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排序方式: 共有498条查询结果,搜索用时 15 毫秒
51.
Studded tyres can significantly wear the road surface and increase particle emissions from the road surface, which has a negative impact on air quality in urban areas. However, road wear might have a positive aspect by roughening the road surface and thus preventing polishing. As a consequence, other vehicles than the ones using studded tyres might also benefit from the usage of studded tyres. The impact of the proportion of studded tyres in the traffic flow on the tyre–ice friction coefficient was studied with a fleet of real cars in a closed environment under strict procedural control. The results show that a proportion of 25–50% studded tyres in the traffic flow is enough to prevent ice from developing in a manner that is critically slippery for non-studded winter tyres. It was also observed that the visual appearance of the ice surface does not indicate if the ice has become more slippery or not. 相似文献
52.
53.
We performed a laparoscopy-assisted hepatectomy on a 52-year-old woman with a large hepatic cavernous hemangioma (longest diameter, 8.5 cm). With the use of Pringle's maneuver, the left lateral segment of the liver was resected with a Cavitron ultrasonic surgical aspirator (CUSA) while lifting the abdominal wall. Postoperative hepatic dysfunction was mild and transient, resolving spontaneously early after surgery. We intend to expand the indications of this minimally invasive procedure for hepatic resection. 相似文献
54.
The supervision of assessment has been greatly neglected in the literature. A model of supervisee development, from novice to master assessor, is presented. The model focuses on the development of the ability to integrate data into a coherent formulation of the person being tested. Appropriate supervision depends on a matching of the supervisor's behavior to the supervisee's needs, as specified by the supervisee's current level of development. This development is dramatized by improvements in interpreting specific data points and in the recognition of larger patterns in the data. This skill acquisition occurs within the affective context of the supervisor–supervisee relationship as the interaction elicits both inter- and intrapersonal issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
55.
Tchamov N.T. Broussev S.S. Uzunov I.S. Rantala K.K. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2007,54(3):277-281
A dual-band LC voltage-controlled oscillator (VCO) architecture suitable for GSM/PCS/DCS applications is presented. The VCO utilizes a fourth-order resonance tank and avoids quality-factor-deteriorating switches. The paper outlines the design tradeoffs and the VCO when using a fourth-order resonator. The 0.8-GHz/1.8-GHz test chip was fabricated in the 0.5-mum IBM-5AM SiGe process and has achieved phase noise of -134 dBc/Hz at a 1-MHz frequency offset from the carrier, with 56-MHz and 121-MHz tuning ranges in the corresponding bands. The VCO core consumes 15 mW from a 2.5-V power supply 相似文献
56.
Humanoid three‐dimensional (3D) models can be easily acquired through various sources, including through online marketplaces. The use of such models within a game or simulation environment requires human input and intervention in order to associate such a model with a relevant set of motions and control mechanisms. In this paper, we demonstrate a pipeline where humanoid 3D models can be incorporated within seconds into an animation system and infused with a wide range of capabilities, such as locomotion, object manipulation, gazing, speech synthesis and lip syncing. We offer a set of heuristics that can associate arbitrary joint names with canonical ones and describe a fast retargeting algorithm that enables us to instill a set of behaviors onto an arbitrary humanoid skeleton on‐the‐fly. We believe that such a system will vastly increase the use of 3D interactive characters due to the ease that new models can be animated.Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
57.
Aydin Atakan Beyza Macunluoglu Yuksel Kaya Elif Ari Halit Demir Ebru Asicioglu Cigdem Kaspar 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):62-69
Cardiovascular disease (CVD) is the main cause of mortality in hemodialysis (HD) patients. Epicardial fat tissue (EFT) is a new risk factor in CVD. The aim of this study was to evaluate the association between EFT and coronary artery flow reserve (CFR), which is an early indicator of endothelial dysfunction in coronary vessels of HD patients. We performed a cross‐sectional study including 71 chronic HD patients and 65 age‐ and sex‐matched healthy controls. Epicardial fat tissue was significantly higher in HD patients when compared to healthy controls (6.53 ± 1.01 mm vs. 5.79 ± 1.06 mm, respectively, P < 0.001). On transthoracic Doppler echocardiography, CFR values were significantly lower in HD patients when compared to healthy controls (1.73 ± 0.11 vs. 2.32 ± 0.28, P < 0.001). Correlation analysis showed CFR values to be inversely correlated with EFT (r = ?0.287, P < 0.05). Multiple linear regression analysis was used to define independent determinants of EFT in HD patients. Artery flow reserve, age, body mass index and total cholesterol levels were independently correlated with EFT thickness. This study demonstrated that EFT was significantly higher among HD patients compared to healthy controls. In addition, this study was the first to demonstrate an inverse correlation between EFT and CFR in this patient population. 相似文献
58.
Although Finland's forest resources have been utilized intensively, the size of the total volume of the growing stock has increased since the mid-1960s, and hence increasing amounts of carbon have been sequestered by forests. The net sequestration by forests has also been substantial when compared with the CO2 emissions resulting from energy generation and consumption based on fossil fuels and peat. It is also important, from the point of view of mitigating the effects of climate change, to assess how the sequestration capacity of forests may change under changing climatic conditions. This paper presents the results of a study assessing the development of the forest and wood-product carbon budget for Finland, based on regionally measured data, detailed dynamic models, and recent predictions concerning the changing climate. At the starting point for the simulation (1990), nearly 90% of the forest sector's carbon storage was found in the forest. Regular management transferred carbon from forests to wood products. Under the current climatic conditions, the simulated forest carbon storage increased 45% by the year 2100, and the wood-product storage by 320%, as a consequence of continuous production. Under changing climate conditions, the forest carbon storage increased, but started to decline when the temperature increase exceeded 2.5°C within 40 years. 相似文献
59.
Ari Rabl 《Solar Energy》1976,18(6):497-511
Compound Parabolic Concentrators (CPC) are relevant for solar energy collection because they achieve the highest possible concentration for any acceptance angle (tracking requirement). The convective and radiative heat transfer through a CPC are calculated, and formulas for evaluating the performance of solar collectors based on the CPC principle are presented. A simple analytic technique for calculating the average number of reflections for radiation passing through a CPC is developed; this is useful for computing optical losses. In most practical applications, a CPC will be truncated because a large portion of the reflector area can be eliminated without seriously reducing the concentration. The effects of this truncation are described explicitly. The paper includes many numerical examples, displayed in tables and graphs, which should be helpful in designing CPC solar collectors. 相似文献
60.
Pirjo Koskela Merja Teirikangas Ari Alastalo Johanna Forsman Jari Juuti Unto Tapper Ari Auvinen Heikki Seppä Heli Jantunen Jorma Jokiniemi 《Advanced Powder Technology》2011,22(5):649-656
Metallic cobalt nanoparticles were synthesized by hydrogen reduction method. Particles were coated in situ with carbon by adding ethene to reaction flow. Particles were characterized by transmission electron microscopy, energy dispersive X-ray emission, X-ray diffraction, X-ray fluorescence and BET method. The observed cobalt particle size distributions in different cobalt batches produced with unvarying reaction parameters was reproducible: The mean diameter of primary cobalt particle varied only 5% from the mean value of 76 nm in different batches. Increased carbon precursor concentration decreased mean diameter of cobalt particles to 17 nm. The produced nanoparticles were used as filler material in 0–3 type metal–polymer composites. Composite samples with varying filler loading were fabricated with mixing extrusion and injection moulding techniques. The magnetic properties of the fabricated composites were measured up to 1 GHz. In order to analyse the particle distribution in composite matrix and its effect on magnetic properties the microstructure was studied. 相似文献