Effects of artificially cultivated biological soil crusts on soil nutrients and biological activities in the Loess Plateau

Biological soil crusts(BSCs) play an important role in the early succession of vegetation restoration in the Loess Plateau, China. To evaluate the effects of artificially cultivated BSCs on the soil surface micro-environment, we obtained natural moss crusts and moss-lichen crusts from the Loess Plateau of Shaanxi province, and subsequently inoculated and cultivated on horizontal and sloping surfaces of loess soil in a greenhouse. The chemical and biological properties of the subsoil under cultivated BSCs were determined after 10 weeks of cultivation. The results indicated that BSCs coverage was more than 65% after 10 weeks of cultivation. Moss crust coverage reached 40% after 5 weeks of cultivation. Compared with the control, soil organic matter and available nitrogen contents in moss crust with the horizontal treatments increased by 100.87% and 48.23%, respectively; increased by 67.56% and 52.17% with the sloping treatments, respectively; they also increased in moss-lichen crust with horizontal and sloping treatments, but there was no significant difference. Available phosphorus in cultivated BSCs was reduced, soil pH was lower and cationic exchange capacity was higher in cultivated BSCs than in the control. Alkaline phosphatase, urease and invertase activities were increased in artificially cultivated BSCs, and alkaline phosphatase activity in all cultivated BSCs was obviously higher than that in the control. Numbers of soil bacteria, fungi and actinomycetes were increased in the formation process of cultivated BSCs. These results indicate that BSCs could be formed rapidly in short-term cultivation and improve the micro-environment of soil surface, which provides a scientific reference for vegetation restoration and ecological reconstruction in the Loess Plateau, China.

Identification of three kinds of Plumeria flowers by DNA barcoding and HPLC specific chromatogram

DNA barcoding and HPLC specific chromatogram were used to identify three kinds of Plumeria flowers respectively. DNAs extracted from the three Plumeria species were amplified by PCR with universal primers, and the psb A-trn H region was selected. All the amplified products were sequenced and the results were analyzed by MEGA 5.0. Chemometric methods including principal components analysis and hierarchical clustering analysis were conducted on the SAS 9.0 software to demonstrate the variability among samples. In conclusion, the psb A-trn H of all samples were successfully amplified from total DNA and sequenced. These three varieties of Plumeria can be differentiated by the psb A-trn H region and clustered into three groups respectively through building neighbor joining tree, which conformed to their germplasm origins. However, it was hard to distinguish them by HPLC specific chromatograms combined with chemometrics analysis. These indicated that DNA barcoding was a promising and reliable tool for the identification of three kinds of Plumeria flowers compared to HPLC specific chromatogram generally used. It could be treated as a powerful complementary method for traditional authentication,especially for those varieties which are difficult to be identified by conventional chromatography.

Deep Multimodal Learning and Fusion Based Intelligent Fault Diagnosis Approach

Industrial Internet of Things(IoT)connecting society and industrial systems represents a tremendous and promising paradigm shift.With IoT,multimodal and heterogeneous data from industrial devices can be easily collected,and further analyzed to discover device maintenance and health related potential knowledge behind.IoT data-based fault diagnosis for industrial devices is very helpful to the sustainability and applicability of an IoT ecosystem.But how to efficiently use and fuse this multimodal heterogeneous data to realize intelligent fault diagnosis is still a challenge.In this paper,a novel Deep Multimodal Learning and Fusion(DMLF)based fault diagnosis method is proposed for addressing heterogeneous data from IoT environments where industrial devices coexist.First,a DMLF model is designed by combining a Convolution Neural Network(CNN)and Stacked Denoising Autoencoder(SDAE)together to capture more comprehensive fault knowledge and extract features from different modal data.Second,these multimodal features are seamlessly integrated at a fusion layer and the resulting fused features are further used to train a classifier for recognizing potential faults.Third,a two-stage training algorithm is proposed by combining supervised pre-training and fine-tuning to simplify the training process for deep structure models.A series of experiments are conducted over multimodal heterogeneous data from a gear device to verify our proposed fault diagnosis method.The experimental results show that our method outperforms the benchmarking ones in fault diagnosis accuracy.

