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Search Results: 1 - 10 of 18955 matches for " Song Mingbo "
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Active Elastic Support/Dry Friction Damper with Piezoelectric Ceramic Actuator
Liao Mingfu,Song Mingbo,Wang Siji
Shock and Vibration , 2014, DOI: 10.1155/2014/712426
Abstract: The basic operation principle of elastic support/dry friction damper in rotor system was introduced and the unbalance response of the rotor with elastic support/dry friction damper was analyzed theoretically. Based on the previous structure using an electromagnet as actuator, an active elastic support/dry friction damper using piezoelectric ceramic actuator was designed and its effectiveness of reducing rotor vibration when rotor traverses its critical speed and blade-out event happened was experimentally verified. The experimental results show that the active elastic support/dry friction damper with piezoelectric ceramic actuator can significantly reduce vibration in rotor system; the vibration amplitude of the rotor in critical speed region decreased more than 2 times, and the active damper can protect the rotor when a blade-out event happened, so the rotor can traverse the critical speed and shut down smoothly. In addition, the structure is much simpler than the previous, the weight was reduced by half and the power consumption was only 5?W. 1. Introduction Rotors in aircraft engines mostly operate above the first critical speed, some even over second and third critical speeds. They must traverse their critical speeds frequently in the operation. When a blade-out event happens in an engine, it must be shut down immediately [1]. However in this case, the rotor will vibrate violently while traversing the critical speed region due to the excessive unbalance. This could cause further damage to the engine [1–3]. In Certification Specifications for Large Airplanes CS-25 [4], some clauses about aircraft engine rotor are as follows. “Design precautions must be taken to minimize the hazards to the airplane in the event of an engine rotor failure.” “There must be means for stopping the rotation of any engine individually in flight.” This is a crucial challenge to the design of aircraft engines. In order to deal with abovementioned problems, effective damping must be incorporated into rotor systems. It has been proven theoretically and experimentally that as a new rotor vibration damper, the elastic support/dry friction damper can significantly attenuate the vibration amplitude of rotor system in the critical speed region [5–7]; moreover, it is convenient to be controlled by adjusting control voltage [8–11]. However, due to its oversized electromagnetic actuator, the application of such a damper in aircraft engines will be restricted. In recent years, smart materials have received more and more attention in structure vibration control. It has brought some new
A Device Monitoring System Based on ARM Upper Computer and WIFI Transmission  [PDF]
Mingbo Zhao, Song Yan, Qingrui Miao
Journal of Computer and Communications (JCC) , 2019, DOI: 10.4236/jcc.2019.79006
Abstract: With the widespread application of WIFI networks and embedded system technology, the device monitoring system based on Embedded System and wireless network came into being. In this paper, we introduce a device monitoring system based on ARM upper computer and WIFI transmission, and we tested this system on workshop equipment. The hardware adopts ARM Cortex-A8 processor architecture of TI company as the main control chip, using IAC-335X-Kit development board for system design, external USB camera module and WIFI wireless module for video capture and data transmission. The software is based on embedded Linux as the platform. The system will collect production data accurately and objectively, and the statistical analysis. At the same time, the system uses QT to develop the upper computer software GUI interface. Compared with the traditional system based on the wired network, our design is more convenient and flexible, which reduces the implementation restriction and maintenance cost of traditional network cabling.
Effects of artificial tending on Pinus tabulaeformis forest growth and its structural characteristics
人工抚育措施对油松林生长及结构特征的影响

CAO Yun,YANG Yie,SONG Bingyu,HUANG Heping,YANG Mingbo,ZHENG Min,
曹云

应用生态学报 , 2005,
Abstract: The investigation on the growth status, community composition, and structural characteristics of Pinus tabulaeformis forest artificially tended for six years showed that there were significant differences in the average DBH, height, and crown size of the forest among the treatments DA (trimming without intermediate cutting), FA (trimming and intermediate cutting) and CK (without trending). Treatment FA had the highest values of average DBH (7.8 +/- 0.29 cm), height (5.5 +/- 0.09 m) and crown size (249 +/- 7.24 cm), while the CK had the lowest ones. The average biomass of new leaf (1-year-old), old leaf (2 or more-year-old), and branch per tree increased significantly (P<0.01) with enhancing tending treatments. The aboveground biomass of treatment FA was the biggest (44.0 t x hm(-2)), and that of CK was the smallest (14.9 t x hm(-2)). The leaf length and SLA at the early and terminal stages of development (May, June and September) had significant difference among the treatments, and the amount of community composition and the cover degree of undergrowth plants increased evidently under artificial tending treatments.
