放射性血管支架制备研究进展

综述了用于预防PTCA后血管再狭窄的放射性血管支架的各种制备方法：同位素离子注入法、活化法及直接表面沉积或涂覆法的研究进展，分析了各种方法的特点，简述各种放射性支架的应用情况，并对发展趋势进行了评述。     

To Intervene or not to Intervene: The Dilemma of Management by Exception

Future air traffic management architectures propose to give aircraft more flight path autonomy and turn the air traffic controller into a manager of exceptions. This article reports on one experiment in a series of studies that empirically explored the cognitive work underlying management by exception in air traffic control. Active practitioners (controllers, pilots, dispatchers) were prepared on the rules of the envisioned system and presented with a series of future incidents, each of which they were required to jointly resolve. Management by exception turns out to trap human controllers in a double bind, where intervening early seems appealing but is difficult to justify (airspace throughput) and carry out (controller workload problems). Late interventions are just as difficult, since controllers will have to take over in the middle of a potentially challenging or deteriorating situation. Computerised decision support that flags exceptions migrates the decision criterion into a device, creating a threshold crossing that is typically set either too early or too late. This article lays out the intertwined trade-offs and dilemmas for the exception manager, and makes recommendations for cooperative human–machine architectures in future air traffic management.     

Computerization of school administration: impact on the principal’s role—a case study

Changes in the principal’s role, resulting from the computerization of a high-school’s instruction-administration subsystem (i.e. a significant technological change), occurred in six major categories: accountability, instruction evaluation, supervision, feedback, frequency of meetings, and shared decision-making. The principal’s interrelations with department heads, homeroom teachers and teachers, tightened significantly. The principal’s interrelations with the school computer administrator (a new role created as a result of the introduction of a school management information system), were found to be tight and on a daily basis. The results of this research might have significant theoretical and practical implications. They should be related to SMIS impact on schooling in general and on the principal’s role in particular.     

TCK钢丝绳在线无损定量检测系统

TCK钢丝绳 (缆 )在线无损定量检测系统采用“缺陷”磁场综合处理法 ,所建数学模型被实验所证实 ,通过微机实现全息检测、定量显示、自动标定 ,做到了准确率高、精度高 ,且检测结果与检测速度无关     

A comparison of CFD‐simulations and measurements of the temperature stratification in a mixing box of an air‐handling unit

This paper presents a comparison between CFD‐simulations and measurements of the temperature stratification in a mixing box of an air‐handling unit. We have used data from field measurements during a period of over a year for different outside temperatures. We performed two‐dimensional CFD‐simulations for four different outside temperatures with commercially available software. The measurements as well as the simulations show that the temperature difference between the upper part and the lower part of the duct downstream of the mixing box is considerable. It increases, as the outside temperature decreases. However, the discrepancies between the measurements and the simulations are large. The reasons for this are uncertain boundary conditions and modelling errors leading to an inaccurate simulation result. The stratification downstream of the mixing box implies large sensor errors and the use of the mixed air temperature for control and fault detection must therefore be questioned. Averaging sensors, which take a mean value over the duct section, can be used but do not consider differences in velocities and are therefore not accurate either. In order to, for example, use CFD as a tool to decide the optimal sensor location a more accurate model and more information regarding the boundary conditions is needed. Copyright © 2001 John Wiley & Sons, Ltd.     

Foot motions in manual material handling transfer tasks: A taxonomy and data from an automotive assembly plant

Ergonomic job analysis commonly applies static postural and biomechanical analysis tools to particular postures observed during manual material handling (MMH) tasks, usually focusing on the most extreme postures or those involving the highest loads. When these analyses are conducted prospectively using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses. In automotive assembly jobs, workers frequently take several steps between task elements, for example, picking up a part at one location and moving to another location to place it on the vehicle. A detailed understanding of the influence of task type and task sequence on the stepping pattern is necessary to accurately predict the foot placements associated with MMH tasks. The current study examined the patterns of foot motions observed during automotive assembly tasks. Video data for 529 pickup and delivery tasks from 32 automotive assembly jobs were analysed. A minimum of five cycles was analysed for each task. The approach angle, departure angle, hand(s) used, manipulation height and patterns of footsteps were coded from the video. Object mass was identified from the job information sheet provided by the assembly plant. Three independent raters coded each video and demonstrated an intraclass correlation coefficient of 0.54 for identification of the configuration of the lower extremities during terminal stance. Based on an analysis of the distribution of stepping behaviours during object transitions (pickups or deliveries), a transition classification system (TRACS) was developed. TRACS uses a compact notation to quantify the sequence of steps associated with a MMH transition. Five TRACS behaviour groups accounted for over 90% of the transition stepping behaviours observed in the assembly plant. Approximately two-thirds (68.4%) of the object transfers observed were performed with only one foot in contact with the ground during the terminal posture. The results from this paper suggest that a predictive model for choosing a transition stepping behaviour, coupled with a model to scale the selected foot behaviours, is needed to facilitate accurate prospective ergonomic analyses. This study proposes a method for categorising the stepping patterns associated with MMH tasks. The influence of task type and task sequence on the stepping patterns observed during several automotive assembly tasks is discussed. For prospective postural analyses conducted using digital human models, accurate prediction of the foot placements is critical to realistic postural analyses.     