内在主义技术伦理:教学评价智能化转型考量

基于教学评价智能化转型的内涵与逻辑,本研究以内在主义技术伦理为考量视角,提出教学评价智能化转型的内在主义技术伦理考量框架,即:智能评价主体应关注技术的道德协同性,智能评价技术应关注道德算法设计,智能评价过程应遵循公平伦理规范,智能评价行为应依赖“人-智”伦理秩序。研究发现,内在主义视角下教学评价智能化转型存在的伦理风险主要体现在人工智能应用僭越教育主体尊严,智能评价数据挖掘违反信息道德界限,智能评价算法偏误破坏教学决策质量与公平,以及智能化教学评价活动偏离人本伦理轨道等多个方面。为此,从内在主义视角提出教学评价智能化转型的技术伦理规约路向:关注人文情感与技术理性的结合,树立需求本位的人机关系准则;实现有道德的算法设计与优化,合理保障师生教育自由与隐私安全;聚焦智能技术蕴含的积极伦理,增强对智能评价算法的动态监测;发挥智能评价的行为影响,构建以人为本的评价伦理秩序。

数字化转型背景下教育技术伦理观照与风险消解

数字化转型背景下,随着人工智能、大数据、区块链等新兴教育技术在教育实践中的应用不断深化,教育技术伦理及其风险引发了社会的广泛关注。本研究通过对教育技术伦理的概念诠释与历史变革回顾,结合数字化转型赋予教育技术伦理的新变化,拆解出数字化转型背景下教育技术伦理的基本向度。当前,数字化转型背景下教育技术伦理仍存在数字教育生态环境平衡遭到破坏、信息资源分配不均加重数字鸿沟、师生数字教育掌舵者地位遭遇挑战与威胁、虚拟交互失范引发道德情感缺失等多方面风险。据此,本研究提出构建指向数字教育系统向善的生态伦理治理体系、完善数字化赋能优质资源供给的决策与保障机制、增强对教育主体权利嬗变的风险监测与评估、营造技术助力情感与人文关怀的数字文化愿景等风险消解路径。

智能时代教育数据伦理风险:典型表征与治理路径

在以人工智能、5G、云计算等技术为支撑的智能时代背景下,教育数据伦理风险及其治理问题备受社会关注。智能时代教育数据伦理风险主要表现为教育数据隐私侵害风险、教育数据利益失衡风险、教育数据责任失守风险、教育数据服务偏见风险。智能时代教育数据伦理风险的治理困境主要涉及师生教育数据隐私权与开放共享存在冲突、教育数据利益博弈失范制约教育数据价值的充分释放、治理主体数据素养不足制约教育数据责任落实、师生教育需求的片面捕捉催生教育数据服务偏见。基于此,提出智能时代教育数据伦理风险的治理路径:尊重教育用户数据隐私控制权,优化数据隐私泄露风险防范体系;注重利益博弈规约,搭建教育数据权益监管体系;立足数据素养培育,培育专业化教育数据伦理风险治理组织;根植动态需求监测,构建“去偏见化”教育数据服务机制。

教育人工智能场域下教师角色与行动取向

教师与人工智能技术的关系是推进教育人工智能发展中需要审慎处理的关键关系,理清教育人工智能场域下的教师角色与行动取向极具现实意义。本文以教师角色分析为出发点,有针对性地选择研究对象,通过半结构化访谈及问卷调查获得样本数据,开展实证研究。研究发现:在智能时代,教师应成为知识信息、数字资源智能传播与呈现的掌舵者。具体而言,在教学功能方面,教师可扮演基于证据的个性化教学决策者与分析者;在辅导功能方面,教师需成为智能时代学生辅导的情感补位者;在管理功能方面,教师需成为非常规类班级及行政管理的人力保障者。基于此,文章提出了教育人工智能场域下教师的行动取向:教师应注重智能时代知识传授及数字资源建设的人文渗透;教师应注重提升智能教学与教育证据的整合能力;教师应实施智能帮扶与情感补位相结合的辅导策略;教师需基于管理情境适度应用与合理省思智能技术。

Analytical calculation method and simulation of deformation and stress of Z-type guide arm for interconnected air suspensions

To design and check the strength of the Z-type guide arm of interconnected air suspensions for semi-trailers rapidly and effectively,this paper proposes the analytical calculation methods of its deformation and stress.First,based on the guide arm structure,it is marked as two parts by its mountpoint on the axle as the boundary.The part containing the eye was marked as Arm-1.The other part was marked as Arm-2.Then the analytical formulas of their stiffness and stress were derived,respectively.With a case study,the deformation and the stress were computed and simulated.The results show that the values computed are close to those simulated.The relative deviations are not more than 5.0%.The results show that the analytical formulas are acceptable.Moreover,it can be seen that for the superimposed Arm-1,when the other structural parameters are fixed,the position of the maximum stress is affected by the thickness ratio of the end thickness to the root thickness for each piece.Finally,a stiffness test was performed on the Z-type guide arm.The results show that the computed stiffness values are closed to those tested and the relative deviations are not more than 3.5%.This further verified the validity of the established model and methods.

