Emerging Challenges for Experimental Mechanics in Energy and Environmental Applications, Proceedings of the 5th International Symposium on Experimental Mechanics and 9th Symposium on Optics in Industry (ISEM-SOI), 2015

Time-average Fourier telescopy appears to provide a way to acquire diffraction-limited imagery in ground-level horizontal-path imaging through turbulence at kilometer-scale distances and with meter-scale apertures. The scheme, which has its basis in Fourier telescopy, uses separate averaging with time of the amplitude and phase of the Fourier telescopy signal to remove the effects of the turbulence. The basic method is described and preliminary results of simulations discussed.

In mechanics of materials it is important to know the stress–strain relation of each material in order to understand their behaviour under different loads. Optical methods are used for determine different kind of stresses and interferometry is the most used tool. In this work it is presented a new alternative to determine the stress–strain based in one beam which is reflected in the surface of the material while it is in a compression test as the ASTM indicates. It is taken the material as a reflective surface which acts as a spherical mirror and it will scatter light, the scattered area will increase as the deformation increases. The reflected beam is analysed applying beam propagation equations and Digital Image Processing for getting the increase of the scattered area. Finally it is plot the relation between the applied stress and the beam propagation. There is also presented the accuracy, sensitivity and a theoretical demonstration of the method.

Increasing human activity has highlighted the need for rapid and accurate chemical analysis of contaminants. Laser Induced Plasma Spectroscopy (LIBS) is an ideal solution because it has advantages such as in-situ analysis capable, it does not require sample preparation and the amount of sample required for analysis is minimal. This paper uses LIBS for heavy metals analysis in receiving water bodies. The LIBS system employed uses a Q: Switched multipulsed Nd:YAG laser, which favors the intensity of the emission spectra, showing sharper and improved detection limits. The obtained results are used in training a neural network to predict the elemental composition.

LIBS technique was used to obtain spectra of Escherichia coli and Staphylococcus aureus for identifying characteristic emission lines and then they were analyzed by K-means classifier for neural network feasibility. The potential of this method for bacteria identification was demonstrated.

The authors developed a portable optical residual stresses measurement device that combines the incremental hole-drilling method with digital speckle pattern interferometry working in polar coordinates. The device is able to measure radial in-plane displacement components around the drilled hole. A set of normalized radial displacement vectors are computed by the Finite Element Method for each hole depth increment, according to the integral method. The radial displacement field around the drilled hole is optically measured and data processed to extract the zero and second order harmonics and fitted by least squares method to the FEM coefficient vectors to quantify the amount of residual stresses in each material layer. The residual stresses profile is then determined for every 0.05 mm. A controlled experiment using a bent plate is used to experimentally evaluate the measurement performance of the developed approach. The results uncertainty are comparable to the strain gauge measurements.

The fundamental equation in X-ray diffraction relates the measured strain quantities to a superposition of six independent components: three normal and three shear components. However, the linear system of equations to solve for the six components leads to a singular matrix. The academic literature recommends regularization methods. In case of using regularization methods, non-unique solution is expected. All these methods only work if the determinant of the matrix is close to zero. In diffraction experiments it is definitely zero because of the existence of the normal component ε₃₃. Therefore in the past biaxial stress states have been assumed. It is shown that by a numerical differentiation the shear components can be simply resolved. Once the shear components have been subtracted from the fundamental equation, the three normal components remain. By a Taylor series development of the fundamental equation it is shown that ε₃₃ and its first derivative at ψ = 0 are independent of the rotation angle φ. This requires a special structure of the matrix to analyze the data at different φ rotations. Once these two values are obtained, they serve as the initial conditions of a differential equation of second kind which is solved numerically. The unknown functions in the differential equation are approximated by a Taylor series expansion whose coefficients are determined by a nonlinear optimization procedure. Together with simulated data, first results are presented.

