Counting w map

Victor Sette Gripp

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ContextMotivationThe motivation of this report is to explore the team contribution to the Dr. Bianco's "Hypertemporal Imaging of NYC Grid Dynamics" proof of concept project, an alternative technology to monitor grid dynamics and energy consumption patterns, in contrast to a traditional approach which is based on in-situ monitoring of energy grids and buildings. This approach can, by analysing the lights of a city landscape, infer similar results obtained by sensors through images taken by a single camera.On the traditional approach, in order to provide reliable and affordable energy distribution, cities have to monitor the health of electric grid and energy consumption patterns. Those measurements are fundamental to provide good service during peak hours, to guarantee that the electrical grid is working in its healthy condition and to support future plans for increasing demand as cities grow and citizens use more electrical equipment.Measurements about electric grid are collected by a Phase Monitor Unit (PMU), a synchrophasor measurement device that captures information about the voltage and phase angle of the system which allows identifying possible shifts on phase and measure grid stability. Also, to access individualized energy consumption information, it is necessary the deployment of smart meters, devices that have to be installed on buildings to report real-time energy consumption information.The deployment of sensors and equipments is expensive and not possible to all cities worldwide. The PMU unitary overall cost is at a range from $40,000.00 - $180,000.00 (U.S. Department of Energy, 2009) and it is estimated that to monitor building energy consumption NYC will spend $1.5B for 1 million buildings during the next five years, values that can be impeditive for many cities in the world.The Hyperthemporal Imaging technology comes as an indirect, real-time, and affordable way to get electric grid health information and a non-intrusive and indirect way to achieve energy disaggregation and observe energy consumption patterns. In this context, this study will explore the expected improvement by using a new camera to capture images of city landscape and a study about cost and area covered by a single camera, estimating the ideal number of cameras needed to cover NYC. Previous Research\citet{bianco_hypertemporal_2016} showed a proof of concept that hypertemporal visible imaging can be used to monitor grid dynamics and identify phase changes in individual light sources from the city landscape. This technique relies on the fact that the United States grid provides electricity as an alternate current (AC) with a frequency of 60 Hz (some countries use 50 Hz standard instead). The alternate current at 60 Hz induces a flickering twice as fast, at 120 Hz, in most of the lights in the city, including incandescent, halogen, and some fluorescent lights. LED and  more modern fluorescent lights have a different behavior.Analyzing a signal with a frequency of 120 Hz would require at the very least a four times faster sampling rate, at 480 Hz, ideally eight times faster, which would require specialized and more expensive equipment. Since one of the main goals of developing this alternative technology is to provide an affordable way for cities in developing nations to monitor the dynamics of their electric grid, the equipment costs had to be kept low and, therefore, the solution was to use a liquid crystal shutter mounted at the lens aperture of the camera. The shutter is then set to oscillate between the states 'open' and 'closed' at a frequency (119.75 Hz) close to the one corresponding to the flickering of the lights (120 Hz), which, in turn, down-converts the flicker to 0.25 Hz, the beat frequency given by Equation 1.
ABSTRACT It was tested whether female citibike subscribers are, on average, younger than male citibike subscribers. The results showed that the difference between the ages of male and female subscribers within the sample analyzed was not statistically significant. DATA The data used in the analysis was downloaded from the citibike website and corresponded to the period from June to August 2015. Only the year of birth and the gender variables were considered in the analysis. Instances with missing values were simply dismissed. An age limit of 95 was considered in order to clean the data from possible outliers. ANALYSIS - Null Hypothesis: The average age of women who bike regularly (subscribers) is the same or higher than the average age of men who bike regularly (subscribers). \(H_0 : AGE_{W_{subs}} >= AGE_{M_{subs}}\) - Alternative Hypothesis: The average age of women who bike regularly (subscribers) is the smaller than the average age of men who bike regularly (subscribers). \(H_a : AGE_{W_{subs}} < AGE_{M_{subs}}\) - Statistical test: The Null Hypothesis was tested with Z-test since this was the most adequate choice to evaluate whether or not the difference in the means of two independent samples were statistically significant. The significance level considered was \(\alpha=0.05\). RESULT The z-score calculated was 0.68. And the corresponding p-value for a one-tailed test was then 0.2484. Since the p-value was higher than the significance level, the null hypothesis can not be rejected and the conclusion is that there is no statistically significant difference between the mean age of female citibike subscribers and male citibike subscribers. Therefore we can not conclude that the average age of female subscribers is lower than the average age of male subscribers.