Digital and Analog Resistive Switching Behavior in Si-NCs Embedded in a Si/SiO2 Multilayer Structure for Neuromorphic Systems.

In this work, we report the digital and analog resistive-switching (RS) characteristics in a memristor based on silicon nanocrystals (Si-NCs) integrated into a complementary metal-oxide-semiconductor (MOS) structure. Si-NCs with a diameter of 5.48 ± 1.24 nm embedded in a SiO2/Si-NCs/SiO2 multilayer structure acts as an RS layer. These devices exhibit bipolar RS with an intermediate resistance step during SET and RESET processes, which is believed to lie in the Si-NCs layer acting as charge-trapping nodes. The endurance studies of about 70 DC cycles indicate an ON/OFF ratio of ~106 and a retention time larger than 104 s. Long-term potentiation (LTP, -2 V) and long-term depression (LTD, +4 V) are obtained by applying consecutive identical pulse voltages of 150 ms duration. The current value gradually increases/decreases (LTP/LTD) as the pulse number increases. Three consecutive identical pulses of -2 V/150 ms (LTP) separated by 5 and 15 min show that the last current value obtained at the end of each pulse train is kept, confirming an analog RS behavior. These characteristics provide a possible way to mimic biological synapse functions for applications in neuromorphic computing in Si-NCs-based CMOS structures.

A Novel Collision-Free Homotopy Path Planning for Planar Robotic Arms.

Achieving the smart motion of any autonomous or semi-autonomous robot requires an efficient algorithm to determine a feasible collision-free path. In this paper, a novel collision-free path homotopy-based path-planning algorithm applied to planar robotic arms is presented. The algorithm utilizes homotopy continuation methods (HCMs) to solve the non-linear algebraic equations system (NAES) that models the robot's workspace. The method was validated with three case studies with robotic arms in different configurations. For the first case, a robot arm with three links must enter a narrow corridor with two obstacles. For the second case, a six-link robot arm with a gripper is required to take an object inside a narrow corridor with two obstacles. For the third case, a twenty-link arm must take an object inside a maze-like environment. These case studies validated, by simulation, the versatility and capacity of the proposed path-planning algorithm. The results show that the CPU time is dozens of milliseconds with a memory consumption less than 4.5 kB for the first two cases. For the third case, the CPU time is around 2.7 s and the memory consumption around 18 kB. Finally, the method's performance was further validated using the industrial robot arm CRS CataLyst-5 by Thermo Electron.

Multiple-Target Homotopic Quasi-Complete Path Planning Method for Mobile Robot Using a Piecewise Linear Approach.

The ability to plan a multiple-target path that goes through places considered important is desirable for autonomous mobile robots that perform tasks in industrial environments. This characteristic is necessary for inspection robots that monitor the critical conditions of sectors in thermal, nuclear, and hydropower plants. This ability is also useful for applications such as service at home, victim rescue, museum guidance, land mine detection, and so forth. Multiple-target collision-free path planning is a topic that has not been very studied because of the complexity that it implies. Usually, this issue is left in second place because, commonly, it is solved by segmentation using the point-to-point strategy. Nevertheless, this approach exhibits a poor performance, in terms of path length, due to unnecessary turnings and redundant segments present in the found path. In this paper, a multiple-target method based on homotopy continuation capable to calculate a collision-free path in a single execution for complex environments is presented. This method exhibits a better performance, both in speed and efficiency, and robustness compared to the original Homotopic Path Planning Method (HPPM). Among the new schemes that improve their performance are the Double Spherical Tracking (DST), the dummy obstacle scheme, and a systematic criterion to a selection of repulsion parameter. The case studies show its effectiveness to find a solution path for office-like environments in just a few milliseconds, even if they have narrow corridors and hundreds of obstacles. Additionally, a comparison between the proposed method and sampling-based planning algorithms (SBP) with the best performance is presented. Furthermore, the results of case studies show that the proposed method exhibits a better performance than SBP algorithms for execution time, memory, and in some cases path length metrics. Finally, to validate the feasibility of the paths calculated by the proposed planner; two simulations using the pure-pursuit controlled and differential drive robot model contained in the Robotics System Toolbox of MATLAB are presented.

A Monte Carlo study of the electrical double layer of a shape-asymmetric electrolyte around a spherical colloid.

