In vivo interactive visualization of four-dimensional blood flow patterns

In this paper we give an overview over a series of experiments to visualize and measure flow fields in the human vascular system with respect to their diagnostic capabilities. The experiments utilize a selection of GPU-based sparse and dense flow visualization algorithms to show the diagnostic opportunities for volumetric cardiovascular phase contrast magnetic resonance imaging data sets. Besides classical hardware accelerated particle and line-based approaches, an extensible tublet-based visualization, a four-dimensional volumetric line integral convolution and a new two-dimensional cutting plane tool for three-dimensional velocity data sets have been implemented. To evaluate the results, several hearts of human subjects have been investigated and a flow phantom was built to artificially simulate distinctive flow features. Our results demonstrate that we are able to provide an interactive tool for cardiovascular diagnostics with complementary hardware accelerated visualizations. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.

Speed scaling with a solar cell

We consider the setting of a device that obtains its energy from a battery and some regenerative source such as a solar cell. We consider the speed scaling problem of scheduling a collection of tasks with release times, deadlines, and sizes, so as to minimize the energy recharge rate of the regenerative source. This is the first theoretical investigation of speed scaling for devices with a regenerative energy source. We show that the problem can be expressed as a polynomial sized convex program. We show that, using the KKT conditions, one can obtain an efficient algorithm to verify the optimality of a schedule. We show that the energy optimal YDS schedule is 2-approximate with respect to the recharge rate. We show that the online algorithm BKP is O(1)$O\left(1\right)$-competitive with respect to recharge rate.     

Design and performance of speculative flow control for high-radix datacenter interconnect switches

High-radix switches are desirable building blocks for large computer interconnection networks, because they are more suitable to convert chip I/O bandwidth into low latency and low cost than low-radix switches [J. Kim, W.J. Dally, B. Towles, A.K. Gupta, Microarchitecture of a high-radix router, in: Proc. ISCA 2005, Madison, WI, 2005]. Unfortunately, most existing switch architectures do not scale well to a large number of ports, for example, the complexity of the buffered crossbar architecture scales quadratically with the number of ports. Compounded with support for long round-trip times and many virtual channels, the overall buffer requirements limit the feasibility of such switches to modest port counts. Compromising on the buffer sizing leads to a drastic increase in latency and reduction in throughput, as long as traditional credit flow control is employed at the link level. We propose a novel link-level flow control protocol that enables high-performance scalable switches that are based on the increasingly popular buffered crossbar architecture, to scale to higher port counts without sacrificing performance. By combining credited and speculative transmission, this scheme achieves reliable delivery, low latency, and high throughput, even with crosspoint buffers that are significantly smaller than the round-trip time. The proposed scheme substantially reduces message latency and improves throughput of partially buffered crossbar switches loaded with synthetic uniform and non-uniform bursty traffic. Moreover, simulations replaying traces of several typical MPI applications demonstrate communication speedup factors of 2 to 10 times.     

The effect of visualizing the flow of multimedia content among and inside devices

This study introduces a user interface, referred to as the flow interface, which provides a graphical representation of the movement of content among and inside audio/video devices. The proposed interface provides a different frame of reference with content-oriented visualization of the generation, manipulation, storage, and display of content as well as input and output. The flow interface was applied to a VCR/DVD recorder combo, one of the most complicated consumer products. A between-group experiment was performed to determine whether the flow interface helps users to perform various tasks and to examine the learning effect of the flow interface, particularly in regard to hooking up and recording tasks. The results showed that participants with access to the flow interface performed better in terms of success rate and elapsed time. In addition, the participants indicated that they could easily understand the flow interface. The potential of the flow interface for application to other audio video devices, and design issues requiring further consideration, are discussed.     

A TCAM-based solution for integrated traffic anomaly detection and policy filtering

The survivability of the future Internet is largely dependent on whether it will be able to successfully address both security and performance issues facing the Internet. On one hand, the Internet becomes more and more vulnerable due to fast spreading malicious attacks. On the other hand, it is under great stress to meet ever growing/changing application demands while having to sustain multi-gigabit forwarding performance. In this paper, we propose a Ternary Content Addressable Memory (TCAM) coprocessor based solution for high speed, integrated TCP flow anomaly detection and policy filtering. The attacking packets with spoofed source IP addresses are detected through two-dimensional (2D) matching. The key features of the solution are: (1) setting flag bits in TCAM action code to support various packet treatments; (2) managing TCP flow state in pair to do 2D matching. We evaluate the solution’s ability to detect TCP-based flooding attacks based on real-world-trace simulations. The results show that the proposed solution can match up OC-192 line rate. The possible modifications of the solution for the detection of low rate TCP-targeted attacks are also discussed.     

