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El proyecto consiste en dimensionar diferentes estructuras de pavimento flexible adaptando la metodología mecanístico-empírica a la práctica actual de diseño de pavimentos en Colombia, para poder determinar los módulos que están desarrollando los materiales granulares de base y sub-base en estas estructuras y a la vez establecer factores camión (factores de daño) para las estructuras evaluadas, que permitan establecer recomendaciones para garantizar que los diseños que se están realizando con metodologías convencionales sean más conservadores y consecuentes con el estado actual del conocimiento. The project consists of sizing different flexible pavement structures adapting the mechanistic-empirical methodology to the current practice of pavement design in Colombia, in order to determine the modules that are developing the granular base and sub-base materials in these structures and at the same time establish truck factors (damage factors) for the structures evaluated, which allow establishing recommendations to ensure that the designs that are being carried out with conventional methodologies are more conservative and consistent with the current state of knowledge. Ingeniero Civil Pregrado

Noise and whole-body vibration measurements were made in a Viking military vehicle to determine the variation that should be expected during repeat measures, the effect of speed (up to 60 km/h in 5 km/h increments), and during travel over different types of terrain (comprising concrete road, gravel track and rough cross-country). Measurements were made at various crew positions (including the driver and commander) in both the front and the rear cabs in the vehicles. Three translational axes of vibration were measured in each seat. Two speeds were investigated over road (35 km/h and 55–60 km/h) and gravel (20 km/h and 35 km/h) surfaces. The effect of varying speed of the vehicle on the measured noise and vibration magnitudes was also investigated. The highest sound pressure level (LAeq) of 104 dB(A) was measured at the commander’s standing position during travel over concrete road at 55 km/h. Higher noise levels occurred for a standing commander compared with when sitting on the seat. A maximum single axis frequency-weighted vibration magnitude of 1.0 m/s2 r.m.s. was measured on the driver’s seat during travel over track at 35 km/h. Higher vibration magnitudes occurred during travel over track compared with travel over road. Both noise and vibration exposure of crew within the Viking vehicle increased with increasing speed of the vehicle.

With solar tracking, it will become possible to generate more energy since the solar panel can maintain a perpendicular profile to the rays of the sun. Even though the initial cost of setting up the tracking system is considerably high, there are cheaper options that have been proposed over time. This research discuss the design and construction of a prototype for a solar tracking system that has a single axis of freedom. Light Dependent Resistors (LDRs) are used for sunlight detection. The control circuit is based on an ATMega328P microcontroller. It was programmed to detect sunlight via the LDRs before actuating the servo to position the solar panel. The solar panel is positioned where it is able to receive maximum light. As compared to other motors, the servo motors are able to maintain their torque at high speed. They are also more efficient with efficiencies in the range of 80-90%. Servos can supply roughly twice their rated torque for short periods. Through tracking, there will be increased exposure of the panel to the sun, making it have increased power output. The trackers can either be dual or single axis trackers. As a single tracking system is cheaper, less complex, and still achieves the required efficiency, so it was used.

The main problem in studying the feasibility of solar systems is the enormous gap between theory and experimental radiation intensity, so to get accurate results there is a need for studying energy production in the site of the system empirically. In this study, the energy production of both fixed PV panel system and the system with single-axis tracking were empirically evaluated in Medina, Saudi Arabia. The two systems had the same 270 Wp PV panel. The fixed system was tilted by 23.5 degrees, and the single-axis tracker was tilted by 26 degrees. Both systems had an azimuth angle of zero degrees. A closedloop three-points controller was used to control the tracker with 120 degrees rotation range. The two systems operated simultaneously in July, and the data were collected for 14 days. The empirical results showed that the tracker increased the generated energy by 48.5% during the testing period. As a comparing method, a modified ASHRAE model was used to estimate the increase in the panel's energy output with and without the single-axis tracker, and RMSE and MBE were calculated. It's been found that the experimental energy generation is 10%, 5% less than the estimation of the modified model for the fixed system and the tracking system, respectively. Finally, based on the analysis, it's been estimated that the singleaxis tracker will increase the generated energy by 22.5% yearly in Medina.

