Search

Segregation can seriously damage the mechanical properties of the aluminum alloys. 6061 aluminum alloy wheel spokes were prepared by squeeze casting. To investigate the formation mechanism of segregation, the microstructure of the alloy was observed using scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and electron microprobe analysis methods. The Gibbs energy of each phase during solidification was calculated by JMatPro. Results show that the segregation phases in the R-joint of the wheel spokes are mainly composed of Mg2Si, β-AlFeSi and Al5Cu2Mg8Si6 intermetallics. During the solidification of the 6061 aluminum alloy wheels, Mg2Si and α-AlFeSi phases precipitate in the mushy zone at first. With the decrease of temperature, α-AlFeSi transforms into β-AlFeSi, while Al5Cu2Mg8Si6 precipitates from the solid-state aluminum alloy after solidification. Segregation at the R-joint of wheel spokes is mainly caused by insufficient cooling, so the cooling during alloy solidification should be enhanced to avoid segregation.

Clinical studies found that regular aerobic exercise has analgesic and antianxiety effects; however, the underlying neural mechanisms remain unclear. Multiple studies have suggested that regular aerobic exercise may exert brain-protective effects by promoting the release of serotonin, which may be a pain modulator. Anterior cingulate cortex (ACC) is a key brain area for pain information processing, receiving dense serotonergic innervation. As a result, we hypothesized that exercise may increase the release of serotonin in the ACC, thus improving pain and anxiety behaviors.Integrative methods were used, including behavioral, electrophysiological, pharmacological, biochemical, and genetic approaches, to explore the effects of regular aerobic exercise and the underlying neural mechanisms.Regular aerobic exercise in the form of voluntary wheel running for 30 min daily for 15 d showed significant effectiveness in relieving pain and concomitant anxiety in complete Freund's adjuvant-induced chronic inflammation pain models. c-Fos staining and multielectrode array recordings revealed alterations in neuronal activities and synaptic plasticity in the ACC. Moreover, systemic pharmacological treatment with 4-chloro-dl-phenylalanine (PCPA) to deplete endogenous serotonin and local delivery of serotonin to the ACC revealed that exercise-related serotonin release in the ACC bidirectionally modulates pain sensitization and anxiety behaviors by modulating synaptic plasticity in the ACC. Furthermore, we found that 5-HT1A and 5-HT7 receptors mediated the serotonin modulation effects under conditions of regular aerobic exercise through local infusion of a selective antagonist and shRNA in the ACC.Our results reveal that regular aerobic exercise can increase serotonin release and modulate synaptic plasticity in the ACC, ultimately improving pain and concomitant anxiety behaviors through the functions of the 5-HT1A and 5-HT7 receptors.

This research investigates the optimal region to achieve balanced thermal and electrical insulation properties of epoxy (EP) under high frequency (HF) and high temperature (HT) via integration of surface-modified hexagonal boron nitride (h-BN) nanoparticles. The effects of nanoparticle content and high temperature on various electrical (DC, AC, and high frequency) and thermal properties of EP are investigated. It is found that the nano h-BN addition enhances thermal performance and weakens electrical insulation properties. On the other side, under HF and HT stress, the presence of h-BN nanoparticles significantly improves the electrical performance of BN/EP nanocomposites. The EP has superior insulation properties at low temperature and low frequency, whereas the BN/EP nanocomposites exhibit better insulation performance than EP under HF and HT. The factors such as homogeneous nanoparticle dispersion in EP, enhanced thermal conductivity, nanoparticle surface modification, weight percent of nanoparticles, the mismatch between the relative permittivity of EP and nano h-BN, and the presence of voids in nanocomposites play the crucial role. The optimal nanoparticle content and homogenous dispersion can produce suitable EP composites for the high frequency and high temperature environment, particularly solid-state transformer applications.