In this work the optical polarization method applied on phase shift digital speckle interferometry (PSDSPI), was performed for measurement of slow, small mechanical out-of-plane induced displacements. A basic experimental setup was used to obtain digital specklegrams related to mechanical displacements induced during specific time intervals. A digital image processing computational analysis was applied on experimental data, combined with analysis of phase shift positions induced by a polarizer and as a result a reliable measurement of displacements was obtained. Although conventional piezoelectric phase shifting methods are well established, the optical polarization method still preserves advantages as less complex instrumentation and low cost implementation.

Among the diversity of methods for glucose level monitoring in human blood, invasive techniques are still the most commonly used. Blood samples, usually obtained with finger-pricking devices, are analysed through enzymatic reactions via electrochemical or photometric principles. In this paper, non-invasive methods for blood glucose monitoring are studied and compared, while also analysing optical and electronic properties of glucose. From this comparative analysis, proposals are made towards the design and characterisation of novel devices capable of monitoring blood-glucose levels through optoelectronic non-invasive procedures. Alteration of electrical parameters of cellular membrane, such as electric permittivity and conductivity as a function of blood glucose concentration, are observed and compared to the responses to optical stimuli. The investigation is developed by establishing a correlation between the effects of diffusion and dispersion of light on the concentration and dispersity of blood particles, and the response of electrical parameters under different glucose concentrations. As a result of the analysis, recommendations are made for the most suitable parameters and instrumental methodology, in terms of feasibility, easiness and precision, for non-invasive monitoring of blood glucose levels.

In this research we implemented a two-step phase shifting system based on two cyclic-path coupled interferometers for slope measurements of transparent samples. The optical system generates two π-shifted interferograms, and the phase shift between interferograms is obtained by rotating a linear polarizer, generating four interferograms with relative π/2-phase shifts; this simplifies the number of phase steps necessary to retrieve the optical phase, since is only necessary perform a shift operating a linear polarizer. The optical phase was processed by a four-step algorithm. In order to present the capabilities of the system, results obtained for slope for transparent structures are presented.

The recognition of microorganisms is important in the diagnosing of the micro-biology. In the medical field the cell disorders can affect body tissues indirectly. In this work we use digital holographic microscopy (DHM) that can achieve high contrast images. This method permits us to obtain phase maps by means of digital reconstruction of a wavefront. Phase differences between two states allows us to realize a quantitative analysis of samples.An off-axis layout is used to determine the morphology of different types of microorganisms. Also, we can directly examine aggregations by corresponding phase maps. The images provide information about the presence or absence of microorganisms that can be used as indicators of the physiological state of the body. By the presented results, we show that DHM may give some new perspectives within biomedical applications.

A simple strategy based on wavefront propagation in Fresnel regime to reduce ringing effect by using an ideal filter in off-axis digital holography is presented. In addition, we demonstrate a better focusing capacity by using this ideal filter than Butterworth and Gaussian. The reconstructed and enhanced image is obtained from the averaging operation between the image at the focused image plane (z = z _hd0 ) and the first Talbot distance order (z = z _hd1 ). This distance is determined by the periodic ringing. Reductions of 50 % of these anomalies are computed in simulation and 30 % is obtained experimentally. Numerical simulations and experimental results are carried out to validate the proposal.

The Schlieren technique has been used to visualize and measure some relevant physical properties in transparent media such as refractive index and some dependent variables on it such as density and temperature. This technique was implemented to visualize temperature gradients that appear from the heat applied into the hot section of a Stirling engine. Temperature gradients and temperature fields are described qualitatively and compared with temperature measurements using chromatic thermometric crayons. Furthermore, natural and turbulent heat convection was visualized from the temperature fields. The obtained results give important information about the heat transfer mechanism and its dissipation on a real engine.

The standard fringe projection technique requires a non-zero angle between projection and observation directions to have sensitivity in the z direction. In this work, a new method is presented where the angle between projection and observation directions is zero, but the system presents sensitivity due to divergent projection which changes the fringes frequency in each one of the normal planes to z-axis. The experimental results compared with the standard fringe projection technique are presented in this work to show the accuracy of the method proposed.

