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71.
Steven Adams 《Landscape Research》2013,38(5):487-508
The French Revolution radically reconfigured citizens' views of both real and imagined space. This article sets out to explore this process of reconfiguration and the relationship between politics and space from the period immediately before the French Revolution in 1789 to the collapse of the Empire in 1815 and its aftermath. Although the liberties brought about by the Revolution made access to space one of its defining characteristics, the spaces of the Revolution were characterized by a diversity in which each political constituency made a space of its own choosing. Those spaces took forms as diverse as the pastoral garden, tales of devil abduction, political festivals, space travel, and hallucinatory visions of Jean-Jacques Rousseau's Switzerland. It was only when Napoléon ‘terminated’ the Revolution in 1799 that space was given a rational, homotopic shape, a shape that endured until the imperatives of the Bourbon Restoration required another configuration. 相似文献
72.
In October 1987 an international symposium on propellants, explosives and pyrotechnics was arranged in Beijing at the Beijing Institute of Technology. I participated in that symposium and presented a paper entitled "Sensitivity Test Methods for approval of Explosives in Sweden". 相似文献
73.
Polypropylene PP (high and low crystallinity) was λ-oxidized, in the presence of air, using different dose rates (from 2 to 100 rad/s). Oxidation outcomes were identified and quantified by FTIR spectroscopy coupled with derivatization reactions (NO and SF4). The difficulty to separate secondary and tertiary hydroperoxides from FTIR measurements after NO treatment was addressed. Polymer physical degradation was also monitored during the λ-irradiation process. GPC was used to follow molecular weight changes and tensile tests for elongation at break modifications. Comparison of the extent of oxidation product for-mation over λ-irradiation allowed us to investigate the importance of λ-dose rate on chemical and physical changes of PP. From this, different mechanisms of ketone and ester formation were examined; relationship between the molecular weight changes and the elongation at break modifications was also investigated. © 1996 John Wiley & Sons, Inc. 相似文献
74.
Several surface treatments, using both commercially available coupling agents and reagents containing multiple amines, were applied to commingled continuous as-received AS4 carbon reinforcing fiber/liquid crystal polymer (LCP) matrix fibers. Unidirectional composites (normally 60 vol% carbon fiber) were prepared from as-received and treated commingled fibers and characterized. To estimate the effect the effect of the treatments on fiber-matrix adhesion, short beam shear (SBS) tests were conducted, the failure surfaces were examined, and spectroscopic studies wee performed. The mean SBS strength of the as-received unidirectional AS4 carbon fiber/LCP matrix composite system was 49 MPa. The best coupling agent and amine treatments yielded increases in composite shear strength of ∼ 10 to 20%, relative to the as-received AS4/LCP system. For the amine treatments, ESCA and FTIR analyses suggested of both the carbon and LCP fibers may have caused the increased adhesion. Moreover, SEM analysis of the failure surfaces of SBS specimens from composites prepared with the treated fibers may have caused the increased adhesion. Moreover, SEM analysis of the failure surfaces of SBS specimens from composites prepared with the treated fibers (both with coupling agents and amines) showed that strong fiber-matrix adhesion was present. That is, failure occurred in the LCP matrix material. 相似文献
75.
Determination of the compressive strength of a composite depends on many experimental parameters. One of them is the adhesive used to bond the tabs to the compression specimen. Experimental results show that the compressive strength has no significant change when different adhesives with different moduli are used. The compressive strength was also shown to be independent of adhesive thickness in a composite compression specimen. A finite element analysis was utilized in this study to investigate the effect of tab adhesive properties, i.e., the modulus and thickness of the adhesive layer, on the compressive strength. The stress distributions along the adhesive layer and stress concentrations at the tab tip of a composite compression specimen are presented. The analytical prediction coincides with the limited experimental data. 相似文献
76.
A flexible uniform elastic disk is clamped at its inner radius and rotates at constant speed. It is shown that certain critical speeds exist at which the spinning disk is unable to support arbitrary spatially fixed transverse loads. These critical speeds are in the range of rotational speeds relevant in certain floppy disk magnetic recording applications. It is then shown that the inclusion of an elastic foundation parameter into the governing equations can raise the critical speeds of rotation. In the case of the floppy disk this corresponds to the use of a baseplate located in close proximity to the spinning disk. The results presented are the effect of the foundation stiffness parameter and clamping radius ratio on the critical speeds. Also included, for the magnetic recording application, is the effect of the baseplate position on the critical speeds. 相似文献
77.
