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排序方式: 共有275条查询结果,搜索用时 15 毫秒
11.
A technique to segment pores from a normal backscattered electron (BSE) image of cement-based materials is presented. The upper threshold grey level for porosity is determined from the inflection point of the cumulative brightness histogram of the BSE image. This represents a critical point where a small incremental grey value will cause a sudden increase in thresholded area, a condition termed as overflow. The proposed technique was found to be more consistent and reliable than existing methods. Significantly fewer images are required to achieve a satisfactory level of statistical confidence for quantifying porosity. 相似文献
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Maguelonne Déjeant-Pons Head of the Spatial Planning Landscape Division 《Landscape Research》2013,38(4):363-384
Adopted in Florence (Italy) on 20 October 2000, the European Landscape Convention is aimed at promoting the protection, management and planning of European landscapes and organising European cooperation on landscape issues. It is the first international treaty to be exclusively concerned with all dimensions of European landscape. It applies to the entire territory of the Parties and relates to natural, urban and peri-urban areas, whether on land, water or sea. It therefore concerns not just remarkable landscapes but also ordinary everyday landscapes and blighted areas. The Convention represents an important contribution to the implementation of the objectives of the Council of Europe: these seek to protect Europeans' quality of life and well-being, taking into account landscape, cultural and natural values. The member states of the Council of Europe signatory to the European Landscape Convention declared their concern to achieve sustainable development based on a balanced and harmonious relationship between social needs, economic activity and the environment. The cultural dimension is also of fundamental importance. 相似文献
14.
DN Maiorov ER Wilton E Badoer D Petrie GA Head SC Malpas 《Canadian Metallurgical Quarterly》1999,815(2):227-236
OBJECT: This study is a retrospective analysis of clinical data obtained in 28 patients affected by obstructive hydrocephalus who presented with signs of midbrain dysfunction during episodes of shunt malfunction. METHODS: All patients presented with an upward gaze palsy, sometimes associated with other signs of oculomotor dysfunction. In seven cases the ocular signs remained isolated and resolved rapidly after shunt revision. In 21 cases the ocular signs were variably associated with other clinical manifestations such as pyramidal and extrapyramidal deficits, memory disturbances, mutism, or alterations in consciousness. Resolution of these symptoms after shunt revision was usually slow. In four cases a transient paradoxical aggravation was observed at the time of shunt revision. In 11 cases ventriculocistemostomy allowed resolution of the symptoms and withdrawal of the shunt. Simultaneous supratentorial and infratentorial intracranial pressure recordings performed in seven of the patients showed a pressure gradient between the supratentorial and infratentorial compartments, with a higher supratentorial pressure before shunt revision. Inversion of this pressure gradient was observed after shunt revision and resolution of the gradient was observed in one case after third ventriculostomy. In six recent cases, a focal midbrain hyperintensity was evidenced on T2-weighted magnetic resonance imaging sequences at the time of shunt malfunction. This rapidly resolved after the patient underwent third ventriculostomy. CONCLUSIONS: It is probable that in obstructive hydrocephalus, at the time of shunt malfunction, the development of a transtentorial pressure gradient could initially induce a functional impairment of the upper midbrain, inducing upward gaze palsy. The persistence of the gradient could lead to a global dysfunction of the upper midbrain. Third ventriculostomy contributes to equalization of cerebrospinal fluid pressure across the tentorium by restoring free communication between the infratentorial and supratentorial compartments, resulting in resolution of the patient's clinical symptoms. 相似文献
15.
A.J. Howard Chairman Head of Tunnels ITA Working Group on Maintenance Repair of Underground Structures 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》1991,6(4)
The International Tunneling Association's Working Group on Maintenance and Repair of Underground Structures is preparing a report dealing with non-destructive methods of inspecting and testing tunnel linings. This request for information details the scope of the group's work and the types of information the group is seeking at this time. 相似文献
16.
