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排序方式: 共有1142条查询结果,搜索用时 15 毫秒
1.
The estimation of the link capacity and its available bandwidth in an end-to-end path is crucial for network management, admission
control and flow control for adaptive applications. This paper introduces an estimation mechanism able to accurately estimate
the available bandwidth of all links in an end-to-end path, through its capacity and cross-traffic estimation. The estimation
procedures resort to the dispersions of packet pairs and trains using the concepts of ICMP Timestamp and Traceroute that,
efficiently used together, enable the measurement of the dispersions in all links in the path. These mechanisms were evaluated
through simulation experiments, where we analyzed the influence of the several network parameters on each estimation mechanism.
The results show that these estimation methods are able to accurately estimate both the capacity and the cross-traffic of
all links in a path with moderate length and with low overhead. 相似文献
2.
Atmospheric corrosion of reference metals in Antarctic sites 总被引:1,自引:0,他引:1
Manuel Morcillo Beln Chico Daniel de la Fuente Elisabete Almeida Günter Joseph Susana Rivero Blanca Rosales 《Cold Regions Science and Technology》2004,40(3):165-178
This paper presents the results obtained at three Antarctic test sites participating in the “Ibero-American Map of Atmospheric Corrosiveness” (MICAT), a project on atmospheric corrosion carried out during the period 1988–1994 at some 70 sites distributed across 12 countries of the Latin-American region, Spain and Portugal. The three Antarctic sites are located near the coastline.The singular climatic characteristics of Antarctic regions are related with the purity of the air, the absence of rainfall and the formation of ice on the metallic surface during an important part of the exposure time. However, electrochemical activity is possible below ice layers. This situation affects the structure and morphology of corrosion product films and the resulting corrosion rates of metallic surfaces. 相似文献
3.
Gonzalo Martínez‐Barrera Enrique Vigueras‐Santiago Susana Hernndez‐Lpez Gonzalo Martínez‐Barrera Witold Brostow Carmina Menchaca‐Campos 《Polymer Engineering and Science》2005,45(10):1426-1431
Fiber reinforced concrete (FRC) contains fibers physically mixed with gravel, sand, cement, and water. So far, adequate mechanical performance of FRC has been obtained at high cost and using complex technologies; important here is the geometry and surface characteristics of the polymers. We have modified polymeric‐fiber surfaces by using gamma radiation. Irradiated polypropylene (PP) fibers were submitted to 0, 5, 10, 50, and 100 kGy of gamma irradiation dosages. First, tensile strength of PP fibers was evaluated, and then fibers blended at 0, 1.0, 1.5, and 2.0% in volume with Portland cement, gravel, sand, and water. The highest values of compressive strength were obtained with irradiated‐fibers at 10 kGy and 1.5% in volume of fiber. The result is 101 MPa, as compared to 35 MPa for simple concrete without fibers. POLYM. ENG. SCI., 45:1426–1431, 2005. © 2005 Society of Plastics Engineers 相似文献
4.
Bosacchi A. Franchi S. Gombia E. Mosca R. Fantini F. Menozzi R. 《Electronics letters》1993,29(8):651-653
Outstanding stability has been observed in Al/Al/sub x/Ga/sub 1-x/As and Al/GaAs/Al/sub x/Ga/sub 1-x/As (x=0.25) Schottky barriers prepared by depositing Al in situ by MBE on annealing up to 400 degrees C. Conventionally evaporated barriers have been fabricated and compared with epitaxial ones. The changes in barrier height and ideality factor induced by annealing are reported.<> 相似文献
5.
Do individual factors matter? A survey of scientists’ patenting in Portuguese public research organisations 总被引:1,自引:0,他引:1
Paula Susana Figueiredo Moutinho Margarida Fontes Manuel Mira Godinho 《Scientometrics》2007,70(2):355-377
This paper addresses scientists’ behaviour regarding the patenting of knowledge produced in universities and other public
sector research organisations (PSROs). Recent years have witnessed a rapid growth in patenting and licensing activities by
PSROs. We argue that the whole process depends to a certain extent on scientists’ willingness to disclose their inventions.
Given this assumption, we conduct research into individual behaviour in order to understand scientists’ views concerning the
patenting of their research results. Data from a questionnaire survey of Portuguese researchers from nine PSROs in life sciences
and biotechnology is presented and analysed and complemented with in-depth interviews. The results reveal that overall the
scientists surveyed show a low propensity to become involved in patenting and licensing activities, despite the fact that
the majority had no “ethical” objections to the disclosure of their inventions and the commercial exploitation of these. Perceptions
about the impacts of these activities on certain fundamental aspects of knowledge production and dissemination are however
divergent. This may account for the low participation levels. Furthermore, most scientists perceived the personal benefits
deriving from this type of activity to be low. Similarly, the majority also believed that there are many difficulties associated
with the patenting process and that they receive limited support from their organisations, which lack the proper competences
and structures to assist with patenting and licensing. 相似文献
6.
