Storage Circuitry Research Articles

Numerical modeling and analysis of self-powered synchronous switching circuit for the study of transient charging behavior of a vibration energy harvester

Enhancement of power harvesting efficiency in piezoelectric energy harvesters through a non-linear electronic interfacing circuit is a well-established research area with potentially significant implications on piezoelectric energy harvesting efficiency. Among various types of synchronous switching circuits available in the literature, a self-powered electronic breaker is widely studied. Nonetheless, due to the interdisciplinary nature of this field, many of the currently available analyses tend to overlook and/or simplify certain aspects of this dynamical system. As a result, a comprehensive model of the system that considers accurate coupling effect of the interfacing and storage circuitry, as well as detailed analysis of the system during transient capacitor charging and energy harvesting operation is still missing. This paper thus aims at the problem of modeling a piezoelectric energy harvester with an Synchronized Switch Harvesting on Inductor (SSHI) circuit and a self-powered electronic breaker. A semi-analytic numerical model is proposed that is able to accurately simulate the operation of the system during transient process of charging an external storage device. Experiment validation confirms the accuracy of the proposed model considering the exact electromechanical coupling effect and transient charging dynamics with SSHI circuit and the model’s performance in estimating system transient behavior. Furthermore, a systematic parametric study is performed in order to analyze the effects of different system components on the energy harvesting efficiency during transient operation.

Head-shaking tilt suppression: a clinical test to discern central from peripheral causes of vertigo.

Tilt suppression refers to both tilting the head away from an Earth vertical axis and a reduction of an induced horizontal nystagmus. This phenomenon of reducing an induced horizontal nystagmus involves a circuitry of neurons within the vestibular nuclei and the cerebellum (collectively referred to as velocity storage) and signals from the otolith end organs. Lesions involving this circuitry can disrupt tilt suppression of induced horizontal nystagmus. We investigated the clinical value of combining the horizontal head-shaking nystagmus test with tilt suppression in 28 patients with unilateral peripheral vestibular hypofunction and 11 patients with lesions affecting the central nervous system. Each of the subjects with peripheral vestibular lesions generated an appropriately directed horizontal nystagmus after head shaking that then suppressed the induced angular slow phase velocity on average 52±17.6% following tilt down of the head. In contrast, patients with central lesions had very little ability to suppress post-head-shaking nystagmus (mean 3.4±56%). We recommend tilting the head after head shaking as a useful clinical test to assist in the differential diagnosis of vertiginous patients. In the case of unilateral peripheral vestibular hypofunction, head tilt suppresses the induced nystagmus via influence of the otolith organ. In the case of central pathology, the inability to suppress the nystagmus is from lesions impairing the otolith mediation on the velocity storage circuitry.

Assumed-modes modeling of piezoelectric energy harvesters: Euler–Bernoulli, Rayleigh, and Timoshenko models with axial deformations

A generalized framework is presented for the electromechanical modeling of base-excited piezoelectric energy harvesters with symmetric and unsymmetric laminates. The electromechanical derivations are given using the assumed-modes method under the Euler–Bernoulli, Rayleigh, and Timoshenko beam assumptions in three sections. The formulations account for an independent axial displacement variable and its electromechanical coupling in all cases. Comparisons are provided against the analytical solution for symmetric laminates and convergence of the assumed-modes solution to the analytical solution with increasing number of modes is shown. Model validations are also presented by comparing the electromechanical frequency response functions derived herein with the experimentally obtained ones in the absence and presence of a tip mass attachment. A discussion is provided for combination of the assumed-modes solution with nonlinear energy harvesting and storage circuitry. The electromechanical assumed-modes formulations can be used for modeling of piezoelectric energy harvesters with moderate thickness as well as those with unsymmetric laminates and varying geometry in the axial direction.

Nonpersistent Errors Optimization in Spin-MOS Logic and Storage Circuitry

By combining the flexibility of MOS logic and the nonvolatility of spintronic devices, Spin-MOS logic and storage circuitries offer a promising approach to implement a highly integrated, power-efficient, and nonvolatile computing and storage systems. Besides the persistent errors due to process variations, however, the functional correctness of Spin-MOS circuitries suffers from additional nonpersistent error that incurred by the randomness of spintronic device operations, i.e., thermal fluctuations. In this work, we quantitatively investigate the impacts of the thermal fluctuations on the operations of two typical Spin-MOS circuitries: one transistor and one magnetic tunnel junction (1T1J) spin-transfer torque random access memory (STT-RAM) cell and a nonvolatile flip-flop design. The possible design techniques to reduce thermal incurred nonpersistent error rate are also discussed. Our experimental results show that the optimization of nonpersistent and persistent errors are closely entangled with each other and should be conducted from both circuit design and magnetic device engineering perspectives simultaneously.

