results showed that MgO-based products prepared by solution–combustion and ball-milling processes,were highly porous,fluffy,nanocrystalline structures in nature,which are unique physico-chemical properties that significantly contribute to enhance their CO_2 *** was found that the MgO synthesized by solution combustion process,using a molar ratio of urea to magnesium nitrate（2：1）,and treated by ball-milling during 2.5 hr（MgO-BM2.5h）,exhibited the maximum CO_2 adsorption capacity of 1.611 mmol/g at 25℃ and 1 atm,mainly via *** CO_2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area,total pore volume,pore size distribution and *** reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO_2adsorption–desorption times,without any significant loss of performance,that supports the potential of MgO-based *** results confirmed that the special features of MgO prepared by solution–combustion and treated by ball-milling during 2.5 hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO_2 capture technologies.

关键词： CO_2 adsorption MgO-based adsorbents Porous materials Solution–combustion synthesis Ball-milling process Textural properties

Classification of anemia for gastroenterologists

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2009年第37期15卷 4627-4637页

作者： Jose Antonio Moreno Chulilla Maria Soledad Romero Colás Martín gutiérrez Martín Department of Hematology University Hospital "Lozano Blesa" University of Zaragoza C/San Juan Bosco 15 Zaragoza 50009 Spain

Most anemia is related to the digestive system by dietary deficiency, malabsorption, or chronic bleeding. We review the World Health Organization definition of anemia, its morphological classifi cation (microcytic, macrocytic and normocytic) and pathogenic classi-fication (regenerative and hypo regenerative), and integration of these classifications. Interpretation of laboratory tests is included, from the simplest (blood count, routine biochemistry) to the more specific (iron metabolism, vitamin B12, folic acid, reticulocytes, erythropoietin, bone marrow examination and Schilling test). In the text and various algorithms, we propose a hierarchical and logical way to reach a diagnosis as quickly as possible, by properly managing the medical interview, physical examination, appropriate laboratory tests, bone marrow examination, and other comple-mentary tests. The prevalence is emphasized in all sections so that the gastroenterologist can direct the diagnosis to the most common diseases, although the tables also include rare diseases. Digestive diseases potentially causing anemia have been studied in preference, but other causes of anemia have been included in the text and tables. Primitive hematological diseases that cause anemia are only listed, but are not discussed in depth. The last section is dedicated to simplifying all items discussed above, using practical rules to guide diagnosis and medical care with the greatest economy of resources and time.

关键词： Anemia Microcytic anemia Iron Deficiency diseases Macrocytic anemia Normocytic anemia

Endoscopic techniques for the diagnosis of pancreatic cystic lesions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2025年第1期31卷 1-7页

作者： Sahib Singh Saurabh Chandan Rakesh Vinayek Jahnvi Dhar Jayanta Samanta Gabriele Capurso Ivo Boskoski Cristiano Spada jorge D Machicado Stefano Francesco Crinò Antonio Facciorusso Department of Internal Medicine Sinai HospitalBaltimoreMD 21215United States Division of Gastroenterology and Hepatology Creighton University School of MedicineOmahaNE 68131United States Department of Gastroenterology Sinai Hospital of BaltimoreBaltimoreMD 21215United States Department of Gastroenterology Postgraduate Institute of Medical Education and ResearchChandigarh 160012India Division of Pancreato-Biliary Endoscopy and Endosonography Pancreas Translational and Clinical Research CenterIRCCS San Raffaele Scientific InstituteVita-Salute San Raffaele UniversityMilano 20132Italy Digestive Endoscopy Unit Fondazione Policlinico Universitario Agostino Gemelli IRCSSUniversitàCattolica del Sacro Cuore di RomaCenter for Endoscopic Research Therapeutics and TrainingRoma 00168Italy Department of Gastroenterology and Endoscopy Catholic UniversityRoma 00168Italy Department of Gastroenterology University of Michigan HealthAnn ArborMI 48107United States Department of Endoscopy University of VeronaVerona 37121VenetoItaly Gastroenterology Unit Department of Medical and Surgical SciencesUniversity of FoggiaFoggia 71122Italy

Pancreatic cysts are mostly incidental findings on computed tomography or magnetic resonance imaging scans,with few patients presenting with abdominal pain or other *** accurate diagnosis of cysts is important as management depends on the type(neoplastic or non-neoplastic).Cross-sectional imaging is fast being replaced with endoscopic ultrasound(EUS)and various techniques based on that such as EUS-guided fine needle aspiration,EUS-guided needle confocal laser endomicroscopy,EUS-through-the-needle biopsy,and contrast-enhanced *** studies have reported varying diagnostic and adverse event rates with these *** addition,American,European,and Kyoto guidelines for the diagnosis and management of pancreatic cysts have provided different *** this editorial,we elaborate on the clinical guidelines,recent studies,and comparison of different endoscopic methods for the diagnosis of pancreatic cysts.

关键词： Endoscopic ultrasound Fine needle aspiration Needle confocal laser endomicroscopy Through-the-needle biopsy Contrast-enhanced endoscopic ultrasound