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51.
52.
In June 2003, a large scale injection experiment started at the Continental Deep Drilling site (KTB) in Germany. A tiltmeter array was installed which consisted of five high resolution borehole tiltmeters of the ASKANIA type, also equipped with three dimensional seismometers. For the next 11 months, 86 000 m(3) were injected into the KTB pilot borehole 4000 m deep. The average injection rate was approximately 200 l/min. The research objective was to observe and to analyze deformation caused by the injection into the upper crust at the kilometer range. A new data acquisition system was developed by Geo-Research Center Potsdam (GFZ) to master the expected huge amount of seismic and tilt data. Furthermore, it was necessary to develop a new preprocessing software called PREANALYSE for long-period time series. This software includes different useful functions, such as step and spike correction, interpolation, filtering, and spectral analysis. This worldwide unique installation offers the excellent opportunity of the separation of signals due to injection and due to environment by correlation of the data of the five stations with the ground water table and meteorological data. 相似文献
53.
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54.
Saul Arlosoroff Gerhard Tschannerl David Grey William Journey Andrew Karp Otto Langenegger 《国际水》2013,38(2):106-111
An estimated 1,800 million people need improved water supplies in the fifteen years to the end of the century, if developing countries are to reach the target of full coverage. The first half of the International Drinking Water Supply and Sanitation Decade (1981–1990) has seen increases in the percentages of the rural population with access to safe water supplies, but only in Asia has the pace been quick enough to envisage a target of essentiahy full coverage by the end of the century (ten years later than the original Decade goals). In Africa, present progress rates would leave half of the rural population still without safe water in the year 2000, while in Latin America, it may be ten years into the next century before full coverage is achieved unless progress improves dramatically. Accelerated progress is hampered by financial and technical resource constraints faced by many developing countries, and the problem is aggravated by the growing number of completed projects which are broken down and abandoned, or functioning much below capacity. Attempts to increase the pace of providing improved community water supplies have often been frustrated because the technology used has proved impossible to sustain in village conditions. To make a lasting impact on the urgent needs, community water supply (CWS) strategies must be based on sustainable and replicable programs, and must take account of the pace at which resource constraints can be overcome. Human resource development programs take time to produce results, and institutional changes can only be accomplished gradually. 相似文献
55.
S. A. Martinez M. P. Blodgett S. Sathish S. Mall 《Metallurgical and Materials Transactions A》2005,36(12):3385-3396
The evolution of fretting fatigue damage was investigated in shot-peened Ti-6Al-4V samples, by measuring the changes in the
surface residual stress, using the X-ray diffraction technique. The surface residual stress was found to relax as the number
of fretting fatigue cycles increased. The relaxation behavior of the residual stress with the increasing number of fretting
fatigue cycles was observed to occur in three stages. In the first 20 pct of the fretting fatigue life, a drastic relaxation
was observed. In the second part (between 20 and 70 pct), a gradually increasing behavior was observed. During the last 20
to 30 pct of the fretting fatigue life, a dramatic relaxation of the residual stress was found to occur. A complete relaxation
of the residual stress occurred in the fracture region. A scanning electron microscope observation of the microstructure of
the damaged region was used to examine the mechanisms leading to the relaxation of the residual stress. The development of
delaminations at the early stages of the accumulation of the fretting fatigue damage was observed to be the main cause of
the initial relaxation. The generation of microcracks from the voids left behind by the delaminations is responsible for the
additional relaxation of the residual stress. The coalescence of the microcracks generated from different delaminated regions
produced yet more relaxation of residual stress and, ultimately, the final fracture of the specimen. 相似文献
56.
Gerhard Klimeck 《Journal of Computational Electronics》2003,2(2-4):177-182
The coupling of the fundamentally quantum mechanical nanoelectronic transport simulation through resonant tunneling diodes to semi-classical drift diffusion in the contacts is demonstrated. The coupling between the non-equilibrium Green function formalism used in NEMO to the drift diffusion equation is established by the use of spatially dependent quasi Fermi levels in the reservoirs. The charge distributions are computed quantum mechanically throughout the whole device using the full bandstructure sp3s* tight binding model that includes band non-parabolicity and band warping. The formalism is applied to the simulation of high current density resonant tunneling diodes. Low mobility contacts are shown to introduce a bi-stability in the negative differential resistance region. 相似文献
57.
