Local Flow Information Research Articles

Perceptions of risk in the post-Soviet world: A qualitative study of responses to falling rockets in the Altai region of Siberia

There is widespread concern among people living in some parts of Altai territory in Siberia about potential health effects from fallout from rockets launched from the Baikonur cosmodrome in Kazakhstan. Extensive research has so far failed to provide evidence to support these concerns. As a consequence, the problem has been labelled by Russian scientists as ‘collective psychosocial distress’ or ‘raketophobia’. The aim of this paper is to provide an understanding of the factors underlying popular concerns about rockets. The paper is based on data collected in 2006 using multiple methods (individual semi-structured interviews, natural group discussions, round tables and participant observation). Concerns related to the impact of the rocket launches among the local population were explored. The analytical framework is informed by discourse analysis and discursive psychology. The findings are that the processes of collective social construction amplify risks perceived to be associated with rocket launches. In the Altai context, this social amplification builds on a societal vulnerability triggered by the collapse of the Soviet ideology. The environmental concern provides opportunities for repressed debates to be expressed that emerge from culturally embedded frustrations and fears that would otherwise be ignored by the political agenda. Moreover, the signals that shape the perception of risk are intrinsic components of local information flows, so that the communication process between experts and policy-makers and the local population itself contributes to the amplification of perceived risks. Concern about the health effects of rockets can be traced to the conditions that existed when the USSR ceased to exist. An effective response must address these deep-seated issues.

Experiments in Associative Urbanism

Abstract‘There has never been a more crucial time to challenge, reassess and propose alternatives to conventional urban masterplanning and its associated conventions, types and standards.’ Tom Verebes describes how the Design Research Laboratory (DRL) at the Architectural Association in London has employed a parametric approach to urbanism that investigates how associative design systems can control local dynamic information flows through interactive systems, spaces and interfaces. Copyright © 2009 John Wiley & Sons, Ltd.

SU‐FF‐I‐128: Regional Time Density Curves (R‐TDC) Derived From Angiographic Sequences for Analysis of Aneurysmal Flow Modification Resulting From Endovascular Image‐Guided Interventions

Purpose: Digital subtraction angiography (DSA) is currently used to evaluate the result of endovascular treatments, either visually or using time‐density curves (TDC) which quantitate the change of contrast as a function of time for the entire aneurysm. Regional analysis (R‐TDCs) of flow patterns in sub‐volumes of an aneurysm was employed in this study to extract local flow information to determine the result of treatment with a partially‐occluding asymmetric vascular stent (AVS). Method and Materials: A patient‐specific, elastomer aneurysm phantom was placed in an in‐vitro pulsatile flow loop containing a glycerin‐water (25/75) solution simulating blood. One cc volumes of iodinated contrast were delivered 20 cm from the aneurysm entrance through a 6‐Fr catheter with an automatic injector. DSA sequences were acquired at 30 frames/sec using a 5‐inch II mode. The neck of the aneurysm was partially covered by a polyurethane‐patch AVS positioned to occlude either the proximal or the distal portion of the orifice. R‐TDCs were obtained for untreated and treated cases. Results: Differences in R‐TDC parameters for untreated, proximally covered, and distally covered cases indicate important modifications of flow occurred in different areas inside the aneurysm that are not evident from the total volume TDC. For example, in one sub‐region with the proximal patch, we measured a 2.3 times increase in peak density compared to the untreated case and a residence time 3.9 times longer, whereas the total aneurysm measurement showed the peak density to be reduced to 0.8 times and the residence time to be increased by a factor of only 1.9 compared to the untreated case. Conclusion: R‐TDC parameters derived from angiographic sequences present a great potential for quantitative in‐vivo assessment of local hemodynamic effects. This approach may provide a valuable, minimally invasive tool for assessing endovascular treatments during the procedure.Support: NIH R01‐NS43924, R01‐EB002873, Toshiba‐Corp.

Peer-to-Peer in Metric Space and Semantic Space

This paper first proposes three improved gossip mechanisms by mapping links into metric space and dynamically adapting the number of selected neighbors to disseminate messages. Experiments and comparisons show that these mechanisms can improve the performance of gossip in peer-to-peer (P2P) networks. This is the effect of mapping a network into a metric space that differentiates nodes and links according to linking characteristics and controlling local information flow with knowing such differences. A further study about query routing on P2P semantic link network shows that mapping a network into a semantic space can also improve the performance. An intrinsic rule is found by experimental comparisons and analysis: the performance of a P2P network can be improved by designing an appropriate mapping from the network into metric space or semantic space. A general framework for networking with metric space and semantic space is suggested

An implicit control-volume finite element method and its time step strategies for injection molding simulation

An implicit control-volume finite element method was proposed for simulation of injection molding, the time steps were controlled for both flow and thermal simulation by local flow information, and then the computing complexity analysis was conducted. The implicit scheme was based on updating the melt–air interface. The time steps of implicit algorithm were controlled by injection ratio and local mesh information of flow front to achieve “one time step, one element-layer” for filling simulation; the sub-time steps of computing temperatures were calculated for each node according to local courant number, and the thermal simulation was conducted by the filled order of nodes. Both analysis and case studies showed that the computing complexity of flow simulation was second-order of mesh size (nodal number) and one of thermal simulation was 1.5-order. As a result, the computing times and complexity of solving temperature were less than those of solving pressure.