Purkinje images are images generated by the reflection of light at different interfaces of the ocular reflective surfaces. The study of the Purkinje images is aimed to determine changes in the alignment of those surfaces. An optoelectronic system capable of generating and detecting Purkinje images in a patient is presented. A symmetric near-infrared illumination array is used to relate the position and orientation of the images obtained with misalignment in the optical axes of the eye. Besides, the images are processed to identify each of the Purkinje images using multi-thresholding.

The ultrasound is a widely extended technique in non-destructive testing (NDT). Some its advantages are: low cost, safety and simplicity to be implemented, environment friendly and reliability. The ultrasound probes are useful to detect gaps, corrosion, breakages, changes of density and impurities in materials. However, the C-Scan used to produce a 3D image is complex and requires the use of a special probe made of a transducers matrix and a powerful computer to run the image processing algorithm. The cross-talk, spurious echoes and the position uncertainty of the reflected point make it harder to locate in the space the true points. This work describes the ultrasonic arc maps (UAM) technique and proposes to use them in NDT. Originally, the UAM was developed in robotics, where it showed good features to locate the true reflected points using a simple pulse-echo transducer. The algorithms for data processing are fast, easier to program and could be embedded in a digital system like a microcontroller or a FPGA.

It is well known that one of the features of a laser diode is its wavelength tunability which can be modulated with a variable injection current and/or temperature of its active region. For many industrial and scientific applications it is desirable that the laser gets stabilized. In this paper, on the contrary, the laser diode is turned on-off for a short period of time. The generated peak variations of voltage and temperature will cause a modulation of its wavelength. This modulation is used to add phase-shifts in an unbalanced Twyman-Green interferometer and by using Carré algorithm the phase of the resulting interference wave will be retrieved.

We present a novel method based on Digital Holographic Interferometry to detect slight physical variations of refractive index with high sensitivity in liquid substances. The technique is grounded in the measurement of a phase difference between two reconstructed wavefields. The optical system was tested using a series of sodium chloride (NaCl) solutions to detect a variation in its physical property such as concentration. A first hologram records a wavefront coming from the light scattered by a common cylindrical glass container filled with certain NaCl solution. Later, a second hologram is recorded when the solution mentioned above slightly changes its concentration. The difference between the phase maps obtained from the correlation from the two holograms will provide information about a refractive index variation, which is directly related to a concentration change. The achieved results have proven to be more accurate and faster to get than with other techniques. The process requires just a few special optical elements and is able to measure the three-dimensional distribution of the refractive index of a sample. This method can be extended to identify adulteration in liquids, measure the variation in refractive index in gaseous flames, apart from analyzing and visualizing the mechanical properties of a liquid sample.

We describe a technique for measuring the local geometrical thickness of semi-transparent thin films by means of the diffractive properties of a transmitted Gaussian beam. In particular, we measure the semi-width of a beam transmitted through the sample with a homodyne technique especially devised for this purpose. We present analytical and experimental results with our technique.

Besides the topography of an object, color and texture are important parameters to study in some fields. In food industries, variations in color and volume of a piece of fruit are important in order to determine its condition. Using the fringe projection technique, the topography of an object is evaluated through time; hence the change of volume. Using colorimetric techniques, optical devices can be profiled and calibrated. The change of topography and color are measured every 3 days during two months in order to make comparisons with the previous measurements of volume and color. Thus, the condition of food or a piece of fruit can be evaluated as it evolves through time.

We present preliminary results of the measurement of temperature distribution fields of a synthetic jet produced by a Helmholtz resonant cavity when used for the cooling of an aluminum plate. The plate is set at 80 °C and background-oriented schlieren images are registered by a high speed camera at 2000 fps. The background consists of sinusoidal fringes printed on a transparent slide and it is back-illuminated by a matrix of 20 3-W white LEDs. A reference image is taken with no jet and a series of images are then recorded with the cavity working in the first resonance frequency, 125 Hz. The observation region corresponds to an area of 1 × 10 cm2. Results show an oscillatory behavior of the temperature distribution at the resonant frequency.