Modifi cation and refinement mechanism of Mg2Si phase in Sr-containing AZ61-0.7Si magnesium
Yang Mingbo,Shen Jia
China Foundry , 2009,
Abstract: The effect of Sr on modifi cation and refi nement of the Mg2Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed. The results indicate that Sr can effectively modify and refi ne the Chinesescript shaped Mg2Si phase in the AZ61-0.7Si alloy. By adding 0.06wt.%-0.12wt.%Sr to AZ61-0.7Si alloy, the Mg2Si phase in the alloy can be changed from the initial coarse Chinese-script shape to fi ne granule and/or irregular polygonal shapes. Accordingly, the Sr-containing AZ61-0.7Si alloy exhibits higher tensile and creep properties than the AZ61-0.7Si alloy without Sr modifi cation. The mechanism on modifi cation and refi nement of the Mg2Si phase in Sr-containing AZ61-0.7Si alloy is possibly related to the following two aspects: (1) adding Sr may form the Al4Sr phase which can serve as the heterogeneous nucleus for the Mg2Si particles and/or (2) adding Sr may lower the onset crystallizing temperature and increase the undercooling level.
Hybrid Precoding for Physical Layer Multicasting
Mingbo Dai,Bruno Clerckx
Mathematics , 2015,
Abstract: This work investigates the problem of downlink transmit precoding for physical layer multicasting with a limited number of radio-frequency (RF) chains. To tackle the RF hardware constraint, we consider a hybrid precoder that is partitioned into a high-dimensional RF precoder and a low-dimensional baseband precoder. Considering a total transmit power constraint over the RF chains, the goal is to maximize the minimum (max-min) received signal-to-noise ratio (SNR) among all users. We propose a low complexity algorithm to compute the RF precoder that achieves near-optimal max-min performance. Moreover, we derive a simple condition under which the hybrid precoding driven by a limited number of RF chains incurs no loss of optimality with respect to the fully digital precoding case. Finally, numerical results validate the effectiveness of the proposed algorithm and theoretical findings.
Transmit Beamforming for MISO Broadcast Channels with Statistical and Delayed CSIT
Mingbo Dai,Bruno Clerckx
Mathematics , 2015,
Abstract: This paper focuses on linear beamforming design and power allocation strategy for ergodic rate optimization in a two-user Multiple-Input-Single-Output (MISO) system with statistical and delayed channel state information at the transmitter (CSIT). We propose a transmission strategy, denoted as Statistical Alternative MAT (SAMAT), which exploits both channel statistics and delayed CSIT. Firstly, with statistical CSIT only, we focus on statistical beamforming (SBF) design that maximizes a lower bound on the ergodic sum-rate. Secondly, relying on both statistical and delayed CSIT, an iterative algorithm is proposed to compute the precoding vectors of Alternative MAT (AMAT), originally proposed by Yang et al., which maximizes an approximation of the ergodic sum-rate with equal power allocation. Finally, via proper power allocation, the SAMAT framework is proposed to softly bridge between SBF and AMAT for an arbitrary number of transmit antennas and signal-to-noise ratio (SNR). A necessary condition for the power allocation optimization is identified from the Karush-Kuhn-Tucker (KKT) conditions. The optimum power allocation to maximize an ergodic sum-rate approximation is computed using Sequential Quadratic Programming (SQP). Simulation results show that the proposed SAMAT scheme yields a significant sum-rate enhancement over both SBF and AMAT.
Reinforcement Learning applied to Single Neuron
Zhipeng Wang,Mingbo Cai
Computer Science , 2015,
Abstract: This paper extends the reinforcement learning ideas into the multi-agents system, which is far more complicated than the previously studied single-agent system. We studied two different multi-agents systems. One is the fully-connected neural network consists of multiple single neurons. Another one is the simplified mechanical arm system which is controlled by multiple neurons. We suppose that each neuron is like an agent and it can do Gibbs sampling of the posterior probability of stimulus features. The policy is optimized in a way that the cumulative global rewards are maximized. The algorithm for the second system is based on the same idea but we incorporate the physics model into the constraints. The simulation results show that for the first system our algorithm converges well. For the second system it does not converge well in a reasonable simulation time length. In summary, we took the initial endeavor to study the reinforcement learning for multi-agents system. The computational complexity is always an issue and significant amount of works have to be done in order to better understand the problem.
