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排序方式: 共有993条查询结果,搜索用时 15 毫秒
851.
Schindler Ines; Staudinger Ursula M.; Nesselroade John R. 《Canadian Metallurgical Quarterly》2006,21(4):737
The development of personal life investment (PLI) during old age was investigated with longitudinal and cross-sectional data from the Berlin Aging Study (N = 516, ages = 70-103 years). PLI measures motivational energy expended in life domains that require (obligatory PLI) or do not require (optional PLI) investment in old age. The authors used structural modeling to determine developmental trajectories and dynamics of the PLI types. On average, obligatory PLI remained unchanged between 70 and 101 years. Optional PLI declined during the transition to the 4th age (between 80 and 90 years). When change on the intraindividual level was considered, reductions in optional PLI were not related to changes in obligatory PLI, but declining obligatory PLI was associated with declining optional PLI. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
852.
A trade off between emergency repair and inventory investment 总被引:1,自引:0,他引:1
In this paper we present an emergency repair model. We model a situation where failed parts arrive at a repair shop according to a Poisson process. If the stock on hand of serviceable spare parts exceeds a given emergency trigger level, the failed part is sent into normal repair. Otherwise the failed part is sent into an alternative emergency repair channel. Upon arrival failed parts are exchanged for serviceable spare parts, if available. Otherwise the demand is backordered. A backorder is filled with the first part that becomes available from either one of the repair processes. The repair times (including transportation time) are assumed to be exponentially distributed. We analyze the impact of using emergency repair on two service measures: the fraction of demand that is satisfied from stock on hand and the expected duration of a backorder. We calculate the initial stock level and the emergency trigger level that minimize the total cost for a given emergency repair rate. The proposed policy is compared with two other policies: (1) emergency repair is not used and (2) emergency trigger level is zero. We find that significant service improvements and cost reductions can be obtained by using our emergency repair policy. We also present simulation results showing that the distribution of the repair times has a negligible effect on the relevant service measures. Finally, we compare our results with the results of an emergency supply model by Muckstadt and Thomas [1] Again we observe significant cost reductions when using our policy. 相似文献
853.
Theories of choice in economics typically assume that interacting agents act individualistically and maximize their own utility. Specifically, game theory proposes that rational players should defect in one-shot prisoners' dilemmas (PD). Defection also appears to be the inevitable outcome for agents who learn by reinforcement of past choices, because whatever the other player does, defection leads to greater reinforcement on each trial. In a computer simulation and 4 experiments, the authors show that, apparently paradoxically, when players' choices are correlated by an exogenous factor (here, the cooperativeness of the specific PD chosen), people obtain greater average reinforcement for cooperating, which can sustain cooperation. This effect arises from a well-known statistical paradox, Simpson's paradox. The authors speculate that this effect may be relevant to aspects of real-world human cooperative behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
854.
Ivo Grabchev Ivanka Moneva Rositza Betcheva Galina Elyashevich 《Materials Research Innovations》2002,6(1):34-37
Microporous polyethylene (PE) films with good mechanical properties have been produced by high-speed extrusion from the melt
followed by annealing, uniaxial stretching and thermal fixation. The films have pores of 0.15–0.45 μm size and relief on the
scale of 1–2 μm. Coloration of the films with fluorescent dyes, 3-aminobenzanthrone and derivatives of 1,8-naphthalimide,
was performed at the room temperature. The quantity of adsorbed dye depends upon the spin draw ratio of PE membranes and has
an influence upon their color shade. The color effect is not observed in the case of only extruded or annealed PE films treated
in the same way. The enhanced adhesion of the dyes on porous films is related to their high surface area. Specifically, the
interactions between dye and polymer at pore walls provide color stability of the microporous films. The effect of relevant
properties of both PE membranes (pores relief and lamellar thickness) and dye molecules (aspect ratio and cohesion) is discussed.
Electronic Publication 相似文献
855.
Ivo Schindler Rudolf Kawalla Jiri Plura Tomas Kubina Stanislav Rusz Eugeniusz Hadasik Vladislav Jurko 《国际钢铁研究》2008,79(10):758-764
The aim of this work was to describe the deformation resistance of austenitized Ti‐IF steel in the temperature range of 650 to 1100°C by a complex equation. The mean flow stress was determined by an original procedure, based on laboratory rolling of flat samples. Deformation resistance was described by a single formula, using a cumulative function in which particular terms are multiplied by a coefficient of 1 or 0, in dependence on a specific temperature. Calculation of specific coefficients had to be proposed in such a way that they could react to exceeding temperature boundaries between individual phase regions. The developed model can be used for off‐line predictions of power/force parameters in the forming of Ti‐IF steel, in a wide range of conditions of hot and warm deformation. 相似文献
856.
