As a hierarchical network architecture, the cluster architecture can improve the routing performance greatly for vehicular ad hoc networks (VANETs) by grouping the vehicle nodes. However, the ...existing clustering algorithms only consider the mobility of a vehicle when selecting the cluster head. The rapid mobility of vehicles makes the link between nodes less reliable in cluster. A slight change in the speed of cluster head nodes has a great influence on the cluster members and even causes the cluster head to switch frequently. These problems make the traditional clustering algorithms perform poorly in the stability and reliability of the VANET. A novel passive multi-hop clustering algorithm (PMC) is proposed to solve these problems in this paper. The PMC algorithm is based on the idea of a multi-hop clustering algorithm that ensures the coverage and stability of cluster. In the cluster head selection phase, a priority-based neighbor-following strategy is proposed to select the optimal neighbor nodes to join the same cluster. This strategy makes the inter-cluster nodes have high reliability and stability. By ensuring the stability of the cluster members and selecting the most stable node as the cluster head in the N-hop range, the stability of the clustering is greatly improved. In the cluster maintenance phase, by introducing the cluster merging mechanism, the reliability and robustness of the cluster are further improved. In order to validate the performance of the PMC algorithm, we do many detailed comparison experiments with the algorithms of N-HOP, VMaSC, and DMCNF in the NS2 environment.
Since there is a competition between subcarriers because FBMC (Filter Bank Multicarrier) modulation technology does not need subcarriers to be orthogonal to each other, we consider the evolutionary ...game method to optimize subcarrier allocation. Because the adjacent subcarriers do not need to be orthogonal to each other in FBMC, there is conflict and competition, thus the evolutionary game theory is used to optimize the subcarrier allocation problem. We innovatively introduced the channel state matrix to show the quality of subcarriers. Considering the height of secondary user and base station’s antenna, the total data transmission rate limit, total power consumption constraint and power consumption constraint on a single subcarrier, a nonlinear fractional programming problem is established where maximum energy efficiency is the objective function, total data transmission rate limit, total power consumption constraint and power consumption constraint on a single subcarrier are constraint conditions. The utility function for each secondary user is established when the evolutionary game operator is designed. When the utility function becomes optimal, the evolutionary game reaches Nash equilibrium, and the strategy combination is considered to be the energy efficient resource allocation scheme. Through experimental simulation, EESA-EG proposed in this paper gives the most reasonable subcarrier allocation scheme, allocates more subcarriers for the subcarriers with better channel state and the energy efficiency in EESA-EG is optimal.
β-type titanium (Ti) alloys have attracted a lot of attention as novel biomedical materials in the past decades due to their low elastic moduli and good biocompatibility. This article provides a ...broad and extensive review of β-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. After briefly introducing the development of Ti and Ti alloys for biomedical applications, this article reviews the design of β-type Ti alloys from the perspective of the molybdenum equivalency (Moeq) method and DV-Xα molecular orbital method. Based on these methods, a considerable number of β-type Ti alloys are developed. Although β-type Ti alloys have lower elastic moduli compared with other types of Ti alloys, they still possess higher elastic moduli than human bones. Therefore, porous β-type Ti alloys with declined elastic modulus have been developed by some preparation methods, such as powder metallurgy, additive manufacture and so on. As reviewed, β-type Ti alloys have comparable or even better mechanical properties, corrosion behavior, and biocompatibility compared with other types of Ti alloys. Hence, β-type Ti alloys are the more suitable materials used as implant materials. However, there are still some problems with β-type Ti alloys, such as biological inertness. As such, summarizing the findings from the current literature, suggestions forβ-type Ti alloys with bioactive coatings are proposed for the future development.
Abstract
In order to clarify the micro‐mechanics of clay during compression, the behavior of clay subjected to one‐dimensional compression is investigated at the particle scale using discrete element ...method (DEM). The flaky clay particles in the simulation are approximated by clumps made of spheres. A new contact model is implemented to account for the double‐layer repulsive force, the van der Waals attractive force and the mechanical contact force. The effect of sphere arrangement in the particle clump is discussed. The DEM model is validated against experimental observations in terms of macroscopic compressibility, particle dip angle as well as the over consolidated behavior. The
e
‐log
σ
v
curve shows a concave‐to‐linear shape. The evolution of dip angle of clay particles indicates that particles tend to have an anisotropy with a preferential orientation towards horizontal direction. The increase of preconsolidation pressure decreases the initial compressibility due to the increase the number of mechanical contacts. The evolution of average coordination and sphere‐sphere contact shows that the majority of mechanical contacts are generated before the compressive stress reaches 100 kPa. Evolution of soil fabric is presented and discussed.
Anthocyanins are a class of water‐soluble flavonoids, which show a range of pharmacological effects, such as prevention of cardiovascular disease, obesity control and antitumour activity. Their ...potential antitumour effects are reported to be based on a wide variety of biological activities including antioxidant; anti‐inflammation; anti‐mutagenesis; induction of differentiation; inhibiting proliferation by modulating signal transduction pathways, inducing cell cycle arrest and stimulating apoptosis or autophagy of cancer cells; anti‐invasion; anti‐metastasis; reversing drug resistance of cancer cells and increasing their sensitivity to chemotherapy. In this review, the latest progress on the anticancer activities of anthocyanins and the underlying molecular mechanisms is summarized using data from basic research in vitro and in vivo, from clinical trials and taking into account theory and practice.
