Process Of Geometry Research Articles

Reform process of solid geometry in the secondary school until the “Mathematics 4 and 5, Category II.”

Reform process of solid geometry in the secondary school until the “Mathematics 4 and 5, Category II.”

Experimental study of a metal hydride driven braided artificial pneumatic muscle

This paper reports the experimental study of a new actuation system that couples abraided artificial pneumatic muscle (BAPM) with a metal hydride driven hydrogencompressor to create a compact, lightweight, noiseless system capable of high forces andsmooth actuation. The results indicate that the metal hydride–BAPM system has relativelygood second law efficiency average of 30% over the desorption cycle. The thermal efficiencyis low, due mainly to the highly endothermic chemical reaction that releases the storedhydrogen gas from the metal hydride. The force to metal hydride weight is very high(∼14 000 NForce/kgMH) considering that this system has not been optimized to use the minimum amount of metalhydride required for a full actuation stroke of the fluidic muscle. Also, a thermodynamicmodel for the complete system is developed. The analysis is restricted in some aspectsconcerning the complexity of the hydriding/dehydriding chemical process of the system andthe three-dimensional geometry of the reactor, but it provides a useful comparison to otheractuation devices and clearly reveals the parameters necessary for optimization of theactuation system in future work. The system shows comparable work output and has thebenefits of biological muscle-like properties for potential use in robotic systems.

Numerical–experimental analysis of metal bars undergoing intermediate strain rate impacts

This work concerns the accurate modelling of plastic deformations in steel bars, loaded dynamically with impacts that cause “intermediate” strain rates (10-1 to 103s-1). The final aim is the description of permanent plastic deformations that are designed deliberately in a wide range of industrial processes, or occur accidentally under undesired overloads. The finite element method is used to perform reliable simulations of impact experiments that produce plastic bending in metal bars. The numerical model accounts for the actual experimental setup used in the experiments, including multiple contact interactions between intruder and deforming bar, rate effects, and friction. For comparative purpose, two different rate dependent constitutive laws are used to model the behaviour of the bar material. The results of the numerical simulations show a remarkable agreement with the experimental data. The validated model is used to conduct a sensitivity analysis, where the influence on the deformation process of test-rig geometry, friction, and constitutive parameters is evaluated.

ACCURACY OF FINITE ELEMENT PREDICTIONS ON BONE/IMPLANT INTERFACE CONTACT PRESSURES FOR MODELS RECONSTRUCTED FROM CT SCANS

Finite element (FE) simulations can be utilized to predict contact pressures at the bone/implant interface as well as to identify the position and shape of the contact region. However, the accuracy and reliability of FE models of the bone/implant interface reconstructed from tomographic images may be affected by a number of factors such as the presence of image artifacts, the magnitude of geometric errors made in the reconstruction process, the type of boundary and loading conditions hypothesized in the model, the nonlinear solver utilized for computing the contact pressure distribution, and the element type. This paper attempts to estimate the global effect of the aforementioned factors. For this purpose, a cylindrical contact problem — pin/muff — portraying a simplified model of the bone/implant interface is considered. The accuracy of numerical predictions is estimated by comparing contact pressures predicted by an FE model reconstructed from computed tomography (CT) scan images and by an "ideal", experimentally validated FE model. Two different couplings, i.e. chromium-cobalt alloy and titanium implants, are considered. In the former case, image artifacts complicate the reconstruction process of model geometry and lead to less accurate predictions on contact pressure distribution; conversely, the limited streaking effects occurring in the titanium pin case allow us to precisely reconstruct coupling geometry. Finally, a rather clear correlation between errors on contact pressure and geometric errors made in the reconstruction process is found only for the titanium pin.

Search for optimum geometry of selected steel sandwich panel joints

Search for optimum geometry of selected steel sandwich panel joints Application of steel sandwich panels to ship structures requires many problems to be solved. Joints between the panels as well as those between the panels and other structures is one of the more difficult problems associated with the structures in question. This paper presents the searching for process of optimum geometry of a panel-to-panel joint of longitudinal arrangement, performed by means of the ANSYS software. A configuration was searched for of parameters which can ensure as-low-as possible values of geometrical stress concentration coefficients at acceptable mass and deformations of the structure. Analysis of the obtained results made it possible to propose the optimum geometry of the considered joint.

Effect of electrode geometry on performance of an EHD thin-film evaporator

This paper presents details of an optimization process of electrode geometry for an electrohydrodynamically (EHD) driven thin-film evaporator. The operation principle of the device is based on the action of the EHD force on the molecules of a dielectric liquid in a highly convergent electric field. The force starts at the end of a pair of electrodes, where the electric field changes from zero far from the electrodes to a finite value in between the electrodes. This force drives the liquid up into the spacing between the electrodes. The electrodes in this study were deposited thinly on a SiO/sub 2//Si wafer, so the liquid could be held within micrometers of thickness over the surface. Since the performance of the device in removing heat from the surface is a function of its pumping head and consequently its electrode geometry, the performances of different electrodes were evaluated by testing twelve sets of electrode pairs with different geometries. Then the optimum electrode design was incorporated into the design of a large size (32/spl times/32 mm/sup 2/) EHD thin-film evaporator. The device was fabricated, and its pumping and heat transfer performances were tested. A pumping head equal to the full height of the electrodes and a heat transfer coefficient of 1.9 W/cm/sup 2/./spl deg/C was achieved using HFE-7100 liquid.