3D shape recovery systems, based on structured light projection, allow recovering three-dimensional shape from complex opaque surfaces. Particularly, when a fringe pattern with sinusoidal profile is projected on a surface and algorithms for recovering optical phase are performed for its demodulation, sub-micrometer resolutions can be obtained. The resolution is closely related to the angle formed by the axis system of projection and the observation direction; other important parameters are the local gradient of the sinusoidal profile projected and the bit depth of the digital camera used to capture the deformed patterns. In this work, the projected sinusoidal fringe pattern is generated by a Gates’ interferometer where an expanded and collimated laser beam is impinged onto a non-polarizing cube beam splitter (parallel to the splitter coating). Internal reflections and refractions of the laser beam passing through the cube generate the interference fringes that are projected over the test object. The Fast Fourier Transform, FFT, technique and a simple phase unwrapping method are used for demodulation of registered fringe patterns. Results of the three-dimensional surface of a coin that has a relief of about 150 μm with a theoretical axial resolution varying from 0.1 to 7 μm are presented.

In this work it is described the integration of a system capable of performing automatically the compositional mapping of surfaces, by the method of laser induced breakdown spectroscopy. This system consists of a mobile mechanical base, a control system whose processing center is a development board Arduino Mega, which interacts with the user through a visual environment programmed in National Instruments LabVIEW and a piece of software for processing the spectrum obtained. Also, it describes the first experimental tests and shows preliminary results.

A new technique for the estimation of the degree of fluorosis based on Dean Index and artificial vision system to improve the diagnostic of dental fluorosis is proposed. A group of 15 people diagnosed with dental fluorosis according with the Dean Index was studied. The images were digitally processed in order to discern and estimate the dental fluorosis using a discrimination algorithm based on one layer of Artificial Neural Networks and statistics criterion. A vision system and the implemented algorithm showed the ability to detect the different degrees of dental fluorosis in accordance with the diagnosis. Additionally, with this technique it was possible to identify the different affectation degrees of fluorosis by dental piece. The inclusion of a vision system and an algorithm for the estimation of dental fluorosis in this technique contributes as an alternative tool for an objective diagnostic by specialists.

In recent years, laser ablation method has been increasingly used in the touch panel industry. Touch panel devices are produced by applying laser ablation process on transparent conductive oxide (TCO) thin films coated on glass substrates. The pattern and the surface profile of the transparent conductive layer on glass substrates after laser ablation are crucial on the quality of the touch panel. Therefore, a self-assembled multifunction optical measurement system was employed to investigate the details of the surface of the test specimen of the TCO thin films after ablation. The system integrates both optical microscope and white-light scanning interferometer to inspect the specimen under the same field of view. The transparency of the test specimen was inspected by the optical microscope to examine the uniformity of the gray levels throughout the ablated region. The depth of the ablated thin films and whether the thin films are fully cut can be determined from the surface profile obtained from the white-light scanning interferometer. Based on the aforementioned experimental results, the self-assembled multifunction optical measurement system is full of potential to be used to determine the manufacturing parameters in laser ablation process.

LIBS technique for the identification of trace elements in oil samples from different sources using a compact LIBS system was used. In order to address the difficulties presented by the characteristics of the samples, two pretreatment stages, freezing and thermal treatment by ultrasound were performed. Obtained results are described and compared in both cases. It is demonstrated the potential of the technique to identify the origin of oil is by its composition.

A sampling moire method is useful to measure deformations of a large structure such as a building and a bridge. The sampling moire method can analyze 3D displacement using two cameras. The sensitivity of the displacement measurement for the z-direction is lower than the displacement measurement in the x- and the y-directions in this method because the cameras are placed near the direction of the z-axis against the object in general. However, the measurement noise level can be decreased with increasing the number of cameras. In this paper, the principle and the calibration method to measure 3D displacement using the sampling moire method with multiple cameras are shown. As the application, 3D displacement distribution measurement of a cantilever using the sampling moire method with multiple cameras is performed. The accuracy of the 3D displacement measured with using three cameras is compared to the displacement of the cantilever.