Gadolinium-enhanced magnetic resonance angiography of the pelvis in patients with erectile impotence
Michael K. Stehling Libin Liu Gerhard Laub Kurt Fleischmann Ulrike Rohde 《Magma (New York, N.Y.)》1997,5(3):247-254
This study evaluted the potential of contrast-enhanced digital-subtraction magnetic resonance angiography (CE-DS-MRA) for
noninvasive angiographic delineation of the arterial supply of the penis in patients with erectile dysfunction. After induction
of an erection with prostaglandin E, a three-dimensional fast imaging with steady-state precision (FISP) sequence with TE
of 1.8–2 milliseconds, TR of 4.4–5 milliseconds, and flip angle of 40°–60° was used to obtain high-resolution angiograms of
the pelvis and penis during the injection of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) 0.3 mmol/kg body weight,
within 30–50 seconds. DS maximum intensity projections (MIPs) and multiplanar reconstructions (MPRs) were compared with clinical
work-up and directional Doppler ultrasound in 11 patients. In all 11 patients (100%), the arterial supply of the penis could
be delineated from the aortic bifurcation via the iliac and internal pudendal arteries to the dorsal and deep penile arteries.
Of the 22 internal pudendal arteries, 6 (27%) were occluded on CE-DS-MRA and 5 (23%) had stenoses, of which 4 (18%) were greater
than 50%. In 7 patients (64%) good correlation between CE-DS-MRA and clinical findings and/or Doppler ultrasound was found;
in 2 patients (18%), the correlation was moderate, and in 2 patients (18%) results were discrepant. In 6 patients (55%), MRA
provided additional information to the clinical and Doppler ultrasound work-up. CE-DS-MRA can delineate small sessels such
as the internal pudendal and penile arteries and thus has the potential to become a noninvasive angiography method in the
work-up of erectile impotence.
Supported by Siemens Medical Systems, Erlangen; Schering AG, Berlin; and Agfa-Gevaert AG, Leverkusen. 相似文献
58.
Data partitioning and load balancing in parallel disk systems 总被引:13,自引:0,他引:13
Peter Scheuermann Gerhard Weikum Peter Zabback 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(1):48-66
Parallel disk systems provide opportunities for exploiting I/O parallelism in two possible ways, namely via inter-request
and intra-request parallelism. In this paper, we discuss the main issues in performance tuning of such systems, namely striping
and load balancing, and show their relationship to response time and throughput. We outline the main components of an intelligent,
self-reliant file system that aims to optimize striping by taking into account the requirements of the applications, and performs
load balancing by judicious file allocation and dynamic redistributions of the data when access patterns change. Our system
uses simple but effective heuristics that incur only little overhead. We present performance experiments based on synthetic
workloads and real-life traces.
Received May 17, 1994 / Accepted June 9, 1997 相似文献
59.
The hardness and yield stress at room temperature and the brittle‐to‐ductile transition temperature of Fe‐Al alloys with 16 at.% Al, which is in the range of the so‐called K‐state with possible short‐range ordering reactions, and ternary additions of 0.5 and 4 at.% of the transition metals Cr, Mo, Mn, V, Ti and Ni were studied with respect to possible hardening effects of the ternary additions. The addition of Cr, Mo and Mn to the Fe‐Al alloys produce solid‐solution hardening which corresponds to the hardening effect of Al. Only Ti, V and Ni produce extra hardening effects which cannot be related to solid‐solution hardening. This extra hardening is attributed to possible fine NiAl precipitates in the Fe‐Al‐Ni case and to possible enhanced short‐range ordering and/or fine carbide precipitates in the cases of Fe‐Al‐V and Fe‐Al‐Ti. 相似文献
60.
Fretting fatigue crack initiation behavior using process volume approach and finite element analysis 总被引:1,自引:0,他引:1
This study investigates crack initiation behavior by incorporating fretting fatigue process volume. Three critical plane based fretting fatigue crack initiation parameters are characterized by computing their averaged values over the process volume and then comparing with their counterparts obtained from the localized approach. Two approaches are used: first one involves the computation of parameter at several points over a rectangular region and then its average, and second approach computes the average state of stress/strain over a radial region from which the averaged parameter is calculated. Both approaches require pre-determination of a critical location at or around which the process volume needs to be placed. Effects of size and location of process volume on the averaged value of parameters are studied in detail. Two radii of cylindrical pad are analyzed to investigate the effect of severity of stress gradient on process volume approach. Effects of finite element mesh refinement are also investigated. Averaged value of parameter decreases with the increase of process volume size. This decrease is higher when the process volume is located in the region that is away from the contact zone. Further, a parameter based on normal stress on the critical plane shows more dependence on the size of process volume than that based on shear stress or on a combination of both shear and normal stresses. Orientation of crack initiation changes within a range that is well within the scatter band of experimental observations as the process volume size increases. Averaged value of parameter for a pad with higher stress gradient has a larger reduction with the increase of process volume size than that with a lower stress gradient. Process volume size has less effect on the averaged value of parameter with coarser finite element mesh. Finally, the localized approach provides a conservative value of fretting fatigue crack initiation parameter compared to its counterpart based on the process volume. 相似文献