Optimization of the Implementation Process and Physical Properties of Cotton (<i>Gossipium hirsutum </i>) and Kenaf (<i>Hibiscus cannabinus </i>L.) Wooden Chipboard

The present study aims at valorizing two residues types of the foodless vegetable biomass which are abundant and very pollutant in Burkina Faso. To do it, first we try to identify the optimal values of chipboard elaboration parameters with kenaf and cotton stems by using a natural binder (the bone glue). Next we proceed to the elaboration of two panels types with optimized elaboration parameters. Besides we determine mechanical and thermal characteristics of elaborated panels with a view of an indoor thermal insulation application. Also it becomes necessary for us to determine by experimenting the thermal conductivity, Young’s modulus, Coulomb’s modulus, and the water inflation rate, taking into account some elaboration parameters on one hand and the correlation between mechanical and thermal properties on the other hand. Finally, the obtained results are compared with the panels properties values required by ANSI A 208.1-1999 standard.

Photo-thermal synergistic excitation:Feasible strategy to detect ethanol for wide bandgap ZIF-8at low work temperature

Zeolitic Imidazolate Framework-8(ZIF-8)material was prepared by chemical precipitation method.The microstructure and physical properties of the as-prepared samples were characterized by XRD,BET,FESEM and UV spectrophotometer.The self-made four-channel measurement device was used to test the gas sensitivity of ZIF-8 material toward ethanol gas under photo-thermal synergistic excitation.The results showed that the sample was typical ZIF-8(E_(g)=4.96 eV)with a regular dodecahedron shape and the specific surface is up to 1793 m^(2)/g.The as-prepared ZIF-8 has a gas response value of 55.04 to 100 ppm ethanol at 75℃ and it shows good gas sensing selectivity and repeated stability.The excellent gas sensitivity can be attributed to the increase of free electron concentration in the ZIF-8 conduction band by photo-thermal synergistic excitation,and the large specific surface area of ZIF-8 material provides more active sites for gas-solid surface reaction.The reaction mechanism of ZIF-8 material under multi-field excitation was also discussed.

A Direct Toolpath Constructive Design Method for Controllable Porous Structure Configuration with a TSP-based Sequence Planning Determination

The inherent capabilities of additive manufacturing(AM)to fabricate porous lattice structures with controllable structural and functional properties have raised interest in the design methods for the production of extremely in-tricate internal geometries.Current popular methods of porous lattice structure design still follow the traditional flow,which mainly consists of computer-aided design(CAD)model construction,STereoLithography(STL)model conversion,slicing model acquisition,and toolpath configuration,which causes a loss of accuracy and manufac-turability uncertainty in AM preparation stages.Moreover,toolpath configuration relies on a knowledge-based approach summarized by expert systems.In this process,geometrical construction information is always ignored when a CAD model is created or constructed.To fully use this geometrical information,avoid accuracy loss and ensure qualified manufacturability of porous lattice structures,this paper proposes a novel toolpath-based con-structive design method to directly generate toolpath printing file of parametric and controllable porous lattice structures to facilitate model data exchange during the AM preparation stages.To optimize the laser jumping route between lattice cells,we use a hybrid travelling salesman problem(TSP)solver to determine the laser jumping points on contour scans.Four kinds of laser jumping orders are calculated and compared to select a minimal laser jumping route for sequence planning inside lattice cells.Hence,the proposed method can achieve high-precision lattice printing and avoid computational consumption in model conversion stages from a geomet-rical view.The optical metallographic images show that the shape accuracy of lattice patterns can be guaranteed.The existence of“grain boundaries”brought about by the multi-contour scanning strategy may lead to different mechanical properties.

Robot Off-Line Programming for Thermal Spraying

The purpose of this study is to introduce the current applications of off-line programming technology in thermal spraying,including some popular methods of path generation,procedure simulation,robot kinematics optimization,etc.Indeed this technology reduces the difficulty of robot programming and enormously improves its facility for thermal spraying.At the last part of this paper,presented two examples of off-line programming in thermal spraying which refer to trajectory optimization on a work piece with a great angle and path generation on the complex work piece.The simulations and experiments have proved that off-line programming can effectively improve the production efficiency and the quality of coating.

Loaded Rubber-Like Materials Subjected to Small-Amplitude Vibrations

This paper proposes a constitutive law and a method for characterizing highly preloaded viscoelastic materials subjected to linear （small-amplitude） vibrations. A multiplicative non-separable variables law has been suggested to model the behavior that depends on both stretch and time/frequency. This approach allows splitting the intricate combined test performed simultaneously on both stretch and frequency, generally in a limited experimental domain up to 100 Hz, into two independent tests. Thus, on one hand, the dynamic complex modulus dependent on frequency alone is evaluated on the basis of vibration tests in a large experimental domain up to 100 kHz. On the other hand, energetic parameters are determined from a quasi-static hyperelastic tensile test. The complex modulus, dependent on both stretch and frequency, is then deduced from the results acquired from uncoupled investigations. This work shows that, in extension, the elastic modulus increases with increasing stretch, and the loss factor decreases with increasing stretch; while, in compression, around the material undeformed state, the modulus increases as the stretch increases till a certain value of compression stretch （upturn point depending on material characteristics）, and then the modulus decreases as the stretch increases. Globally, preload rigidifies materials but reduces their damping property. These results closely match a well-known observation in solid mechanics.