Psychophysical modelling for combined manual materials-handling activities

Most psychophysical studies in manual materials handling (MMH)are involved only with single MMH activities, i.e. lifting, lowering, carrying, holding, pushing or pulling. Very little research has been reported on the determination of operator capacities for combinations of MMH activities (e.g. lifting a box, then carrying the box, or carrying a box, then lowering the box). These kinds of combined activities are prevalent in industry and in our daily lives. The objective of this study was to utilize the psychophysical approach to examine the effects of combinations of lifting, carrying and lowering activities. Twelve male students served as subjects for the study. The capacities that were determined as the maximum acceptable workloads for a 1-h work period for four individual MMH activities—lifting from floor to knuckle height (LFK), lifting from knuckle to shoulder height (LKS), lowering from knuckle to floor height (LOW) and carrying for 3·4 m (C) —and three combined MMH activities—LFK + C, LFK + C + LKS and LFK + C + LOW—were determined psychophysically under three frequency conditions: one time maximum, one handling per minute and six handlings per minute. Combined MMH capacities models were developed using the following three methods: a limiting individual MMH capacity, isoinertial 1·83-m maximum strength and fuzzy-set theory. The advantages and disadvantages of different models were discussed.     

A detailed mineralogical assessment of sphalerites from the Gamsberg zinc deposit, South Africa: The manganese conundrum

The Gamsberg zinc deposit, located in the Northern Cape Province, represents South Africa’s greatest and most important unexploited base metal resource. Yet, in spite of its size, the low zinc grade combined with the high manganese content of the sphalerite continues to prohibit development of the deposit, as the high manganese content makes the zinc concentrates unsuitable for processing by conventional smelting methods, i.e. roasting, leaching/solvent extraction and/or electrowinning.Although numerous published investigations of the Gamsberg deposit have been undertaken, few have focused on the correlation between petrography and mineral chemistry of sphalerite and their implications on mineral processing. In accordance, the aims of this investigation are to highlight the importance of conducting a detailed geometallurgical investigation, as well as provide some new constraints on the metallurgical behavior of sphalerite and zinc concentrates from the Gamsberg deposit. Detailed analysis of sphalerite by petrographic and various microanalytical techniques reveal a marked absence of correlation between crystal morphology and mineral chemistry, necessitating a chemically based classification scheme. As such, six sphalerite populations where identified. They are: zinc-, cobalt-, iron- and manganese-rich, as well as manganese-enriched and manganese-poor. The zinc- and cobalt-rich populations display high zinc contents and low concentrations of iron and manganese, while the iron-rich population displays higher iron contents. Dominating the sphalerites of the mineralized pelitic schist is the manganese-enriched population. Of volumetrically lesser importance are the manganese-poor and -rich populations. The manganese-rich population contains high levels of iron, manganese, cobalt and cadmium relative to the zinc-rich population. In contrast, the manganese-poor population displays similar concentrations of cobalt and cadmium to the zinc-rich population, with iron and manganese intermediate between the zinc- and iron-rich populations.Comparisons between the sphalerite populations and milling size fractions reveal a consistent correlation between sphalerite mineral chemistry and size fractions with the coarser-grained concentrates being economically less favorable compared to the finer-grained concentrates, which display higher zinc contents. Combined with other lines of evidence, this suggests that the sphalerites of mineralized pelitic schist exhibit extensive solid solution that will have an effect on process optimization. For instance, it suggests that milling to a finer grain size will not remove or reduce the iron and manganese content. Another concern to processing will be the variable mineral chemistry of sphalerite, which might cause some sphalerites to display a delayed response during flotation or misreport to the lead concentrate. In spite of this, using solvent extraction, the elevated manganese content of the concentrates could be controlled, while simultaneously recovering zinc and manganese for sale. Hence, the recovery of manganese metal as a by-product could potentially enhance the economics of the deposit. Alternatively, other forms of mineral processing and metal extraction must be evaluated to meet the target grades and recoveries.     

A multi-objective multi-sectoral economy–energy–environment model: Application to Portugal

Portugal is faced with important challenges concerning the definition of policies to achieve energy and environmental targets, taking also into account the economic and social issues. A multi-sectoral economy-energy-environment model has been developed to perform a prospective analysis of the changes in the economic structure and the energy system, as well as to assess the corresponding environmental impacts, providing decision support in policy making. This model is a multi-objective linear programming model that allows for the explicit consideration of distinct axes of evaluation, generally conflicting and non-commensurate, of the merit of distinct policies. The policy recommendations obtained are subject to the inherent uncertainty associated with the model coefficients and, therefore, they may not be robust in face of changes of the input data. The specification of less energy or carbon-intensive technologies is done by considering pollutant/energy coefficients defined as intervals. This analysis is crucial for understanding the role of technology in carbon mitigation efforts and other energy system planning settings, allowing to explore the effects of distinct policies on the total system costs, the fuel and technology mix, and the levels of greenhouse gases and other emissions.     

Foot-ground forces on sloping ground when lifting∗

Slipping risk associated with manual material handling on inclined surfaces was investigated using a 2⁴ factorial experimental design under controlled laboratory conditions. The reaction force data at the shoe sole-sloping surface interface, the box trajectories, and the subjects’ assessment of the risk involved in carrying out the prescribed tasks were obtained and analysed both analytically and statistically. The results of these analyses are presented in this paper.