Modeling and simulation of twin-tube hydraulic shock absorber thermodynamic characteristics and sensitivity analysis of its influencing factors

In order to find out the sensitivity of the thermophysical and structural parameters to the thermodynamic characteristics of twin-tube hydraulic shock absorbers,based on the bench test,a method for calculating the time-varying rate of the external work on the shock absorber oil is proposed.And then,a thermodynamic model of the twin-tube hydraulic shock absorber is established by using the basic thermodynamic principles.By analyzing the influence of each parameter on the thermodynamic characteristics of the shock absorber,it can be seen that,the radius of the working cylinder outer wall has the greatest influence on the temperature rise of the shock absorber,followed by the thermal conductivity of the oil,the height of the oil,the heat transfer length of the cylinder barrel,the radius of the oil storage cylinder outer wall,the emissivity of the oil storage cylinder outer wall,the height of the nitrogen,the thermal conductivity of the nitrogen,the specific heat capacity of the oil,the density of the oil,the thermal conductivity of the cylinder,and the mass of the working oil.The kinematic viscosity of the oil has the least influence on the temperature rise of the shock absorber.The research can provide an effective theoretical guidance and reference for the design of the twin-tube hydraulic shock absorber.

Simulation of nonlinear vibration responses of cab system subject to suspension damper complete failure for trucks

The strong vibration responses of the cab system can be restrained by the damper force and the friction of the suspensions for trucks.After the failures of dampers,especially in the case of the complete failure,the anti vibration effect of the friction is prominent.However,the nonlinear vibration response characteristics of the cab subject to the damper complete failure have not been revealed.In order to reveal the nonlinear vibration response characteristics,a dynamic model of the cab system was established and its vibration equations were given.The friction forces existing in the suspensions were determined by the bench test.The influences of the friction forces on the cab vibration under different amplitude harmonic inputs were investigated when the dampers completely fail.The cab vertical displacement changes with the excitation amplitude and the vibration represents various motion states,including the periodic motion,the quasi-periodic motion,and the chaotic motion.The simulation results show that when the dampers fail,the proper friction forces help to suppress the quasi-periodic motion and the chaotic motion of the cab and to reduce the amplitude of the periodic motion.The proper friction forces can make the cab movement far away from the chaos area.They also help to avoid the fatigue damage of the cab floor and suspension parts to improve the service life of the suspension parts and to reduce the maintenance cost of the cab suspensions.

Analytical modeling and simulation on lateral mechanical characteristics of high-speed train traction motor hanging leaf spring

In this paper,using the theoretical analysis method,according to the actual structure of the hanging leaf spring of the traction motor mounted on the frame,the lateral force model of the hanging leaf spring of the traction motor was established.Then,through theoretical deduction,the deformation analytical calculation formula and the stress analytical calculation formula of the hanging leaf spring were established.The correctness of the leaf spring’s lateral force model was established and its deformation and stress analytical formulae were verified using ANSYS finite element analysis software.Based on this,according to the deformation analytical formula and the stress analytical formula of the leaf spring established,the influence of the main structural parameters on the mechanical characteristics of the leaf spring was discussed,and the reliability of the analytical analysis method of the lateral mechanical characteristics of the traction motor hanging leaf spring was verified by the loading–unloading test.The results show that the deformation and the load of the leaf spring change linearly.The changes of leaf spring’s stress at different positions can be considered as being composed of three sections:a linear change section in the root,a nonlinear change section in the middle,and a nonlinear change section in the end.In the structural parameters,the end thickness h2 has the greatest influence on the stiffness and the stress of the leaf spring,and the maximum thickness of the leaf spring eye h1 has the least influence on the stiffness and the stress of the leaf spring.The influence degree of other parameters on the stiffness of the leaf spring is h_(3),L_(1),L_(3),L_(2) in order,and the influence degree on the stress of the leaf spring is h_(3),L_(1),L_(2),L_(3) in order.In addition,when the root thickness h_(3) is greater than a certain value,the maximum stress point of the leaf spring appears at the end position L_(2).This study can provide a useful reference for the intelligent forward design and the rapid analysis of the mechanical characteristics of high-speed train traction motor hanging leaf spring.