Shedding Light on Local Organizational Principles in the Primary Sensory Cortex

Humans see the world in rich color and detail. Rodents supplement their vision with long whiskers that provide tactile information about their environment. Neuroscientists can investigate how these senses are represented in the brain by identifying general organizational principles of the underlying neural circuits; different parts of the body surface have been mapped to specific brain areas. However, the resolution of this topographical brain map is coarse. It is analogous to a world map that shows the highways connecting major cities, but without details about local streets in each region. Tapping into the finer details of local information flow is a daunting task, because each cubic centimeter of the brain contains millions of neurons connected by billions of synapses.

A mathematical model for airflow and heat transfer through fibrous webs

A mathematical model based on computational fluid dynamics has been developed to investigate the airflow and heat transfer through fibrous webs. The model is based on the porous media concept and involves solving equations for continuity, momentum, and energy. A thermal energy equation is developed, which incorporates the heat of fusion of fibres in the fibrous web. Local flow information such as air velocity, temperature, and melt fraction of fibres is obtained from the simulations. An important outcome of the simulation is the prediction of time required to melt fibres in the web under different working conditions. This information can be used potentially in the design of through-air bonding process for nonwovens manufacturer.

A Micromechanical Flow Sensor for Microfluidic Applications

We fabricated a microfluidic flow meter and measured its response to fluid flow in a microfluidic channel. The flow meter consisted of a micromechanical plate, coupled to a laser deflection system to measure the deflection of the plate during fluid flow. The 100 /spl mu/m square plate was clamped on three sides and elevated 3 /spl mu/m above the bottom surface of the channel. The response of the flow meter was measured for flow rates, ranging from 2.1 to 41.7 /spl mu/L/min. Several fluids, with dynamic viscosities ranging from 0.8 to 4.5/spl times/10/sup -3/ N/m, were flowed through the channels. Flow was established in the microfluidic channel by means of a syringe pump, and the angular deflection of the plate monitored. The response of the plate to flow of a fluid with a viscosity of 4.5/spl times/10/sup -3/ N/m was linear for all flow rates, while the plate responded linearly to flow rates less than 4.2 /spl mu/L/min of solutions with lower dynamic viscosities. The sensitivity of the deflection of the plate to fluid flow was 12.5/spl plusmn/0.2 /spl mu/rad/(/spl mu/L/min), for a fluid with a viscosity of 4.5/spl times/10/sup -3/ N/m. The encapsulated plate provided local flow information along the length of a microfluidic channel.

Modeling of polymer melting, drop deformation, and breakup under shear flow

AbstractPolyethylene (PE) or polycarbonate (PC) drop deformation and the breakup mechanism in a PE melt under shear flow were investigated using numerical simulations. The volume of fluid (VOF) method in FIDAP was used to track the dynamic interface. Two models were built for the investigation of a PE/PE system and a PE/PC system. Experimental data of polymer properties, such as specific heat capacity, viscosity, and heat conductivity, were incorporated in the simulations. For the PE/PE system, a temperature‐dependent viscosity model was used for the matrix PE and the dispersed PE. For the PE/PC system, generalized viscosity models were used for PE and PC with time‐dependent moving boundaries. An erosion mechanism similar to that observed in previous experiments was found for deformation and breakup of both PE and PC in the PE melt under simple shear flow. Local flow information, such as temperature, shear rate, viscosity, and shear stress, was obtained from the simulation results. The shear stress at the interface was much higher than the shear stress either in the dispersed phase or in the matrix phase, which could explain the erosion breakup mechanism. Polym. Eng. Sci. 44:1258–1266, 2004. © 2004 Society of Plastics Engineers.

Locality of global stochastic interaction in directed acyclic networks.

The hypothesis of invariant maximization of interaction (IMI) is formulated within the setting of random fields. According to this hypothesis, learning processes maximize the stochastic interaction of the neurons subject to constraints. We consider the extrinsic constraint in terms of a fixed input distribution on the periphery of the network. Our main intrinsic constraint is given by a directed acyclic network structure. First mathematical results about the strong relation of the local information flow and the global interaction are stated in order to investigate the possibility of controlling IMI optimization in a completely local way. Furthermore, we discuss some relations of this approach to the optimization according to Linsker's Infomax principle.