Effects of Drought Stress Simulated by Polyethylene Glycol on Seed Germination, Root and Seedling Growth, and Seedling Antioxidant Characteristics in Job’s Tears  [PDF]
Can Wang, Lingbo Zhou, Guobing Zhang, Yan Xu, Xu Gao, Ne Jiang, Liyi Zhang, Mingbo Shao
Agricultural Sciences (AS) , 2018, DOI: 10.4236/as.2018.98069
Abstract: Two Job’s tears cultivars, yy18-1 (high resistance to drought stress) and yy12-7 (susceptible to drought stress) were used to investigate the responses of seed germination, root and seedling growth, and seedling antioxidant characteristics to drought stress simulated by polyethylene glycol (PEG) 6000 solutions with 0, -0.05, -0.1, -0.15, and -0.2 MPa osmotic potentials. The results showed that the germination energy, germination rate, germination index, root and seedling lengths, root and seedling diameters, root and seedling fresh masses, root and seedling dry masses, and seedling relative water content (RWC) decreased with the decrease of the osmotic potential of PEG 6000 solution. The contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline in seedling increased with the decrease of the osmotic potential of PEG 6000 solution. The activities of peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in seedling increased and then decreased with the decrease of osmotic potential of PEG 6000 solution. -0.1 MPa was the optimal osmotic potential of PEG 6000 solution simulated drought stress at germination stage for Job’s tears. The proline content and activities of POD and CAT were important mechanisms for the maintenance of drought resistance in Job’s tears seedling.
Effect of Different Inducers on the Essential Oil of Suspension Culture Cells from Cinnamomum longepaniculatum  [PDF]
Linman He, Kuan Yan, Mingbo Xiao
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105803
Abstract:
In this study, the effects of different inducers on the accumulation of essential oil (1,8-eucalyptus) in suspension cells of Cinnamomum longepaniculatum were studied by adding different inducers, and the differences in the effects of different inducers on the yield and quality of essential oil in suspension cells of C. longepaniculatum were revealed. The results showed that under the same conditions, the addition of CaSO4 1.5 mg/L, Li2SO4 1.0 mg/L, SA15 mg/L and H2O2 9 mmol/L in B5 medium could significantly promote the accumulation of essential oil, which was 60.94%, 54.69%, 36.72% and 35.16% higher than that of CK, reaching 0.0824 mg/L, 0.0792 mg/L, 0.0700 mg/L and 0.0692 mg/L, respectively. Through orthogonal test, it was found that 2.0 mg/L CaSO4 combined with, H2O2 9 mmol/L, SA 15 mg/L and Li2SO4 0.5 mg /L presented significant differences compared with other combinations (P < 0.05), and the yield reached 0.1768 mg/L, which increased by 245.31%. The experiment showed that the addition of inducer was an effective way to promote the accumulation of essential oil in suspension cells, and provided a reference for the manual regulation and strengthening of metabolism synthesis in this lifetime of suspension cells.
Fine-scale temporal and spatial variation of taxon and clonal structure in the Daphnia longispina hybrid complex in heterogeneous environments
Mingbo Yin, Adam Petrusek, Jaromir Seda, Justyna Wolinska
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-12
Abstract: In both reservoirs, we observed temporal (generation-to-generation) and spatial (along the heterogeneous reservoir environment) changes in Daphnia community structure. In the single-species reservoir, the clonal diversity of D. galeata increased with time, as a few dominant clones were replaced by a higher number of less common clones. A loss in selective advantage for the dominant clones may have been due to gradual changes in the environment, or due to selection acting in a negative frequency-dependent manner. In the multispecies reservoir, there were no apparent temporal trends in clonal diversity but we observed significantly lower clonal diversity in the interspecific hybrids than in the coexisting parental species, supporting the existence of reproductive barriers between the parental genomes.Our study, tracing clonal lineages of Daphnia in time and space by the fine-resolution markers, contributes to the understanding of how clonal reproduction impacts community structure in cyclically parthenogenetic organisms.Cyclically parthenogenetic organisms, which reproduce both sexually and asexually, are common in nature, in both the animal and plant kingdoms [1,2]. This mode of reproduction, especially its asexual (clonal) component, has attracted considerable interests among population geneticists and evolutionary biologists. Asexual phase of the cyclically parthenogenetic reproduction cycle may have profound impact on population structures. For example, in the long-term, clonal reproduction may reduce the number of genetically distinct individuals within a population and hence decrease the effective population size (e.g. [3,4]). It may also lead to a spatial genetic autocorrelation, which could be falsely attributed to limited propagule dispersal or kin-structured colonization (e.g. [5]). Finally, as clones differ in fitness under varying environmental conditions [6], changes in clone frequencies are expected across the growing season [7]. Consequently, clonal sel
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