Popularity-Guided Cost Optimization for Live Streaming in Mobile Edge Computing

Live streaming service usually delivers the content in mobile edge computing (MEC) to reduce the network latency and save the backhaul capacity. Considering the limited resources, it is necessary that MEC servers collaborate with each other and form an overlay to realize more efficient delivery. The critical challenge is how to optimize the topology among the servers and allocate the link capacity so that the cost will be lower with delay constraints. Previous approaches rarely consider server collaborations for live streaming service, and the scheduling delay is usually ignored in MEC, leading to suboptimal performances. In this paper, we propose a popularity-guided overlay model which takes the scheduling delay into consideration and utilizes MEC collaboration to achieve efficient live streaming service. The links and servers are shared among all channel streams and each stream is pushed from cloud servers to MEC servers via the trees. Considering the optimization problem is NP-hard, we propose an effective optimization framework called cost optimization for live streaming (COLS) to predict the channel popularity by a LSTM model with multiscale input data. Finally, we compute topology graph by greedy scheme and allocate the capacity with convex programming. Experimental results show that the proposed approach achieves higher prediction accuracy, reducing the capacity cost by more than 40% with an acceptable delay compared with state-of-the-art schemes.

Cyclic overlay model of p-y curves for laterally loaded monopiles in cohesionless soil

The bearing behaviour of large-diameter monopile foundations for offshore wind turbines under lateral cyclic loads in cohesionless soil is an issue of ongoing research. In practice, mostly the p-y approach is applied in the design of monopiles. Recently, modifications of the original p-y approach for monotonic loading stated in the API regulations (API 2014) have been proposed to account for the special bearing behaviour of large-diameter piles with small length-to-diameter ratios (e.g. Thieken et al. 2015, Byrne et al. 2015). However, cyclic loading for horizontally loaded piles predominates the serviceability of the offshore wind converters, and the actual number of load cycles cannot be considered by the cyclic p-y approach of the API regulations. This research is therefore focusing on the effects of cyclic loading on the p-y curves along the pile shaft and aiming to develop a cyclic overlay model to determine the cyclic p-y curves valid for a lateral load with a given number of load cycles. The “Stiffness Degradation Method (SDM)” (Achmus et al. 2009) is applied in a three-dimensional finite element model to determine the effect of the cyclic loading by degrading the secant soil stiffness according to the magnitude of cyclic loading and number of load cycles based on the results of cyclic triaxial tests. Thereby, the numerical simulation results are used to develop a “cyclic overlay model”, i.e. an analytical approach to adapt the monotonic (or static) p-y curve to the number of load cycles. The new model is applied to a reference system and compared to the API approach for cyclic loads.

Mapping Interflow Potential and the Validation of Index-Overlay Weightings by Using Coupled Surface Water and Groundwater Flow Model

Interflow is an important water source contributing to river flow. It directly influences the near-surface water cycles for water resource management. This study focuses on assessing the interflow potential and quantifying the interflow in the downstream area along the Kaoping River in southern Taiwan. The interflow potential is first determined based on the modified index-overlay model, which employs the analytical hierarchy process (AHP) to calculate the ratings and weightings of the selected factors. The groundwater and surface water flow (GSFLOW) numerical model is then used to link the index-overlay model to quantify the interflow potential for practical applications. This study uses the Monte Carlo simulations to assess the influence of rainfall-induced variations on the interflow uncertainty in the study area. Results show that the high potential interflow zones are located in the high to middle elevation regions along the Kaoping River. Numerical simulations of the GSFLOW model show an interflow variation pattern that is similar to the interflow potential results obtained from the index-overlay model. The average interflow rates are approximately 3.5 × 104 (m3/d) in the high elevation zones and 2.0 × 104 (m3/d) near the coastal zones. The rainfall uncertainty strongly influences interflow rates in the wet seasons, especially the peaks of the storms or heavy rainfall events. Interflow rates are relatively stable in the dry seasons, indicating that interflow is a reliable water resource in the study area.