Modeling and simulation of railway vehicle vertical dynamic behavior by considering the effect of passenger-carbody coupling vibration

In order to reflect the vertical random vibration characteristics of railway vehicles more truly and effectively,this paper regards the human body as a single-degree-of-freedom system attached to the bottom of the carriage,and establishes a vertical dynamic model of railway vehicles by considering the influence of the coupling vibration effect between the passenger and the car body.The correctness of the model is verified by the real vehicle test.Then,the influence of the passengers on the vertical vibration characteristics of railway vehicles is analyzed,and the influence of the railway vehicle vibration on the vertical vibration characteristics of passengers is discussed in this paper.The research made in this paper can provide an effective model reference for the analysis of the vertical random vibration characteristics of railway vehicles and passengers,and for the optimization design of the suspension system parameters.

Analytical simulation of dynamic characteristics of seat system with nonlinear suspension considering friction effects

The friction inevitably exists in the nonlinear suspension system for seats.It affects dynamic characteristics of the seat with the nonlinear suspension system.Analysis of the influences of the friction on the seat vibration responses is helpful to improve comfort.Moreover,it is also an important part of promoting the industrialization application of the nonlinear suspension system for seats.In order to verify the influences,a model of the seat with the nonlinear suspension system considering friction effects was established by combining experiments.Based on the model,by using the harmonic balance method,the analytical formulas of the seat frequency-domain vibration response considering friction effects were deduced,and the influences of the friction on the frequency response characteristics of the system were simulated and analyzed.Moreover,the influences of the friction on the time-domain response characteristics were investigated.The results show that the existence of the friction can help to reduce the vibration in the peak region and to increase the system stability,however,it is not conducive to the improvement of the seat comfort under random road conditions.

Vibration characteristics simulation and comparison of traditional cab system model and seat–cab coupled model for trucks

To define the application fields of the traditional cab system model and the seat–cab coupled model,this paper mainly aims to investigate the differences of the vibration characteristics of the two models.First,the two models and their motion equations were introduced.Then,based on the mechanical parameters of the seat and cab system for a truck,the transmissibility characteristics of the two models were analyzed.The results show that the traditional model can relatively accurately predict the pitch and roll vibration characteristics of the real seat–cab system.However,it overvalues the vertical vibration transmitted from the front suspensions of the cab.Third,the typical excitation conditions and the measuring points were selected.Finally,under the typical excitation conditions,the dynamic responses of the measuring points were calculated.The results show that under the vertical excitation condition,the dynamic responses of the two models have obvious differences.Under the roll excitation condition and the pitch excitation condition,the roll responses and the pitch responses of the cab between the two models show almost no obvious difference.Under the random excitation condition,the vertical acceleration responses have relatively larger deviations between the two models,however,the angular acceleration responses are almost the same.For the preliminary design of the cab system,the traditional cab system model can be used.However,for the accurate design and the optimization of the seat–cab system,the seat–cab coupled model is recommended.

Modeling and analytic optimization of dynamic comfort for wheelchair robots undergoing random roads

To make a rapid comfort assessment and a reasonable dynamic parameters choice of wheelchair robots,this paper proposes a dynamic comfort coefficientκand analytically optimizes the cushion damping.Firstly,a traveling vibration model of the occupantwheelchair system for wheelchair robots running on random roads was created.Secondly,the analytic formula of the occupant RMS(root mean square)acceleration was deduced.Moreover,the dynamic coefficientκwas proposed and its influence laws were revealed.Finally,the cushion system optimal damping ratio was calculated based onκ.The results show that theκvalue is only determined by the parameters of the occupant-wheelchair system.The smaller theκvalue is,the better the dynamic comfort is for wheelchair robots running on random roads.By minimizingκ,the occupant-wheelchair system can achieve a statistically optimal dynamic comfort effect.

Test verification of a seat-cabin system vertical dynamic model for high-grade fork lift trucks

The seat-cabin system of fork lift trucks has a great influence on ride comfort.On the basis of the structure and characteristics of the seat-cabin system for a high-grade fork lift truck,a seat-cabin system vertical dynamic model was created.The vertical dynamic responses of the model under the random irregularities excitation were calculated.The calculated responses including the seat dynamic response and the cabin dynamic responses at the four corners are very close to the field measurement data and the relative deviations of the(root mean square)RMS acceleration responses are all less than 6.0%.The results show that the vertical dynamic model is acceptable and can truly describe the basic mechanical behavior of the seat-cabin system.The model provides a good basis for investigating the relations between the dynamic parameters and the vibration attenuation characteristics of the seat-cabin system to further improve ride comfort.