Research on Anti-Fluctuation Control of Winding Tension System Based on Feedforward Compensation

In the fiber winding process,strong disturbance,uncertainty,strong coupling,and fiber friction complicate the winding constant tension control.In order to effectively reduce the influence of these problems on the tension output,this paper proposed a tension fluctuation rejection strategy based on feedforward compensation.In addition to the bias harmonic curve of the unknown state,the tension fluctuation also contains the influence of bounded noise.A tension fluctuation observer(TFO)is designed to cancel the uncertain periodic signal,in which the frequency generator is used to estimate the critical parameter information.Then,the fluctuation signal is reconstructed by a third-order auxiliary filter.The estimated signal feedforward compensates for the actual tension fluctuation.Furthermore,a time-varying parameters fractional-order PID controller(TPFOPID)is realized to attenuate the bounded noise in the fluctuation.Finally,TPFOPID is enhanced by TFO and applied to control a tension control system considering multi-source disturbances.The stability of the method is analyzed by using the Lyapunov theorem.Finally,numerical simulations verify that the proposed scheme improves the tracking ability and robustness of the system in response to tension fluctuations.

Resonance and Bifurcation of Fractional Nonlinear Systems with Power Damping Term for Robot Grinding

A fractional nonlinear system with power damping term is introduced to study the forced vibration system in order to solve the resonance and bifurcation problems between grinding wheel and steel bar during robot grinding.The robot,grinding wheel and steel bar are reduced to a spring-damping second-order system model.The implicit function equations of vibration amplitude of the dynamic system with coulomb friction damping,linear damping,square damping and cubic damping are obtained by average method.The stability of the system is analyzed and explained,and the stability condition of the system is proposed.Then,the amplitude-frequency characteristic curves of the system under different fractional differential orders,nonlinear stiffness parameters,fractional differential term coefficients and external excitation amplitude are analyzed.It is shown that the fractional differential term in the dynamic system is the damping characteristic.Then the influence of four kinds of damping on the vibration amplitude of the system under the same parameter is investigated and it is proved that the cubic damping suppresses the vibration of the system to the maximum extent.Finally,based on the idea that the equilibrium point of the system is the constant part of the Fourier series expansion term,the bifurcation behavior caused by the change of damping parameters in linear damping,square damping and cubic damping systems with different values of fractional differential order is investigated.

Dynamic Analysis and Dimensional Synthesis of Easy-to-Protect Large-Load Robot for Extracting Fermented Grains

To improve the operation situation of difficulty and low efficiency in the extraction of fermented grains(FG),a high-load and large-workspace reclaiming robot for ceramic cylinder fermentation is designed,and a reclaiming effector is designed according to the operating characteristics.Firstly,the kinematics and singularity of the mechanism are analyzed.A multi-domain polar coordinate search method is proposed to obtain the workspace and the volume of the mechanism.Secondly,the dynamic modeling is completed and the example simulation is carried out.Thirdly,the motion-force transmission index of the mechanism is established.And based on the global transmissibility and the good-transmission workspace,the dimensional synthesis of the driving mechanism is completed by using the performance atlas-based method.Finally,aiming at the regular workspace size,stiffness and loading capacity,the Pareto optimal solution set of the executive mechanism dimension is obtained by using the multi-objective particle swarm optimization(MOPSO)algorithm.This paper can provide a theoretical basis for the optimal design and control of FG reclaiming robot.

Reliable and Efficient Agrobacterium tumefaciens-Mediated Genetic Transformation of Dianthus spiculifolius

Dianthus spiculifolius is a perennial herbaceous flower with strong environmental adaptability and is an important ornamental ground cover plant.In this study,seeds of D.spiculifolius were used as explants for callus induction,adventitious bud differentiation,and rooting by adding different concentrations of 2,4-dichlorophenoxyacetic acid(2,4-D),6-benzyl aminopurine(6-BA),and naphthaleneacetic acid(NAA)to Murashige and Skoog medium.The calli generated were co-cultured with Agrobacterium tumefaciens EHA105 containing pBI121-GUS or pBI121-GFP plasmids for 30 min,and transgenic regenerated plants were obtained by kanamycin(30mg·L^−1)screening.RT-PCR confirmed the stable expression of the exogenous GUS and GFP genes in the D.spiculifolius.Theβ-glucuronidase(GUS)histochemical staining confirmed GUS gene expression in transgenic calli,adventitious buds,and regenerated plants of D.spiculifolius.The green fluorescent protein(GFP)visual analysis showed GFP gene expression in transgenic calli.Furthermore,subcellular localization analysis showed that the three organelle marker proteins were not only successfully expressed but also accurately localized to their corresponding organelles in D.spiculifolius callus cells.These results indicated a successful establishment of a reliable and efficient A.tumefaciens-mediated genetic transformation system,which will contribute to functional gene research and genetic improvement of D.spiculifolius.

