The paper presents the results of theoretical modeling of axisymmetric gradient gratings of an periodic and aperiodic amplitude profile (Fresnel, Fibonacci) positioned within a circular hollow dielectric waveguide. Su...
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We investigate the problem of minimizing the overall transmission delay of data packets in a single-user wireless communication system, where the transmitter has a fixed amount of energy to transmit all of the data pa...
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We investigate the problem of minimizing the overall transmission delay of data packets in a single-user wireless communication system, where the transmitter has a fixed amount of energy to transmit all of the data packets. We consider two different scenarios. In the first scenario, we assume that packets arrive randomly at the transmitter. We propose two different approaches to solve this problem. First, we develop an iterative algorithm that allocates the total energy of the transmitter to its individual packets, in a way to minimize the total delay. As a second approach, we develop a dynamic programming formulation for the problem. In the second scenario, we assume that all of the packets have already arrived before the transmission starts. In this situation, the cost function has a fixed form, and is convex and differentiable. In this scenario, the iterative algorithm we develop is guaranteed to converge to the unique global optimal solution.
The prevalence of social media has increased the propagation of toxic behavior among users. Toxicity can have detrimental effects on users' emotion and insight and disrupt beneficial discourse. Evaluating the prop...
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ISBN:
(纸本)9780998133157
The prevalence of social media has increased the propagation of toxic behavior among users. Toxicity can have detrimental effects on users' emotion and insight and disrupt beneficial discourse. Evaluating the propagation of toxic content on social networks such as Twitter can provide the opportunity to understand the characteristics of this harmful phenomena. Identifying a mathematical model that can describe the propagation of toxic content on social networks is a valuable approach to this evaluation. In this paper, we utilized the SEIZ (Susceptible, Exposed, Infected, Skeptic) epidemiological model to find a mathematical model for the propagation of toxic content related to COVID-19 topics on Twitter. We collected Twitter data based on specific hashtags related to different COVID-19 topics such as covid, mask, vaccine, and lockdown. The findings demonstrate that the SEIZ model can properly model the propagation of toxicity on a social network with relatively low error. Determining an efficient mathematical model can increase the understanding of the dynamics of the propagation of toxicity on a social network such as Twitter. This understanding can help researchers and policymakers to develop methods to limit the propagation of toxic content on social networks.
This paper makes a study of method of reactive power compensation to improve the efficiency of transmission and distribution grid. A simulation model based on instantaneous reactive power is proposed as an example for...
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ISBN:
(纸本)9781424448135
This paper makes a study of method of reactive power compensation to improve the efficiency of transmission and distribution grid. A simulation model based on instantaneous reactive power is proposed as an example for three-phase unbalanced power grid to show that unbalanced current could be compensated completely. By means of reactive power compensation to unbalanced electric power grid, line loss is greatly decreased and power quality is improved, which has practical applications and reference value in engineering.
Task analysis is a well-accepted component of user-centered design. It is often left out of the design process, however, due to a lack of practical methods, the difficulty in predicting the amount of resource required...
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Task analysis is a well-accepted component of user-centered design. It is often left out of the design process, however, due to a lack of practical methods, the difficulty in predicting the amount of resource required to perform it, and a short supply of people with the appropriate skills. A solution to these problems is a structured set of activities that compose a task analysis and relate to the overall design process. The general framework into which these activities fit has three phases: Data Collection, Data Analysis, and Design. During the Data Collection phase, user and task data are collected and validated. The Data Analysis phase requires analyzing the user and task data in a way that results in suggestions for information representation, navigation, terminology, and consistency. Finally, the Design phase requires translating the suggestions from the Data Analysis phase into a viable product. A prototype task analysis workbook was developed to assess the feasibility of the structured approach to task analysis. The workbook includes tools for data collection, data analysis, and design, as well as instructions for how to use the tools. Over a period of two years, the workbook was used in five different development projects. A representative from each group was interviewed to determine how the workbook was used and which parts were most useful. Results of the interviews indicate that the workbook approach has merit.
In order to achieve the high precision fabrication of the large-aperture off-axis Wedged Focus Lens (WFL) for high power laser device, the involved fabrication technologies including the ultra precision grinding, the ...
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作者：
Chiu, ShenSpace-Based Radar Group
Radar Systems Section Defence R and D Canada - Ottawa 3701 Carling Ave Ottawa Ont. K1A 0Z4 Canada
The SAR interferogram, defined as the product of the first channel and the complex conjugate of the second, is one way of comparing two SAR channels. When the two sub-apertures are aligned along the flight path, targe...
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The SAR interferogram, defined as the product of the first channel and the complex conjugate of the second, is one way of comparing two SAR channels. When the two sub-apertures are aligned along the flight path, targets with non-zero radial velocities can be detected by exploiting the phase information of the interferogram. This paper examines the effect of clutter interference on the interferometric phase and provides a simple method for mitigating the clutter contamination by using time-frequency (TF) analysis techniques and a velocity-offset matched filter (VOMF). Both simulated and airborne results are presented.
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