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In this paper, the characteristics and mechanism of laser-assisted machining (LAM) of C/SiC composites with different fiber orientations (0°, 45°, 90°, 135°) are studied. For the purpose of this study, a series of LAM experiments have been carried out and supported by a comparative analysis over the conventional machining (CM). Furthermore, the effect of fiber orientation on surface morphology, roughness, and sub-surface damage was explored. It is found that the surface quality of the workpiece treated by LAM is better than that of CM, and a lower surface roughness Ra value is obtained. It is shown that depending on different fiber orientations, the surface roughness decreases in different degrees. The roughness at 90° fiber orientation witnesses the maximum reduction, followed by 0° and 45° fiber orientation, and the roughness at 135° fiber orientation undergoes the slightest reduction. Moreover, surface micro-defects under LAM are significantly reduced, and fiber fractures are tidier. On the other hand, the matrix is mixed with fiber debris under high temperatures and sticks to the machined surface, filling and repairing surface pits and holes and hence improving the processed surface quality. These results provide new guidance for improving the machining quality of C/SiC composites.

Theoretical studies suggest that dispersion and repulsion are two important interactions that occur within non-polar particles. Enlightened by this, we propose a simple model for flocking of autonomous agents interacting by physicochemically inspired dispersion and repulsion interactions. This interdisciplinary effort provides a generic framework for design and analysis of distributed flocking by introducing virtual electrons (VEs). We innovatively utilize the functional theory to construct the energy functional with the distribution density of VEs as the basic variable and then solve the Lagrangian equation to derive the control law of multiagent flocking. Theoretical analysis reveals that the proposed protocol can ensure that autonomous agents asymptotically converge to an equilibrium configuration from chaotic movement and meanwhile all agents tend in time to a common velocity. Numerical simulations are presented to verify the effectiveness of theoretical results. We also give a comparison with the collective potential method and found that the proposed approach can realize the rapid transition of autonomous agents from disordered to ordered movement. This implies that the proposed framework can effectively avoid the limitation of constructing a complicated empirical field and thus may have broad application prospects.

In this paper, a new path planning algorithm is developed to address the problem of persistent and cooperative coverage using a group of robots in a complex environment. Previous works have mainly used geometric division to achieve collaborative coverage search, but ignored the environmental complexity and the path length difference of each robot. In contrast, this paper presents a novel strategy for multi-robot persistent coverage, which aims to obtain more equal coverage route for each robot while guaranteeing both the obstacle avoidance and the minimization of the coverage period. The strategy first deploys the sensors in the target region to satisfy coverage requirements. Then it classifies the sensor points by improved k-means clustering which introducing the feedback mechanism to balance the length of each route. Finally, the approach solves the travelling salesman problem to obtain the closed route for each robot. The numerical simulations show that the proposed approach is feasible to implement the cooperative and persistent coverage in consideration of complicated obstacles, equilibrium of the path length, and the minimization of total cost.

In recent years, formation control of multi-agent has been a significant research subject in the field of cooperative control. However, previous works have mainly concentrated on formation control for simple point-mass model and linear model. In contrast, this paper presents a novel cooperative algorithm for multiple air vehicles formation control, which aims to devise a control strategy based on guidance route to achieve precisely coordinated formation control for a group of fixed-wing aircraft in a complex task environment. The proposed method introduces the leader-follower structure for effective organization of the multi-agent coordination. Moreover, the Partial Integrated Formation and Control (PIFC) is adopted to design the control law for Guidance-Route based Formation Control (GRFC). Additionally, the proposed approach designs two guidance-route generation strategies for two special situations to demonstrate the effectiveness of GRFC in complex task environments. Theoretical analysis reveals that the proposed control protocol for guidance command can ensure the overall stability and tracking accuracy of the system. Numerical simulations are performed to illustrate the theoretical results, and verify that the proposed approach can achieve coordinated formation control precisely in a complex task environment. Keywords: Complex task environments, Cooperative formation control, Fixed-wing aircraft, Guidance route, Leader-follower structure, Partial integrated formation and control

TB8 titanium alloy is widely used in the aerospace industry because of its excellent properties. In this paper, laser-assisted orthogonal micromachining of TB8 titanium alloy was carried out. Observe the microstructure of the workpiece section after processing, and measure the microhardness of the processed surface. The advantages of laser-assisted cutting are analyzed by comparing conventional cutting with laser-assisted cutting. The influence of different machining parameters on the microstructure of TB8 titanium alloy was obtained by changing different machining parameters. Compared with conventional cutting, laser-assisted cutting can greatly reduce grain fragmentation. With the increase of cutting depth, the grain fragmentation decreases first and then increases. With the increase of laser power, the grain fragmentation decreases first and then increases. The grain breakage increased first and then decreased with the increase of cutting speed, and better grain quality could be obtained with smaller and larger cutting speeds. Compared with conventional cutting, laser-assisted cutting can improve the surface hardness of the workpiece, and the maximum improvement is 16.9% when the cutting speed is 50mm/s. The surface microhardness of laser-assisted cutting increases with the increase of cutting speed, but decreases first and then increases with the increase of cutting depth.

