Continuous Well-Composedness Implies Digital Well-Composedness in n-D

Journal of Mathematical Imaging and Vision - In this paper, we prove that when a n-D cubical set is continuously well-composed (CWC), that is, when the boundary of its continuous analog is a...     

Tight performance bounds in the worst-case analysis of feed-forward networks

Network Calculus theory aims at evaluating worst-case performances in communication networks. It provides methods to analyze models where the traffic and the services are constrained by some minimum and/or maximum envelopes (arrival/service curves). While new applications come forward, a challenging and inescapable issue remains open: achieving tight analyzes of networks with aggregate multiplexing. The theory offers efficient methods to bound maximum end-to-end delays or local backlogs. However as shown in a recent breakthrough paper (Schmitt et al. 2008), those bounds can be arbitrarily far from the exact worst-case values, even in seemingly simple feed-forward networks (two flows and two servers), under blind multiplexing (i.e. no information about the scheduling policies, except FIFO per flow). For now, only a network with three flows and three servers, as well as a tandem network called sink tree, have been analyzed tightly.We describe the first algorithm which computes the maximum end-to-end delay for a given flow, as well as the maximum backlog at a server, for any feed-forward network under blind multiplexing, with piecewise affine concave arrival curves and piecewise affine convex service curves. Its computational complexity may look expensive (possibly super-exponential), but we show that the problem is intrinsically difficult (NP-hard). Fortunately we show that in some cases, like tandem networks with cross-traffic interfering along intervals of servers, the complexity becomes polynomial. We also compare ourselves to the previous approaches and discuss the problems left open.     

Intelligent antenna selection decision in IEEE 802.15.4 wireless sensor networks: An experimental analysis

The goal of this paper is to study the feasibility of making intelligent antenna selection decision in IEEE 802.15.4 Wireless Sensor Networks (WSNs). This study provides us the basis to design and implement software defined intelligent antenna switching capability to wireless sensor nodes based on Received Signal Strength Indicator (RSSI) link quality metric. First, we discuss the results of our newly designed radio module (Inverted-F Antenna) for 2.4 GHz bandwidth (WSNs). Second, we propose an intelligent antenna selection strategy to exploit antenna diversity. Third, we propose the prototype of our diversity antenna for the TelosB mote and the intelligent switch design. Finally, we compare the performance of the built-in TelosB antenna with our proposed external antenna in both laboratory and realistic environments. Experimental results confirm the gain of 6–10 dB of the proposed radio module over the built-in radio module of the TelosB motes.     

四功能引发剂引发的苯乙烯自由基本体聚合速度的测定和模拟

介绍一种新型的四功能引发剂LuperoxJWEB50，利用它引发苯乙烯自由基本体聚合，引发剂效率随引发剂浓度降低和聚合湿度的增加而增加，当湿度增加到－145℃时，引发剂效率在不同的引发剂深度下几乎相同，约0.78-0.8。实验表明，在湿度范围125－145℃时，采用该四功能引发剂引发的苯乙烯本体聚合的凝胶效应并不明显，并介绍一种单体转化率的测定方法，建立了考虑渗透和热引发的动力学模型来模拟聚合进程，模拟结果表明，即使单体转化率很高，此模型也能令人满意地预测聚合反应的进展。     

Neuromatrix: The World is Embodied in our Brain

Our brain is an interpreter, probably the most powerful ever conceived by Nature. However, just like every interpreter, it is limited and sometimes it can get things wrong. Most of us take it for granted that what we touch, hear, see, taste and smell is “reality”. But this reality is an illusion, a construct, which only exists in our brain, that is, a mental representation. Indeed, what if we could perceive infrared radiations like Cobras or Predator? What if we could see in very low light like cats? What if we could smell people and foods hidden from view 500 yards away? Surely “reality” would feel much different to us if our sensors and brain were able to extract and process such information from the external world. Even more puzzling is the fact that our senses can betray us completely. This is what happens when we see things that are not there or, on the contrary, when we do not see things that are before our eyes. During this lecture, I will attempt to show how the world in embodied in our brain by looking at examples of interactive visual illusions, by showing the power of attention in defining what we see in the world around us, and by introducing patients with brain lesions or mental illness who perceive the world differently.     

Optimization of occupancy rate in dial-a-ride problems via linear fractional column generation

In this paper, we consider a dial-a-ride problem where the objective is to maximize the passenger occupancy rate. The problem arises from an on-demand transportation system developed in a rural zone in France, where the objective of encouraging people meeting is pursued. We address the solution of the problem with a column generation approach, applied to a set partitioning formulation where the objective function is fractional. Based on the literature on linear fractional programming, two methods are developed to deal with this fractional objective. Experiments permit to compare these two approaches and to evaluate the impact of the new objective compared to a standard min-cost or min-time optimization.