Susana Criado Norman A. García Maria I. Gutirrez Vicente Avila Sonia G. Bertolotti Rio Cuarto 《European Journal of Lipid Science and Technology》1996,98(5):172-175
The ability of mono-, di-, tri-and tetra-hydroxyflavones (7-and 3-hy-droxyflavones, 7, 8-dihydroxyflavone, baicalein and fisetin) to act as photoprotectors against singlet molecular oxygen [O2(Δg)]-initiated photooxidation of fats has been established by a kinetic study. The overall quenching rate constants for a series of five hydroxyflavones perfectly parallel their respective behaviour as inhibitors of the sensitized photooxidation of linoleic acid. The best antioxidative effect was exerted by 7-hydroxyflavone which does not chemically react with O2(1Δg). Nevertheless for the remaining flavonoids of the series, the physical deactivation of O2(1Δg) largely prevails over the chemical process. As for the cases of phenols and related hydroxy-aromatic derivatives, the ionization of the -OH group in the flavones, dramatically accelerates the rate of photooxidation. Under these conditions, the 7-hydroxyflavone also reacts effectively with O2(1Δg). Given that flavonoids are natural oil components, this medium effect should be taken into account during the oil-refining process, in order to avoid the flavonoid photodestruction. 相似文献
7.
The paper deals with I/O versions of receding horizon controllers based on the minimization of multistep quadratic costs with the constraint that the terminal state goes to zero. The resulting control law yields stable closed-loop systems under sharp conditions. Simulation results are presented to both verify the theoretical analysis and relate the new control law with GPC 相似文献
8.
P Casolo D Mosca C Amorotti B Drei A Raspadori P Di Blasio E Ganz G De Luca G Colli R De Maria D Amuso 《Canadian Metallurgical Quarterly》1997,68(2):207-11; discussion 212
Primary and sole breast lymphoma is a very rare disease. With the review of our series of 616 cases operated on for breast cancer, only 3 cases (0.48%) of primary breast non-Hodgkin lymphoma (LNH) have been observed. The authors outline the problems concerning diagnosis and therapy of this rare disease: pathological and immunohistochemical aspects are discussed. They stress the importance of staging in order to plan a correct multidisciplinary approach. 相似文献
9.
F Mosca 《Canadian Metallurgical Quarterly》1994,14(5):525-533
Vestibular disorders may be treated by means of drugs, surgical tools or rehabilitation. Cervical electrostimulation may be regarded as physical therapy and its activity is connected to neural pathways between cervical receptors and vestibular nuclei. In present study electrodes were placed lateral to cervical column on the opposite side of vestibular deficit as pointed by electronystagmography; stimulus duration was 18 msec and frequency 100 Hz. Every stimulation lasts for 30 minutes and were repeated twice a week for a total number of 10. The ability to adjust vestibulo-ocular reflex was evaluated by means of a Compensatory Index. The following materials were enrolled in the study: 20 normal subjects were observed before and after a cycle of stimulations: 24 patients suffering from acute labyrinthitis or neuritis, 48 cervical vertigo, 8 cervical traumatic injures and 3 patients operated for acoustical neuroma. All these groups were coupled with control groups composed of the same pathology and the same number of subjects. Statistical treatment of reports was evaluated by t-student test before therapy after one month and after 3 months. Results point out good effects of electrostimulation on vestibulo-ocular reflex compensation, especially in cervical vertigo and labyrinthitis or neuritis with respect to control groups. No important results were obtained in neuroma group and in normal subjects. Electrostimulation may act on vestibular nuclei by direct spino-vestibular pathway but also by repeated decompensations mainly mediated via the cerebellum or spino-reticular connections. 相似文献
10.
Julia Peas-Martínez María N. Barrachina Ernesto Jos Cuenca-Zamora Gins Luengo-Gil Susana Beln Bravo Eva Caparrs-Prez Raúl Teruel-Montoya Jos Eliseo-Blanco Vicente Vicente ngel García Irene Martínez-Martínez Francisca Ferrer-Marín 《International journal of molecular sciences》2021,22(4)
Exosomes are extracellular vesicles that contain nucleic acids, lipids and metabolites, and play a critical role in health and disease as mediators of intercellular communication. The majority of extracellular vesicles in the blood are platelet-derived. Compared to adults, neonatal platelets are hyporeactive and show impaired granule release, associated with defects in Soluble N-ethylmaleimide-sensitive fusion Attachment protein REceptor (SNARE) proteins. Since these proteins participate in biogenesis of exosomes, we investigated the potential differences between newborn and adult plasma-derived exosomes. Plasma-derived exosomes were isolated by ultracentrifugation of umbilical cord blood from full-term neonates or peripheral blood from adults. Exosome characterization included size determination by transmission electron microscopy and quantitative proteomic analysis. Plasma-derived exosomes from neonates were significantly smaller and contained 65% less protein than those from adults. Remarkably, 131 proteins were found to be differentially expressed, 83 overexpressed and 48 underexpressed in neonatal (vs. adult) exosomes. Whereas the upregulated proteins in plasma exosomes from neonates are associated with platelet activation, coagulation and granule secretion, most of the underexpressed proteins are immunoglobulins. This is the first study showing that exosome size and content change with age. Our findings may contribute to elucidating the potential “developmental hemostatic mismatch risk” associated with transfusions containing plasma exosomes from adults. 相似文献