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71.
72.
Muscular capabilities and workload of flight attendants for pushing and pulling trolleys aboard aircraft 总被引:2,自引:2,他引:0
Karlheinz Schaub Knut Berg Gabriele Winter Rolf Ellegast Ulrich Glitsch Hans Jürgen Ottersbach Matthias Jger Gerhard Franz 《International Journal of Industrial Ergonomics》2007,37(11-12):883
Increasingly in the recent years, passengers’ services are extended into the ascent and descent flight phases on short distance flights. Trolleys containing the required meal and beverage items are used for these service operations and pushed or pulled along the aisles of the aircraft. Flight attendants reported about increased musculo-skeletal disorders and had been complaining about high physical workload from handling trolleys. In order to ensure acceptable load levels for pushing or pulling operations of trolleys, the physical capabilities of the collective “flight attendants” had been investigated by means of force measurements at maximum voluntary contraction (MVC) level and associated relevant anthropometrical and biometrical data. CEN and ISO standards as well as international and national German methods were used to derive recommended force limits for pushing/pulling operations with respect to the physical capabilities of the target group “flight attendants”. Comparing these recommended limits with the force requirements per shift under various conditions of trolley handlings (inclination of the floor, type and weight of trolley, mode of handling, frequency of operation) showed that especially for higher floor inclinations and trolley weights, flight attendants work (substantially) above recommended limits. It became also apparent that the handling of half-size trolleys is unexpectedly high demanding due to high vertical force components, caused by the unfavorable location of their center of gravity.
Relevance to industry
On short-distance flights, passengers’ services are performed by means of trolleys from the ascent to the descent flight phases. Flight attendants had been complaining about high physical workload. This study offers recommendations on maximum force limits for the handling of trolleys with respect to the muscular capacities and work situations of flight attendants on short-distance flights. 相似文献73.
Physical workload of flight attendants when pushing and pulling trolleys aboard aircraft 总被引:2,自引:2,他引:0
Ulrich Glitsch Hans Jürgen Ottersbach Rolf Ellegast Karlheinz Schaub Gerhard Franz Matthias Jger 《International Journal of Industrial Ergonomics》2007,37(11-12):845
The musculoskeletal loads from moving trolleys aboard aircraft were assessed by observation of trolley handling on planes and by physical workload analyses of pushing and pulling of trolleys in a laboratory set up. Trolley handling by a total of 15 female flight attendants was observed on 10 short- and medium-distance flights in different types of aircraft. About 25 selected flight attendants (22 females; 3 males) of five German airlines took part in the laboratory study, which comprised three-dimensional (3D) measurements of posture and hand forces during pushing and pulling of trolleys in a variety of configurations. From the on-flight observations performed, between 150 and 250 trolley movements can be projected for a work shift. The greatest physical workload is to be expected at the beginning of service: The trolleys are fully laden then, and the cabin floor can still be inclined up to 8°, as the aircraft is still climbing, particularly on short-distance flights. The laboratory investigation revealed that the musculoskeletal workload from pushing and pulling depends essentially on the trolley load and on the gradient of the cabin floor. In addition, the degree of stressing depends significantly on the trolley type, mode of handling and personal dexterity. The up/down force component perpendicular to the direction of motion often achieved considerable amplitudes-in some cases equal to or exceeding the force in the direction of movement. The posture analysis demonstrated that pulling forced the flight attendants to adopt ergonomically unfavourable postures such as pronounced flexion of the back, particularly among female subjects. The highest values for flexion of the back occurred while pulling the half-size trolley. The results demonstrate that female flight attendants are likely to overload themselves if they frequently have to move heavily laden trolleys unaided on an inclined cabin floor.
Relevance to industry
On short distance flights, flight attendants have been complaining increasingly of high physical workload from manoeuvring trolleys. On the basis of the presented data airline companies may improve the trolley handling skills of their flight attendances by practical trainings and may ergonomically optimize the general service procedures aboard aircrafts. 相似文献74.
Matthew Arnold Michael Hsiao Ulrich Kremer Barbara G. Ryder 《International journal of parallel programming》2001,29(2):111-137
The frequent occurrence of implicitly thrown exceptions poses one of the challenges present in a Java compiler. Not only do these implicitly thrown exceptions directly affect the performance by requiring explicit checks, they also indirectly impact the performance by restricting code movement in order to satisfy the precise exception model in Java. In particular, instruction scheduling is one transformation that is restricted by implicitly thrown exceptions due to the heavy reliance on reordering instructions to exploit maximum hardware performance. The goal of this study is two-fold: first, investigate the degree to which implicitly thrown exceptions in Java hinder instruction scheduling, and second, find new techniques for allowing more efficient execution of Java programs containing implicitly thrown exceptions. Experimental results show that with aggressive scheduling techniques, such as superblock scheduling, the negative performance impact can be greatly reduced. 相似文献
75.
Making decisions can be hard, but it can also be facilitated. Simple heuristics are fast and frugal but nevertheless fairly accurate decision rules that people can use to compensate for their limitations in computational capacity, time, and knowledge when they make decisions [Gigerenzer, G., Todd, P. M., & the ABC Research Group (1999). Simple Heuristics That Make Us Smart. New York: Oxford University Press.]. These heuristics are effective to the extent that they can exploit the structure of information in the environment in which they operate. Specifically, they require knowledge about the predictive value of probabilistic cues. However, it is often difficult to keep track of all the available cues in the environment and how they relate to any relevant criterion. This problem becomes even more critical if compound cues are considered. We submit that knowledge about the causal structure of the environment helps decision makers focus on a manageable subset of cues, thus effectively reducing the potential computational complexity inherent in even relatively simple decision-making tasks. We review experimental evidence that tested this hypothesis and report the results of a simulation study. We conclude that causal knowledge can act as a meta-cue for identifying highly valid cues, either individual or compound, and helps in the estimation of their validities. 相似文献
76.
