Optimal Information Retrieval with Complex Utility Functions

Existing retrieval models all attempt to optimize one single utility function, which is often based on the topical relevance of a document with respect to a query. In real applications, retrieval involves more complex utility functions that may involve preferences on several different dimensions. In this paper, we present a general optimization framework for retrieval with complex utility functions. A query language is designed according to this framework to enable users to submit complex queries. We propose an efficient algorithm for retrieval with complex utility functions based on the a-priori algorithm. As a case study, we apply our algorithm to a complex utility retrieval problem in distributed IR. Experiment results show that our algorithm allows for flexible tradeoff between multiple retrieval criteria. Finally, we study the efficiency issue of our algorithm on simulated data

A Real-time Nonlinear Model Predictive Controller for Yaw Motion Optimization of Distributed Drive Electric Vehicles

This paper proposes a real-time nonlinear model predictive control (NMPC) strategy for direct yaw moment control (DYC) of distributed drive electric vehicles (DDEVs). The NMPC strategy is based on a control-oriented model built by integrating a single track vehicle model with the Magic Formula (MF) tire model. To mitigate the NMPC computational cost, the continuation/generalized minimal residual (C/GMRES) algorithm is employed and modified for real-time optimization. Since the traditional C/GMRES algorithm cannot directly solve the inequality constraint problem, the external penalty method is introduced to transform inequality constraints into an equivalently unconstrained optimization problem. Based on the Pontryagin’s minimum principle (PMP), the existence and uniqueness for solution of the proposed C/GMRES algorithm are proven. Additionally, to achieve fast initialization in C/GMRES algorithm, the varying predictive duration is adopted so that the analytic expressions of optimally initial solutions in C/GMRES algorithm can be derived and gained. A Karush-Kuhn-Tucker (KKT) condition based control allocation method distributes the desired traction and yaw moment among four independent motors. Numerical simulations are carried out by combining CarSim and Matlab/Simulink to evaluate the effectiveness of the proposed strategy. Results demonstrate that the real-time NMPC strategy can achieve superior vehicle stability performance, guarantee the given safety constraints, and significantly reduce the computational efforts

Water Quality Analysis and Recommendations through Comprehensive Pollution Index Method

Recently, the quality of surface water has become one of significant environmental planning and management issues in China. To investigate the quality of surface water, three monitoring sites, such as Majiawan Site, Huxin Site and Huguan Site, have been established by Qilu Lake, located in the north of Tonghai County, Yuxi Region, Yunnan Province, by Chinese government. In this paper, we applied comprehensive pollution index method to analyze and monitor water quality, obtained a series of determination factors which could be used to differentiate V class and Interior V class of the water quality of Qilu Lake. Accordingly, we suggest relevant recommendations from the aspects of engineering measures, chemical and biological methods

Network Externality and Trust in Agent-Based Social Commerce

The social commerce platform engages users in an agent-led network, leveraging local ties and communal trust. Agents are neighborhood influencers facilitating user referral, community engagement, and product marketing. We study the economic value of the agents to the platform based on their native endowed network externality and the trust formulated from the interaction with the users. Using detailed performance and referral data from a leading social commerce platform in Indonesia, we find that (1) agents with a higher level of endowed network externality outperform the ones with a lower level; (2) a more trustworthy and, surprisingly, less connected agent produces higher community sales; and (3) user’s perceived benevolence of the agent positively moderates the referral effect. The results suggest that the platform faces a trade-off between capitalizing on agents’ social connections and nurturing community trust

Use of strain ultrasound elastography versus fineneedle aspiration cytology for the differential diagnosis of thyroid nodules: a retrospective analysis

OBJECTIVE: Fine-needle aspiration cytology is the risk stratification tool for thyroid nodules, and ultrasound elastography is not routinely used for the differential diagnosis of thyroid cancer. The current study aimed to compare the diagnostic parameters of ultrasound elastography and fine-needle aspiration cytology, using surgical pathology as the reference standard. METHODS: In total, 205 patients with abnormal thyroid function test results underwent ultrasound-guided fine-needle aspiration cytology on the basis of the American College of Radiology Thyroid Imaging-Reporting and Data System classification and strain ultrasound elastography according to the ASTERIA criteria. Histopathological examination of the surgical specimens was performed according to the 2017 World Health Organization classification system. Moreover, a beneficial score analysis for each modality was conducted. RESULTS: Of 265 nodules, 212 measured X1 cm. The strain index value increased from benign to malignant nodules, and the presence of autoimmune thyroid diseases did not affect the results (p40.05 for all categories). The sensitivities of histopathological examination, ultrasound elastography, and fine-needle aspiration cytology for detection of nodules measuring X1 cm were 1, 1, and 0.97, respectively. The working area for detecting nodule(s) in a single image was similar between strain ultrasound elastography and fine-needle aspiration cytology for highly and moderately suspicious nodules. However, for mildly suspicious, unsuspicious, and benign nodules, the working area for detecting nodule(s) in a single image was higher in strain ultrasound elastography than in fine-needle aspiration cytology. CONCLUSION: Strain ultrasound elastography for highly and moderately suspicious nodules facilitated the detection of mildly suspicious, unsuspicious, and benign nodules

Effects of magnetic field on thermo-hydraulic performance of Fe3O4-water nanofluids in a corrugated tube

© 2018 Elsevier Ltd An experimental system is established to investigate the thermo-hydraulic performance of Fe3O4-water nanofluids in a corrugated tube under various magnetic fields. The influences of magnetic induction intensities (B = 0 G, 100 G, 200 G, 300 G), nanoparticle mass fractions (ω = 0.0%, 0.1%, 0.3%, 0.5%), electromagnet arrangement modes (one-side electromagnet and two-side staggered electromagnet), kinds of tubes (smooth tube and corrugated tube), Reynolds numbers (Re = 800–12,000) on flow and heat transfer characteristics are discussed. It is obtained that the augmentation of heat transfer is more sensitive to high nanoparticle mass fraction, high magnetic induction intensity, two-side staggered electromagnet and corrugated tube. A Comprehensive evaluation index is applied to estimate the thermo-hydraulic performance. It can be discovered that the comprehensive evaluation index increases with the increasing Reynolds number at first and then decreases, and the rough surface of corrugated tube delays the appearance of critical Reynolds number