The temperature field of laser-assisted machining (LAM) of C/SiC ceramic matrix composites is affected by the material's physical parameters, laser power, spot diameter and scanning speed. The absorption rate of C/SiC composites was obtained by combining experiments and simulation based on the laser heating effect. According to the theory of heat conduction, a finite element method is used to establish a temperature field prediction model for laser-assisted machining of C/SiC composites. Comparing the effects of different laser power, spot diameter, and moving speed on the temperature field, the characteristics of LAM machining are summarized, and suggestions are made to select C/SiC composites laser-assisted machining process parameters.

Community detection is a hot issue in the study of complex networks. Many community detection algorithms have been put forward in different fields. But most of the existing community detection algorithms are used to find disjoint community structure. In order to make full use of the disjoint community detection algorithms to adapt to the new demand of overlapping community detection, this paper proposes an overlapping community detection algorithm extended from disjoint community structure by selecting overlapping nodes (ONS-OCD). In the algorithm, disjoint community structure with high qualities is firstly taken as input, then, potential members of each community are identified. Overlapping nodes are determined according to the node contribution to the community. Finally, adding overlapping nodes to all communities they belong to and get the final overlapping community structure. ONS-OCD algorithm reduces the computation of judging overlapping nodes by narrowing the scope of the potential member nodes of each community. Experimental results both on synthetic and real networks show that the community detection quality of ONS-OCD algorithm is better than several other representative overlapping community detection algorithms.

In this paper, a multi-robot persistent coverage of the region of interest is considered, where persistent coverage and cooperative coverage are addressed simultaneously. Previous works have mainly concentrated on the paths that allow for repeated coverage, but ignored the coverage period requirements of each sub-region. In contrast, this paper presents a combinatorial approach for path planning, which aims to cover mission domains with different task periods while guaranteeing both obstacle avoidance and minimizing the number of robots used. The algorithm first deploys the sensors in the region to satisfy coverage requirements with minimum cost. Then it solves the travelling salesman problem to obtain the frame of the closed path. Finally, the approach partitions the closed path into the fewest segments under the coverage period constraints, and it generates the closed route for each robot on the basis of portioned segments of the closed path. Therefore, each robot can circumnavigate one closed route to cover the different task areas completely and persistently. The numerical simulations show that the proposed approach is feasible to implement the cooperative coverage in consideration of obstacles and coverage period constraints, and the number of robots used is also minimized.

The problem of community detection in complex networks has been intensively investigated in recent years. And it was found that the communities of complex networks often overlap with each other. So in this paper, we propose an improved genetic-based link clustering for overlapping community detection. The first, the algorithm changes the node graph into the link graph. The second, the algorithm adopts the genetic algorithm to detect the link communities. The Third, the algorithm transforms the link communities into the node communities. Automatically, the nodes, which are linked with edges belonged to different link communities, will be the overlapping nodes. The last, in order to improve the quality of community detection, we define an effective method to solve the “excessive overlap” problem. The experimental results shows that the proposed algorithm is effective and efficient on both simulate networks and real networks.

Color recognition plays an important role in Machine Vision and Artificial Intelligence. In this article, a system based on FPGA applying to image acquisition, storage, display and color recognition is designed mainly to complete the recognition and calibration of fixed colors. Color images are captured by the analog camera in the system, which are decoded into standard YCbCr 4:2:2 data streams by AD chip. Then data streams are converted to the data of RGB video format by performing color space conversion. In the RGB color space, the color recognition method is proposed to identify the target color and calibrate on the display device. The experimental results demonstrate that the method can effectively achieve the identification of certain kinds of colors.

Magnetic nanoparticles (MNPs), in comparison with traditional drug solutions or suspensions, represent a promising vehicle to achieve the controlled drug delivery to targeted cell/tissue regions in cancer treatment. In this study, the biodegradable chitosan-modified magnetite (Fe3O4) NPs (CS-MNPs) are firstly synthesized using as nanocarriers, and then encapsulated with anti-tumor drug doxorubicin (DOX) to construct DOX-loaded CS-MNPs (DOX-CS-MNPs), which are further applied to assay apoptosis of glioblastoma multiforme U251 cells. The properties of the DOX-CS-MNPs including particle size, shape and magnetization, are characterized. The stability, drug release, magnetic response and redispersion of the DOX-CS-MNPs within an external magnetic field are evaluated. Furthermore, the biological effects of the DOX-CS-MNPs on U251 glioblastoma cells, particularly cytotoxicity, cell viability, actin cytoskeleton and apoptosis rate, are subsequently investigated. The data show that the prepared DOX-CS-MNPs are spherical in shape with average diameter of 60 nm approximately. The fabricated DOX-CS-MNPs also exhibit specific properties including low aggregation, high saturation magnetization, satisfactory magnetic-responsive aggregation, and redispersion in water, etc. The biological assays show that the DOX-CS-MNPs can efficiently enter the cells, reduce cell viability, and inhibit cell proliferation in a dose-dependent manner, and a high rate of cell apoptosis is induced in U251 glioblastoma cells after DOX-CS-MNPs treatment. Therefore, the present results indicate that the constructed DOX-CS-MNPs may be a promising vehicle for efficiently inhibiting proliferation of human U251 glioblastoma cells.

