Yang Xu

Chongqing Metrology Quality Inspection and Research Institute

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Study on kinematic characteristics of SMA bionic flexible dexterous hand

Yang Xu Yanxiang Fu Yingqian Ni Xiangrui Yang Yikun Xiong

D-H parameter method is employed to conduct forward kinematic analysis of the dexterous hand in this article, in order to obtain the mechanical performance of the SMA biomimetic flexible dexterous hand for object grasping. The D-H parameters of the dexterous hand are determined, and the position expression of the fingertip relative to the base coordinate is obtained through theoretical calculations. Furthermore, inverse kinematic theoretical analysis of the biomimetic dexterous hand is conducted to obtain the joint angle parameters of each finger. A forward kinematic simulation model of the biomimetic dexterous hand is established, and the relationship between finger joint angles and fingertip position curves is obtained through simulation. The simulation results are compared with the theoretical analysis results to validate the correctness of the kinematic analysis of the dexterous hand, providing insights for its optimized design.

Bionics

Position (finance)

Forward kinematics

10.1117/12.3030338

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Three New Oblongolides from Phomopsis sp. XZ-01, an Endophytic Fungus from Camptotheca acuminate

Molecules (2011)

Ting Lin Guang Hui Wang Xiang Lin Zhi Yu Hu Quan Cheng Chen

Four new metabolites, including three new oblongolides named C1, P1, and X1 (1-3) and 6-hydroxyphomodiol (10), along with eight known compounds – oblongolides B (4), C (5), D (6), O (7), P (8) and U (9), (3R,4aR,5S,6R)-6-hydroxy-5-methylramulosin (11), and (3R)-5-methylmellein (12) – were isolated from the endophytic fungal strain Phomopsis sp. XZ-01 of Camptotheca acuminate. Their structures were elucidated by spectroscopic analyses, including 1H- and 13C-NMR, 2D NMR (HSQC, HMBC, 1H-1H COSY and NOESY) and HR-FT-MS. Cytotoxic activities of these compounds were evaluated. Some of them showed weak selective activities.

Phomopsis

10.3390/molecules16043351

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Founding Conditions and New Firm Growth: Evidence from U.S. Startups (WITHDRAWN)

Academy of Management Proceedings (2017)

Yang Xu

In this paper we explored the role of founding conditions in new firm growth with a sample of 4923 firms in the longitudinal panel database from the Kauffman Firm Survey conducted over the period of 2005 ~ 2010. Findings show that founding size and intellectual properties drive growth in the early years of a startup, but are replaced with entrepreneurial human capital in the later years. These results suggest a dynamic link between founding conditions and new firm growth.

Longitudinal sample

Sample (material)

Longitudinal data

Capital (architecture)

10.5465/ambpp.2017.10028abstract

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Size, Trade, Technology and the Division of Labor

National Bureau of Economic Research (2021)

Nuno Limão Yang Xu

We model the implications of the classical ideas that larger markets allow for a finer division of labor and this division feeds back into larger market size. Market size affects specialization due to firm-level increasing returns to scale arising from fixed costs of adopting intermediate-intensive technologies. The impacts are magnified in general equilibrium by an endogenous multiplier—due to input-output linkages in a roundabout structure—and a selection effect due to heterogeneous fundamental productivity and entry costs. Market size expansions imply (i) larger real income gains than under fixed specialization; (ii) an increase in the aggregate variable cost share for intermediates and a decrease for labor; (iii) increased concentration; (iv) increased average productivity for survivors; and (v) an increase in the intermediate trade share. We derive similar results for intermediate productivity improvements. The effects in (ii)-(v) are absent in a similar model with exogenous specialization. In a calibration to U.S. manufacturing in 1987-2007 we isolate trade and intermediate productivity shocks, quantify their effects. Trade cost reductions increased effective market size by 7 log points (lp) and generated (i) a real income gain 1.4 times higher than under exogenous specialization; (ii) increases in the intermediate share in production and trade of 2 lp and a reduction in the labor share of value added of similar magnitude. Two counterfactuals highlight the importance of industrial and trade policy. First, a tax that induces firms to specialize increases real income; so the initial equilibrium is inefficient. Second, an increase in trade costs of 16 lp—similar to the recent trade war—reduces market size and real income substantially: almost half way to trade autarky.

Fixed cost

Returns to scale

Market share

Ceteris paribus

Source

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Analysis on the Prevention and Encouragement Policy of EU on Unemployment

Renkou xuekan (2003)

Yang Xu

The commitment to the prevention of unemployment and increased degree of activation in employment policy lies at the heart of the employment strategy. Since 1998, clear progress was noted in implementation of preventive and active policies, and in the modernization of PES. It received a positive response from EU member states at different levels.

Flexicurity

Source

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Optimization of Biodiesel Injection Parameters Based on Support Vector Machine

Mathematical Problems in Engineering (2013)

Fuxi Shi Jun Chen Yang Xu Hamid Reza Karimi

For the running diesel engine, spray-atomization, mixed-combustion, and thermal-power conversion processes are inseparable, which causes difficulty to investigate atomization effect separately. This study was conducted to improve the atomization efficiency of the soybean fatty acid methyl ester (SFAME) in engine, to achieve the minimum effective specific fuel consumption in specific engine working conditions, the different injection parameters combination were explored on the influence of effective specific fuel consumption at elevated fule temperature. The effective specific fuel consumption prediction model was established based on support vector machine (SVM). With small samples, the intrinsic functional relationship was determined and the best injection parameters were validated under seven different experimental conditions. The study results have shown that the engine’s spray-thermal-power conversion process could be simulated accurately by using SVM. It will be more favorable to improve application effect of biodiesel in the engine to select the fuel temperature as injection parameters which influence atomization effect. Furthermore, using enumeration-verification methods to simulate the parameters might save a lot of resources as compared to the similar experiments.