中国、美国及世界结直肠癌流行病学与疾病负担的对比和思考

结直肠癌是全球最常见的恶性肿瘤之一。本文回顾了全球、中国及美国的结直肠癌统计结果和文献,总结了目前世界、中国及美国结直肠癌的流行病学现状、时间趋势、危险因素及筛查现状,并对比了中国与美国及世界的差异。目前,全球结直肠癌负担依然沉重。尽管中国结直肠癌发病率低于美国等发达国家,但发病率持续上升。由于结直肠癌早期筛查普及率较高,美国等发达国家发病率及死亡率处于下降趋势。中国等发展中国家发病率则逐年上升,应进一步加大结直肠癌筛查范围以降低结直肠癌发病率及死亡率。

Research on Bionic Jumping and Soft Landing of Single Leg System in Quadruped Robot

This paper proposed a novel multi-motion wheel-leg-separated quadruped robot that can adapt to both the structured and unstructured grounds.The models of the positive/inverse position,velocity,acceleration,and workspace of the single leg mechanism in the quadruped robot were established.A single leg complex dynamic model of the quadruped robot is derived,considering the mass and inertial force of all the components in the mechanical leg.Combined with the human jumping law in situ,the jumping trajectory of the single leg was planned.To reduce landing impact,a soft landing strategy based on motion planning was proposed by simulating human knee bending and buffering action.The change law of the kinetic energy and momentum of all the links in the single leg mechanism during the jump process was studied,and the influencing factors of jump height were analyzed to realize the height control of the jump.Single leg jumping dynamics model was established,and a dynamic control strategy for trajectory tracking with foot force compensation was proposed.In Adams and MATLAB/Simulink software,the jump simulation of single leg mechanism was carried out.The prototype of quadruped robot was developed,and the jumping experiment of the single leg mechanism was tested.The robot's single leg bionic jumping and soft landing control are realized.

不可切除肝癌患者转化治疗后行根治性手术的临床特征分析

目的探讨不可切除肝癌患者转化治疗成功后行根治性手术的临床疗效。方法回顾性分析2019年11月至2021年12月于北京大学人民医院肝胆外科转化治疗成功并行根治性手术的10例肝癌患者的临床资料。结果10例患者中位年龄64(51.25,68.50)岁。转化治疗周期数中位值11(4.75,25.00)。转化治疗期间,患者未出现严重不良反应。转化治疗完成后8例患者行肝部分切除术,2例患者行射频消融术。术后4例患者出现并发症。所有并发症Clavien-Dindo分级均为Ⅰ级或Ⅱ级。随访时间中位值13(9.75,49.75)周。3例患者肿瘤术后复发。复发患者中,1例患者死于肝衰竭。结论转化治疗是临床不可切除肝癌患者的有效治疗方法。肝癌转化治疗严重不良反应发生率低。可对全身状况及肝脏功能良好的患者安全实施转化治疗。不可切除肝癌患者转化治疗成功后行根治性手术能够延长患者的生存时间。

Coupling effects of water and nitrogen on photosynthetic characteristics,nitrogen uptake,and yield of sunflower under drip irrigation in an oasis

An experiment was conducted in an oasis area in northwest China to assess the coupling effects of water and nitrogen supply through drip irrigation on photosynthetic characteristics,nitrogen uptake,and yield of sunflower(Helianthus annuus L.),as well as the nitrate distribution in the root-zone soil.The experiment included three irrigation levels(210[W1],300[W2],and 390[W3]mm),three nitrogen levels(162[N1],232[N2],and 302[N3]kg/hm^(2)),and control treatment(no fertilization during whole growth period and only irrigated at the budding stage).A nitrogen content over-accumulation in the soil was observed under the low irrigation amount with high fertilizer supply,which cannot enhance the sunflowers’absorption of nitrogen.Excessive irrigation caused leach of the soil nitrogen,reduced nitrogen content in the root-zone soil(0-40 cm)and limited nitrogen uptake by the crop.Although low irrigation amount with high fertilizer supply can increase the nitrogen content in the soil,it cannot enhance the sunflowers’absorption of nitrogen.At the vegetative stage of sunflower growth,the accumulation of nitrogen in the organs was mainly concentrated in the leaves,while it was transferred to the flower disk at the reproductive growth stage.Reasonable coupling of water and nitrogen improved the transport of nitrogen from leaves and stems to the flower disk and promoted the formation of yield components.Six regression equations were established with irrigation and fertilization amount as independent variables,and seed rate,seed weight per flowerdisk,1000 grain weight,yield,water use efficiency and nitrogen partial factor productivity as dependent variables,respectively.Multiple regression and spatial analysis suggested that the irrigation amount of 241.62-253.35 mm and the fertilization application of 202.02-209.40 N kg/hm^(2)was a good irrigation strategy,under which all six factors exceed 75%of their maxima,and the yield of sunflower reached 3229.3 kg/hm^(2).