Dynamic evolution of a fault system through interactions between fault segments

We simulate the dynamic evolution process of fault system geometry considering interactions between fault segments. We calculate rupture propagation using an elastodynamic boundary integral equation method (BIEM) in which the trajectory of a fault tip is dynamically self‐chosen. We consider a system of two noncoplanar fault segments: a preexisting main fault segment (fault 1) and a subsidiary one (fault 2) and, allowing the tip of fault 2 to deviate from its original plane, trace its trajectory in the step over region between the two fault segments. Our simulation results show that the final geometry of fault 2 depends on the initial configuration of the two fault segments. If the initial overlap of the two fault segments is smaller than the half length of fault 1, fault 2 coalesces with fault 1 when the step over is narrower than about 1/4–1/2 the length of the latter but is repelled from fault 1 when the step over width is larger than this threshold value. We also show that the inclination angle of fault 2 is sensitive to the rupture velocity; the inclination is larger for faster rupture propagation. Our simulation results imply that as ruptures occur repeatedly, a fault system evolves from an array of relatively small fault segments into a sequence of larger ones. Our results seem consistent with the field observations of natural fault system geometries, which are often characterized by a set of noncoplanar segments interconnected with relatively small jogs at oblique angles.

Picosecond Laser Photolysis Studies on Chain-Length, Solvent and Temperature Dependences of the Intramolecular Photoreduction Process of Benzophenone by Diphenylamine

Abstract Photoinduced hydrogen abstraction (HA) processes of 1-(4-anilinophenyl)-2-(4-benzophenoxy)ethane, 1-(4-anilinophenyl)-3-4-benzophenoxy)propane, and 1-(4-anilinophenyl)-8-(4-benzophenoxy)octane (BP–O–(CH2)n–O–DPA: n = 2, 3, and 8) in benzene, acetonitrile, and N,N-dimethylformamide solutions were investigated by means of picosecond transient absorption spectroscopy. In benzene solution, apparent mechanism of the hydrogen abstraction reaction was “direct” process and no absorption spectrum of the charge separated state was observed. The decay of triplet benzophenone moiety (3BP*) was regulated by the dynamic rearrangement process of the mutual geometry between 3BP* and DPA to a more compact one. In polar solutions, the electron transfer (ET) from DPA to 3BP* moiety took place in addition to the direct HA from DPA by 3BP*. The rate of the ET reaction was regulated mainly by the distance between the reactant moieties. Moreover, the intra-ion pair (IP) proton transfer (PT) resulting in the HA product formation was observed, although such PT process in the IP state between the unlinked 3BP* and the secondary amine was not observed. By integrating the present results on the linked systems with those of the unlinked systems, the role of the ET or CT interaction in the HA process of 3BP* from the secondary amine was discussed.

Study on the instructing process of the Descriptive Geometry by means of the Student—Problem Score Table Analysis

Until now the instructing process of the Descriptive Geometry has been judged by the experience gained through instructing without the scientific measurements. So in this paper the author studied the instructing process of the Descriptive geometry by means of the Student-Problem Score Table Analysis that had attracted special interest recently. Then the author obtained several useful results by investigating many S-P table data as follows;(1) The author could describe the S-P curves by scale transformation and calculate the difference coefficient D, i.e. D*=0.34 (Exercise), D*=0.24 (Test) . Then it became clear that the contents of problems were suitable because of D* being less than 0.6.(2) It became clear that since the learning unstability or the lack of readiness depends on the graduate course, elimination of lack of readiness is effective for the qualitative improvement of learning.(3) The author was able to characterize each student by the attention coefficient C.S and the right answer rate P.(4) The author was able to find the improper or heterogeneity problems by the attention coefficient of problems C.P and the right answer rate P.(5) It became clear that the problems including the fundamental instruction elements is difficult unexpectedly for the students attending the lecture of the Descriptive Geometry.

S-P表分析による図学の教授過程に関する研究

S-P表分析による図学の教授過程に関する研究

Acquisition of associative knowledge by the frustration-based learning method in an auxiliary-line problem

We have developed a learner, AUXIL, which has the ability to solve auxiliary-line problems in geometry in an intelligent way. First, we show that a basic mechanism for producing auxiliary-lines is to associate a certain condition or subgoal in the problem with an appropriate figure-pattern and that AUXIL can produce a successful auxiliary-line by making use of associative strategies, which we call figure-pattern strategies . Secondly, we proposed a new method, frustration-based learning , which can acquire associative strategies through experiences of solving a variety of auxiliary-line problems. AUXIL simulates the following expert behavior. When an expert tries to solve such a problem, he feels frustrated because enough information is not given in a problem space for him to proceed an inference and to find a correct path from given conditions to the goal. Here, he concentrates himself on the conditions or subgoals which have caused frustration. After he has produced an auxiliary-line and made a complete proof-tree, he would learn several associative strategies. Each frustration-causing condition or subgoal will constitute the if-part of each strategy. He will then recognize several lumps of figure-patterns in the proof-tree, each of which has contributed to resolving each frustration. All pieces of geometrical information of each figure-pattern will constitute the then-part of each strategy. Learning an auxiliary-line problem through frustration-based learning means to understand it as a composition of figure-patterns each of which has those features represented in the THEN-part of the corresponding strategy. The frustration-based learning method is regarded as a method for learning some essential figure-patterns which underlie and structurize a problem solving process of elementary geometry.