OBJECTIVES: Beta2-integrin (CD11b/CD18) expression, an indicator of neutrophil activation, has been associated with the development of acute respiratory distress syndrome. Leumedins act directly on leukocytes to inhibit the up-regulated expression of beta2-integrins involved in leukocyte adhesion. We examined the effect of such a new anti-inflammatory agent, NPC 15669 (N-[9H-(2,7-dimethylfluorenyl-9-methoxy)-carbonyl]-L-leucine), on neutrophil-mediated acute lung injury in an animal model. DESIGN: Prospective, randomized, blinded, controlled animal study. SETTING: An animal laboratory in a university setting. SUBJECTS: Adult New Zealand rabbits. INTERVENTIONS: After repeated lung lavages with normal saline to induce acute lung injury, anesthetized rabbits were randomly assigned to one of two groups (n = 6 per group): a) treatment group (pretreated with NPC 15669 [10 mg/kg i.v. bolus] 30 mins before lavage, followed by a continuous infusion [5 mg/kg/hr] for the duration [4 hrs] of the experiment); or b) control group (pretreatment and continuous infusion with placebo). All animals were mechanically ventilated with identical pressure settings over 4 hrs and were killed at the end of the experiment. MEASUREMENTS AND MAIN RESULTS: PaO2, PaCO2, and tidal volumes were repeatedly measured and airway pressure settings were noted every 30 mins. At the end of the experiment, lungs were taken out for measurements of the myeloperoxidase content, for conventional histology (hematoxylin and eosin staining), and for intracellular adhesion molecule-1 immunohistostaining. Pretreatment with NPC 15669 profoundly improved oxygenation from a PaO2 of 52 +/- 5 torr (6.9 +/- 0.7 kPa) to 250 +/- 161 torr (33.3 +/- 21.5 kPa) within 60 mins after lung lavage (p < .05). Oxygenation continued to improve throughout the study, reaching a maximal PaO2 value of 395 +/- 98 torr (52.7 +/- 13.1 kPa) at 4 hrs. In the control group, oxygenation remained poor throughout the observation period. PaO2 values differed significantly (51 +/- 20 torr [6.8 +/- 2.7 kPa] vs. 306 +/- 126 torr [40.8 +/- 16.8 kPa], p < .005) at 90 mins and at all subsequent measurements from those values in the NPC 15669 group. Dynamic lung compliance improved significantly 60 to 90 mins after repeated lung lavage. Histology demonstrated markedly less lung damage (hyaline membrane formation and leukocyte infiltration) in treated animals (p < .05) than in controls. CONCLUSIONS: NPC 15669 seems to block inflammatory reactions by inhibiting the sequestration of neutrophils in acute, ventilator-associated lung injury. As a result, gas exchange and total lung compliance improve. Application of this and similar compounds affecting neutrophil adhesion warrants further investigation as a treatment modality for acute lung injury. 相似文献
17.
Hounsell N.B. Shrestha B.P. McLeod F.N. Palmer S. Bowen T. Head J.R. 《Intelligent Transport Systems, IET》2007,1(2):131-137
London's bus network is one of the largest and most comprehensive urban transport systems in the world. The contribution of buses is recognised by implementing a series of initiatives including bus priority at traffic signals. London has a long history of the implementation of bus priority at traffic signals. It has kept pace with the development of new technologies by updating its bus priority system. Now, London is moving towards a bus management system based on global positioning system (GPS), which will also be used to provide bus priority at traffic signals. The authors describe theoretical work carried out by TRG on behalf of Transport for London Bus Priority Team to tackle the challenge posed by locational error associated with GPS where a traffic signal is close to a bus stop 相似文献
18.
Hounsell N.B. Shrestha B.P. Head J.R. Palmer S. Bowen T. 《Intelligent Transport Systems, IET》2008,2(3):193-200
London has a long history of successful schemes for bus priority at traffic signals. Recently, transport for London (TfL) has procured a modern automatic vehicle location (AVL) system for bus fleet management, passenger information and bus priority. The new system is known as iBUS and is based on Global Positioning System (GPS) and supporting technologies for bus location. The system eliminates the need for on-street hardware for detecting buses and provides more flexibility and opportunity for using bus detectors. However, bus location based on this system is less accurate than location based on fixed infrastructure (e.g. beacons) and could result in reduced benefits from bus priority. This paper first summarises how bus priority at traffic signals works within iBUS, and then explores the effects of GPS locational errors on bus priority benefits. This is followed by a discussion of opportunities available in the context of iBUS to build an even more efficient and beneficial bus priority system by taking advantage of its cost-effective multiple detection capabilities. The paper is based on various studies carried out by the Transportation Research Group (TRG) at the University of Southampton for TfL. 相似文献
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20.
E. Renaot Y. Hermier M. H. Valin G. Bonnier F. Adunka A. Van Der Linden M. Dobre M. Šmíd A. Bronnum T. Weckstrom E. Tegeler U. Noatsch M. Anagnostou E. Turzo-Andras S. Nemeth M. White P. Marcarino P. Steur A. Pauzha V. Augevicius M. de Groot J. Nielsen F. Helgesen W. Roszkowski E. Grudniewicz R. Kuna E. Filipe I. Lobo S. Gaita V. Chimenti J. Ivarsson S. Duris J. Ranostaj J. Bojkovski A. Steiner S. Ugur J. Gray S. Bruce R. Rusby D. Head 《International Journal of Thermophysics》2008,29(3):991-1000
The EUROMET.T-K3 comparison is the regional extension of CCT-K3. The comparison involved the six European national metrology
institutes (NMIs) previously involved in CCT-K3 (LNE-INM/CNAM, SMU, INRiM, NMi-VSL, NPL, PTB) and 18 additional European national
laboratories. The comparison was divided into five different loops, each coordinated by a co-pilot chosen from the laboratories
having participated in the CCT-K3 comparison. LNE-INM/CNAM played the role of pilot in linking the five loops. In each loop,
an artifact in the form of a standard platinum resistance thermometer (SPRT, 25 Ω) was circulated among the participating
laboratories. To have sufficient information about the possible drift of the SPRTs, the co-pilots performed a calibration
over the full temperature range at the beginning and at the end of the loop. A EUROMET reference value (ERV), taking into
account the whole comparison, was defined, and the differences (T
Lab − T
ERV) were calculated with the associated uncertainties. The method for establishing the link between the participants in CCT-K3
and in EUROMET.T-K3 is described.
Institut National de Métrologie (BNM-INM/CNAM at the time of the comparison, LNE-INM/CNAM since 1 January 2005), Paris, France. 相似文献