Fast floorplanning for effective prediction and construction

Floorplanning is a crucial phase in VLSI physical design. The subsequent placement and routing of the cells/modules are coupled very closely with the quality of the floorplan. A widely used technique for floorplanning is simulated annealing. It gives very good floorplanning results but has major limitation in terms of run time. For circuit sizes exceeding tens of modules simulated annealing is not practical. Floorplanning forms the core of many synthesis applications. Designers need faster prediction of system metrics to quickly evaluate the effects of design changes. Early prediction of metrics is imperative for estimating timing and routability. In this work we propose a constructive technique for predicting floorplan metrics. We show how to modify the existing top-down partitioning-based floorplanning to obtain a fast and accurate floorplan prediction. The prediction gets better as the number of modules and flexibility in the shapes increase. We also explore applicability of the traditional sizing theorem when combining two modules based on their sizes and interconnecting wirelength. Experimental results show that our prediction algorithm can predict the area/length cost function normally within 5-10% of the results obtained by simulated annealing and is, on average, 1000 times faster     

The effect of circular bridge piers with different inclination angles toward downstream on scour

A fundamental principle in the safe design of bridge piers is to estimate maximum scour depth. As such, many researchers devoted their efforts to study the phenomenon of scour around bridge piers and to present relationships to estimate maximum scour depth. In the current research, scour around circular bridge piers with two different diameters and different inclination angles toward downstream has been investigated experimentally under clear water and different discharges. The obtained results revealed that increase in the inclination angle leads to a significant decrease in the scour depth, dimensions of sediment ridge and scour hole. Moreover, by comparing the data obtained from vertical bridge pier and well-known relationships, a relationship having the most agreement with the results was selected and modified to estimate equilibrium scour depth around inclined piers.     

Estimating the drift time for processes subject to linear trend disturbance using fuzzy statistical clustering

Although control charts can notify the state of out-of-control in a process by generating a signal, the indication is usually followed by a considerable amount of delay. Identifying the real time of the change in a process would provide a starting point for further investigation of an assignable cause. This paper addresses the problem of detecting the change point in different processes when the quality characteristics drift steadily away from an in-control state. For this purpose, a fuzzy statistical clustering (FSC) method is used to estimate the drift time in different processes. Since the application of an FSC method requires both in- and out-of-control values of the process parameter, a linear regression model is utilised to estimate the trend rate and then calculate the out-of-control process parameter. Through extensive simulations, the performance of the proposed change point estimation method is analysed and compared with the most recent estimators for several control charts. The results demonstrate that the proposed method is more effective in detecting the drift time through a wide range of trend rates. Furthermore, it is shown that the proposed method offers a higher estimation precision compared to conventional statistical methods.     

Synthesis,characterization and evaluation of bioactivity and antibacterial activity of quinary glass system (SiO2–CaO–P2O5–MgO–ZnO): In vitro study

Bioactive glasses in the systems SiO₂–CaO–P₂O₅–MgO (BGZn0) and SiO₂–CaO–P₂O₅–MgO–ZnO (BGZn5), were prepared by sol–gel method and then characterized. Surface reactivity was studied in simulated body fluid (SBF) to determine the effect of zinc (Zn) addition as a trace element. The effect of Zn addition to the glass matrix on the formation of apatite layer on the glass surface was investigated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR) and scanning electron microscopy (SEM). Also, inductively coupled plasma–optical emission spectroscopy (ICP–sOES) was used to determine the concentrations of released ions in SBF solution after different time intervals in SBF solution. The antibacterial activity of Zn containing glass against Pseudomonas aeruginosa was measured by the halo zone test. The presence of Zn in glass composition improved chemical durability, slowed down the formation rate of Ca–P layer and decreased the size of crystalline apatite particles. Zn containing glass exhibited an excellent antibacterial activity against P. aeruginosa which could demonstrate its ability to treat bone infection.     