FPGA-based real-time optical-flow system

We describe a pipelined optical-flow processing system that works as a virtual motion sensor. It is based on a field-programmable gate array (FPGA) device enabling the easy change of configuring parameters to adapt the sensor to different speeds, light conditions and other environmental factors. We refer to it as a "virtual sensor" because it consists of a conventional camera as front-end supported by an FPGA processing device, which embeds the frame grabber, optical-flow algorithm implementation, output module, and some configuration and storage circuitry. To the best of our knowledge, this is the first study that presents a fully stand-alone optical-flow processing system to include measurements of the platform performance in terms of accuracy and speed.

Subpixel motion computing architecture

A pipelined optical-flow processing system that works as a virtual motion sensor has been described. It is based on a field programmable gate array (FPGA) device enabling the easy change of configuring parameters to adapt the sensor to different speeds, light conditions and other environmental factors. It is referred to as a 'virtual sensor' because it consists of a conven- tional camera as front-end supported by an FPGA processing device, which embeds the frame grabber, optical-flow algorithm implementation, output module and some configuration and storage circuitry. This is the first fully stand-alone working optical-flow processing system to include both accuracy and speed of measurement of the platform performance. The customisability of the system for different hardware resources and platforms has also been discussed, showing the resources and performance for a stand-alone board and a PCI co-processing board. Optical flow computation consists in extracting a dense velocity field from an image sequence assuming that inten- sity is conserved during displacement. This result may then be used for other applications such as 3-D reconstruction, time interpolation of image sequences, video compression, segmentation from motion, tracking, robot navigation, time-to-collision estimation and so on. The technical problem with estimating the motion of objects in 3-D is that, in the image formation process, because of the perspec- tive projection of the 3-D world onto the 2-D image plane, some of the information is lost. There are several ways of recovering the 3-D information from 2-D images using various cues. These cues are motion, binocular stereopsis, texture, shading and contour. In this paper, we will describe the implementation of a real-time motion flow system, leaving the potential applications for future studies. Optical-flow algorithms have been widely described in the literature. Some authors have addressed a comparative study of the accuracy of different approaches with synthetic sequences (1). Their evaluation using real-life sequences is difficult to address because the real optical flow of such sequences is unknown. We have focused on a classical gradient model based on Lucas and Kanade's (L & K) approach (1, 2). Several authors have emphasised the satis- factory trade-off between accuracy and efficiency in this model, which is an important factor when deciding which model is most suitable to use as a real-time processing system. For a comparative study (1), the L & K algorithm provides very accurate results, added to which, other authors specifically evaluating the efficiency against accu- racy trade-off of different optical-flow approaches (3) also regard the L&K model as being quite efficient. Finally,

Current Limiting Protector for Low Voltage, High Current Applications

ABSTRACTA pyrotechnic current limiting interrupter (CLI) has been developed for use in high current, 60‐Hz, 480‐volt, 3‐phase electrical bus circuits. The interrupter design combines a high continuous current (4800 A rms) rating with a high current (210 kA rms sym.) interruption capability. Its electrical power loss is low and its mechanical construction uses no complex moving mechanisms. The CLI is used with a current sensor, electronic logic, and energy storage circuitry. The current sensor continuously monitors the current through the CLI and provides input to logic circuits which analyze and determine the validity of the fault condition. Both the fault current magnitude and rate of current increase are used in combination to make the decision when to activate the CLI. Using stored electrical energy, a detonator is activated causing an explosive cord to generate shock waves sufficient to cut the current carrying conductors. Detection and initiation of the interruption process occurs within 1/4 cycle for a symmetrical fault and within 1/2 cycle for an asymmetrical fault. The first peak in the fault current is limited to the first half cycle.

A rapid, flexible, parallel-access, heca-bit reading and storage scheme

A paper tape data-handling system is described which can present 288 bits of information simultaneously; each bit having its own isolated output. The system utilizes a fast single-line paper tape reader, storage circuitry and circuitry to control the entry into storage. The rate of changing from one block of bits to a new block is 200 msec; this means that 5 blocks of information can be scanned per second. Aside from the speed of entry, the storage capacity can easily be increased or decreased depending on the need. The feasibility and the reliability of this system rely on the characteristics of a solid state ring counter which can handle load requirements without buffer circuitry and whose cost and size are much less than similar gating devices. The authors describe, a reader system which is felt to be the preferred alternative to the block reader in preprogrammed data situations.