Purpose. To verify the beneficial effects of Nanobubbles water curcumin extract (NCE) supplementation on health promotion and to demonstrate the application of NCE in reducing the risk of musculoskeletal injury. Methods. In the current study, 12 females were randomly assigned to NCE (15g/day) and maltodextrin groups. Performance and related body composition were evaluated at 2 time points—presupplementation (pre-) and after 4 weeks of postsupplementation (post-). The posttest consists of a set of biochemical parameters for antifatigue activity and injury status evaluation. Results. NCE group exhibited significantly lower levels of alanine aminotransferase (ALT), alkaline phosphatase (ALP), triglycerides (TG), and higher high-density lipoprotein (HDL) after a 4-week supplementation, compared with the placebo group. After a 15-minute session on the spinning bike, serum lactate and ammonia levels were decreased and glucose was economized in the NEC group. 4-week-NCE supplementation was also able to reduce the peak vertical ground reaction force (PVGRF) during drop jump. Therefore, the risk of musculoskeletal system in lower extremity could be reduced. Conclusion. We demonstrate that 4-week-NCE supplementation can also be used in explosiveness exercise for better physiological adaptation. Thus, NCE has potential for use with nutrient supplements toward a variety of benefits for athletics.

For the shortcomings of existing multi-axis aircraft rack design a new folding mechanism of the machine arm, and then design a six-axis folding rack. By calculating the structural strength of the machine arm and apply engineering analysis software for the six-axis folding rack mechanics simulation analysis to verify its structural design is reasonable. Use 3D software to build a three-dimensional model of the six-axis folding rack, and use rapid prototyping technology, access to the kind of physical prototype six-axis folding rack, after the actual test, consistent with mission requirements.

Traditional cable insulation status diagnosis method is comprised of withstand voltage experiment. However, withstand voltage experiment injures the insulation part. Insulation resistance and tanδ provide the limited information because of single frequency test. However polarization and depolarization(PDC) can be used for determining the ageing extent of the cables. Existing equipments have poor anti-jamming capability, Aiming at the problems, we have developed cable insulation diagnosis equipment based on (PDC) process in dielectric insulation. This equipment can collect the low current which can be used to analyze cable insulation status by applying high voltage excitation. Due to possible device noise and environment electromagnetic interference, low current measurement encounters is usually the most difficult issue in device development. To solve this, first of all, the equipment using the modular components avoid self-interference. Then, to achieve good polarization/depolarization current measurement, software Butterworth filter is employed to deal with the noise in measured current waveforms. In addition, the equipment is designed with floating potential in order to have the ability to measure the current without disconnecting grounding wires of the device under test. Calibration of the equipment is also conducted with the usage of a precise RC network. In this paper, the equipment with high accuracy is verified, and tests in the field, which get good results. It can be used more widely due to small volume and reliable operation.

It is hard for normal traffic to travel on rugged road and polluted for the environment. So a new multi-legged walking machine with double mixed power is designed. The machine is made up of several parts, including mechanic walking part with eight legs, transmission part with two gears, two electric control footboards, two power motors and a folded beach umbrella. Detailed explanation of designed idea and process for mechanic walking legs is made. Detailed explanation of transmission ratio, circuit diagram and working principle for gear transmission is made as well. It makes simulation analysis for mechanic legs by software AUTODESK INVENTOR. The result shows that moving distance and strength are satisfied and meet standard.

As a mature access technology for the communication in smart grid, Ethernet Passive Optical Network (EPON) is widely considered as a promising solution due to high bandwidth capacity and stability. In recent years, EPON technology has received much attention and introduced into smart grid. The particularity of smart grid largely depends on bandwidth allocation. In this paper, we evaluate the performances of smart grid with three bandwidth allocation algorithms, i.e., Poll with Stop (PS), Max and Min Bandwidth Bounds (MMBB) and Cyclic Strategy (CS), respectively. The simulation results in this paper show the advantages of CS algorithm in terms of packet delay and throughput.

