A Novel Fixed Twin-Rotor Unmanned Aerial Vehicle with Variable Angle Louver Rudder

Yixin Zhang,Jianfeng Zhou,Shaoping Wang,Mengqi Yang,Shaoshi Li 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

A novel fixed twin-rotor unmanned aerial vehicle (UAV) based on the variable angle louver rudder (VALR) is developed in this work. In view of the mechanical characteristics under the action of the louver rudder, specific kinematics and dynamics models are derived. The aerodynamic characteristics of the UAV are studied through computational fluid dynamics simulation, and a ground measurement system is designed to analyze the aerodynamic characteristics of the prototype. An attitude control model is proposed, and maneuvers such as take-off, landing, hovering, and braking are realized through flight experiments, which verify the feasibility of the prototype design. This research shows that the new layout with the VALR system, combined with the advantages of rudder control and vector control, can reduce the structural complexity and deadweight of the UAV while ensuring flight stability and improving maneuverability. Moreover, the novel UAV has higher energy efficiency and economy.

Hemicastration induced spermatogenesis-related DNA methylation and gene expression changes in mice testis

Yixin Wang,Long Jin,Jideng Ma,Li Chen,Yuhua Fu,Keren Long,Silu Hu,Yang Song,Dazhi Shang,Qianzi Tang,Xun Wang,Xuewei Li,Mingzhou Li 아세아·태평양축산학회 2018 Animal Bioscience Vol.31 No.2

Objective: Hemicastration is a unilateral orchiectomy to remove an injured testis, which can induce hormonal changes and compensatory hypertrophy of the remaining testis, and may influence spermatogenesis. However, the underlying molecular mechanisms are poorly understood. Here, we investigated the impact of hemicastration on remaining testicular function. Methods: Prepubertal mice (age 24 days) were hemicastrated, and their growth was monitored until they reached physical maturity (age 72 days). Subsequently, we determined testis DNA methylation patterns using reduced representation bisulfite sequencing of normal and hemicastrated mice. Moreover, we profiled the testicular gene expression patterns by RNA sequencing (RNA-seq) to examine whether methylation changes affected gene expression in hemicastrated mice. Results: Hemicastration did not significantly affect growth or testosterone (p>0.05) compared with control. The genome-wide DNA methylation pattern of remaining testis suggested that substantial genes harbored differentially methylated regions (1,139) in gene bodies, which were enriched in process of protein binding and cell adhesion. Moreover, RNA-seq results indicated that 46 differentially expressed genes (DEGs) involved in meiotic cell cycle, synaptonemal complex assembly and spermatogenesis were upregulated in the hemicastration group, while 197 DEGs were downregulated, which were related to arachidonic acid metabolism. Integrative analysis revealed that proteasome 26S subunit ATPase 3 interacting protein gene, which encodes a protein crucial for homologous recombination in spermatocytes, exhibited promoter hypomethylation and higher expression level in hemicastrated mice. Conclusion: Global profiling of DNA methylation and gene expression demonstrated that hemicastration-induced compensatory response maintained normal growth and testicular morphological structure in mice.

Business Software Rapid Development Platform based on SOA

Haigen Yang,Xiaoting Rui,Yixin Liu,Junyi He 보안공학연구지원센터 2013 International Journal of Database Theory and Appli Vol.6 No.3

Spatial–Temporal Clustering and Optimization of Aircraft Descent and Approach Trajectories

Zhao Yang,Rong Tang,Yixin Chen,Bing Wang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.6

This study presents a procedure for the spatial–temporal clustering and optimization of aircraft descent and approach trajectories. First, the spatial–temporal similarity between two trajectories is defined. Clustering analysis are conducted to identify the prevailing trajectories. The clustering centers obtained based on spatial–temporal distance are compared with those obtained based on the traditional Euclidean distance. Second, a multi-objective optimization model is established to minimize fuel consumption, aircraft emission and noise impact considering flight constraints. The Pareto solution that has the highest similarity with the prevailing trajectories is selected as the final optimized trajectory. The performance indicators of the optimized trajectory are compared with the average values of historic trajectories. It is found that travel time, fuel consumption and noise impact for the optimized trajectory are reduced by 5.34%, 0.96% and 11.86%, respectively. The percentages are 0.96%, 1.32%, 9.18%, 3.54% and 4.00% for CO2, SOx, NOx, CO and HC, respectively. Also, the performance indicators for the two clustering centers based on spatial–temporal distance are generally closer to average performance of original trajectories, as well as those of the optimized trajectories, as compared with the two clustering centers based on Euclidean distance. The spatial–temporal clustering methods may help to discover the valuable information that lies in those indicators associated with features reflected in time dimension.

The construction of the Ni/La2O2CO3 nanorods catalysts with enhanced low-temperature CO2 methanation activities

Hui Yang,Xueying Wen,Siyuan Yin,Yixin Zhang,Cai-e Wu,Liang Xu,Jian Qiu,Xun Hu,Leilei Xu,Mindong Chen 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

In this work, the La(OH)3 nanorods were successfully synthesized by precisely regulating the parametersof the hydrothermal method. Then, a series of Ni-based CO2 methanation catalysts were fabricated via theincipient-wetness impregnation and deposition–precipitation methods by employing the La(OH)3 nanorodsas the supports. The influences of the support morphology and the preparation method on the metalsupportinteraction, Ni dispersion, and the surface basicity were carefully investigated based on varioustechniques, such as XRD, SEM, H2-TPR, CO2-TPD, XPS, ect. It was found that the rod-shaped La(OH)3 supportedcatalyst prepared by the deposition–precipitation method performed the optimum activity andstability. The reason for this could be derived from the confinement effect of the crystal plane of therod-shaped support, which would promote the formation of the strong metal-support interaction andthe construction of the Ni-La interface with high activity. Furthermore, the online-tandem TG-MS andin-situ DRIFTS technologies were used to investigate the thermal decomposition performance of the catalystprecursors in the calcination process and the reaction intermediates of the CO2 methanation. Therefore, the fundamental roles of support morphology and catalyst preparation method were expectedto direct the advancement of the Ni-based nanostructured catalysts with outstanding low-temperatureperformances.