In this paper, we present a Monte Carlo simulation study on the structure of the electrical double layer around a spherical colloid surrounded by a binary electrolyte composed of spherical and non-spherical ions. Results are provided for the radial distribution functions between the colloid and ions, the orientation correlations between the colloid and non-spherical particles, and the integrated charge. Work is reported mainly for non-spherical particles modeled as spherocylinders, although a particular comparison is made between spherocylindrical particles and dimers. For the conditions investigated here, spherocylinders and dimers produce essentially the same structural information. Additionally, it is shown that spherocylinders mostly orient tangentially to the colloid at its surface; this preferred orientation disappears for larger distances. We also evidence that, near the colloid, the integrated charge attenuates monotonically when the macroparticle is highly charged, whereas for intermediate and low charged states of the colloid, the integrated charge can display charge reversal, overcharging, or both, with magnitudes that are sensitive to the salt concentration and to the localization of charge inside the spherocylinders.

Nonlinearities distribution Laplace transform-homotopy perturbation method.

This article proposes non-linearities distribution Laplace transform-homotopy perturbation method (NDLT-HPM) to find approximate solutions for linear and nonlinear differential equations with finite boundary conditions. We will see that the method is particularly relevant in case of equations with nonhomogeneous non-polynomial terms. Comparing figures between approximate and exact solutions we show the effectiveness of the proposed method.

A handy approximate solution for a squeezing flow between two infinite plates by using of Laplace transform-homotopy perturbation method.

This article proposes Laplace Transform Homotopy Perturbation Method (LT-HPM) to find an approximate solution for the problem of an axisymmetric Newtonian fluid squeezed between two large parallel plates. After comparing figures between approximate and exact solutions, we will see that the proposed solutions besides of handy, are highly accurate and therefore LT-HPM is extremely efficient.

A handy approximation for a mediated bioelectrocatalysis process, related to Michaelis-Menten equation.

In this article, Perturbation Method (PM) is employed to obtain a handy approximate solution to the steady state nonlinear reaction diffusion equation containing a nonlinear term related to Michaelis-Menten of the enzymatic reaction. Comparing graphics between the approximate and exact solutions, it will be shown that the PM method is quite efficient.

Comportamiento de la polineuropatía epidémica en un municipio / Development of epidemic polyneuropathy in a municility

Resumen: Se realiza un estudio de carácter explorativo descriptivo en el período del 1ro. de enero de 1993 al 1ro. de enero de 1997 (4 años) en la población correspondiente al municipio Lajas de la provincia Cienfuegos de 81 pacientes afectados por polineuropatía epidémica, los cuales se mantuvieron bajo seguimiento por el médico y la enfermera de la familia. Los enfermos fueron entrevistados, examinados, y se aplicó un formulario para la obtención de datos de interés como sexo, edad, raza, forma clínica, hábitos tóxicos, síntomas, signos y secuelas. Se comprueba el predominio del sexo femenino (66,6 porciento) y los grupos etáreos más afectados fueron del 25 a 44 y el de 45 a 64 años, el 44,5 porciento presentó forma clínica periférica y el 32 porciento óptica. El estrés fue un factor asociado en el 64,2 porciento, la debilidad de miembros inferiores y la disminución de la agudeza visual fueron los síntomas más frecuentes y los trastornos de sensibilidad, el signo más señalado; predominó la evolución favorable y los enfermos con secuelas se relacionaron con tener hábitos tóxicos. Se realiza test de significación estadística chi cuadrado y los principales resultados se expresan en tablas(AU)

Comportamiento de la polineuropatía epidémica en un municipio / Development of epidemic polyneuropathy in a municility

Resumen: Se realiza un estudio de carácter explorativo descriptivo en el período del 1ro. de enero de 1993 al 1ro. de enero de 1997 (4 años) en la población correspondiente al municipio Lajas de la provincia Cienfuegos de 81 pacientes afectados por polineuropatía epidémica, los cuales se mantuvieron bajo seguimiento por el médico y la enfermera de la familia. Los enfermos fueron entrevistados, examinados, y se aplicó un formulario para la obtención de datos de interés como sexo, edad, raza, forma clínica, hábitos tóxicos, síntomas, signos y secuelas. Se comprueba el predominio del sexo femenino (66,6 porciento) y los grupos etáreos más afectados fueron del 25 a 44 y el de 45 a 64 años, el 44,5 porciento presentó forma clínica periférica y el 32 porciento óptica. El estrés fue un factor asociado en el 64,2 porciento, la debilidad de miembros inferiores y la disminución de la agudeza visual fueron los síntomas más frecuentes y los trastornos de sensibilidad, el signo más señalado; predominó la evolución favorable y los enfermos con secuelas se relacionaron con tener hábitos tóxicos. Se realiza test de significación estadística chi cuadrado y los principales resultados se expresan en tablas