Effects of biodegradable mulching films on soil hydrothermal conditions and yield of drip-irrigated cotton(Gossypium hirsutum L.)

The pollution of cotton fields by residual films is serious on ground that has been subjected to long-term drip irrigation in Xinjiang,China,and biodegradable mulches are therefore advocated as an alternative to plastic ones.In this study the mulching with biodegradable films under drip irrigation conditions in the extremely arid region of Xinjiang was investigated to determine the effects on soil hydrothermal conditions and cotton(Gossypium hirsutum L.)yield over two consecutive years(2019-2020)using plastic mulch made from polyethylene(PE)film and four types of biodegradable films,including black opaque oxidation-biodegradable film(M1),colorless transparent oxidation-biodegradable film(M2),black opaque fully biodegradable film(M3)and white translucent fully biodegradable film(M4),which had different levels of biodegradability(i.e.different degradation times and rates).The biodegradability,soil water contents,soil temperatures and cotton yields were compared between the degradable(M1 to M4)and PE films.The results indicated that M2 was degraded the quickest and showed the highest degree of degradation compared with the other degradable films and PE films.The degradation rates of the various mulching films were ranked in a descending order as M2,M4,M1,M3 and PE,but the PE mulch exhibited the best performance in terms of soil water and heat conservation throughout the growth period.The soil heat preservation and moisture conservation performance under biodegradable films mulching at the cotton seedling stage and budding stage was similar to that of PE film.The average soil temperature at a depth of 5 cm under mulching with the degradable films was 2.66°C-5.06°C(p<0.05)lower than that under traditional PE films at the flowering stage.At the late stage of cotton growth,the water content of shallow soil mulched with PE film was better for plant grown than that under the biodegradable films.The effect of film degradation on the shallow soil water content was much greater than that in deep soil,especially at a depth of 0-40 cm.However,in all treatments,the seedling rate and growth index of cotton under M2 were equivalent to that found under the PE film.Moreover,the cotton yield using M2 was slightly higher than that for the PE film.Compared with the PE film,the yield of cotton mulched with M1,M3 and M4 was decreased by 7.50%,6.45%and 2.83%in 2019,and 9.82%,6.48%,and 2.13%,in 2020,respectively.Therefore,based on the performance in improving cotton yield and maintaining soil moisture,the biodegradable transparent film(M2)with an 80 d induction period is recommended as a competitive alternative to plastic mulch to enhance crop yield and control soil pollution.

Controlling threshold in soil salinity when planting spring wheat and sequential cropping silage corn in Northern Xinjiang using drip irrigation

Xinjiang Region of China is one of the most typical and representative arid areas worldwide,along with severe soil salinization issue.Planting spring wheat and sequential cropping silage corn in Northern Xinjiang using drip irrigation has become an effective way to relieve soil salinity stress,which improves the simple agricultural structure in the past and ensures food security in this area.However,neither the effects of different soil salinities on the growth and yield of spring wheat and silage corn,nor their desalination effect correspondingly was clear until now.Therefore,a pot experiment was conducted at Shihezi,Xinjiang from March to June 2015.The study aimed to establish the quantitative correlations between the parameters mentioned above and came up with the appropriate soil salinity threshold in Northern Xinjiang area.The results confirmed that the soils in all treatments were desalinated after the whole growth period,and the decreasing rates varied within 18.89%-44.08%and 11.06%-30.83%for two plants,which showed linear and quadratic correlations with initial soil salinity,respectively(R^(2)>0.92^(**),p<0.05).Meanwhile,higher soil salinity would inhibit crop growth and yield,and the initial soil salinity also represented the negative quadratic correlations with growth parameters(R^(2)>0.92^(**),p<0.01).The inhibition effect was enhanced with larger initial soil salinity.After the comprehensive consideration of soil salinity variation,crop growth and yield,the initial soil salinity was recommended under 8.91 g/kg and 5.54 g/kg to plant spring wheat and sequential cropping silage corn in Northern Xinjiang using drip irrigation.