Optimization and Engineering - The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is considered among the most frequently used techniques to deal with multi-criteria group... 相似文献
The forthcoming 5G technology aims to provide massive device connectivity and ultra-high capacity with reduced latency and costs. These features will be enabled by increasing the density of the base stations, using millimeter-wave (mmWave) bands, massive multiple-input multiple-output systems, and non-orthogonal multiple access techniques. The ability to support a large number of terminals in a small area is in fact a great challenge to guarantee massive access. In this context, this paper proposes a new receiver model for the uplink of 5G mmWave cellular networks. The receiver, called Iterative Decoding and Interference Cancellation (IDIC), is based on the Slotted Aloha (SA) protocol and exploits the capture effect alongside the successive IC process to resolve packet collisions. A 5G propagation scenario, modeled according to recent mmWave channel measurements, is used to compare IDIC with the widely adopted Contention Resolution Diversity SA (CRDSA) scheme to show the performance gain of IDIC, when elements of practical relevance, like imperfect cancellation and receive power diversity, are considered. The impact of packet and power diversity is also investigated to derive the preferable uplink random access strategy that maximizes the system throughput according to the offered channel load.
This article presents a comparison of different Word Sense Induction (wsi) clustering algorithms on two novel pseudoword data sets of semantic-similarity and co-occurrence-based word graphs, with a special focus on the detection of homonymic polysemy. We follow the original definition of a pseudoword as the combination of two monosemous terms and their contexts to simulate a polysemous word. The evaluation is performed comparing the algorithm’s output on a pseudoword’s ego word graph (i.e., a graph that represents the pseudoword’s context in the corpus) with the known subdivision given by the components corresponding to the monosemous source words forming the pseudoword. The main contribution of this article is to present a self-sufficient pseudoword-based evaluation framework for wsi graph-based clustering algorithms, thereby defining a new evaluation measure (top2) and a secondary clustering process (hyperclustering). To our knowledge, we are the first to conduct and discuss a large-scale systematic pseudoword evaluation targeting the induction of coarse-grained homonymous word senses across a large number of graph clustering algorithms. 相似文献
The independent threat scenario of sudden column loss under localised damage is usually considered in progressive collapse assessment. The effect of the sudden removal of a column is like the sudden application of the gravity load on the structure when significant deformations occur. This conventional approach is based on the simplifying but realistic hypothesis that the peak dynamic response can be assessed with reasonable accuracy using the nonlinear static response. In this approach, amplified gravity loads are applied to the bays that are affected by the removed column to compensate for the dynamic effects corresponding to the real load redistribution. The paper investigates the dynamic increase factor to be considered in the nonlinear pushdown analysis of seismically designed steel moment-resisting frames. The influence of the fundamental parameters involved in progressive collapse analysis was highlighted. The effect of various design variables, such as the number of stories, the number of bays, the location of the removed column and the level of seismic design load was investigated. The dynamic increase factor was estimated in a way to generate the best match of the peak dynamic responses through the nonlinear static analysis. Finally, the values obtained were expressed as a function of the vertical displacement at the location of the removed column and then compared with the GSA formulation based on the ductility factor. 相似文献
The use of foam has the potential for energy absorption enhancement. Many types of materials can be produced in the form of foams, including metals and polymers. Of the metallic based foams, aluminium based are among the most advanced. Aluminium foams couple good specific mechanical properties with high thermal stability. Among the various aspects still to be investigated regarding their mechanical behaviour is the influence of a hydrostatic state of stress on yield strength. Unlike metals, the hydrostatic component affects yields. Therefore, different loading conditions have to be considered to fully identify the material behaviour. Another important issue in foam structure design is the analysis of composite structures. The mechanical behaviour of an aluminium foam has been examined. The foam was subjected to uniaxial, hydrostatic stress, pure deviatoric stress, and combinations thereof. Results obtained will be presented as quasi-static and dynamic uniaxial compression and quasi-static bending and shear loading. Moreover, composite structures were made by assembling the foam into aluminium cold extruded closed section 6060 aluminium tubes. The results show that the energy absorption capability of the composite structures is much greater than the sum of the energy absorbed by the two components, the foam and the tube. 相似文献
Skeletal muscle is essential to maintain vital functions such as movement, breathing, and thermogenesis, and it is now recognized as an endocrine organ. Muscles release factors named myokines, which can regulate several physiological processes. Moreover, skeletal muscle is particularly important in maintaining body homeostasis, since it is responsible for more than 75% of all insulin-mediated glucose disposal. Alterations of skeletal muscle differentiation and function, with subsequent dysfunctional expression and secretion of myokines, play a key role in the pathogenesis of obesity, type 2 diabetes, and other metabolic diseases, finally leading to cardiometabolic complications. Hence, a deeper understanding of the molecular mechanisms regulating skeletal muscle function related to energy metabolism is critical for novel strategies to treat and prevent insulin resistance and its cardiometabolic complications. This review will be focused on both cellular and animal models currently available for exploring skeletal muscle metabolism and endocrine function. 相似文献
Esketamine (ESK) has been approved as a rapid-acting intranasal treatment for treatment-resistant depression (TRD). Although existing studies have investigated the efficacy of ESK in the 4-week induction phase, our knowledge about long-term ESK efficacy remains poor. The aim of this systematic review was to summarize the available data on long-term ESK efficacy for TRD. A systematic search was performed including articles in English, up to 31 March 2021. The search found 7 relevant studies, involving 1024 adult TRD patients. Continuing treatment with ESK after the 4-week induction phase may be associated with stable efficacy in relapse prevention among TRD patients. Conversely, the long-term antidepressant effectiveness upon discontinuation of ESK might be limited, although data from three studies had a moderate to high risk of bias. Overall, the results on the effectiveness of this compound in the long term are mixed. According to our findings, ESK treatment should be continued following the induction phase to reach a stable efficacy in relapse prevention, while the long-term antidepressant and anti-suicidal effects of ESK after discontinuation are inconsistent. Currently, the level of proof of ESK efficacy in long-term TRD treatment remains low and more RCTs with larger sample sizes and active comparators are needed. 相似文献
The electron current density in nanoscale junctions is typically several orders of magnitude larger than the corresponding one in bulk electrodes. Consequently, the electron-electron scattering rate increases substantially in the junction. This leads to local electron heating of the underlying Fermi sea in analogy to the local ionic heating that is due to the increased electron-phonon scattering rates. We predict the bias dependence of local electron heating in quasi-ballistic nanoscale conductors and its effect on ionic heating and discuss possible experimental tests of our results. 相似文献