引领学生在概念学习中参与“工程实验”

核心素养是核心概念、关键能力及责任态度的结合体,它指向体悟过程,而非记住事实性知识。因此,培养核心素养需要让科学概念透过生活与行为进入学生的认知体系。在教科版二年级《不同的季节》教学中,以静态现象的再现和比较来认识四季特征的学习活动,容易出现探究活动形式化、思维过程答题化、认知结果碎片化的问题,不利于学生建立四季现象及内在成因的系统认识。笔者尝试通过“设计制作季节馆”主体活动,将概念学习的科学探究与模型建构的技术工程统一为一体,形成一种在实践中探究的“工程实验”学习模式,促进技术与工程、学科核心概念和跨学科概念的融合发展。

Isolation of Endophyte and Screening for Antagonistic Bacteria in Solanaceae

[ Objective] The aim of this study was to isolate the endophyte of three solanaceae fruits and vegetables such as tomato, pepper and eggplant, to screen and identify the bacterial wilt antagonistic bacteria. [ Methodl According to the lapping liquid culture method, the endophyte of three plants was isolated by the selective medium and purified by the plate streaking method, so the purified enclophyte was screened by the hyphal pieces confront culture method. Furthermore, the screened antagonistic and endophyteic bacteria was identified and classified through culture characteristics of isolates and morphological features of thallus, Gram stain as well as physiological and biochemical reactions. [ Result] Fifty-three endophytic bacteria, fifty-three endophytic fungi and forty-four endophytic actinomycetes were separated from the endophyte of three plants. The screened fourteen endophytic bacteria with strong antagonistic effect on the bacterial wilt were classified to Bacillus, Escherichia, Klebsiella, Agromonas, Erwinia and Curto Bacterium respectively. Especially, Bacillus was the dominant species, which had the strongest antagonistic effect on the bacterial wilt. [ Conclusion] This study provides an effective way for biological control of the bacterial wilt in solanaceae.

Experimental and Theoretical Analysis of the Impinging Stream Drying

The experiments of one-stage semi-circular and two-stage semi-circular impinging stream drying as well as the vertical and semi-circular combined impinging stream drying were carried out. The velocity distribution and the mean residence time of particles, and the influence of various factors on drying characteristics were studied. A mathematical model of granular material drying in a semi-circular impinging stream dryer was proposed, in which the flow characteristics as well as the heat and mass transfer mechanisms were considered. Reasonable numerical methods were used to solve the equations. Under various conditions, the calculated results agree well with the experimental data. The unsteady-state drying dynamic equation, as well as the variations of drying rate and moisture content versus time were obtained. The results indicate that constant drying rate period does not exist in a semi-circular impinging stream dryer. Appropriate semi-circular stage number and curvature radius, flow-rate ratio, air velocity, and higher inlet air temperature should be used for enhancing the drying process.

NETLAB-An Internet based laboratory for electrical engineering education

This article describes an Internet based laboratory (NETLAB) developed at Zhejiang University for electrical engi- neering education. A key feature of the project is the use of real experimental systems rather than simulation or virtual reality. NELTAB provides remote access to a wide variety of experiments, including not only basic electrical and electronic experiments but also many innovative control experiments. Students can effectively use the laboratory at any time and from anywhere. NETLAB has been in operation since July 2003.

Calculation of the ultimate depth of a scour pit after debris flow through drainage canal ribs

Drainage canals are engineering structures widely used for debris flow mitigation.When passing through a drainage canal,debris flow usually scours the gully bed at the back of the rib sill of the drainage canal,which leads to failure of the rib sill.Therefore,the scour depth at the back of the rib sill is an important design problem and it is related to the economic benefits of engineering and service years.To explore the law of the depth of the scour pit after debris flow through drainage canal ribs,we first proposed a formula for the calculation of the maximum scour depth at the back of a rib sill based on energy conservation.We then conducted a series of simulation experiments to test the proposed formula.The experimental results show that the scour depth,trench slope and the distance between ribs all increase with a decrease in debris flow density.We then compared the results of experiments and formula calculations.Through the testing analysis,we found that the calculation results of the conductedformula correspond with the experimental results better.Finally,taking Qipan Gully as an example,we designed the ultimate depth of a drainage canal for debris flow using the calculation formula.

FEM-DEM coupled modeling of cone penetration tests in lunar soil

Cone penetration test(CPT)is an appropriate technique for quickly determining the geotechnical properties of lunar soil,which is valuable for in situ lunar exploration.Utilizing a typical coupling method recently developed by the authors,a finite element method(FEM)-discrete element method(DEM)coupled model of CPTs is obtained.A series of CPTs in lunar soil are simulated to qualitatively reveal the flow of particles and the development of resistance throughout the penetration process.In addition,the effects of major factors,such as penetration velocity,penetration depth,cone tip angle,and the low gravity on the Moon surface are investigated.