Simultaneous synthesis and single-step sintering of lead magnesium niobate ceramic using mixed nanopowders

A high density single-phase lead magnesium niobate ceramic with the highest peak dielectric constant reported so far, has been synthesized and sintered simultaneously via a modified mixed oxide route, using mixed oxide nanopowder and single-step sintering. The mixed nanopowder was sintered at 1200 °C in air and PbO atmospheres. By comparison, samples sintered in air, gained pyrochlore structure, while those samples sintered in PbO atmosphere had pure perovskite structure. Pellets sintered for 2.5 h exhibited best dielectric properties with peak dielectric constant of 18,672 at the frequency of 1 kHz at −13 °C. The dielectric properties, compressibility, phase formation, densification, and microstructure of the samples were investigated.     

A stochastic well-test analysis on transient pressure data using iterative ensemble Kalman filter

Neural Computing and Applications - Accurate estimation of the reservoir parameters is crucial to predict the future reservoir behavior. Well testing is a dynamic method used to estimate the...     

计及动态修正的自适应广域低频减载

传统分轮逐次逼近的低频减载方法,对系统运行变化缺乏足够的适应性,会造成过切、欠切等问题,所以提出一种基于广域测量系统计及动态修正的自适应低频减载策略。在低阶频率响应模型的基础上,考虑电压对不平衡功率的影响,利用较短周期内的系统响应轨迹估计系统不平衡功率;考虑系统频率自恢复调节能力,采用频率变化率变化梯度逐轮对减载量进行动态修正;各负荷节点减载量由计及负荷特性、发电机受扰程度的多因素综合指标确定。IEEE 68节点系统仿真结果表明,所提方法可有效减少负荷切除量,同时能明显缩短频率恢复时间,保证了系统的稳定运行。     

A diversity control mechanism in many objective optimizations

Multi-objective evolutionary optimization algorithms are among the best optimizers for solving problems in control systems, engineering and industrial planning. The performance of these algorithms degrades severely due to the loss of selection pressure exerted by the Pareto dominance relation which will cause the algorithm to act randomly. Various recent methods tried to provide more selection pressure but this would cause the population to converge to a specific region which is not desirable. Diversity reduction in high dimensional problems which decreases the capabilities of these approaches is a decisive factor in the overall performance of these algorithms. The novelty of this paper is to propose a new diversity measure and a diversity control mechanism which can be used in combination to remedy the mentioned problem. This measure is based on shortest Hamiltonian path for capturing an order of the population in any dimension. In order to control the diversity of population, we designed an adaptive framework which adjusts the selection operator according to diversity variation in the population using different diversity measures as well as our proposed one. This study incorporates the proposed framework in MOEA/D, an efficient widely used evolutionary algorithm. The obtained results validate the motivation on the basis of diversity and performance measures in comparison with the state-of-the-art algorithms and demonstrate the applicability of our algorithm/method in handling many-objective problems. Moreover, an extensive comparison with several diversity measure algorithms reveals the competitiveness of our proposed measure.     

Isolation of stem cells from adult rat kidneys

The kidney has an inherent ability for recovery and regeneration following acute damage. However, there has been much contention as to the source of regenerating renal cells. The aim of this study was to isolate and characterize these cells. Normal rat kidneys were minced and cells were isolated with collagenase I and were cultured in an expansion medium. Adherent cells were isolated and expanded for more than 120 days in vitro. These cells had the potential of trans-lineage differentiation into neural cells, adipocytes and osteocytes. These cells also expressed Nucleostemin, Cyclin D1, Notch1 and Survivin which are commonly expressed in stem cells. The results of the current work show that the adult kidney contains a population of multipotent stem cells.     

Impact of gender, age and experience of pilots on general aviation accidents

General aviation (GA) accounts for more than 82% of all air transport-related accidents and air transport-related fatalities in the U.S. In this study, we conduct a series of statistical analyses to investigate the significance of a pilot's gender, age and experience in influencing the risk for pilot errors and fatalities in GA accidents. There is no evidence from the Chi-square tests and logistic regression models that support the likelihood of an accident caused by pilot error to be related to pilot gender. However, evidence is found that male pilots, those older than 60 years of age, and with more experience, are more likely to be involved in a fatal accident.