Distributed odor source localization

This paper presents an investigation of odor localization by groups of autonomous mobile robots. First, we describe a distributed algorithm by which groups of agents can solve the full odor localization task. Next, we establish that conducting polymer-based odor sensors possess the combination of speed and sensitivity necessary to enable real world odor plume tracing and we demonstrate that simple local position, odor, and flow information, tightly coupled with robot behavior, is sufficient to allow a robot to localize the source of an odor plume. Finally, we show that elementary communication among a group of agents can increase the efficiency of the odor localization system performance.

A numerical study on the coupling of hydrodynamics and orthokinetic agglomeration

Numerical studies on orthokinetic agglomeration in a turbulent channel flow and in a stirred tank are presented. By using a lattice Boltzmann scheme to simulate the turbulent flow field, and a Monte Carlo algorithm to solve the particle size distribution, the dependence of the agglomeration rate on the shear rate and the turbulent transport of particles is investigated. It is found that local flow information is needed to model agglomeration and that a description in terms of a volume-averaged agglomeration rate constant β 0 is inadequate for both geometries. Furthermore, turbulent transport of particles is found to be an important factor in the overall agglomeration rate.

ローカル潮流情報に基づくTCSC制御

ローカル潮流情報に基づくTCSC制御

Can the Visual System Measure Expansion Rates without using Optic Flow?

As an observer moves towards a surface, the visual image of the surface expands over time. Traditional approaches to measuring this expansion rely on computing the divergence of the local flow field. A complementary approach which would work well in contexts with poor flow information would be to measure shifts in the Fourier amplitude spectra of textures over time (analogous to size changes). To test whether the visual system uses the information provided by such a measure, we have created a set of novel stimuli which contain, on average, no local flow. We filtered successive frames of spatiotemporally white noise with band-pass spatial filters whose peak frequency varied in inverse proportion to time. The resulting stimulus is temporally uncorrelated, but contains changes in the spatial Fourier amplitude spectrum consistent with a constant expansion rate. We tested whether subjects could consistently match the expansion rate of such stimuli, which have no local flow information, to the expansion in random-dot kinematograms designed to have no change in their Fourier amplitude spectrum over time. A temporal 2AFC task was employed to find points of subjectively equal expansion between the two types of stimuli. Several rates of expansion were tested and the start and end frequencies in the textured non-flow stimuli were randomised between trials. We found that the matched expansion rates of the non-flow texture stimuli were monotonic and nearly linear with the true expansion rates of the dot (flow) stimuli. Settings were also consistent across different start and end frequencies. The results suggest that the visual system can use the change in the amplitude spectra of textures over time to make judgments about expansion.

Inefficiencies in the geographical operation of labour markets

Curry L. (1985) Inefficiencies in the geographical operation of labour markets, Reg. Studies 19, 203–215. After postulating an efficient overall competitive spatial price equilibrium in labour markets, the real world map of wages and labour flows is introduced as an inefficient form of this configuration because of opportunities not being exploited and wages not being ‘correct’ due to ignorance. Since these markets operate via local information and income flows the employment status of an individual affects that of his neighbours. Depending on the intensity of labour demand and the coupling strength between contiguous pairs on a regular lattice, the economy can break up into polarized patches of different economic climates. Singularities now develop and previously monotonic functions develop flat parts.

The Neighbourhood Effect: A Test of the Butler-Stokes Model

The purpose of this brief note has been to test the behavioural postulates of the neighbourhood effect. The results do not support the construction that minority voters are converted to the majority view by local information flows. These findings suggest the model of the neighbourhood effect needs to be amended and that alternative explanations of the polarization trends need to be examined more closely.

Cervical carotid imaging with a continuous-wave Doppler flowmeter.

A noninvasive technique for carotid arteriography using an ultrasonic directional Doppler flowmeter to image the carotid bifurcations is described. The technique uses a position sensing arm to hold the sharply focusing probe and translates the position of arterial flow onto an image storage screen. By multiple manual sweeps across the cervical carotids, a two-dimensional projection of the locus of arterial flow is developed. The probe beam is then applied through the eyelids to assess the posterior orbital ophthalmic flow. The adequacy of the internal carotid circulation and the presence of stenosis and calcified plaques are determined. Experience with the first 60 patients surveyed using the Doppler technique demonstrated a high degree of accuracy and reproducibility. The ultrasonic angiography provided local flow and velocity information that x-ray angiography did not. X-ray angiography is frequently indicated by the ultrasonic findings when risks of x-ray angiography might not otherwise be taken. The technique was found especially sensitive in detecting calcified atherosclerotic plaques and may be used in screening for the stroke-prone patient and following arterial lesions over extended periods of time.