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81.
Dirk Obergfell Bahman Azarhoushang Andrés Fabián Lasagni 《Advanced Engineering Materials》2023,25(19):2300757
Due to its high corrosion resistance and mechanical properties, stainless steel is commonly used in various industrial applications. Although different types of stainless steel are similar in their chemical composition, they can differ significantly in their thermal diffusivity. This property is relevant in the ability of a material to conduct heat and thus, in laser processing. In this frame, this study compares the ablation efficiency and characteristics of polished stainless steel samples of the alloys AISI 304, AISI 420, and AISI 316Ti. They are irradiated with single ultrashort pulses having pulse durations between 250 fs and 10 ps as well as using GHz burst modii. The goal is to investigate the differences in both the ablation threshold and the ablation rate to improve the ablation efficiency. The results show that shorter pulse durations lead to a more efficient ablation process. On the other hand, GHz bursts are found to be, in general, less efficient. In addition, there is a significant difference in the surface morphology depending on the process parameters. The differences in the thermal diffusivity do not significantly influence the ablation threshold fluence but surface morphology and the ablation rate. 相似文献
82.
Masoud Mohazzab Norbert Mulders Melora Larson Al Nash 《Journal of Low Temperature Physics》1998,113(5-6):1031-1036
In this paper we discuss a pulsed second sound experiment, aimed at determining accurately the critical exponent , and the predicted logarithmic correction to scaling, for the superfluid density along a tricritical path in the
3
He-
4
He phase diagram. We present an accurate estimate for the limits for closest approach to the tricritical point, as set by gravitationally induced sample inhomogeneities and finite size effects, and discuss some of the complications associated with measurements close to the tricritical point. 相似文献
83.
Norbert Wilke 《Magma (New York, N.Y.)》1998,6(2-3):147-147
84.
Georg Birkenheuer Andr�� Brinkmann Mikael H?gqvist Alexander Papaspyrou Bernhard Schott Dietmar Sommerfeld Wolfgang Ziegler 《Journal of Grid Computing》2011,9(3):355-377
Infrastructure federation is becoming an increasingly important issue for modern Distributed Computing Infrastructures (DCIs):
Dynamic elasticity of quasi-static Grid environments, incorporation of special-purpose resources into commoditized Cloud infrastructures,
cross-community collaboration for increasingly diverging areas of modern e-Science, and Cloud Bursting pose major challenges
on the technical level for many resource and middleware providers. Especially with respect to increasing costs of operating
data centers, the intelligent yet automated and secure sharing of resources is a key factor for success. With the D-Grid Scheduler
Interoperability (DGSI) project within the German D-Grid Initiative, we provide a strategic technology for the automatically
negotiated, SLA-secured, dynamically provisioned federation of resources and services for Grid-and Cloud-type infrastructures.
This goal is achieved by complementing current DCI schedulers with the ability to federate infrastructure for the temporary
leasing of resources and rechanneling of workloads. In this work, we describe the overall architecture and SLA-secured negotiation
protocols within DGSI and depict an advanced mechanism for resource delegation through means of dynamically provisioned, virtualized
middleware. Through this methodology, we provide the technological foundation for intelligent capacity planning and workload
management in a cross-infrastructure fashion. 相似文献
85.
Patrick Schalberger Marcus Herrmann Steffen Hoehla Norbert Fruehauf 《Journal of the Society for Information Display》2011,19(7):496-502
Abstract— In the past, a five‐mask LTPS CMOS process requiring only one single ion‐doping step was used. Based on that process, all necessary components for the realization of a fully integrated AMOLED display using a 3T1C current‐feedback pixel circuit has recently been developed. The integrated data driver is based on a newly developed LTPS operational amplifier, which does not require any compensation for Vth or mobility variations. Only one operational amplifier per column is used to perform digital‐to‐analog conversion as well as current control. In order to achieve high‐precision analog behavior, the operational amplifier is embedded in a switched capacitor network. In addition to circuit verification by simulation and analytic analysis, a 1‐in. fully integrated AMOLED demonstrator was successfully built. To the best of the authors' knowledge, this is the first implementation of a fully integrated AMOLED display with current feedback. 相似文献
86.
André Maués Brabo Pereira Marcos Aurélio Marques Noronha 《Engineering with Computers》2010,26(1):35-47
Most post-processors for boundary element (BE) analysis use an auxiliary domain mesh to display domain results, working against
the profitable modelling process of a pure boundary discretization. This paper introduces a novel visualization technique
which preserves the basic properties of the boundary element methods. The proposed algorithm does not require any domain discretization
and is based on the direct and automatic identification of isolines. Another critical aspect of the visualization of domain
results in BE analysis is the effort required to evaluate results in interior points. In order to tackle this issue, the present
article also provides a comparison between the performance of two different BE formulations (conventional and hybrid). In
addition, this paper presents an overview of the most common post-processing and visualization techniques in BE analysis,
such as the classical algorithms of scan line and the interpolation over a domain discretization. The results presented herein
show that the proposed algorithm offers a very high performance compared with other visualization procedures. 相似文献
87.
