The general and traditional opinion regarding the materials used to build bells, musical instruments or sound transmitters is that those materials must be only from the bronze alloyed with tin category. In order to ap...
The general and traditional opinion regarding the materials used to build bells, musical instruments or sound transmitters is that those materials must be only from the bronze alloyed with tin category. In order to approach this idea from a scientific point of view, the materials with acoustic properties must be analyzed starting from the physical theory and experimental determination that sound travels only through bodies with elastic properties. It has been developed an experimental white cast iron, medium alloyed with Cr and Ni, in order to obtain a material with special acoustic properties. There were determined on specific samples: the vibration damping capacity, the unit energy, the tensile strength and elasticity modulus. These properties were correlated with the properties of other known acoustic materials.
Due to the development of thermal spray deposition technologies, thus obtained layers have more applications and fields of use. One of the coatings with increased application is the one produced from Ni-based self-flu...
Due to the development of thermal spray deposition technologies, thus obtained layers have more applications and fields of use. One of the coatings with increased application is the one produced from Ni-based self-fluxing alloys, which besides the good wear resistance, shows a satisfactory corrosion resistance. In this study it was observed the behavior of three types of coatings produced by Flame Spray method, both at wear and especially corrosion in the environment simulating acid rain. As a result of the experiments it was found that these layers became compact enough after applying the self-fluxing heat treatment, so in their structure are not present defects such as pores and micro-cracks, unmelted particles etc., which could be points of corrosion initiation.
As witnessed in several behavioural studies, a complex relationship exists between people's cultural background and their general acceptance towards robots. However, very few studies have investigated whether a ro...
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One of the improvements that can be made to internal combustion engines, without significantly altering the structural elements, is increasing the temperature in the combustion chamber by coating its component element...
One of the improvements that can be made to internal combustion engines, without significantly altering the structural elements, is increasing the temperature in the combustion chamber by coating its component elements with thermal barrier coatings (TBC). In this paper were analysed from the microstructure point of view the coating-substrate interfaces of three layers deposited by thermal spraying: S1 - Cr2C3 - NiCr, S2 - MgZrO - NiCr and S3 - ZrO - CaO. The investigations were performed by electronic microscopy on the cross sections taken from the samples after they were subjected to similar heating to the one produced during the operation. It has been observed that all three types of coatings have a much better density, are chemically stable and have good adhesion to the substrate, which recommends them for this type of use.
Image-guided minimally invasive robotic surgery is commonly employed for tasks such as needle biopsies or localized therapies. However, the nonlinear deformation of various tissue types presents difficulties for surge...
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Recent years have seen a rapid increase in the level of sophistication in modern day devices which has given rise to the demand for better performance in all of their components, one of which is the heating element. T...
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Recent years have seen a rapid increase in the level of sophistication in modern day devices which has given rise to the demand for better performance in all of their components, one of which is the heating element. Two excellent approaches to this need would be to improve the materials from which these Joule’s heating elements are made and the other to design improved heater geometries for best temperature distribution. In this paper, we discuss a high performance electrothermal heater prepared from laser reduced graphene oxide (LrGO) deposited on Polyethylene Terephthalate (PET) flexible Substrate. The surface morphology and structural properties of the prepared LrGO films were investigated by means of Scanning Electron Microcopy (SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). Electrothermal (ET) responses of the fabricated electrothermal heaters to different driving DC voltages were studied by Infrared thermal Imagery. An electrothermal heater with a low Sheet resistance of ∼52 O/square was fabricated and it can attained a steady state temperature of up to 135 °C in only 10 s when a low voltage of 9 V was applied. A finite Element model (FEM) was prepared for this heater which agreed well with the experimental results. Power consumption for this heater is as low as 0.389 W/cm 2 , making it a suitable candidate for energy-saving applications such as wearable electronic.
This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the ...
This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.
Based on an observation from a previous work, the authors use the degree of passive freedom of a mechanism with roller follower to propose a new type of mechanism. In the new mechanism, the roller is replaced by a joi...
Based on an observation from a previous work, the authors use the degree of passive freedom of a mechanism with roller follower to propose a new type of mechanism. In the new mechanism, the roller is replaced by a jointed element that forms two contacts with the cam. The obtaining of the cam profile is the main disadvantage of the cam mechanisms but in the present work, by using a cam formed by two connected discs, it is aimed to be avoided. The method is illustrated by designing the mechanism in CAD software followed by the simulation of its movement. To optimize the movement of the final element, the equivalent mechanism with lower pairs is used which has the advantage that the lengths of the elements are constant. The kinematics of the final element is particularly sensitive to the variation of the dimensions of the mechanism, fact illustrated by an example.
The paper presents the manner of finding the conjugate profile of a circular tooth of a spur gear. A synthesis of the method of enveloping applied to the cam mechanisms is presented in order to relate it the profile o...
The paper presents the manner of finding the conjugate profile of a circular tooth of a spur gear. A synthesis of the method of enveloping applied to the cam mechanisms is presented in order to relate it the profile of the spur gears. The main argument of employing cam mechanisms is the possibility of obtaining any follower law of motion using a minimum number of parts- the cam and the follower. In the case of the mechanisms with flat face follower, the cam is obtained as an envelope of successive positions of the follower. The gear mechanisms are a particular case of cam mechanisms. The major requirement imposed to this mechanism is to transmit the rotational motion between two shafts with a constant transmission ratio. From here it results that the profile a geared wheel can be completely identified when there are known the distance between the axes, the transmission ratio and the profile of one of the wheels. The most used curve as tooth flank is the involute of a circle, due to the fact that this curve has as conjugate curve an involute, too. Although the involute profiles are common in most of the technical appliances, there are cases when they cannot satisfy the functional constraints of certain devices. As example, in the mechanical watches technology, large transmission ratios are needed and the gears with small number of teeth are used as routine. But this necessity is better fulfilled by cycloidal profiles than the involute ones. The circular profiles for the spur gear are the oldest gears due to the simple profile. The exact conjugate profile of a circular tooth obtained by enveloping by means of dedicated software is presented.
A dynamical system with one degree of freedom is modelled in two manners: the first one considers that only the dynamical sliding friction is present and the second considers the presence of both dynamic friction and ...
A dynamical system with one degree of freedom is modelled in two manners: the first one considers that only the dynamical sliding friction is present and the second considers the presence of both dynamic friction and static friction. It is difficult to apply the model of revealed static friction only for the zero relative velocity. For this reason, an approximate model for the static friction was identified, that accepts that the static friction occurs when the magnitude of relative velocity in contact decreases under a certain value, the critical value. The integration of the equations of motion of the two models reveals that for important values of the relative velocity, the two models estimate the same behaviour of the system. An experimental set-up was used to validate the theoretical results.
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