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排序方式: 共有380条查询结果,搜索用时 19 毫秒
51.
The ability of wood to adsorb Telon Blue (Acid Blue 25) has been investigated. The effects of contact time, particle size and adsorption capacity have been studied. In addition a series of fixed bed experiments were performed to study the flow system in an attempt to simulate industrial conditions on a small scale. 相似文献
52.
The letter discusses the sums of m sequences generated by a feedback shift register where the summed sequences are not necessarily from successive stages. A method for obtaining all the possible probability-density functions is given. The particular case of five stages is studied in detail. It is found that, for this case and a number of other cases tested, the rth moment (or central moment) is identical for all the situations in which there are at least r interdependent stages in the sum. 相似文献
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54.
Pieter Coenen Genevieve N. Healy Elisabeth A. H. Winkler David W. Dunstan Neville Owen Marj Moodie 《Ergonomics》2018,61(9):1187-1195
We examined the association of musculoskeletal symptoms (MSS) with workplace sitting, standing and stepping time, as well as sitting and standing time accumulation (i.e. usual bout duration of these activities), measured objectively with the activPAL3 monitor. Using baseline data from the Stand Up Victoria trial (216 office workers, 14 workplaces), cross-sectional associations of occupational activities with self-reported MSS (low-back, upper and lower extremity symptoms in the last three months) were examined using probit regression, correcting for clustering and adjusting for confounders. Sitting bout duration was significantly (p < 0.05) associated, non-linearly, with MSS, such that those in the middle tertile displayed the highest prevalence of upper extremity symptoms. Other associations were non-significant but sometimes involved large differences in symptom prevalence (e.g. 38%) by activity. Though causation is unclear, these non-linear associations suggest that sitting and its alternatives (i.e. standing and stepping) interact with MSS and this should be considered when designing safe work systems.
Practitioner summary: We studied associations of objectively assessed occupational activities with musculoskeletal symptoms in office workers. Workers who accumulated longer sitting bouts reported fewer upper extremity symptoms. Total activity duration was not significantly associated with musculoskeletal symptoms. We underline the importance of considering total volumes and patterns of activity time in musculoskeletal research. 相似文献
55.
Residual orientation in injection‐moulded plaques of atactic‐polystyrene I: The effect of processing conditions 下载免费PDF全文
Injection moulded polymer articles often have residual macromolecular or crystalline orientation which can have a significant impact on the optical and mechanical properties of the moulded article. Small angle neutron scattering (SANS) was used to measure the molecular shape and orientation of deuterated blends of injection moulded polystyrene. For ~1‐mm‐thick mouldings of uniform rectangular cross‐section, the eccentricity in the SANS pattern gave a direct measure of the residual molecular orientation over the length scale ~100–1,500 Å. The residual orientation was found to vary significantly with injection moulding conditions with comparative residual orientation decreasing with decreasing mould fill‐time, and increasing with mould thickness and moulding temperatures. The orientation was found to be a minimum in the centre of the mould and highest near the surface and the average orientation at a particular position in the mould was found to be strongly correlated with the volume of material deposited as a solid skin layer during injection moulding. POLYM. ENG. SCI., 58:1322–1331, 2018. © 2017 Society of Plastics Engineers 相似文献
56.
Romanov DA Healy DM Brady JJ Levis RJ 《Journal of the Optical Society of America. A, Optics, image science, and vision》2008,25(5):1039-1050
We propose a new approach to the classical detection problem of discrimination of a true signal of interest from an interferent signal, which may be applied to the area of chemical sensing. We show that the detection performance, as quantified by the receiver operating curve (ROC), can be substantially improved when the signal is represented by a multicomponent data set that is actively manipulated by means of a shaped laser probe pulse. In this case, the signal sought (agent) and the interfering signal (interferent) are visualized by vectors in a multidimensional detection space. Separation of these vectors can be achieved by adaptive modification of a probing laser pulse to actively manipulate the Hamiltonian of the agent and interferent. We demonstrate one implementation of the concept of adaptive rotation of signal vectors to chemical agent detection by means of strong-field time-of-flight mass spectrometry. 相似文献
57.
Comparison of ICEJAM and RIVJAM Ice Jam Profile Models 总被引:1,自引:0,他引:1
A review and comparison of two numerical ice jam profile models is provided. The first is the RIVJAM model, developed at the National Water Research Institute in Canada. The second is the ICEJAM model, which was developed at the University of Alberta and which forms the basis of the solution algorithm in the ice jam calculation routine recently implemented in HEC-RAS. Both the RIVJAM and ICEJAM models solve an ice jam stability equation in conjunction with one-dimensional, steady, gradually varied flow, and both have the capacity to compute profiles for equilibrium and nonequilibrium ice jams. The focus of the investigation is to compare the analytical equations solved, the numerical solution approaches, the required boundary conditions, and the relative sensitivity of the models' calibration parameters. Similarities between the models' governing equations and solution techniques are illustrated through direct comparison of the analytical equations and through model application. Differences between the models' boundary conditions and relative success of calibration are illustrated through the application to case studies. 相似文献
58.
I. Alexandrou I. Zergioti M.J.F. Healy G.A.J. Amaratunga C.J. Kiely H. Davock A. Papworth C. Fotakis 《Surface & coatings technology》1998,110(3):1365-152
In surface coatings technology, especially in carbon-based materials, the deposition of energetic species is acknowledged as one of the most important factors in producing hard coatings. Pulsed laser deposition (PLD) of carbon under vacuum creates such energetic species and so carbon films with very high hardness values have been reported. However, when PLD takes place in a gas ambient, the ablated carbon species are decelerated to an extent that depends on the background pressure. As a result, during CNx deposition, although the carbon species react effectively with N2 at the beginning of their trajectories, when they reach the substrate they usually do not have sufficient kinetic energy to form a hard coating. In this paper we describe a new technique that combines the intense environment of an expanding N2 jet with low-pressure PLD to produce CNx species that travel almost free of collisions and reach the substrate with high kinetic energies. This new configuration is based on the synchronised pulsing of a N2 jet with the laser pulse. The CN films produced are shown to have an increased film hardness without suppressing the nitrogen content. Furthermore, electron energy-loss spectroscopy shows the layers to have a very high proportion of π bonding, which can be correlated to the existence of sp-hybridised carbon in the form of –CN bonds. 相似文献
59.