Geospatial Modeling of Landslide Vulnerability and Simulating Spatial Correlation with Associated Factors in Bandarban District

The present study aims at identifying and predicting landslide vulnerable areas in Bandarban District of Chittagong Hill Tracts (CHT) using weighted overlaying of the multiple geospatial layers to determine landslide hazard areas. The historical landslide inventory map was prepared using Google Earth image and through PRA technique. Then ten landslide triggering factors including landuse, rainfall, slope, elevation, cut-fill, soil types, geology, distance to rivers, roads and stream orders, population density, income, education of the inhabitants were chosen as effective factors on a landslide in the study area. Subsequently, the landslide vulnerability map was constructed using the weighted overlay model in Geographic Information System (GIS). Bandarban District has 348 landslides vulnerable locations. Among them, 6 are extremely vulnerable and 342 are highly vulnerable to landslides. Model results show that the Upazila Ruma and Thanchi are extremely vulnerable to landslides. About 91 percent of the landslides will occur within 10 degrees of slope, about 65 percent will occur within 50 meters elevation. The model shows that there is a strong relationship between landslides and physical, economic and social variables. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 8(2), 2019, P 51-56

Prediksi Model 2d Data Magnetotelurik Terbaik Berdasarkan Pendekatan Model Irisan Di Cekungan Tomori dan Sekitarnya

2D modeling of magnetotelluric data produce various models that are influenced by noise and differences in coordinate measurement systems with strike directions, so the results are inaccurate. A technique that can be done to identify the accuracy of the data is the rotation analysis based on the overlay model approach. The type of rotation used are strike angle and fix angle. The strike angle rotation is done by maximizing the anti-diagonal impedance value, while the rotation fix angle refers to the isotropic homogeneous earth model by eliminating the static effect on the surface. The overlay model approach is based on the assumption that the distribution of resistivity variations of the rock in the subsurface has same value in various models. 2D modeling used in this analysis consists of three trajectories of correlation results from 30 magnetotelluric measurement points in the Tomori and surrounding areas. The results of the analysis show that the strike angle rotation model is the best model that can be used in the study area with the approach of determination value reaches 0.7735, therefore it can reduce subsurface geological interpretation deviation based on various 2D models.Keywords: Magnetotelluric, impedance rotation, strike angle rotation, fix angle rotation

Prediksi Model 2d Data Magnetotelurik Terbaik Berdasarkan Pendekatan Model Irisan Di Cekungan Tomori dan Sekitarnya

2D modeling of magnetotelluric data produce various models that are influenced by noise and differences in coordinate measurement systems with strike directions, so the results are inaccurate. A technique that can be done to identify the accuracy of the data is the rotation analysis based on the overlay model approach. The type of rotation used are strike angle and fix angle. The strike angle rotation is done by maximizing the anti-diagonal impedance value, while the rotation fix angle refers to the isotropic homogeneous earth model by eliminating the static effect on the surface. The overlay model approach is based on the assumption that the distribution of resistivity variations of the rock in the subsurface has same value in various models. 2D modeling used in this analysis consists of three trajectories of correlation results from 30 magnetotelluric measurement points in the Tomori and surrounding areas. The results of the analysis show that the strike angle rotation model is the best model that can be used in the study area with the approach of determination value reaches 0.7735, therefore it can reduce subsurface geological interpretation deviation based on various 2D models.Keywords: Magnetotelluric, impedance rotation, strike angle rotation, fix angle rotation

Combining the Overlay Model and Bayesian Networks to Determine Learning Styles in AHES

First of all, it is important to note that the work presented here lies within the modeling part of the learner in an adaptive educational system construed as computational modeling of the learner. Modeling the learner in adaptive systems involves different information such as knowledge of the domain, the performance of the learning goals, background, learning styles, etc. Although there are several methods to manage the learner model, like the stereotype model or learner profiles, they do not handle the uncertainty in the dynamic modeling of the learner. The main hypothesis of this work is to show the link between the structure of the learner model and especially the characteristics of a learning profile and the learning style of a learning situation. This chapter shows how the combination of these two approaches to learner modeling can address the dynamic aspect of the problem in the modeling of the learner.