A moving-actuator type electromechanical total artificial heart. I.Linear type and mock circulation experiments

A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless dc motor inside of a rolling-cylinder, two arc-shaped pusher-plates and two polyurethane sacs. The moving-actuator type electromechanical pump has structural advantages of small size and light weight, as compared to other reported motor-driven pumps with fixed-actuator mechanisms. The results of the mock circulation tests are reported in this paper with a cardiac output of 9 L/min at an aortic pressure of 120 mmHg and a heart rate of 120 bpm. The fulfillment of the basic control requirements of the artificial heart was also confirmed, i.e., preload sensitive and afterload insensitive cardiac output response and balanced right and left ventricular outputs.     

Development of a microcontroller-based automatic control system forthe electrohydraulic total artificial heart

An automatic physiological control system for the actively filled, alternately pumped ventricles of the volumetrically coupled, electrohydraulic total artificial heart (EHTAH) was developed for long-term use. The automatic control system must ensure that the device: (1) maintains a physiological response of cardiac output, (2) compensates for any nonphysiological condition, and (3) is stable, reliable, and operates at a high power efficiency. The developed automatic control system met these requirements both in vitro, in week-long continuous mock circulation tests, and in vivo, in acute open-chested animals (calves). Satisfactory results were also obtained in a series of chronic animal experiments, including 21 days of continuous operation of the fully automatic control mode, and 138 days of operation in a manual mode, in a 159-day calf implant     

The electrostrictor—A new type of electromechanical semiconductor oscillator

An investigation is carried out of unexpected electrical oscillations generated across germanium crystals which are subjected to strong electric fields; the latter are obtained by the application of a current pulse through a small area metallic electrode. The oscillations are found to be of electromechanical nature; i.e., it is shown that the electrical oscillations are accompanied with mechanical oscillations of the same frequency and, furthermore, that the latter have a definite phase relation with the former. The frequency of oscillation is identified as the mechanical natural frequency of vibration of the crystal-electrode combination. The electromechanical coupling in germanium is found to be due to a large electrostrictive property of this crystal. The electro-mechanical regenerative path responsible for the generation of oscillation is postulated to be due to the elastroresistance effect in germanium. Finally an electromechanical equivalent circuit for this novel device, called henceforth the electrostrictor, is derived predicting most of its experimentally observed characteristics.     

Experimental validation of the linear drive train for a total artificial heart system

In industrialized countries cardiovascular diseases are the major cause of death. Beside heart transplants, which are a limited option due to the limited number of available human donor hearts, Total Artificial Hearts (TAHs) are the only therapy available for some patients with terminal heart diseases. For various reasons a total implantable artificial heart is desirable, but also sets restrictions in terms of weight and dimensions due to the limited space in the human thorax. Therefore a precise requirement profile is needed for the drive design to provide sufficient force for the blood pump and to avoid oversizing of the drive and to prevent blood damage by overheating.     

An electromechanical model of the heart for image analysis and simulation

This paper presents a new three-dimensional electromechanical model of the two cardiac ventricles designed both for the simulation of their electrical and mechanical activity, and for the segmentation of time series of medical images. First, we present the volumetric biomechanical models built. Then the transmembrane potential propagation is simulated, based on FitzHugh-Nagumo reaction-diffusion equations. The myocardium contraction is modeled through a constitutive law including an electromechanical coupling. Simulation of a cardiac cycle, with boundary conditions representing blood pressure and volume constraints, leads to the correct estimation of global and local parameters of the cardiac function. This model enables the introduction of pathologies and the simulation of electrophysiology interventions. Moreover, it can be used for cardiac image analysis. A new proactive deformable model of the heart is introduced to segment the two ventricles in time series of cardiac images. Preliminary results indicate that this proactive model, which integrates a priori knowledge on the cardiac anatomy and on its dynamical behavior, can improve the accuracy and robustness of the extraction of functional parameters from cardiac images even in the presence of noisy or sparse data. Such a model also allows the simulation of cardiovascular pathologies in order to test therapy strategies and to plan interventions.     

一种新型混沌系统及其电路实验的研究

通过构造只含一个参数的分段函数,研究一种新型混沌系统,其主要特征是随着参数的变化,系统可产生单层双螺旋,三层双螺旋,双层双螺旋,三层单螺旋,双层单螺旋,单层单螺旋六种不同的混沌吸引子,其中三层双螺旋,三层单螺旋是本电路实验中所发现的两类新的混沌吸引子,并分析该混沌系统随着参数变化的分叉图,最大李雅普诺夫指数谱以及三层双螺旋和三层单螺旋功率谱,最后进行该新型混沌系统的电路实验研究,给出理论分析和实验结果.     

An intelligent remote monitoring system for artificial heart.

A web-based database system for intelligent remote monitoring of an artificial heart has been developed. It is important for patients with an artificial heart implant to be discharged from the hospital after an appropriate stabilization period for better recovery and quality of life. Reliable continuous remote monitoring systems for these patients with life support devices are gaining practical meaning. The authors have developed a remote monitoring system for this purpose that consists of a portable/desktop monitoring terminal, a database for continuous recording of patient and device status, a web-based data access system with which clinicians can access real-time patient and device status data and past history data, and an intelligent diagnosis algorithm module that noninvasively estimates blood pump output and makes automatic classification of the device status. The system has been tested with data generation emulators installed on remote sites for simulation study, and in two cases of animal experiments conducted at remote facilities. The system showed acceptable functionality and reliability. The intelligence algorithm also showed acceptable practicality in an application to animal experiment data.     

