Hybrid Query Expansion Model Based on Pseudo Relevance Feedback and Semantic Tree for Arabic IR

In this paper, the authors propose and readapt a new concept-based approach of query expansion in the context of Arabic information retrieval. The purpose is to represent the query by a set of weighted concepts in order to identify better the user's information need. Firstly, concepts are extracted from the initially retrieved documents by the Pseudo-Relevance Feedback method, and then they are integrated into a semantic weighted tree in order to detect more information contained in the related concepts connected by semantic relations to the primary concepts. The authors use the “Arabic WordNet” as a resource to extract, disambiguate concepts and build the semantic tree. Experimental results demonstrate that measure of MAP (Mean Average Precision) is about 10% of improvement using the open source Lucene as IR System on a collection formed from the Arabic BBC news.

Data-Driven Competitor-Aware Positioning in On-Demand Vehicle Rental Networks

We study a novel operational problem that considers vehicle positioning in on-demand rental networks, such as car sharing in the wider context of a competitive market in which users select vehicles based on access. Existing approaches consider networks in isolation; our competitor-aware model takes supply situations of competing networks into account. We combine online machine learning to predict market-level demand and supply with dynamic mixed integer nonlinear programming. For evaluation, we use discrete event simulation based on real-world data from Car2Go and DriveNow. Our model outperforms conventional models that consider the fleet in isolation by a factor of two in terms of profit improvements. In the case we study, the highest theoretical profit improvements of 7.5% are achieved with a dynamic model. Operators of on-demand rental networks can use our model under existing market conditions to build a profitable competitive advantage by optimizing access for consumers without the need for fleet expansion. Model effectiveness increases further in realistic scenarios of fleet expansion and demand growth. Our model accommodates rising demand, defends against competitors’ fleet expansion, and enhances the profitability of own fleet expansions.

Analysis of Damage Tolerance of the Stiffened Structure Based on XFEM

A calculation method of damage tolerance of stiffened structure based on extended finite element method (XFEM) is proposed.The crack propagation process is divided into small intervals to calculate the amplitude of stress intensity factor of the structure under different crack lengths. Each small interval is integrated to calculate the crack growth life. The accuracy of the method is verified by calculating the stress intensity factor, the load at both ends and crack growth life. The flat slab structure model with different numbers of stiffeners is established. The above calculation method shows that the stiffeners can share the load for the structure, reduce the amplitude of stress intensity factor, increase the fatigue life.The more the number of stiffeners, the more obvious the improvement effect. The equivalent treatment of the stiffened structure was conducted, and the equal area widening model, unfolding model and thickening model were established. The calculation results show that the calculation results of expansion model is very close to the stiffened structure. It shows that the stiffeners share the load for the structure by increasing the local thickness of the area, reduce the amplitude of stress intensity factor and improve the fatigue intensity.

A study of developing a spatial entity greenway in the case of Irbid City – Jordan

Greenways are urban elements that are designed to show the linear consistency and connectivity between open green spaces and cause a development in the urban texture. As a city starts to grow, the absolute metropolitan development should be followed by an ongoing protection of the rural and urban territories. The nexus between the city development and the fortification of the open agricultural and rural lands is deemed a good strategy in order to result in a homogenous urban fabric of the city. The study aims to present a greenway model of development to work as a prototype applied on an existing route in Irbid City-Jordan by using the methods of testing and analyzing the route during the site visit and by using GIS base maps in order to come up with an absolute combination between monitoring the city growth, maintaining the quality of the agricultural lands and serving the public and local needs in order to result in a more balanced and controlled growth of the city. Irbid city is located in the northern part of Jordan with a radial urban expansion model of growth extending from the historical center and spreading toward the outskirts of the city. Regarding the significant increase in the number of population in Irbid City-Jordan since the 1970s until nowadays and the continuous need for habitats, there was a huge number of housing projects in the inner part of the city that expanded toward the outer part including the rural areas, resulting in a huge lack of agricultural lands and open recreational spaces where people can benefit from. Those spaces form an outlet of the city connected with the inner part by a route. Establishing a greenway along the route raises the integration between people and their lands and encourages farmers to develop and harvest. According to this study, the greenway development, which forms a breath out to the highly built-up area in the city, has become a great tool to result in tremendous beneficial outcomes to the city development.

Control-Oriented Modeling for Nonlinear MIMO Turbofan Engine Based on Equilibrium Manifold Expansion Model

This paper investigates the control-oriented modeling for turbofan engines. The nonlinear equilibrium manifold expansion (EME) model of the multiple input multiple output (MIMO) turbofan engine is established, which can simulate the variation of high-pressure rotor speed, low-pressure rotor speed and pressure ratio of compressor with fuel flow and throat area of the nozzle. Firstly, the definitions and properties of the equilibrium manifold method are presented. Secondly, the steady-state and dynamic two-step identification method of the MIMO EME model is given, and the effects of scheduling variables and input noise on model accuracy are discussed. By selecting specific path, a small amount of dynamic data is used to identify a complete EME model. Thirdly, modeling and simulation at dynamic off-design conditions show that the EME model has model accuracy close to the nonlinear component-level (NCL) model, but the model structure is simpler and the calculation is faster than that. Finally, the linearization results are obtained based on the properties of the EME model, and the stability of the model is proved through the analysis of the eigenvalues, which all have negative real parts. The EME model constructed in this paper can meet the requirements of real-time simulation and control system design.