Sparse Channel Estimation in OFDM Systems via Improved Tap Detection

Xiaolin Shi,Yixin Yang,Long Yang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.10

Many wireless channels encountered in practice tend to exhibit the structure of sparse multipath due to large bandwidth or large number of antennas. High-rate data wireless communications over multipath wireless channels usually require that the channel response be known at the receiver. In this paper, a novel scheme for the estimation of sparse wireless channels is developed. The initial estimation of the channel taps is obtained by the unstructured least-squares (LS) method. Then, the presence of a channel tap is detected via an improved threshold obtained by applying the nature of sparse channels and the statistics of the noise vector. At last, the channel estimate is refined by deploying the knowledge previously acquired on the position of the nonzero taps and the structured LS method. The proposed method is compared and contrasted with the existing sparse estimation methods. And the results show the validity of the proposed method.

Study on the Micro-vibration Suppression of a MnCu Spring Isolation Platform with Low Stiffness and High Damping

Xianbo Yin,Yang Xu,Xiaowei Sheng,Song Wan,Yixin Wang 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

Reaction wheels are the primary micro-vibration sources for microsatellites. To reduce the adverse effects of micro-vibrations, a six-degree-of-freedom (6-DOF) vibration isolation scheme with low stiffness and high damping is proposed. Through six-component force measurements, the harmonic characteristics of the micro-vibrations generated by a reaction wheel are determined. Based on an assumption of small deformation linear elasticity, a dynamic model of a convergent isolation platform is established. With high damping characteristics, helical springs made of MnCu (manganese copper) alloy are selected as the isolation element of the platform. After a modal analysis and stiffness design, the key structural parameters of the isolator are determined. According to the coupling of degrees of freedom, the transmissibility of the isolator is simulated and compared to titanium and aluminum alloys. Combined with on-ground and on-board tests, the effectiveness of the isolation platform is verified. The research shows that the 6-DOF isolation platform based on the MnCu spring realizes multidirectional low-frequency and low-magnitude micro-vibration suppression. The minimum initial isolation frequency of the designed isolator is 16.8 Hz, and the best suppression effect reaches 17.5 dB. The proposed isolator’s application successfully controls high-order harmonics and sensitive load response behaviors.

Fast Direction of Arrival Estimation with the Coexistence of both Uncorrelated and Coherent Signals

Yaoping Zeng,Yixin Yang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.2

This paper proposes a novel fast direction of arrival (DOA) estimation method for scenarios when uncorrelated and coherent signals exist simultaneously. First, using uniform transformation, we change complex matrix into real matrix, then, just by exploiting real propagator method (RPM), we can attain the uncorrelated signals DOA fastly. Second, based on new spatial difference technique, we can eliminate the effection of uncorrelated signals and make coherent signals become uncorrelated. Finally, utilizing RPM technique, coherent signals DOA can be estimated swiftly. Simulation results validate the performance improvement of the proposed algorithm.

Fundamental Frequency Tracking of Distorted Power Signal Based on the Improved EKF Algorithm

Zhang Xiaobing,Yang Mengchen,Yan Yixin,Fang Guozhi 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.10

To reduce the impacts of harmonics and noises on frequency measurements, a novel method of frequency tracking is presented based on improved EKF algorithm and wavelet transform. Firstly, the power signal was preprocessed to extract the fundamental wave by wavelet filtering. Then, an improved Extended Kalman Filter was introduced to achieve fast and accurate frequency tracking. By adding a robust factor and modifying the covariance matrix in real time, it enhanced the stability for detecting distorted signals. The proposed tracking algorithm can effectively solve the problems of traditional Extended Kalman Filter such as lack of adaptability, instability and divergence. And it improved the tracking speed and accuracy. Finally, Detailed simulations on several typical models of power signals have been carried out and the Simulation results shown that the new algorithm increases the speed, convergence and accuracy. It effectively suppresses the impacts of harmonics and noises on the frequency tracking results.

Experimental Analysis of the Mechanical Properties of Austenitic S30408 Stainless Steel Welded Joints at Low Temperatures

Hongbo Liu,Longxuan Wang,Yixin Yang,Ting Zhou,Jing Li 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.5

Austenitic S30408 stainless steel exhibits good low-temperature resistance and good welding performance. This steel is often used in liquefied natural gas stainless steel storage tanks. During the construction process, the tank wall is primarily connected by butt weld joints. Because welded joints are easily affected by temperature, low-temperature weld cracking can reduce the safety of structures. To study the cryogenic mechanical properties of austenitic S30408 stainless steel welded joints at low temperatures, the low-temperature mechanical properties of austenitic S30408 stainless steel base metal and welded joint components were studied by tensile tests from − 60 to 20 °C and scanning electron microscopy analysis of fractures at various temperatures. The results show that when the temperature decreases, the stress–strain curve of base metal components changes from a power function type to an inverted "s" type; in addition, secondary hardening occurs. The yield strength and tensile strength of the welded joint and base metal increased with decreasing temperature, and the elongation and reduction of area decreased. The plastic deformation capacity of the welded joint was significantly lower than that of the base metal, and there were obvious inclusions in the microstructure.