Thermal efficiency

10.1155/2013/893084

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Citations (10)

Interactions between invertebrate and mycotoxin-producing fungi

Yang Xu

Interactions between fungi and invertebrates nearly occur in every ecosystem. Grazing affects fungal biomass density and is species-dependent. However, how invertebrates affect mycotoxin-producing fungi has not been studied yet. In our study, we exposed three well-known mycotoxin-producing Fusarium strains (F. graminearum, F. culmorum and F. verticillioides), two Aspergillus strains (A. nidulans and A. ochraceus) and one Penicillium strain (P. viridicatum) to intense grazing by Folsomia candida and determined fungal biomass gravimetrically and by quantitative real-time PCR. Our results indicated that only A. nidulans and F. verticillioides were consumed in larger amounts by the collembolan. The mycelial biomass of A. ochraceus even increased after grazing commenced. Our results suggest that collembolan grazing caused variable effects on the mycelial growth of mycotoxin-producing fungal strains but no uniform reduction.Collembolans are selective feeders. Their food preference contributes to shaping of fungal community composition in various ecosystems. Previous experiments showed that F. candida grazing caused different fungal biomass loss effect on F. verticillioides and F. graminearum. This is intriguing regarding to their biological similarity. In this study, we explored the food preference of the springtail Folsomia candida between F. verticillioides and F. graminearum in terms of various aspects: (1) which spies is more attractive, F. verticillioides or F. graminearum; (2) how attractive are the mycotoxin-deficient F. graminearum strains, ∆DON (lacks deoxynivalenol), ∆ZEN (lacks zearalenone), ∆AUR (lacks aureofusarin); and (3) to which extent does mixing of cultures affect collembolan grazing. Collembolan activity was determined by eye observation and real time PCR of DNA mycelium extracts. In our assays, F. candida prefers F. verticillioides and avoids F. graminearum. However, the one F. graminearum mutant is attractive to F. candida over F. verticillioides. In addition, springtails prefer mixtures of two fungal strains to a single strain. Even the avoided F. graminearum is consumed in higher amounts, when another fungal strain is present. The obtained provide support for the hypothesis that fungal secondary metabolitecan contribute to the avoidance of a specific fungal species by a collembolan grazer. Additionally, a fungal strain that produces a feeding deterrent compound can be consumed in higher amounts in a mixed community than a sole food source.

Fusarium culmorum

Beauvericin

10.53846/goediss-7192

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Optimization of Opening Scheme of ETC/MTC Toll Lane Based on Cost and Benefit Analysis

IOP Conference Series Earth and Environmental Science (2021)

Hao Zhang Cheng Cheng Changjian Zhang Jie He Yang Xu

Abstract In recent years, with the popularization of electronic toll collection systems (ETC), expressway toll stations in China have developed into a mixed toll form jointly deployed by ETC toll lanes and MTC toll lanes, presenting a development trend based on ETC toll lanes. Since the toll collection system has the important function of “credit repayment“, the relationship between operation benefit and cost will become an important indicator for measuring the toll station system. Taking the minimum cost and the maximum benefit of the toll station under normal operating condition as the optimization goals, a multi-objective nonlinear optimization model is established within the seek for balance between cost and benefit, so as to obtain an open plan with better toll lanes. The Nanjing-Hangzhou toll station is used as an example to verify the model. Furthermore, based on the trend of the future traffic flow and the increase in the proportion of ETC vehicles, the distribution law of the optimal opening schemes of the toll lane under different traffic volumes and different traffic flow structures is analyzed, which provides experience support for the construction and operation of toll stations in the future.

Electronic toll collection

10.1088/1755-1315/638/1/012032

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The Study of Thermal process and Temperature Calibration for a Vacuum Drying Oven Based on Numerical Simulation

IOP Conference Series Earth and Environmental Science (2021)

Ying Liu Wen Zhang Yang Xu Jing Zhang

Abstract Vacuum drying technique is widely used in food a processing, pharmaceutical and other industry which needs to be calculated regularly. In order to establish temperature calibration method for vacuum drying oven, temperature profile needs to be studied. In this paper, a three-dimensional (3D) unsteady mathematical model has been developed to study heat transfer in a vacuum drying oven. Governing equations are discretized in implicit form by using the control volume method. PRESTO! scheme was used for the discretization of the pressure modified equation. SIMPLE algorithm is adopted to solve the coupling of pressure and velocity. The natural-convection flow forced by buoyancy force was numerically calculated based on Boussinesq assumption. Results of the model calculation showed that temperature distribution in the vacuum drying oven significantly changed when the pressure in the oven is close to vacuum. Temperature uniformity in the vacuum drying box increases with the increase of vacuum degree. It is not appropriate to directly investigate the temperature uniformity of the vacuum drying oven by using JJF 1101-2019. The results can be used to lay a theoretical foundation for the establishment of calibration method for vacuum drying oven.

Control volume

Vacuum chamber

Vacuum drying

Vacuum furnace

10.1088/1755-1315/661/1/012032

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A Tentative Analysis of the Offsetting Factors in Increasing Household Income Differential

Journal of Guizhou College of Finance and Economics (2003)

Yang Xu

The purpose of socialist production is to ultimately realize common prosperity, but the present household income differential has given rise to many social prob lems. In the long run, however, there are factors offsetting the increasing diff erence.

Prosperity

Household income

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