Research on the different content of weathered sand influence on expansive characteristic of a highway expansive soil in Yichang

This paper aims at widespread presence of expansive soil which can be obtained in the project from Xiaoxita to Yaqueling first-class highway rebuilding engineering in Yichang City of Hubei Province and weathered sand which can be made full use locally,many experiments have been made. Compaction experiments and expansibility index indoor experiments of undisturbed expansive soil and expansive soil mixed with sand ranging from 10 % to 50 % have been made. Through the test mixing undisturbed expansive soil with different content of weathered sand,it can change the expansive soil water characteristics and compaction characteristics. It can influence the expansibility of the expansive soil index and significantly inhibit the expansibility of the expansive soil and reach the standard of roadbed filler.

Finite element and experimental analysis of pinion bracket-assembly of three gorges project ship lift

The pinion bracket-assembly(PBA) is a major part of three gorges project(TGP) ship lift drive system. The static strength,fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder(HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m,the vertical elastic deformation of the pinion shaft is between-8.58 and 10.50 mm. When upward outage-load(1580 k N) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80-800.80 k N. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively; the maximum impact on the pin caused by vibration is 19.89 k N; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack(1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate.From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.

The Implementation of Decision Support System for Realizing Effective Usability of CNC Operator Knowledge Capturing System

This article describes experimental evaluations of the authors＇ previous studies on the knowledge-based system （KBS） aimed at capturing and managing CNC （Computer Numerical Control） operator knowledge. The proposed KBS follow thinking steps of CNC operators when they assess machining parameters described in the CAM （Computer Aided Manufacturing） file before proceeding to CNC machining processes. Also, the decision support system equipped with expert system （ES） has been proposed to realize efficient knowledge capturing system and effective usability of captured knowledge, and to recommend actions and decisions. From the viewpoint of providing useful information, the KBS should be aware of context or constraints in which the user has to deal with. In this study, the usefulness of DSS （Decision Support System） and ES is experimentally evaluated using real cases. Comparing the results of the testing participants with and without the DSS and ES, the effectiveness and usefulness were demonstrated. In addition, it was shown that the proposed system is also useful to narrow the discrepancies between CAM and CNC operators, focusing on CNC milling operations.

Modified Augmented Lagrange Multiplier Methods for Large-Scale Chemical Process Optimization

Chemical process optimization can be described as large-scale nonlinear constrained minimization. The modified augmented Lagrange multiplier methods (MALMM) for large-scale nonlinear constrained minimization are studied in this paper. The Lagrange function contains the penalty terms on equality and inequality constraints and the methods can be applied to solve a series of bound constrained sub-problems instead of a series of unconstrained sub-problems. The steps of the methods are examined in full detail. Numerical experiments are made for a variety of problems, from small to very large-scale, which show the stability and effectiveness of the methods in large-scale problems.

Recent Progress in Cartilage Tissue Engineering--Our Experience and Future Directions

Given the limited spontaneous repair that follows cartilage injury, demand is growing for tissue engi- neering approaches for cartilage regeneration. There are two major applications for tissue-engineered cartilage. One is in orthopedic surgery, in which the engineered cartilage is usually used to repair cartilage defects or loss in an articular joint or meniscus in order to restore the joint function. The other is for head and neck reconstruction, in which the engineered cartilage is usually applied to repair cartilage defects or loss in an auricle, trachea, nose, larynx, or eyelid. The challenges faced by the engineered car- tilage for one application are quite different from those faced by the engineered cartilage for the other application. As a result, the emphases of the engineering strategies to generate cartilage are usually quite different for each application. The statuses of preclinical animal investigations and of the clinical translation of engineered cartilage are also at different levels for each application. The aim of this review is to provide an opinion piece on the challenges, current developments, and future directions for cartilage engineering for both applications.

Automatic Spike Sorting Based on Robust Clustering

The collected spikes from extracellular recordings usually contain noisy data and outliers, which make it difficult to separate them. A method for spike sorting based on robust clustering is proposed to deal with the problem. The clustering method combines the advantage of fuzzy clustering and robust statistical estimators. The number of dusters is obtained by fuzzy cluster validity. In order to reduce the influence of outliers, the validity index is calculated using the weighting intra-cluster distances. The proposed method is suitable to separate neural spikes in the presence of noisy data and outfiers. The experiment on real data shows its performance.