The article examines existing works considering the process of tearing of flax fibre, specifically fibrous matrix and linkages within it. In particular authors point out the necessity of taking into account the destruction of individual fibres during deformation and tearing process. The end result of this analysis is a multipart mechanical model allowing for various effects that may take place during the said process. This model is implemented in software and used to model the behaviour of several strands of fibre of varying quality. The results match the observed behaviour of actual samples with similar properties, which allows using the model presented to estimate the effect various properties of flax fibre have on its tensile strength.

Although some authors realized various measurement techniques and relevant standards in the experimental verification, the existing contributions still did not mention more complex automated workplaces with industrial robotic arm participation. To solve this, we provide a different view of the interconnection between individual devices (positioner, robot, etc.) controlled by third-party methods (Siemens products). Also, to obtain the necessary effectiveness, we tested and verified selected accuracy parameters for the participating device component (positioner). The proposed work tries to fulfill expectations for a precise welding technology (to ensure simultaneous movements of both the industrial robotic arm and positioner) to achieve higher quality and productivity. However, the components are from different manufacturers.

In this paper, a novel evacuated tube solar collector (ETSC) is first designed and built. Then, the impact of adding reflector, reflector plus single-axis sun tracker and reflector plus two-axis su...

Five-axis machining plays an important role in manufacturing by dint of its high efficiency and accuracy. While two rotation axes benefit the flexibility of machining, it also brings limitations and challenges. In order to further balance machining precision and efficiency, an improved feedrate scheduling method is presented considering geometric error and kinematic constraints for the Non Uniform Rational B-Spline (NURBS) interpolation in five-axis machining. A simplification method is proposed to calculate the geometric error which describes the deviation between the ideal tool path and the real tool path induced by the non-linear movement. A linear relation between geometric error and feedrate is built to limit the feedrate. The constraints determined by single axis kinematic performance and tangential kinematic performance are also considered. Under these constraints, a constrained feedrate profile is determined. Aiming to get more constant feedrate in the difficult-to-machine areas, this work proposes a scheduling method which combines morphological filtering and S-shape acceleration/deceleration (acc/dec) mode. Simulations and experiments are performed to compare the proposed feedrate scheduling method with two previous feedrate scheduling method and the results prove that the proposed feedrate scheduling method is reliable and effective.

The algorithm of the turn of the spacecraft from an initial arbitrary angular position at an arbitrary angular rate to a solar-oriented attitude is investigated. Minimum essential equipment of the motion control system required for the purpose of ensuring maintenance of solar orientation is defined: a solar sensor, a single-axis angular-rate sensor, low-thrust liquid rocket engines. A solution of the problem of defining the spacecraft angular rate vector by the measurements of the deviation of the optical axis of the solar sensor from the sun vector and the single-axis angular-rate sensor is presented. The conditions under which control action on the rocket engines for the purpose of changing the value of the angular-rate vector for the Sun to get into the field of viewing of the solar sensor or for the spacecraft stabilization are defined. Mathematical modeling of the spacecraft attitude control system with the unknown initial state vector of motion is carried out. The results of mathematical modeling confirmed the efficiency of the proposed algorithm in terms of reducing propellant fuel consumption and high-speed performance. In comparison with the known methods of solving the problem of reducing angular speed (a lengthy process with the use of a magnetic system or a fast process with the use of a three-axis angular-rate sensor and rocket engines) the duration of the process of reducing angular speeds is the same as in normal operation, however, at the same time the problem of bringing spacecraft into the solar oriented attitude is solved.

This is an experimental study. As current posterior-substituting (PS) total knee arthroplasties have been reported to incompletely restore intrinsic joint biomechanics of the healthy knee, the recently designed single axis radius PS knee system was introduced to increase posterior femoral translation and promote ligament isometry. As there is a paucity of data available regarding its ability to replicate healthy knee biomechanics, this study aimed to assess joint and articular contact kinematics as well as ligament isometry of the contemporary single axis radius PS knee system. Implant kinematics were measured from 11 cadaveric knees using an in vitro robotic testing system. In addition, medial collateral ligament (MCL) and lateral collateral ligament (LCL) forces were quantified under simulated functional loads during knee flexion for the contemporary PS knee system. Posterior femoral translation between the intact knee and the single axis radius PS knee system differed significantly (p

Process monitoring and in-process control in milling requires reliable sensor data from rotating tooling systems. Vibration sensing by an instrumented tool holder close to the cutting zone has been proven useful in mitigating chatter. A model is presented that enables the interpretation of vibration data of the rotating sensor and tool system to identify edge chipping. Thus, data from a single axis accelerometer can be interpreted to identify the existence of edge chipping on one of multiple cutting edges. The classification of observed effects is derived from methods developed for machine learning, which is demonstrated and evaluated by experimental results.

