540 research outputs found
The Friendly Settlement of Human Rights Abuses in the Americas
We present a new method for estimation of seismic coda shape. It falls into the same class of methods as non-parametric shape reconstruction with the use of neural network techniques where data are split into a training and validation data sets. We particularly pursue the well-known problem of image reconstruction formulated in this case as shape isolation in the presence of a broadly defined noise. This combined approach is enabled by the intrinsic feature of seismogram which can be divided objectively into a pre-signal seismic noise with lack of the target shape, and the remainder that contains scattered waveforms compounding the coda shape. In short, we separately apply shape restoration procedure to pre-signal seismic noise and the event record, which provides successful delineation of the coda shape in the form of a smooth almost non-oscillating function of time. The new algorithm uses a recently developed generalization of classical computational-geometry tool of alpha-shape. The generalization essentially yields robust shape estimation by ignoring locally a number of points treated as extreme values, noise or non-relevant data. Our algorithm is conceptually simple and enables the desired or pre-determined level of shape detail, constrainable by an arbitrary data fit criteria. The proposed tool for coda shape delineation provides an alternative to moving averaging and/or other smoothing techniques frequently used for this purpose. The new algorithm is illustrated with an application to the problem of estimating the coda duration after a local event. The obtained relation coefficient between coda duration and epicentral distance is consistent with the earlier findings in the region of interest
Adaptive control algorithm to provide bus priority with a pre-signal
In urban areas, where road space is limited, it is important to provide efficient public and private transportation systems to maximize person throughput, for example from a signalized intersection. To this end, this research looks at providing bus priority using a dedicated bus lane which is terminated upstream of the intersection, and placing an additional signal at this location, called a pre-signal. Although pre-signals are already implemented in some countries (e.g. UK, Denmark, and Switzerland), an adaptive control algorithm which responds to varying traffic demands has not yet been proposed and analyzed in the literature. This research aims to fill that gap by developing an adaptive control algorithm for pre-signals tailored to real-time private and public transportation demands. The necessary infrastructure to operate an adaptive pre-signal is established, and guidelines for implementation are provided. The relevant parameters regarding the boundary conditions for the adaptive algorithm are first determined, and then quantified for a typical case using a micro-simulation model. It is demonstrated with case studies that, under all considered scenarios, implementing a pre-signal with the proposed adaptive control algorithm will result in the least average person delay at the intersection. The algorithm is expected to function well with a wide range of car demands, bus frequencies, and bus passenger occupancies. Moreover, the algorithm is robust to errors in these input values, so exact information is not required
MODELLING AND ANALYSIS OF THE BUS PRIORITY IMPLEMENTATION
Bus is expected to play an important role in providing a reliable travel in congested conditions. Therefore, it has been widely studied to minimize the travel time and the delay of the bus by proposing bus priority scheme to increase the attractiveness of public transport against private vehicles. Signal timing optimization combined with the bus priority scheme are discussed in this research as the alternatives to improve the intersection performances. Further, identifying the effects of these alternatives towards the general vehicles and public transport system performances were the aims of this research as well. As the result of this research, bus advance area with pre-signal method is able to reduce the travel time and delay of the bus for routes 2A and 3A by 11%, 23% and 14% , 0% respectively and able to reduce travel time, delay, and queue of vehicles by 25%, 26%, 7% consecutively. Thus bus advance area with pre-signal method is proposed as the best alternative due to its impact to reduce the bus travel times and delay without degrading the other vehicles performance. Keywords: bus priority, optimizing signal timing, Aimsun simulation, travel time-delay-queue
Optimising Activation of Bus Pre-signals
This report describes preliminary analysis of strategies to activate and deactivate a bus pre-signal using vehicle count data. The bus pre-signal currently operates during preset times to regulate access to a length of road controlled at the other end by vehicle-actuated traffic signals. However, vehicle flows at the pre-signal vary on a daily basis so a more demand-based approach would be more effective. There has been much research performed to optimise pre-signal cycle times and bus priority at pre-signals. We focus on identifying the optimal strategy to activate and deactivate the bus pre-signal using vehicle demand rather than the current fixed time strategy. The ideal strategy should be stable, robust, consistent and timely. We investigate strategies using vehicle counts, queueing theory and estimation and prediction. Our recommended strategy combines aspects of all three areas
Optical imaging of the peri-tumoral inflammatory response in breast cancer
<p>Abstract</p> <p>Purpose</p> <p>Peri-tumoral inflammation is a common tumor response that plays a central role in tumor invasion and metastasis, and inflammatory cell recruitment is essential to this process. The purpose of this study was to determine whether injected fluorescently-labeled monocytes accumulate within murine breast tumors and are visible with optical imaging.</p> <p>Materials and methods</p> <p>Murine monocytes were labeled with the fluorescent dye DiD and subsequently injected intravenously into 6 transgenic MMTV-PymT tumor-bearing mice and 6 FVB/n control mice without tumors. Optical imaging (OI) was performed before and after cell injection. Ratios of post-injection to pre-injection fluorescent signal intensity of the tumors (MMTV-PymT mice) and mammary tissue (FVB/n controls) were calculated and statistically compared.</p> <p>Results</p> <p>MMTV-PymT breast tumors had an average post/pre signal intensity ratio of 1.8+/- 0.2 (range 1.1-2.7). Control mammary tissue had an average post/pre signal intensity ratio of 1.1 +/- 0.1 (range, 0.4 to 1.4). The p-value for the difference between the ratios was less than 0.05. Confocal fluorescence microscopy confirmed the presence of DiD-labeled cells within the breast tumors.</p> <p>Conclusion</p> <p>Murine monocytes accumulate at the site of breast cancer development in this transgenic model, providing evidence that peri-tumoral inflammatory cell recruitment can be evaluated non-invasively using optical imaging.</p
Accuracy of bubble velocity measurement with a four-point optical fibre probe
For the operation of high void fraction bubbly flows in bubble\ud
columns, insight in primary parameters such as bubble size,\ud
shape and velocity as well as gas volume fraction is essential.\ud
At high gas volume fractions the flow system becomes\ud
opaque, ruling out non-intrusive optical techniques. As an\ud
alternative optical fibre probes can be used, which have the\ud
advantage of low cost, simplicity of setup and easy\ud
interpretation of the results.\ud
By using four-point optical fibre probe, properties of bubbles\ud
can be studied, such as bubble velocity, bubble size, etc.\ud
However, the effect of bubble wobbling behaviour and\ud
physical properties of liquids on the accuracy of the velocity\ud
measurements has not been investigated in detail.\ud
In the present study, the performance of a four-point optical\ud
fibre probe was evaluated for five different liquids. The probe\ud
performance and causes of inaccuracies are discuss
Optimization of the Design of Pre-Signal System Using Improved Cellular Automaton
The pre-signal system can improve the efficiency of intersection approach under rational design. One of the main obstacles in optimizing the design of pre-signal system is that driving behaviors in the sorting area cannot be well evaluated. The NaSch model was modified by considering slow probability, turning-deceleration rules, and lane changing rules. It was calibrated with field observed data to explore the interactions among design parameters. The simulation results of the proposed model indicate that the length of sorting area, traffic demand, signal timing, and lane allocation are the most important influence factors. The recommendations of these design parameters are demonstrated. The findings of this paper can be foundations for the design of pre-signal system and show promising improvement in traffic mobility
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