GeoQuest Project Computer Class Role Playing Game as Innovative Teaching Methodology to Foster STEAM Education

GeoQuest Project is the design of a new teaching and learning technology based on Computer Class Role Playing Games （RPG） to teach Earth Science in a STEAM educational approach. It ensures interdisciplinarity, multilinguai approach （CLIL compliance） and interactive activities in classrooms. This educational game uses students＇ personal tablets and smartphones to interact with the game, with a system more comprehensible and funny for young people compared to traditional methodologies. Students are bringing ＂in situation＂ by the adventure, so teachers can get a rigorous assessment of their skills. The Game includes several adventure paths, suitable for different age students. They are focused on scientific topics, humanities, hands-on activities in interdisciplinary way. If used conditions do not allow practical or laboratorial activities provided by the game, players can see some videos to understand the activities. Experimental results were outstanding： the RPG appreciation is in agreement with the experiments outcome. This work experience gets excellent feedbacks by teachers, in terms of efficacy of this new teaching methodology and of results achieving.

The Use of Acoustic Quality Assessment in the Management of the Road Noise Reduction Project

The article presents a new approach to the tasks of noise assessment and reduction in the urbanized environment endangered by road noise sources. It was proposed to include the acoustic quality model in the currently applied quantitative noise assessment in the management of urbanized environment. In particular, this model takes into account subjective features of sound quality, i.e.： loudness, sharpness, roughness, and fluctuation strength as well as noise mmoya^ce assessment obtained in laboratory conditions. The proposed way can be used in estimating investment costs of an acoustic barrier at the design stage

Numerical Investigation of a New Method for Reducing Bends Erosion from Particles Impacts

The present paper intends to introduce a new method for reducingbends erosion from particles impacts: the ribbed bend erosionprotection method. Ribs are evenly fixed in the range of 20 deg-80deg on the inner-wall of inside 90 deg bend and the bend (includingribs) is made of medium carbon steel. Three-dimensional numericalworks is performed and the result shows satisfactory agreement withthe experimental measurement. Numerical simulation studies thecharacteristics of axial gas flow along the bend and secondary flowat cross section.

Effect of Engineering Character on Stress-Strain Relationship in Post-Peak Area

Constitutive experiments are the base of all rock mechanics works. The effect of engineering character on constitutive law is a new problem of rock mechanics. The results of series specimens based on the uniaxial and plane strain compression experiments were presented and discussed. It is found that engineering or experiment character has obvious effects on stress-strain relationship and especially on mechanic parameters in post-peak area. And the law of size effect of softening materials was also discussed.

Fuzzy Modeling in Environmental Geotechnics

High level of industrialization of northern regions of Russia cause significant pollution problems in the soil. The new approach based on fuzzy modeling for reception and processing of the geocryological information is offered. The technique and methodology of presentation of variables in a logic and linguistic way in a combination to elements of the experimental planning theory is developed. Comparison of the calculated data on model has shown its high adequacy of the experimental data of the various authors. The forecast of geoecological processes in cryolitozone on the basis of the described method will allow increasing reliability of the accepted design decisions.

Practice and experience of engineering culture development in the Sutong Bridge project

To keep up with the time,culture is integrated to large-scale construction project management in China,which will absolutely add more vitality into construction project management in our country.Engineering culture is an integration of project construction and engineering culture.However,engineering culture development enjoys its own particularity as a project is constructed once only within a limited period of time.This paper gives affirmative opinion that engineering culture development in large-scale projects backs project management on the basis of thorough investigation of engineering culture development in Sutong Bridge Project and after deepened analysis,proposes new thinking pattern of engineering culture development in large-scale projects in a systematic manner,including thorough understanding of the essence of engineering culture,principle and contents of engineering culture development as well as efficient method in respect of establishment and implementation of engineering culture,and therefore provides a standard reference and systematic thinking pattern for engineering culture development in future large-scale projects.

Industry Based ＂Hands-On＂ Undergraduate Vibration Course for Engineering and Engineering Technology Students

Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students＇ education. This paper demonstrates how hands-on experiments performed in industry support and increase the students＇ understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today＇s job market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology （MMET） program at Oregon Institute of Technology （OIT） - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this project. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.

Dynamics of Anchor Last Deployment of Submersible Buoy System

Submersible buoy systems are widely used for oceanographic research,ocean engineering and coastal defense.Severe sea environment has obvious effects on the dynamics of submersible buoy systems.Huge tension can occur and may cause the snap of cables,especially during the deployment period.This paper studies the deployment dynamics of submersible buoy systems with numerical and experimental methods.By applying the lumped mass approach,a three-dimensional multi-body model of submersible buoy system is developed considering the hydrodynamic force,tension force and impact force between components of submersible buoy system and seabed.Numerical integration method is used to solve the differential equations.The simulation output includes tension force,trajectory,profile and dropping location and impact force of submersible buoys.In addition,the deployment experiment of a simplified submersible buoy model was carried out.The profile and different nodes' velocities of the submersible buoy are obtained.By comparing the results of the two methods,it is found that the numerical model well simulates the actual process and conditions of the experiment.The simulation results agree well with the results of the experiment such as gravity anchor's location and velocities of different nodes of the submersible buoy.The study results will help to understand the conditions of submersible buoy's deployment,operation and recovery,and can be used to guide the design and optimization of the system.