Long-Reach Passive Optical Network (LR-PON) is widely acknowledged as a promising solution for communication system in smart grid. Survivability is one of the key issues in the planning of LR-PON because massive high-rate traffic flows may be interrupted in case of network component failure. However, the survivability issue of LR-PON is addressed in few works. Most of previous works focus on single distribution fiber failure and remain untouched the simultaneous failure of multiple distribution fibers. In this paper, we focus on the survivability of LR-PON against single Shared-Risk Link Group (SRLG) failure. A reliability model is proposed to represent the probability of reliable connection for each Optical Network Unit (ONU). Based on this reliability model, we propose a novel Backup Fibers Protection (BFP) approach, aiming at the optimization of joint allocating backup capacity and deploying backup fibers. Through extensive simulation, we investigate the performance of BFP and demonstrate its effectiveness in different scenarios.

As a promising technology for broadband communication, Passive Optical Network (PON) has been deployed to support the communication in smart grid system. This paper theoretically analyzes the influences on Directly Modulated Laser (DML)-based PON system performance including Bit Error Rate (BER) and power budget. First, we establish the DML-based PON system model, and then the system performances are simulated under different linewidth enhancement factor, received optical power and fiber length. Simulation results show the increase in received optical power to maintain a given BER due to fiber nonlinearities. This research provides a theoretical guidance on the PON system design.

As a promising communication technology for smart grid system, Fiber-Wireless (FiWi) broadband access network integrating wireless and optical access technologies, is becoming a promising “last mile” access technology. As the front-end of FiWi broadband access network, Wireless Mesh Network (WMN) has the features of high transmission rate, wide coverage and low cost of networking, etc, which can make FiWi broadband access network have the advantages of self-healing, self-configuring and flexibility. As one of the key technologies in WMN, wireless routing protocols play an important role in the performance optimization of WMN, which directly influence FiWi broadband access network. Thus, this paper mainly studies the routing protocols in WMN based on OPNET network simulation platform. By simulation and analysis, this paper shows that Ad hoc On-demand Distance Vector (AODV) routing protocol has low data dropped and good performance in network delay. Dynamic Source Routing (DSR) protocol has low network load. Meanwhile, Optimized Link State Routing (OLSR) protocol has high network throughput.

Infilled wall is always regarded as a nonload bearing element, its energy-dissipation capacity and impact for the frame structure under earthquake have not been taken seriously. In this paper the function of infilled wall for frame structure was discussed, energy-dissipation capacity of different measures were analysed and compared from the point of passive control theory. This paper provides the reference for the further research of filler wall.

In current large databases, there is a widespread defect of poor immunity. It is mainly due to the huge amount of data which makes the traditional algorithm falling into a defect of low efficiency of local search, causing inconspicuous effect to detect potential risks and other defects. To this end, we propose an intrusion detection model of medical information diversity database under cloud computing. By using the similar risk attributes of data, an intrusion test model under cloud computing environment is constructed. The use of intrusion tolerance theory can reduce the impact of failure report phenomenon for the stability of whole system. This model can effectively resist denial of service attacks, but also through the mutual cooperation between the servers to prevent the single failure node attacking to the system, ensure the safety and smooth of the cloud computing services at the greatest degree, in order to enhance the user experience. Experiments show that the algorithm improves the accuracy of the intrusion detection of medical information diversity database, and achieves good results.

This research determined the proper gradation of clay brick powder, PET to clay brick powder ratio, and curing temperature. Density, compressive, and tensile strength of the PET-Brick Powder Mixture were also studied. The research results indicate that the mixture had lower density and water absorption. The strength increased quickly and reached the 94% of 28-day strength at 6 hours. The proper initial curing temperature is 180°C.

Deflection and stress of different cross section forms and its value are compared by finite element analysis of timberwork design model under the impact loading. The result indicates that decreasing the size of cross section or changing the section shape can effectively avoid the model too heavy and conservative design. In the case of horizontal loads applied on first floor, strengthening the column of first floor obviously reduces the deflection of model and improves the lateral stiffness. Keeping the column size of the first floor and choosing I-section significantly reduce the overall weight on condition of meeting the bearing capacity and stability, it also make the material higher utilization.