基于单元的孤立点检测算法改进及应用

研究基于单元的孤立点检测算法,给出数据空间的单元格划分及数据对象分配算法。针对该算法中阈值M设置的不足,对算法进行改进并应用于纳税行为的分析。与其他孤立点检测算法对比的结果表明,该算法不仅能有效挖掘纳税行为中的孤立点,还能确定孤立点的位置,有利于对纳税行为的分析。     

Investigating the influence of age,social capital affinity,and flow on positive outcomes reported by e-commerce site users

This study investigated the role of social capital affinity (the sense of community and likeness felt for people online) and the experience of flow (concentrated engagement in/enjoyment of an activity) as antecedents to a variety of positive outcomes associated with the use of e-commerce sites. Also, based on socio-emotional selectivity theory, the current study assessed the influence of age on social capital affinity and flow. As a subset of data from a telephone sample of Internet users in the USA, 282 e-commerce users responded to questions about site satisfaction, perceived focused and incidental knowledge-gains, and affirmation, in addition to flow and social capital affinity. As predicted by socio-emotional selectivity theory, there was a negative relationship between age and social capital affinity and flow. Flow, for its part, mediated the effects of age and social capital affinity on perceived focused and incidental knowledge-gain, satisfaction and affirmation among participants reporting e-commerce use. Finally, the current results indicated that satisfaction and perceived incidental learning predicted participant affirmation for their chosen e-commerce site.     

The influence of goal clarity,curiosity, and enjoyment on intention to code

The purpose of this study is to examine the influence of goal clarity, curiosity, and enjoyment – dimensions of flow theory – on the intention to write programming code. This research refines and extends previous information systems (IS) research in two significant ways: first, this research is focused specifically on systems development behaviour; second; this is the first research that isolates specific flow theory constructs associated with systems development behaviour. We used SmartPLS to test our model, as partial least squares is the appropriate statistical methodology for theory building and model testing. Findings are based on survey data from computer IS classes at two different universities. Goal clarity and curiosity independently and significantly contributed to enjoyment when programming, which significantly and positively influenced a future intention to code. Recommendations for practitioners and faculty include testing for curiosity characteristics, providing clear goals, and providing stimuli to pique curiosity.     

Solution algorithms for synchronous flow shop problems with two dominating machines

In this paper, we present solution algorithms for synchronous flow shop problems with two dominating machines. In such an environment, jobs have to be moved from one machine to the next by an unpaced synchronous transportation system, which implies that the processing is organized in synchronized cycles. This means that in each cycle the current jobs start at the same time on the corresponding machines and after processing have to wait until the last job is finished. Afterwards, all jobs are moved to the next machine simultaneously. Motivated by a practical application, we investigate the special case of two dominating machines where the processing times of all jobs on these two machines are at least as large as the processing times of all jobs on the other machines and hence always determine the cycle times. After formulating the considered problem as a special vehicle routing problem, we propose mixed integer linear programming formulations and a tabu search algorithm. Finally, we present computational results for randomly generated data and show the efficiency of the approaches.     

Stability of Local On‐Ramp Metering Control Laws

A framework for stability analysis of local on‐ramp metering control strategies based on the cell transmission model is presented. Within this framework, it is possible to formulate Lyapunov and input‐state stability results for on‐ramp metering control strategies in an open section of highway with on‐ramps. Using this analysis, recommendations for the design of on‐ramp metering control laws set points are derived. Two examples on the use of such analysis are presented. One deals with the stability analysis of a local on‐ramp metering control law and the other with the design of a disturbance observer that, used in combination with the local on‐ramp metering control law, provides a more robust response to traffic regulation. Simulation results are included that confirm the possibility of using this framework to test the impact of local on‐ramp metering control strategies.