The use of machining systems by Computer Numerical Control (CNC) has notable advantages in the area of industrial production compared with traditional techniques. This facilitates a significant decrease of time, higher precision and optimization of operation parameters. The control of sequences in these systems is based on codes that define the parameters to produce the machining of a determined piece. However, the generation of these codes presents two major challenges, first, know the tridimensional information of the piece to produce, and second, define the sequence by CNC machining. In this work, the fringe projection technique is used to obtain three-dimensional information from an object and based on this information, automatically generate programming codes for the machining routine of a three-axial CNC milling machine. The results are compared to apply the fringe projection technic to recover three-dimensional shape of an object based on Least Squares Algorithm, using information from three to eight images.

The use of robotic manipulators is a subject that has become relevant in the process of automation in different branches of industrial manufacturing. Today is possible to make routines works with robotic manipulator in dangerous conditions for human operators, providing flexibility in production lines, doing multiple types of tasks and executing actions with precision and quickly. All operations of a robotic arm is controlled by a computer system that controls the mechanism positions. Since the work of these machines is to manipulate tools or pieces, it is necessary to have tridimensional information of the environment or manipulated elements. In this work, the fringe projection technique is used to obtain three-dimensional shape of an object, and based on this information to generate the trajectories of the manipulator for the painting of complex objects through paint spraying. The obtained results have been successful, generating simulated trajectories for the painting of pieces with good quality and short times compared with times using traditional methods to program sequences.

We have been working on different stages of a project and the last one was remote monitoring. Now part of a sensor application will be reviewed on a machine that can exert loads in an industrial scale. Some results obtained by this system are shown. The principle on which this research is based is the fact that any load applied to a soil or column will scroll causing deformation, with reference to a point on an unloaded ítem, which is the absolute reference. Optomechatronics loading lets us determine how different points deform; for example in a column a pair of optical sensors (transmitter and receiver) send signals to a DAQ NI and they are read in LABVIEW VI. They received data are written in a database for analysis. The complete design system is applied to measuring force and stress in industrial machinery.

This paper reports the construction of an experimental setup to attenuate the ASE (Amplified Spontaneous Emission) noise around 1548.4 nm. A Sagnac Interferometer (SI) which uses high-birefringence fiber (Hi-Bi fiber) at 8, 22 and 110 cm is used as band pass filter for attenuating the ASE noise. Temperature variations are made to tune in the filter SI. A test signal containing noise ASE is taken from an erbium-doped optical fiber and a fiber Bragg grating (FBG), therefore the 1548.4 nm signal surrounded for ASE is obtained. This test signal is introduced into the SI filter and the transmitted power of the interferometer is measured, the transmitted signal of SI has periodic variations with maximums and minimums, the SI is tuned in with temperature to bring the maximum transmitted power at the same wavelength of the signal 1548.4 nm. We found experimentally that is possible to attenuate the ASE noise contribution around 1548.4 nm by comparing the input test signal versus the output signal at the output port of SI. In addition, we found the displacement of the transmittance with respect to temperature (Δλ/ΔT) and the period of the transmitted power (Δλ).

Its well known that there is a variety of techniques to obtain n-phase shifts in one shot, and most of them use diffractive elements, holographic ones or pixelated phase masks attached to a CCD camera, among others, to generate from 4 to 9 interferograms simultaneously; nevertheless, some of the components utilized in this arrangements are still expensive, and in order to reduce the cost of operations, we developed an alternative system that does not use diffractive elements, in this research we present a simultaneous phase-shifting interferometer based on polarizing coupled interferometers, this device can be measured the optical phase of non-birefringent microscopic phase samples, generating four interferograms in single capture of the ccd camera with relative phase shifts of π/2. In order to present the capabilities of the system, the results obtained for the phase measurement of Red Blood Cells (RBC) and non-birefringent transparent samples are presented.