Recently, structured LDPC codes have been focused on due to excellent performance and lower complexity. An improved construction of QC-LDPC based on a modified PEG algorithm is proposed in this paper. The modified Progressive Edge-Growth algorithm is a PEG algorithm with Approximated Cycle Extrinsic Message Degree (ACE) metric, which is used to describe the connectivity of cycles. The approach can maximize the girth of the cycles, improve the connectivity of cycles and have the advantages of QC algorithms. The simulation results demonstrate that the PEG algorithm based on ACE has lower Bit Error Rate (BER) and Frame Error Rate (FER) than the original PEG algorithm at the low Signal Noise Ratio (SNR) values, and has a relatively lower computational complexity.

We study the overload control problem of application server in the next generation electric communication network in this paper. We introduce an energy efficiency overload control algorithm based on simulated annealing. Firstly, by considering the overload control and energy efficiency, we construct the relations function between the input rate control and energy efficiency using rate allocation. Then, we construct the optimal overload control model of energy efficiency by regarding this relation function as objective function and overload control as constraint conditions. Thirdly, we use simulated annealing algorithm to solve this model, and then obtain the optimal solution during the iterative process. The simulation results show that our algorithm is feasible and effective.

In this literature, we explore the solution of network traffic recovery in smart grid. Taking account of dimensionality of network traffic in smart grid, we propose a novel reconstruction model via network tomography. In our algorithm, we use the low-dimension nature of traffic matrix and the greedy adaptive dictionary algorithm to convert the network tomography into the problem of sparse reconstruction at first. Then we solve network traffic by an iterative greedy algorithm. Simulation results indicate that proposed algorithm exhibits noticeably improvement in estimation error comparing with previous work.

In this paper, we address the problem of real-time network traffic monitoring in the communication network of smart grid. And we propose an effective distributed network traffic monitoring approach. In our algorithm, instead of measuring all the origin-destination pairs, we just need to measure partial origin-destination pairs that flows our communication network. From the measured origin-destination pairs, we can obtain all the origin-destination pairs via our recovery algorithm. Finally, we validate the properties of our method by real network data.

This paper studies the overload control problem of the Parlay gateway in next-generation electric power communication network. First, this paper analyses the effectiveness and fairness of the overload control of the Parlay gateway. And then taking the energy efficiency of the electric power communication network as target, we establish the optimization model of energy efficiency overload control. Thirdly, we put forward an energy efficiency overload control algorithm based on the ant colony algorithm. Simulation results show that our algorithm is feasible and effective.

This paper studies the problem of QoS graded optimization in the next generation electric power communication network and proposes an energy-efficient QoS graded optimization method based on artificial fish swarm algorithm. Firstly, this paper discusses the networks model of the QoS graded optimization and describes the networks model using delay and packet loss ratio in time-variant network. Secondly, we set up the model of networks throughput and energy consumption using the characteristics of delay and packet loss ratio in time-variant network. Finally, simulation results show that our approach is effective.

With the rapid development of the information and communication technology (ICT) and the considerable increasing of the network business, the energy consumption of the network equipments improves continually. Thus building the technology of the next generation electric power communication network based on energy efficiency has become the research focus of the current electric power communication field. This paper researches the problem of the QoS graded optimization in the next generation electric power communication network. First of all, we discuss the network model of the networks QoS graded optimization, and analyze the delay and the packet loss ratio in time-variant networks. Secondly, we introduce the mathematical description of the throughput capacity and the energy consumption in time-variant networks and build the optimizing model of the energy efficiency which describes the networks QoS classification through considering the QoS constraints such as the networks delay and packet loss ratio etc. Thirdly, we propose using Genetic Algorithm to solve the model and find the QoS classes which make the networks reach the maximum energy efficiency through iterative optimization. Finally, the simulation results indicate the method proposed in this paper is available.

