A cost-effective heuristic to schedule local and remote memory in cluster computers

Cluster computers represent a cost-effective alternative solution to supercomputers. In these systems, it is common to constrain the memory address space of a given processor to the local motherboard. Constraining the system in this way is much cheaper than using a full-fledged shared memory implementation among motherboards. However, memory usage among motherboards can be unfairly balanced.     

冀东油田人工岛试油安全环保管理探讨与实践

滩海油田人工岛特殊的海况和工况条件,对岛内的油气生产作业提出了全新的安全和环保理念。为此探讨和实践新领域内的试油安全环保管理模式,能够最大限度地保障人工岛试油期间的安全环保控制,实现试油与全岛各类油气生产作业的有序整体融合。     

Velocity Volatility Assessment of Monetary Shocks on Cash-in-Advance Economies

A projection method employing finite elements and a parameterized expectations algorithm is proposed for the global approximation of the equilibrium of a cash-in-advance model economy. The algorithm is shown to be accurate and efficient approximating highly nonlinear regions of the policy functions, specifically along the space of state variables where the slackness multiplier of the cash-in-advance constraint alternates between zero and strictly positive values. This favorable trait allows for a rigorous analysis on the variability of velocity of money. Velocity volatility, measured by its coefficient of variation, arises in the model on a consumption smoothing purpose by the agent at instances where the variation of expected marginal utility of consumption is relatively high due to the realization of a sufficiently low serially correlated monetary shock. In a simulation of the stochastic economic environment responding to a Markovian series of monetary growth rates and no frictions present, the equilibrium approximated via the proposed numerical solution method explains 80.3% of the velocity variability recently observed in the data; a significant improvement over previous attempts found in the literature.     

A “four-ferrocene” modified stem-loop structure as a probe for sensitive detection and single-base mismatch discrimination of DNA

We report the use of a four-ferrocene modified oligonucleotide as a probe for DNA detection with a gold electrode microsystem. This oligonucleotide is synthesized by automated solid-phase synthesis with four successive ferrocene moieties at the 5′-end and a C6-thiol modifier group at the 3′-end. The grafting of this 4Fc-DNA probe on a gold electrode microsystem results in the appearance of the ferrocene redox couple in cyclic voltammetry. The probe sequence is a stem-loop structure that folds efficiently on the electrode, thus optimizing electron transfer. Such architecture serves as sensor for DNA detection which is based on hybridization. The resulting disposable voltammetric sensor allowed direct, reagentless DNA detection in a small volume (20 μL). Electrochemical response upon hybridization with complementary short sequence (30-base length) and long sequence (50-base length) strands was observed by differential pulse voltammetry. Current variations were compared. The longer the sequence, the greater the decrease in current. The system's detection limit was estimated at 3.5 pM (0.07 fmol in 20 μL) with the 50-base length target and provided a dynamic detection range between 3.5 pM and 5 nM. Single mismatch detection showed a good level of sensitivity. The system was regenerated twice with no significant loss of Fc signal. Finally, 1 pM sensitivity was reached with a long chain analog of DNA PCR products of Influenza virus.     

Mapping low-Reynolds-number microcavity flows using microfluidic screening devices

Low-Reynolds-number flows in cavities, characterized by separating and recirculating flows are increasingly used in microfluidic applications such as mixing and sorting of fluids, cells, or particles. However, there is still a lack of guidelines available for selecting the appropriate or optimized microcavity configuration according to the specific task at hand. In an effort to provide accurate design guidelines, we investigate quantitatively low-Reynolds-number cavity flow phenomena using a microfluidic screening platform featuring rectangular channels lined with cylindrical cavities. Using particle image velocimetry (PIV), supported by computational fluid dynamics (CFD) simulations, we map the entire spectrum of flows that exist in microcavities over a wide range of low-Reynolds numbers (Re = 0.1, 1, and 10) and dimensionless geometric parameters. Comprehensive phase diagrams of the corresponding microcavity flow regimes are summarized, capturing the gradual transition from attached flow to a single vortex and crossing through two- and three-vortex recirculating systems featuring saddle-points. Finally, we provide design insights into maximizing the rotational frequencies of recirculating single-vortex microcavity systems. Overall, our results provide a complete and quantitative framework for selecting cavities in microfluidic-based microcentrifuges and vortex mixers.     

建科技交流平台 助冶金行业发展

《河北冶金》作为河北省冶金行业唯一的国内外公开发行的科技期刊,创刊于1979年11月,伴随着我国的改革开放走过了33年的历程,在改革中诞生,在改革中成长。33年中,《河北冶金》承载着河北冶金行业科技工作者的厚望,历经磨难,奋力拼搏,以其高质量、有特色赢得了广泛赞誉,成为今天在国内外期刊界有一定影响力的科技刊物,以其独有的专业特色和综合性内容展现出自己的风采,标识出存在的价值,屹立于中国科技期刊之林。     

Research on seismic resistance and mechanic behavior of reinforced lightweight aggregate concrete walls after high temperature

This study focused on the mechanical behavior of reinforced lightweight aggregate concrete (RLAC) walls under repeated horizontal loads after a standard temperature‐rising fire‐resistance test and compared the specimen walls' ultimate loads, yielding loads, cracked loads, stiffness, and ductility with those of reinforced normal‐weight aggregate concrete (RNAC) walls. Steel reinforcing bar spacing, aggregate types, wall widths, and high temperatures were variables in this study. The experimental results showed that, after the fire‐resistance test, the smaller the steel reinforcing bar spacing of RLAC walls, the higher the yield and ultimate loads, yet the worse the ductility and the hysteresis loop's energy, whereas the greater the width of the wall, the greater the stiffness and the higher the hysteresis loop's energy. The differences in terms of stiffness, ductility, and hysteresis between RLAC walls with and without the fire‐resistance test were insignificant, indicating that RLAC walls do not lose their basic mechanical behavior during a high‐temperature fire. RNAC walls showed, indeed, a significant downward trend for strength and hysteresis after the fire‐resistance test, but the decrease was much less clear for stiffness. Therefore, RLAC walls did show better seismic resistance than RNAC walls under the same testing conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Data‐driven bounded‐error fault detection

In this paper, a new data‐driven fault‐detection method is proposed. This method is based on a new nonparametric system identification approach, which constitutes the principal contribution to this work. The fault‐detection method is a parametric model‐free approach that can be applied to nonlinear systems that work at various operating points. Not only can the fault‐detection process be applied to the steady state of each operating point, but it can also be applied to the transient state resulting from a change in the operating point. In order to detect faults, the proposed method uses an interval predictor based on bounded‐error techniques. The utilization of techniques based on bounded error enables system uncertainties to be included in an explicit way. This in turn leads to the possibility of obtaining interval predictions of the behaviour of the system, which include information on the reliability of the prediction itself. In order to show the effectiveness of the fault‐detection method, two examples are presented: in the form of a simulated process (counter‐flow shell‐and‐tube heat‐exchanger system) and an example of a real application (two‐tanks system). A comparison with two fault‐detection methods has also been included. Copyright © 2013 John Wiley & Sons, Ltd.