Label propagation algorithm (LPA) is an extremely fast community detection method and is widely used in large scale networks. In spite of the advantages of LPA, the issue of its poor stability has not yet been well addressed. We propose a novel node influence based label propagation algorithm for community detection (NIBLPA), which improves the performance of LPA by improving the node orders of label updating and the mechanism of label choosing when more than one label is contained by the maximum number of nodes. NIBLPA can get more stable results than LPA since it avoids the complete randomness of LPA. The experimental results on both synthetic and real networks demonstrate that NIBLPA maintains the efficiency of the traditional LPA algorithm, and, at the same time, it has a superior performance to some representative methods.

In this paper, we study how to design algorithms of a satellite queuing system so that all the users have self-interest in controlling congestion when it happens. Most of the algorithms proposed to accomplish this in terrestrial Internet may not be implemented in satellite router due to satellite hardware constraints or performance differences. After investigating characteristics of satellite traffic traces, we propose a new fair AQM algorithm, called Selective Differentiated Penalization. SDP use the recent buffer resources allocation history to differentially penalize misbehaving flows by dropping more of their packets to make a tradeoff between scalability and fairness. The first principle of SDP is that the resulting throughput of each flow should be bounded by the max-min fair share bandwidth. The performance of SDP is aided by the fact that the recent history of buffer resource allocations can provide accurate rate estimates of active flow and the fair share threshold. Simulated results suggest that SDP provides a reasonable degree of max-min fair bandwidth allocation in a wide variety of operating conditions.

Congestion is a natural phenomenon in core network, and is unavoidable if the queuing system is operated near capacity. Providing fairness among users with different levels of aggressiveness, and different levels of responsiveness is necessary for efficient network flow control. The scalability of current solutions depends on the number of active flows and the number of flows whose rate is greater that the current fair share. In this paper we propose a new fair active queue management scheme, called SDP (Selective Differentiated Penalization), that use the recent buffer resources allocation history to differentially penalize misbehaving flows by dropping more of their packets to make a tradeoff between scalability and fairness. The first principle of SDP is that the resulting throughput of each flow should be bounded by the max-min fair share bandwidth. The performance of SDP is aided by the fact that the recent history of buffer resource allocations can provide accurate rate estimates of active flow and the fair share threshold. Simulated results suggest that SDP provides a reasonable degree of max-min fair bandwidth allocation in a wide variety of operating conditions.

Purpose. Indapamide, a non-thiazide antihypertensive diuretic agent, has been widely coadministered with other classes of antihypertensive agents to reach target systolic blood pressure. Indapamide is extensively metabolized by cytochromes P450. Interaction of indapamide and other antihypertensive drugs are unknown. We investigated the effects of other antihypertensive drugs on the metabolism and pharmacokinetics of indapamide in vitro and in vivo. Methods. Indapamide metabolism was studies in vitro using human liver microsomes pretreated with or without different concentrations of CYP-selective inhibitors and seven major antihypertensive drugs, felodipine, nifedipine, nitrendipine, telmisartan, irbesartan, valsartan and puerarin. Furthermore, the pharmacokinetics of indapamide was determined by HPLC-MS/MS to evaluate the effects of felodipine coadministered on the bioavailability of indapamide in rats in vivo. Results. The Km and Vmax of indapamide metabolism were 114.35 ± 3.47 μM and 23.13 ± 6.61 μmol/g/min. The metabolites of indapamide, hydroxyl-indapamide and dehydrogen-indapamide, were followed. CYP3A4 and CYP2C19 were involved in indapamide metabolism in human live microsomes. In addition, felodipine, nifedipine and nitrendipine significantly inhibited indapamide metabolism with the maximum inhibitory rates of 82.6%, 72% and 95%, respectively. Felodipine significantly elevated indapamide plasma concentration and prolonged its half-life. Conclusions. Combination therapy of indapamide and felodipine might lead to the alteration of indapamide metabolism and pharmacokinetics. The consequence of such an interaction that may include increased effectiveness and side effect needs to be tudeis in human. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.