88.
Jorge E. Mendoza Bruno Castanier Christelle Guéret Andrés L. Medaglia Nubia Velasco 《Computers & Operations Research》2010,37(11):1886-1898
The multi-compartment vehicle routing problem (MC-VRP) consists of designing transportation routes to satisfy the demands of a set of customers for several products that, because of incompatibility constraints, must be loaded in independent vehicle compartments. Despite its wide practical applicability the MC-VRP has not received much attention in the literature, and the few existing methods assume perfect knowledge of the customer demands, regardless of their stochastic nature. This paper extends the MC-VRP by introducing uncertainty on what it is known as the MC-VRP with stochastic demands (MC-VRPSD). The MC-VRPSD is modeled as a stochastic program with recourse and solved by means of a memetic algorithm. The proposed memetic algorithm couples genetic operators and local search procedures proven to be effective on deterministic routing problems with a novel individual evaluation and reparation strategy that accounts for the stochastic nature of the problem. The algorithm was tested on instances of up to 484 customers, and its results were compared to those obtained by a savings-based heuristic and a memetic algorithm (MA/SCS) for the MC-VRP that uses a spare capacity strategy to handle demand fluctuations. In addition to effectively solve the MC-VRPSD, the proposed MA/SCS also improved 14 best known solutions in a 40-problem testbed for the MC-VRP. 相似文献
89.
Christian Liebchen Michael Schachtebeck Anita Schöbel Sebastian Stiller André Prigge 《Computers & Operations Research》2010,37(5):857-868
In the past, much research has been dedicated to compute optimum railway timetables. A typical objective has been the minimization of passenger waiting times. But only the planned nominal waiting times have been addressed, whereas delays as they occur in daily operations have been neglected. Delays have been rather treated mainly in an online context and solved as a separate optimization problem, called delay management.We provide the first computational study which aims at computing delay resistant periodic timetables. In particular we assess the delay resistance of a timetable by evaluating it subject to several delay scenarios to which optimum delay management will be applied.We arrive at computing delay resistant timetables by selecting a new objective function which we design to be somehow in the middle of the traditional simple timetabling objective and the sophisticated delay management objective. This is a slight extension of the concept of “light robustness” (LR) as it has been proposed by Fischetti and Monaci [2006. Robust optimization through branch-and-price. In: Proceedings of AIRO]. Moreover, in our application we are able to provide accurate interpretations for the ingredients of LR. We apply this new technique to real-world data of a part of the German railway network of Deutsche Bahn AG. Our computational results suggest that a significant decrease of passenger delays can be obtained at a relatively small price of robustness, i.e. by increasing the nominal travel times of the passengers. 相似文献
90.
The availability of multicore processors and programmable NICs, such as TOEs (TCP/IP Offloading Engines), provides new opportunities for designing efficient network interfaces to cope with the gap between the improvement rates of link bandwidths and microprocessor performance. This gap poses important challenges related with the high computational requirements associated to the traffic volumes and wider functionality that the network interface has to support. This way, taking into account the rate of link bandwidth improvement and the ever changing and increasing application demands, efficient network interface architectures require scalability and flexibility. An opportunity to reach these goals comes from the exploitation of the parallelism in the communication path by distributing the protocol processing work across processors which are available in the computer, i.e. multicore microprocessors and programmable NICs.Thus, after a brief review of the different solutions that have been previously proposed for speeding up network interfaces, this paper analyzes the onloading and offloading alternatives. Both strategies try to release host CPU cycles by taking advantage of the communication workload execution in other processors present in the node. Nevertheless, whereas onloading uses another general-purpose processor, either included in a chip multiprocessor (CMP) or in a symmetric multiprocessor (SMP), offloading takes advantage of processors in programmable network interface cards (NICs). From our experiments, implemented by using a full-system simulator, we provide a fair and more complete comparison between onloading and offloading. Thus, it is shown that the relative improvement on peak throughput offered by offloading and onloading depends on the rate of application workload to communication overhead, the message sizes, and on the characteristics of the system architecture, more specifically the bandwidth of the buses and the way the NIC is connected to the system processor and memory. In our implementations, offloading provides lower latencies than onloading, although the CPU utilization and interrupts are lower for onloading. Taking into account the conclusions of our experimental results, we propose a hybrid network interface that can take advantage of both, programmable NICs and multicore processors. 相似文献