Hand amputation is typically the result of a traumatic injury and/or disease related complications. The loss of a hand has a profound physical and psychological impact on the amputee. A high quality prosthesis can be facilitative in restoring an amputee’s body image. Traditional methods of manufacturing prostheses are time consuming and often lack the anatomical features to ensure the comfort of the user. The emergence of modern print manufacturing techniques can ensure a higher quality product with increased anatomical accuracy. In this study, we designed a print manufacturing process for myoelectric hand prosthetic. The process commenced with the use of a 3D scanner to obtain an anatomically accurate image of the non-amputated hand, of which a mirror image of the amputated hand was then generated. The resulting data was then transferred to a 3D printer. Individual fingers of the hand were print manufactured from a pliable material as separate components for the purpose of emphasizing the movement of the phalanges. By applying the above print manufacturing method we are confident that the customized prosthesis would contain the majority of the bodily features of the non-amputated hand. In turn, this method could also be applied for the construction of prostheses for other body limbs.

The objective of this study was to identify a material for a transfer system used in the packaging of gains for human consumption which is in compliance with the regulations established by Federal Commission for Protection Against Health Risks (COFEPRIS) of México.A static material analysis was performed testing different materials to determine the optimal plastic material for connecting the grain dispenser hopper mechanism to the bagging system. SolidWorks, a computer aided engineering software was implemented for finite-element analysis testing, testing the strength, displacement and safety of four Mexican food industry COFEPRIS compliant materials. The study revealed that the most suitable material for the connection mechanism is Polyamide commercially known as “Nylon” because of the material’s high-rigidity, low-friction and positive dimensional stability.

In the process of closing three-phase vacuum circuit breakers (VCBs), the collisions between the contacts in the vacuum interrupters cause the contacts to bounce. Consequently, repetition of make-and-break of the electrical circuit happens. If the duration of this phenomenon exceeds a certain time length, the surfaces of the contacts are damaged by the heat of the arcs between the contacts. This causes deterioration of the intrinsic functions of the VCB.The paper presents an experimental process to investigate this phenomenon using a 10 kV 40 kA VCB as an example. Since disconnection of the contacts in the closing process occurs when the magnitude of the reaction forces between the contacts falls below a certain level, we examined the following process to predict the bounce phenomenon. First, the time functions of the contacts’ collision forces were estimated using the frequency response functions of the structural system and the response vibrations of the structure measured in the closing process. Second, the reaction force functions between contacts were estimated using the frequency response functions and the collision forces. Next, the bounce duration was derived by evaluating these reaction forces. Finally, we investigated a method to decrease the duration.

Wood is one of the most useful and important natural materials with diverse applications in civil, architectural and constructional engineering. The stiffness of the wood depends on the fiber orientation, distribution of knot and percentage of latewood, etc. Japanese cedar (Cryptomeria japonica) was used to prepare the tensile test specimen in this paper to investigate the effects of fiber orientation on wood stiffness. Before performing the tensile test, surface image of the test specimen was captured and the image was analyzed by least squares method and digital image processing software of MATLAB to obtain the fiber orientation. Based on the obtained fiber orientation, finite element method (FEM) software package ANSYS was employed to calculate the strain distribution of the test specimen. Three-dimensional digital image correlation (3D-DIC) method was also used to verify the FEM results. The DIC software, VIC-3D, was used to analyze the surface deformation of the test specimen under tension. Strain distribution differences between the earlywood and latewood were investigated. With the integration of the digital image analysis technique, FEM and 3D-DIC method, the effective stiffness of the wood can be predicted and the reliability and safety of wood construction can be ensured.

The development of analytical system has been focused on two aspects, first in the design of large versatile and robust equipment where operation is performed in a controlled laboratory. The second aspect developed in parallel, is focused on miniaturization and automation of analytical systems that can be used in the place where the sample is taken and generate results in real time. In this work, an automated hydrodynamic system was implemented with miniaturized actuators to provide a micro-flow injection and auto-calibration. The micro-flow injection procedure was operated exploited the multicommutation technique for handling solutions. The auto-calibration was operated by a virtual instrument allowing the response control process in real time. Automated micro-flow injection was developed to perform calibration. The auto-calibration process, the precision and accuracy of the hydrodynamic system was evaluated by spectrophotometric determination of cobalt concentration. A linear response was observed from 0.1 to 3.0 mg L−1. The result was validated with a commercial instrument.