Linked Articles
This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc
Summary
The goal of mobile ad hoc network (MANET) routing protocol is to establish a correct and effective route with minimal control overhead and bandwidth consumption. Dynamic source routing ...protocol (DSR) is a simple on‐demand routing protocol designed specifically for MANETs. The choice of routing path only adopts the simplest minimum hop count algorithm, while it did not take the node energy into account. In order to improve the control overhead of the network, we comprehensively consider the node energy information when searching the routes to the destination nodes. We propose a genetic algorithm (GA)‐bacterial foraging optimization algorithm to perform the selection of the optimal routing. After searching out multiple routes to the destination node, the paths are initialized then the GA algorithm is started. This algorithm quickly finds the positions of the maximum probability optimal paths, which are the initial positions of bacteria for the bacteria foraging optimization (BFO) algorithm. Through using the BFO algorithm, it is easy to search out the extreme value and the optimal path in order to compensate for the poor accuracy of GA algorithm. Our proposed optimized strategy improves the routing selection algorithm without change the complexity of DSR and proves the convergence of the algorithm to the global optimal solution. The simulation shows that the proposed algorithm is feasible and applicable and also has better experimental result.
We comprehensively consider the node energy information and propose a Generic Algorithm‐Bacterial Foraging optimization algorithm to perform the selection of the optimal routing. Our proposed optimized strategy improves the routing selection algorithm without change the complexity of DSR, and proves the convergence of the algorithm to the global optimal solution. The simulation shows that the proposed algorithm is feasible and applicable, and also has better experiment result.
The metastable pitting corrosion behavior of laser powder bed fusion (LPBF) produced Ti-6Al-4V is still unclear. Therefore, this work investigated the metastable pitting corrosion of LPBF-produced ...Ti-6Al-4V in Hank’s solution by electrochemical methods. The LPBF-produced sample (dominant by α′ phase in the microstructure) shows a higher frequency of pit nucleation than the annealed counterpart (composed by α + β dual phase). The passive films formed on the LPBF-produced sample exhibit a higher flux of oxygen vacancies, resulting in the absorption of more aggressive ions (e.g., Cl-) thereby producing more cation vacancies. The condensation of excessive cation vacancies contributes to the pit nucleation.
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•Laser powder bed fusion (LPBF) produced Ti–6Al–4 V alloy was used as the sample.•Corrosion behavior of the LPBF-produced sample was investigated in Hank’s solution.•The LPBF-produced Ti-6Al-4 V shows frequent metastable pitting corrosion.•The flux of oxygen vacancy is large in the passive film of LPBF-produced Ti-6Al-4 V.•Redundant vacancies assemble and condense into a void at metal/film interface.
The basic helix-loop-helix (bHLH) transcription factors are involved in several biological processes both in plant development and stress responses. Agarwood, a major active and economical product, ...is only induced and accumulated when the roots, stems, or branches are wounded in Aquilaria sinensis. Although genome-wide comprehensive analyses of the bHLH family have been identified in many plants, no systematic study of the genes in this family has been conducted in A. sinensis. In this study, 105 bHLH genes were identified in A. sinensis through genome-wide analysis and named according to their chromosomal locations. Based on a phylogenetic tree, AsbHLH family proteins were classified into 18 subfamilies. Most of them were distributed on eight chromosomes, with the exception of two genes. Based on the tissue-specific expression characteristics and expression patterns in response to methyl jasmonate (MeJA) treatment, seven AsbHLH genes were likely involved in wound-induced agarwood formation. The results provide comprehensive information on AsbHLHs that can be used to elucidate the molecular functions and physiological roles of these proteins in A. sinensis.
A viscoplastic constitutive model is developed to describe the viscoplastic behavior of unsaturated soils. The proposed model accounts for the stain‐rate and suction effects on yield by adopting an ...unsaturated isotach concept. The nonstationary flow surface theory (NSFS) is applied for modeling the viscoplastic behavior, with the yield surface which can evolve with the viscoplastic strain, viscoplastic strain rate and suction. Meanwhile, the progressively hardening concept is adopted for reproducing the viscoplastic behavior of soil at an over‐consolidated state. For the validation, a series of loading conditions are considered based on the data from the literature. Results show that the proposed model is able to reproduce the main viscoplastic behaviors of unsaturated highly compacted Gaomiaozi (GMZ) bentonite, Glenroy silt and Qianjiangping landslide (QL) soil, including CRS compression tests, rate‐dependent triaxial shear tests, and triaxial creep tests.
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•The methods toward chiral Si-, P-, and S-containing compounds are discussed.•Of these methods to construct them, asymmetric C–H activation strategy is highlighted.•The key ...stereo-discriminating steps in C–H activation mechanisms are elucidated.•The applications and further transformations of related products are presented.
Chiral Si-, P-, and S-containing organic compounds with central, planar, and axial chiralities have found a plethora of applications in various fields of chemistry. Despite significant efforts to explore new catalytic methodologies and synthetic applications to access such compounds, there are still only a few examples which are low in number and limited in diversity. The catalytic construction of Si-, P-, and S-stereogenic organoheteroatom compounds is undoubtedly one of the most exciting and challenging aspects in asymmetric catalysis and the application of catalytic asymmetric C–H activation reaction for the construction of chiral organoheteroatom compounds is still in its infancy. In this Review, we highlighted the main progress on the corresponding catalytic asymmetric reactions that apply to the construction of Si-, P-, and S-stereogenic centers and related chiral organoheteroatom compounds in a catalytic C–H activation fashion.
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