With over 30 million people worldwide requiring assistive devices, there is a great need for low-cost and high-performance prosthetic technologies that can enable kinematics close to able-bodied gait. Low-income users of prosthetic knees in the developing world repeatedly report the need for n inconspicuous gait to mitigate the severe socioeconomic discrimination associated with disability. However, passive prosthetic knees designed for these users have primarily focused on stability and affordability, often at the cost of the high biomechanical performance that is required to replicate able-bodied kinematics. In this study, we present the design and preliminary testing of two distinct mechanism modules that are novel for passive prosthetic knee applications: the stability module and the damping module. These mechanisms are designed to enable users of single-axis, passive prosthetic knees to walk with close to able-bodied kinematics on level-ground, specifically during the transition from the stance phase to the swing phase of the gait cycle. The stability module was implemented with a latch mounted on a virtual axis of a four-bar linkage, which can be engaged during early stance for stability and disengaged during late stance to initiate knee flexion. The damping module was implemented with a concentric stack of stationary and rotating pairs of plates that shear thin films of high-viscosity silicone oil. The goal of the resulting first-order damping torque was to achieve smooth flexion of the prosthetic knee within the able-bodied gait range (64 ± 6 deg). For preliminary user-centric validation, a prototype prosthetic knee with the stability module and two different dampers (with varying damping coefficients) was tested on a single subject with above-knee amputation in India. The stability module enabled smooth transition from stance to swing with timely initiation of knee flexion. The dampers also performed satisfactorily, as the increase in the damping coefficient was found to decrease the peak knee flexion angle during swing. The applications of the mechanisms presented in this article could significantly improve the kinematic performance of low-cost, passive prosthetic knees.

In the past decade, flexible physical sensors have attracted great attention due to their wide applications in many emerging areas including health-monitoring, human-machine interfaces, smart robots, and entertainment. However, conventional sensors are typically designed to respond to a specific stimulus or a deformation along only one single axis, while directional tracking and accurate monitoring of complex multi-axis stimuli is more critical in practical applications. Multidimensional sensors with distinguishable signals for simultaneous detection of complex postures and movements in multiple directions are highly demanded for the development of wearable electronics. Recently, many efforts have been devoted to the design and fabrication of multidimensional sensors that are capable of distinguishing stimuli from different directions accurately. Benefiting from their unique decoupling mechanisms, anisotropic architectures have been proved to be promising structures for multidimensional sensing. This review summarizes the present state and advances of the design and preparation strategies for fabricating multidimensional sensors based on anisotropic conducting networks. The fabrication strategies of different anisotropic structures, the working mechanism of various types of multidimensional sensing and their corresponding unique applications are presented and discussed. The potential challenges faced by multidimensional sensors are revealed to provide an insightful outlook for the future development.

Las sondas magneticas (tambien conocidas como bobinas de punto B) son dispositivos electromagneticos utilizados para medir la variacion del campo magnetico en muchos rangos de frecuencia. La frecuencia del campo magnetico a medir se relaciona directamente con el metodo elegido para realizar la calibracion de la bobina de punto B. Este trabajo presenta una calibracion de bobina de punto B en un rango de frecuencia de 6.16 kHz a 36.63 kHz. Un inductor L (bobina de Helmholtz) se conecta en paralelo con un banco de condensadores variable C var para formar un circuito resonante LC var acoplado. El circuito LC var se alimenta con un oscilador de medio puente. La capacidad C var varia hasta que el circuito se encuentra en estado resonante a diferentes frecuencias. El circuito resonante produce oscilaciones sinusoidales en la frecuencia de banda mencionada. La sensibilidad se calcula utilizando el voltaje V out de la bobina de punto B y el voltaje V H medido desde las terminales de Helmholtz

This work presents a study in the theoretical and experimental performance of PV cells and tracking surfaces using the isotropic and anisotropic (HDKR) models’ simulations for single and dual axis ...