This paper presents the development of a polynomial equation of second degree which allows to predict the value of the stress concentration factor on a flat bar with two notches under to axial load for different rations r/L (notch radio/distance between notches) y W/L (bar width/distance between notches). To obtain the mentioned equation, one hundred simulations are carried out on finite element software to determine maximum stress on the bar and then the stress concentration factor is calculated. A regression analysis using the least square method is applied to fit the data to a quadratic polynomial equation which depends on the rations r/L y W/L. The equation obtained presents a correlation value R2 = 0.98, thus this equation represents reliably the obtained data. The results estimated by the proposed equation for stress concentration factor are compared with the results presented by other authors; a good matching among these approaches is obtained.

This article presents the virtual experimentation of the dynamics for diverse multipoint grasping mechanisms, similar to the anthropometric mechanism of a human hand, using a multibody dynamic simulator. These simulations will allow us to evaluate diverse mechanisms, for selecting the one with the best performance; that is the one that has the greater energy efficiency while presenting the most equal distribution of the force along the contact points.The result tests the implementation of a grasping mechanism, and a support mechanism that allows a kinematic synergy between all the links of the mechanism, providing an immediate adaptation to the object shapes held by a force distribution along the contact points, increasing the stability of the supported object.As another result, the mechanism also allows the transmission of force in a unidirectional way by means of a mechanical arrange in the support mechanism, which in turn allows undetermined interlocking resulting in greater energy efficiency because during this period there is no energy consumption by the actuator.

Distributed fiber sensors based on the frequency domain analysis of Rayleigh backscattered light are well established. They exhibit very good performance in both sensitivity and spatial resolution, but their application can be limited due to their cost and the complexity of the analysis. In this work we present a system based on coherent optical frequency domain reflectometry, used in Rayleigh distributed sensors, implemented with more readily available components and simplified analysis. A sensing fiber is prepared by printing uniformly spaced, ultra-low reflectivity fiber Bragg gratings of the same Bragg wavelength. When tuneable source light is introduced to the fiber the reflections from the gratings interfere with the reflection from the tip of the fiber. The gratings’ reflectivity varies randomly which produces a frequency domain trace that shares some of the properties of a Rayleigh spectral trace, but is significantly stronger. This removes the need for specialized detection equipment. These Bragg gratings act as reflectors and not as sensors per se. Use of a reference interferometer and signal processing algorithms make it possible to replace a high precision linearly tuneable laser with a standard tuneable laser as optical source.

A technique to represent object surface via NURBS and genetic algorithms is presented. In this technique, the surface is generated based on control points. Then, the control points and the weights are optimized via genetic algorithms to find the NURBS, which represents the object surface. The genetic algorithm is constructed through an objective function, which is deduced from the NURBS surface. This objective function is minimized by using the simulated binary crossover. The proposed genetic algorithm improves accuracy and speed of the NURBS surface representation. The contribution of the proposed method is elucidated by an evaluation based on model accuracy and speed of traditional genetic NURBS surface representation.

Polystyrene films were exposed to UV-B radiation during 2, 5Abstract, 7, 9 and 13 days, whose effects were evaluated by infrared spectroscopy, IR, with attenuated total reflectance, ATR. The infrared spectra of the films exposed to the UV-B radiation presented an increase in the absorbance in different bands and regions, like, the band at 2847–2975 cm−1, CH vibration, the region from the 3050–3150 cm−1, CH of the aromatic ring; this increasing in absorbance indicates that the polystyrene films are undergoing an oxidation reaction due to UV-B radiation; in the same way, the band at 1452 cm−1, CH₂ group, presents an increase in absorbance; while, the bands of 700 and 760 cm−1, aromatic ring, show a decrease. Therefore, using UV-B irradiation it is possible to change the molecular structures of polystyrene films.

This work deals with the dynamic analysis of a new design of trawl doors. The model is constrained to steady towing conditions with velocity constant, flat seabed and gear symmetry. The Ordinary Differential Equations (ODE) of the system includes the effects of the warp and the ropes in terms of external forces. In the mathematical model the influences of the hydrodynamic forces over the trawl doors are considers. This paper is mainly focus in show preliminary results of the mathematical model of a new design of trawl doors used to catch shrimp in the Mexican littoral by bottom trawls system. This result will be used in the future to validate the numerical model of the system with experimental results using a prototype of trawl doors designed in the laboratory of the institute.