Ulrich Schoch Jürg Lüthy und Christian Schlatter 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1984,178(5):351-355
Zusammenfassung In Rohextrakten von 18Penicillium camemberti- und 6P. roqueforti-Stämmen, die als Reifungsorganismen bei der Schimmelkäseproduktion in Schweizer Käsereien eingesetzt werden, wurde das mutagene Potential mit Hilfe des Ames-Testes bestimmt. In keinem der geprüften Extrakte konnte eine mutagene Aktivität festgestellt werden. Roquefortin, ein in Blauschimmelkäsen nachweisbares Mykotoxin vonP. roqueforti, erwies sich im Ames-Test als nicht mutagen. Die ermittelten Resultate ergaben keine Anhaltspunkte für genotoxische Effekte durch die Konsumation von schimmelgereiftem Käse.
Auszug aus der Dissertation von U. Schoch, Mykotoxine in schimmelgereiften Käsen, Diss. ETH Nr. 7278, ETH Zürich, 1983 相似文献
Mutagenicity testing of commercialP. Camemberti- andP. roqueforti-strains
Summary We tested the mutagenic potential of crude extracts of 18 strains ofPenicillium camemberti- and 6 strains ofP. roqueforti, which are used commercially in the production of mould ripened cheese in Switzerland. No mutagenic activity could be detected in any of the extracts. Roquefortine, a mycotoxin ofP. roqueforti, often found in Blue cheese, was negative in the Amestest. The results obtained do not lead reasons for experting undesired long term effects from the consumption of mould ripened cheese.
Auszug aus der Dissertation von U. Schoch, Mykotoxine in schimmelgereiften Käsen, Diss. ETH Nr. 7278, ETH Zürich, 1983 相似文献
77.
Spirkl FM Kunz S Schweinberger FF Farnbacher AN Schröter R Heiz U 《The Review of scientific instruments》2012,83(1):013114
The separation of ultraviolet photoelectron spectroscopy (UPS) and metastable impact electron spectroscopy (MIES) is usually performed by a time-of-flight (ToF) separation using pre-set ToF for both types of signal. In this work, we present a new, improved ex situ signal separation method for the separation of MIES and UPS for every single measurement. Signal separation issues due to changes of system parameters can be overcome by changing the ToF separation and therefore allowing for the application of a wider range of measuring conditions. The method also enables to identify and achieve separation of the two signals without any time consuming calibration and the use of any special material for the calibration. Furthermore, changes made to the discharge source are described that enable to operate an existing MIES/UPS source over a broader range of conditions. This allows for tuning of the yield of UV photons and metastable rare gas atoms leading to an improved signal to noise ratio. First results of this improved setup are well in agreement with spectra reported in literature and show increased resolution and higher signal intensities for both MIE and UP spectra compared to the previous, non-optimized setup. 相似文献
78.
Islam Z Capatina D Ruff JP Das RK Trakhtenberg E Nojiri H Narumi Y Welp U Canfield PC 《The Review of scientific instruments》2012,83(3):035101
We present a pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies with the magnetic field applied on or close to the scattering plane. The apparatus consists of a single large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields close to ~30 T with a zero-to-peak-field rise time of ~2.9 ms are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (~23.6°) on the entrance and exit sides of the magnet bore by virtue of a novel double-funnel insert. This instrument will facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using split-pair and narrow-opening solenoid magnets. Furthermore, it offers a practical solution for preserving optical access in future higher-field pulsed magnets. 相似文献
79.
Lieferantenportfolio-Management für IT-Services unter Berücksichtigung von Diversifikationseffekten 总被引:1,自引:1,他引:0
By means of service-oriented architectures the IT support of processes can be designed as a portfolio of individual IT services provided by different suppliers. The processes are designed based on selection decisions between IT services that potentially have to be included. Many companies formulate a multitude of requirements for investments in IT services at ever shorter intervals. However, the scope of the desired investments usually exceeds the available budget. Thus, companies face the challenge of allocating the limited budget to investments in the most promising combination of IT services. This is hardly possible without methodical support. In addition, the allocation is often done intuitively and subject to the decision-makers?? affinity with IT. Therefore, this paper develops a quantitative, multi-period procedure model for the purpose of maximizing the enterprise value in accordance with value based management, which considers the dependencies of the periodical selection decisions. In the following, a decision logic for the heuristic solution to the selection problem is presented and its application is demonstrated by means of an illustrative case example. 相似文献
80.
Ulrich Mutze 《Granular Matter》2006,8(3-4):185-194
This paper describes a method to simulate the dynamics of granular systems consisting of irregularly shaped grains. This method is a simplification and partial improvement of a method that has been developed and employed earlier in simulating the toning process in electro-photographic copiers. Here, grains are modeled as rigidly connected overlapping spherical particles. For each grain a bounding sphere around the center-of-mass is known. Therefore, it can efficiently be decided whether two particles intersect and thus exert contact forces upon each other. A second order time stepping algorithm for such grains is given which needs only one evaluation of the interparticle forces in a time step. In a ten grain example system a favorable but poorly understood phenomenon of energy restoration is exemplified.U. Mutze retired from R&D for a subsidiary of Heidelberger Druckmaschinen AG, after R&D work for a subsidiary of Eastman Kodak Company. 相似文献