R Schnell E Vitetta J Schindler S Barth U Winkler P Borchmann ML Hansmann V Diehl V Ghetie A Engert 《Canadian Metallurgical Quarterly》1998,30(5-6):525-537
Immunotoxins (ITs) consisting of a cell-binding component and a potent toxin were developed as a new class of biological anti-tumor agents to improve adjuvant therapy. Hodgkin's lymphoma (HL) has been demonstrated to be an excellent target for ITs because high concentrations of lymphocyte activation markers such as CD25 and CD30 are expressed on Hodgkin and Reed-Sternberg (H-RS). Several ITs against these antigens have shown potent antitumor effects against H-RS cells in vitro and in different HL animal models. On the basis of its superiority in preclinical models, the anti-CD25 IT RFT5-SMPT-dgA was subsequently evaluated in a phase I study in patients with refractory Hodgkin's lymphoma. The IT was constructed by linking the monoclonal antibody (Moab) RFT5 via a sterically hindered disulfide linker (SMPT) to deglycosylated ricin A-chain (dgA). All 15 patients enrolled in this trial were heavily pretreated with a mean of five different prior therapies. The IT was administered intravenously over four hours on days 1-3-5-7 for total doses per cycle of 5, 10, 15, or 20 mg/m2. Side effects were reversible and related to the vascular leak syndrome (VLS), i.e. decrease in serum albumin, edema, weight gain, hypotension, tachycardia, myalgia, and weakness. In all three patients receiving 20 mg/m2 NCI toxicity grade III was observed. Thus, 15 mg/m2 is the maximal tolerated dose (MTD) of RFT5-SMPT-dgA. 50% of the patients developed human anti-ricin A-chain antibodies (HARA) and/or human anti-mouse antibodies (HAMA). Clinical results included two partial remissions (PR), one minor response (MR), three stable disease (SD) and nine progressive disease (PD). In an extension of the phase I trial, five additional patients have been treated at the MTD. 相似文献
857.
Slavica Tomovic Kenji Yoshigoe Ivo Maljevic Igor Radusinovic 《Wireless Personal Communications》2017,92(1):181-196
Rapid increase in number and diversity of Internet-connected devices raises many challenges for the traditional network architecture, which is not designed to support a high level of scalability, real-time data delivery and mobility. To address these issues, in this paper we present a new model of Internet of Things architecture which combines benefits of two emerging technologies: software-defined networking and Fog computing. Software-defined networking implies a logically centralized network control plane, which allows implementation of sophisticated mechanisms for traffic control and resource management. On the other hand, Fog computing enables some data to be analysed and managed at the network edge, thus providing support for applications that require very low and predictable latency. In the paper, we give detailed insight into the system structure and functionality of its main components. We also discuss the benefits of the proposed architecture and its potential services. 相似文献
858.
Solvent‐Induced Rearrangement of Ion‐Transport Channels: A Way to Create Advanced Porous Membranes for Vanadium Flow Batteries
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Wenjing Lu Zhizhang Yuan Mingrun Li Xianfeng Li Huamin Zhang Ivo Vankelecom 《Advanced functional materials》2017,27(4)
Porous membranes with critically hydrophobic/hydrophilic phase‐separated‐like structures for use in vanadium flow battery application are first realized by solvent‐induced reassembly of a polymer blend system. Porous poly(ether sulfone) (PES)/sufonated poly(ether ether ketone) (SPEEK) blend membranes with tunable pore size are prepared via the phase inversion method. After solidification, isopropanol (IPA) is introduced to induce the reassembly of sulfonated groups and further form ion‐transport channels by using the interaction between IPA and functional groups in SPEEK. As a result, a highly phase separated membrane structure is created, composed of a highly stable hydrophobic porous PES matrix and hydrophilic interconnected small pores. The charged pore walls are highly beneficial to improving proton conductivity, while pores are simultaneously shrunk during the IPA treatment. Therefore, the resultant membranes show an excellent battery performance with a coulombic efficiency exceeding 99%, along with an energy efficiency over 91%, which is among the highest values ever reported. This article supplies an ease‐to‐operate and efficient method to create membranes with controlled ion‐transport channels. 相似文献
859.
860.
Gero Göbel Kirsten Schubert Ivo W. Schubart Waqas Khalid Wolfgang J. Parak Fred Lisdat 《Electrochimica acta》2011,(18):6397
Quantum dots (QD) immobilised on electrodes show a light-triggered current depending on the applied potential. In this study it is investigated whether multiple layers of QD can be formed on electrodes and used for an enhanced photocurrent generation. Therefore multilayers of QD and the redox protein cytochrome c (cyt c) are constructed verified by quartz crystal microbalance (QCM) measurements. The voltammetric investigation of these multilayer assemblies shows no enhancement of the redox signal from cyt c in contrast to multilayers of cyt c and polyelectrolytes or gold nanoparticles. But photocurrent measurements reveal a slight enhancement of the signal which is depending on the number of deposited QD layers. In a second step QD multilayers with a positively charged polyelectrolyte are built up verified by QCM. Chronoamperometric investigations reveal an increase of the photocurrent which is proportional to the number of deposited layers. This indicates an efficient electron transfer between the QD layers. At an electrode with 5 bilayers (QD and polyallylamine) the light-induced current is increased about 5 times compared to a monolayer. 相似文献