This paper presents a new approach to reduce the measurement time by the prediction of the steady-state using the transient response to ethanol for quartz crystal microbalance gas sensors coated with ethyl cellulose. The experimentally measured response curves were successively fitted using a mathematical model based on the sum of two exponentials with different time constants. The parameters of the model were determined, and the time constants and the magnitude of the steady-state response were analyzed. Even though the time constants did not stabilize well, the parameter corresponding to the magnitude of the steady-state response quickly converged and stabilized after 37 s. Moreover, this calculated parameter was highly correlated with the measured values of the steady-state response, which was measured at five times the longest time constant (83 s) of the model. Therefore, the steady-state response could be predicted with a 55% reduction in the measurement (detection) time.
The development of gas sensors based on quartz crystal resonators requires the use of a frequency counter to measure the sensor response. However, commercial frequency counters have at most two channels, and in odour sensory systems (electronic noses), arrays of at least eight sensors are used. Furthermore, it is also desirable that the signal processing and data analysis stage can be included in the same system. A field-programmable gate array (FPGA) can provide a solution to these kinds of problems. This work involves the development of a system to measure the response of quartz crystal resonators, which is implemented using a high resolution frequency counter using an FPGA capable of processing and storing the data in 32-bit registers. Data transfer and acquisition were performed using a microcontroller. The virtual instrumentation software LabVIEW was used for the sensor response display and data storage in a computer. A frequency range from 0 Hz to 100 MHz with a resolution and stability of 1 Hz was achieved using a timebase of 1 s. Tests were performed using gas sensors to obtain real data. The system was escalated to four channels, verifying that it behaves in a correct and stable way.
In modern industry, flexible manufacturing systems (FMS) are indispensable to increase productivity and product quality. The cells that constitute them have several work stations connected to each other through a communication protocol, therefore, with which they are able to identify and distinguish between the different parts or products processed in the system. Furthermore, they have the ability of adaptation to the demand of processing different products and quantities. In the FMS communication protocols are used such as Device Net, Ethernet, among others. However, there are cases in which there are no communication modules; however, it is necessary to develop alternative devices to communicate the work stations with each other to integrate a flexible manufacturing cell with the necessary characteristics. This paper presents the results obtained from the study of infrastructure for the development of a communication interface to integrate a flexible manufacturing cell using a microcontroller, with the capability of communicating two work stations. In this particular case, a FANUC M6iB robot with a HAAS VF2 machining center.
In medical applications, specifically in the handling of mechanical utensils, hygiene and safety must be ensured, which implies a complete cleaning and sterilization of these, as well as the absence of burrs on support edges, in order that there are no harmful cuts of the tissues that are being examinated or manipulated. In such a way, the so-called mirrors or vaginal dilators are very useful elements in the review of women's health and should not be exempt from the minimum quality of hygiene and safety. These devices, are developed using a special polymer, which are commonly elaborated through plastic injectors using molds, due to, they are implemented using different parts, generate the creation of sharp edges and shavings that must be eliminated. The geometry of the mirrors implies a certain complexity in the elimination of the cutting elements. In the present work the design of a polishing machine is presented, which is designed under the principle of fusion of sharp edges and shavings by applying heat from butane gas flames. The proposed machine transports the mirrors to the position to the location of the heating source, with the proper orientation, in order to eliminate the edges and shavings.
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