This paper theoretically analyzes the atmospheric influences on Ultraviolet (UV) communication, in which the main considerations include atmospheric absorption and atmospheric scattering. Through the establishment of mathematical model, this paper describes the atmospheric transmittance with different wavelengths. Finally, the atmospheric transmittance is simulated under different visibilities, rainfall and paths. The results show that the atmospheric transmittance will be different with different wavelengths, visibilities and rainfall. The atmospheric transmittance in horizontal path is larger than that in the vertical path. This research provides a theoretical guidance on the using of UV communication for the information transmission in power grid.

In this paper, we study the problem of end-to-end network traffic estimation in the electric power communication network. Based on principal component analysis and multifractal wavelet model, we propose an effective and precise approach to estimate each origin-destination pair. Numeral results state that our method can capture the changes of end-to-end network traffic accurately in electric power communication network.

Mobile Ad hoc Network (MANET) is an effective method to solve the bottleneck of information collection and wireless transmission in Smart Grid. The particularity of MANET determines the importance of routing protocols. In order to improve the performance of MANET routing protocol, in this paper we evaluate the routing protocol, i.e., Ad hoc On demand Distance Vector (AODV), from several perspectives that did not draw attention in previous works. Furthermore, we also compare AODV with the routing protocol Dynamic source Routing (DSR). The simulation shows that AODV outperforms DSR in generally, and the former is suitable for larger MANET network. The simulation results in this paper not only provide effective evidence for further optimized routing protocols and the current protocols, but also provide feasible solution for Smart Grid to collect and transmission data by using MANET technology.

In order to meet the requirements of Smart Grid in data acquisition, transmission reliability, stability, robustness and low power consumption of devices, ZigBee with its significant advantages of low power, low cost, low rate and easy to use, can play an important role in Smart Grid. As one of the key technologies of ZigBee, routing technology plays an important role in the performance optimization of network. Thus, in this paper, we focus on cluster-tree routing algorithm and hybrid routing algorithm in ZigBee network. Simulation and results show that, hybrid routing algorithm has better performance than cluster-tree routing algorithm in network throughput, average traffic received, average number of hops, network delay and network load.

As an alternative insulating liquid of mineral oil, the silicone oil is widely used in the high voltage apparatuses where fireproofing and environment must be considered. Both the thermal aging and moisture threaten the reliability of the oil-paper insulating system. As a nondestructive measurement method, the frequency domain spectroscope (FDS) property of the electric apparatus has been used to assess the moisture content and aging condition of the mineral oil-paper composed insulating system. However, whether FDS is suitable for the assessment of silicone oil-paper composed insulating system is still unknown. To clarify how the thermal aging and moisture influence the FDS property of the silicone oil-paper is significantly meaningful. In this paper, the accelerated thermal aging experiments are performed on both silicone oil and mineral oil impregnated paper samples at high temperature. FDS measurements of samples with different aging time and moisture are performed then. Experiment results show that for the mineral oil-paper system, both the thermal aging and moisture impact the FDS results a lot in the low frequency region and it is very hard to separate them apart clearly. However, for the silicone oil-paper system, the moisture significantly impacts the FDS results while the thermal aging plays a slight role. Therefore, compared to the mineral oil-paper system electric apparatuses, the FDS method maybe much more suitable to estimate moisture content for the silicone oil-paper insulation apparatuses.

Dielectric response(DR) measurement has been deployed as a non-destructive and potential diagnostic method for moisture or aging condition of power system apparatuses. In order to promote the application of DR method, development of precise, easy-to-use and cost-effective testing devices is an urgent issue, in which accurate acquisition of the insulation current is critical. In this paper, a DR testing device which combine time-domain Polarization and Depolarization Current(PDC) and Frequency-Domain Spectroscopy(FDS), which are two major approaches for DR measurement, is developed. Firstly, the principle of PDC and FDS is introduced. Then the technical specification, hardware and software structure are demonstrated. In addition, using high input impedance PCI data acquisition card, phase lag error of the current measurement module is calibrated by measuring the voltage signal at both the input and the output ends of current measurement module. Finally, PDC and FDS test waveform of XLPE cable and bushing sample are demonstrated, and the effectiveness of this device is proved.