This article describes a program developed in Matlab that simulates an Adaptive Optics system, which allows observing a graphically simulated wavefront to understand the main concepts of an Adaptive Optics system and the constraints that have to be presented in classical control algorithms. The program is based on: (a) Simulation of a wavefront Shack-Hartmann sensor as a detection system and the wavefront reconstruction using Zernike polynomials from the slopes of the wavefront and (b) Simulation of a deformable mirror as the wavefront correction. This was characterized using the so called influence functions and Zernike polynomials. The voltage vector needed for the deformation that adopts the correction mirror wavefront was also calculated. Our results were corroborated graphically by the reconstruction of the wavefront and the deformation of the deformable mirror.

In modern physiological research the focus has advanced from the mechanostat theory to the functional muscle-bone-unit, investigating the relationship between muscle and bone. A recent study yielded in vivo data on the deformation of the human tibia and an inverse FE algorithm, which was developed to calculate the muscle forces triggering these deformations. In this context an Artificial Muscles Biomechanical Rig (AMBR) was developed, in order to validate the methods used and obtain further data on the relationship of muscle forces and bone deformations. With AMBR the biomechanical behavior of the human tibia can be simulated, comparable to the FE simulation. It is a custom-made mechanical platform including pneumatic actuators combined with a control system to simulate the lower leg muscles. The specimen tested is a biomechanical replica of the tibia. For validation and verification with AMBR, tests focused on the accuracy and repeatability of data acquisition of the specimen deformation during force application by using a motion capture system. The rig was able to serve its purpose by validating the inverse FE algorithm. Its further applications might comprise of profounder studies on various mechanical effects of muscles on bones and create new biomechanical insights for prevention and rehabilitation.

The use of the laser technology in medicine has allowed us to expand the knowledge of the cell and its functions. In particular, flow cytometry is a sophisticated equipment, which can do a simultaneous multi-parametric analysis of the physical, and chemical properties of thousands of particles per second. Flow cytometry is routinely used in the diagnosis of health disorders, particularly blood cancers, but it has many other applications in basic research, clinical practice, and clinical trials. Given the extensive available information, flow cytometry was used to study the route by which transduce PKCζ leads the activation of GSK-3β, and the physiological significance of its accumulation in the nucleus.

In photovoltaic industry the research at solar cells is in continuous development from the innovation at organic molecules until efficient plastics new products have been presented recently, improving efficiencies and costs. In this work we prepared photovoltaic solar organic cells based on the work of J.L Maldonado et al., where the authors proposed an improvement of the solar cells when it is used fullerene-60 as doped material. We characterized the generated solar cells using the optical fringe projection technique and scanning electron microscope (SEM) imaging, the results gives us 40 μm, for the cells width; and an electric characterization measuring currents of 8 mA.

In this work we report a numerical simulation of a fiber Bragg sensor based on the Gires-Tournois Interferometer as a sensor. This sensor is useful for detection of the high harmonics in an induction electric motor. The high harmonics cause improper working of this type of motor. The sensor is calibrated for a range of ambient temperatures from 25 to 350 °C, but in this work we present a range from −25 to 30 °C.

In this paper a method for cleaning tantalum capacitors terminals, using the technique of selective ablation by pulsed laser is proposed. Such ablation is studied by the LIBS technique to characterize capacitors and determine the resin composition and possible contaminants adhered. In addition, OCT measurements are performed to recreate the damage done to the samples.

A procedure to polish the edges of glass microscope slides (corning 2947B) for integrated optics is presented in this paper. As usual, the procedure includes six steps: cut of glass substrates, assembly of the glass substrates over a plane surface (blocking), grinding, polishing, disassembly (unblocking) and cleaning. It is possible to fabricate waveguides before or after the polishing procedure. Finally, the outcomes of a practical application are shown. In our opinion, the manufacture of integrated optics devices will increase gradually.