W. M. Adams 《Landscape Research》1996,21(3):265-276
Conservation practice has recently begun to be transformed by the rhetoric of creative ecology and the possibility of creating (or re-creating) desired ecological conditions. This paper explores the potential conflict between these new developments and the conservation movement's long-standing dependence on a widely-shared (and widely disseminated) sense of 'the naturalness' of habitats and landscapes, and fear of their destruction. Conservation has long been driven by fear of loss of habitat, familiar features of landscapes, and of specific places. The paper discusses the potential for creative conservation to be carried out in such a way that its potential gains can be realized without cutting off the cultural engine of concern that drives conservation forwards. 相似文献
78.
Missouri-96 and Kentucky-31 hays were chopped with a tub grinder containing screens with apertures of 31, 63, or 100 mm in diameter and fed to dairy cows or heifers. Particle sizes (geometric mean diameter) were 1218, 1486, and 1933 micron, respectively, for the 31, 63, and 100-mm treatments. In Trial 1, the six treatments were fed ad libitum to 24 lactating cows; concentrate was offered at 1 kg/2 kg of milk. Dry matter intake and NDF digestibility were greater for Kentucky-31, but there were no other effects of variety. Particle size did not affect DM intake, DM or fiber digestibility, nitrogen partition, milk yield, or milk fat percentage. Crude protein digestibility was greatest for the 63-mm particle size treatment. In trial 2, the six treatments were fed ad libitum to 24 dairy heifers. Intake was greater for the 31 than for the 100-mm treatment but was unaffected by variety. Variety and particle size did not affect DM digestibility, nitrogen utilization, or daily gain. In this study fescue hay chopped through screens having apertures ranging from 31 to 100 mm was without effect on milk yield or composition. Reducing particle size increased intake and nitrogen utilization but not DM or fiber digestibility. 相似文献
79.
Hereditary hypertrophic cardiomyopathy (HCM), due to mutations in sarcomere proteins, occurs in more than 1/500 individuals and is the leading cause of sudden cardiac death in young people. The clinical course exhibits appreciable variability. However, typically, heart morphology and function are normal at birth, with pathological remodeling developing over years to decades, leading to a phenotype characterized by asymmetric ventricular hypertrophy, scattered fibrosis and myofibrillar/cellular disarray with ultimate mechanical heart failure and/or severe arrhythmias. The identity of the primary mutation-induced changes in sarcomere function and how they trigger debilitating remodeling are poorly understood. Support for the importance of mutation-induced hypercontractility, e.g., increased calcium sensitivity and/or increased power output, has been strengthened in recent years. However, other ideas that mutation-induced hypocontractility or non-uniformities with contractile instabilities, instead, constitute primary triggers cannot yet be discarded. Here, we review evidence for and criticism against the mentioned hypotheses. In this process, we find support for previous ideas that inefficient energy usage and a blunted Frank–Starling mechanism have central roles in pathogenesis, although presumably representing effects secondary to the primary mutation-induced changes. While first trying to reconcile apparently diverging evidence for the different hypotheses in one unified model, we also identify key remaining questions and suggest how experimental systems that are built around isolated primarily expressed proteins could be useful. 相似文献
80.
Wind power is the world's fastest growing renewable energy source, but operations and maintenance costs are still a major obstacle toward reliability and widescale adoption of wind power, accounting for a large part of the cost of energy for offshore installations. Structural health monitoring systems have been proposed for implementing condition‐based maintenance. The wind energy industry currently uses condition monitoring systems that are mostly adapted from roating machinery in other power generation industries. However, these systems have had limited effectiveness on wind turbines because of their atypical operating conditions, which are characterized by low and variable rotational speed, rapidly varying torque, extremely large rotors and stochastic loading from the wind. Although existing systems primarily take measurements from the nacelle, valuable information can be extracted from the structural dynamic response of the rotor blades to mitigate potentially damaging loading conditions. One such condition is rotor imbalance, which not only reduces the aerodynamic efficiency of the turbine and therefore its power output but can also lead to very large increases in loading on the drivetrain, blades and tower. The National Renewable Energy Laboratory's fast software was used to model both mass and aerodynamic imbalance in a 5 MW offshore wind turbine. It is shown that a combination of blade and nacelle measurements, most of which can be obtained from standard instrumentation already found on utility‐scale wind turbines, can be formulated into an algorithm used to detect and locate imbalance. The method described herein allows for imbalance detection that is potentially more sensitive than existing on‐line systems, while taking advantage of sensors that are already in place on many utility‐scale wind turbines. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献