Morphological estimation of total number of influenza A type virion spikes.

When purified and stored influenza A type virions were observed by the negative staining method in electron microscopy, we found disintegrated virions associated with a population of dispersed but clustered spikes. The total spike numbers of the clusters were morphologically counted, and their peak number (about 200) was consistent with the spike number measured by the molecular biology method, described in the other report.     

A note on type II convolutional codes

The result of a search for the world's second type II (doubly-even and self-dual) convolutional code is reported. A rate R=4/8, 16-state, time-invariant, convolutional code with free distance d_free=8 was found to be type II. The initial part of its weight spectrum is better than that of the Golay convolutional code (GCC). Generator matrices and path weight enumerators for some other type II convolutional codes are given. By the “wrap-around” technique tail-biting versions of (32, 18, 8) Type II block codes are constructed     

On the application and design of artificial neural networks formotor fault detection. II

For part I see ibid., vol.40, no.2, p.181-8 (1993). Some neural network design considerations, such as network performance, network implementation, size of training data set, assignment of training parameter values, and stopping criteria, are discussed. A fuzzy logic approach to configuring the network structure is presented, to automate the network design. Successful results are obtained from using artificial neural networks (ANNs) on motor fault detection and fuzzy logic in the network configuration design. It is concluded that these emerging technologies are promising for future widespread industrial usage     

Conductivity image reconstruction from defective data in MREIT: numerical simulation and animal experiment

Magnetic resonance electrical impedance tomography (MREIT) is designed to produce high resolution conductivity images of an electrically conducting subject by injecting current and measuring the longitudinal component, Bz, of the induced magnetic flux density B = (Bx, By, Bz). In MREIT, accurate measurements of Bz are essential in producing correct conductivity images. However, the measured Bz data may contain fundamental defects in local regions where MR magnitude image data are small. These defective Bz data result in completely wrong conductivity values there and also affect the overall accuracy of reconstructed conductivity images. Hence, these defects should be appropriately recovered in order to carry out any MREIT image reconstruction algorithm. This paper proposes a new method of recovering Bz data in defective regions based on its physical properties and neighboring information of Bz. The technique will be indispensable for conductivity imaging in MREIT from animal or human subjects including defective regions such as lungs, bones, and any gas-filled internal organs.     

A new type of artificial larynx using a PZT ceramics vibrator as asound source

Various speech production substitutes which aim to reconstruct speech functions have been developed and used practically, for vocalization-handicapped persons. However, current speech production substitutes have problems, and it is hoped that perfect speech production substitutes are developed. We pay attention to a PZT ceramics vibrator as a sound source of an artificial larynx. We try to produce the artificial larynx which uses a PZT ceramics vibrator, and we evaluate the performance. The power spectrum of the produced artificial larynx user's voice is similar to that of a nonhandicapped person's voice. The vocalized sound of the produced artificial larynx user shows good characteristics at formant frequency, which is important for vowel discrimination. Based on the result of listening estimation, this voice has good clarity. We hope that the proposed artificial larynx will be widely used in the future     

Identification of spinal deformity classification with total curvature analysis and artificial neural network

In this paper, a multilayer feed-forward, back-propagation (MLFF/BP) artificial neural network (ANN) was implemented to identify the classification patterns of the scoliosis spinal deformity. At the first step, the simplified 3-D spine model was constructed based on the coronal and sagittal X-ray images. The features of the central axis curve of the spinal deformity patterns in 3-D space were extracted by the total curvature analysis. The discrete form of the total curvature, including the curvature and the torsion of the central axis of the simplified 3-D spine model was derived from the difference quotients. The total curvature values of 17 vertebrae from the first thoracic to the fifth lumbar spine formed a Euclidean space of 17 dimensions. The King classification model was tested on this MLFF/BP ANN identification system. The 17 total curvature values were presented to the input layer of MLFF/BP ANN. In the output layer there were five neurons representing five King classification types. A total of 37 spinal deformity patterns from scoliosis patients were selected. These 37 patterns were divided into two groups. The training group had 25 patterns and testing group had 12 patterns. The 25-pattern training group was further divided into five subsets. Based on the definition of King classification system, each subset contained all five King types. The network training was conducted on these five subsets by the hold-out method, one of cross-validation variants, and the early stop method. In each one of the five cross-validation sessions, four subsets were alternatively used for estimation learning and one subset left was used for validation learning. Final network testing was conducted with remaining 12 patterns in testing group after the MLFF/BP ANN was trained by all five subsets in training group. The performance of the neural network was evaluated by comparing between two network topologies, one with one hidden layer and another with two hidden layers. The results are shown in three tables. The first table shows network errors in estimation learning and the second table shows identification rates in validation learning. The network errors and identification rates in the last round of network training and testing are shown in the third table. Each table has a comparison for both one hidden layer and two hidden layer networks.     

Technologies and applications of silicon-based micro-optical electromechanical systems: A brief review

Micro-optical electromechanical systems (MOEMS) combine the merits of micro-electromechanical systems (MEMS) and micro-optics to enable unique optical functions for a wide range of advanced applications. Using simple external electromechanical control methods, such as electrostatic, magnetic or thermal effects, Si-based MOEMS can achieve precise dynamic optical modulation. In this paper, we will briefly review the technologies and applications of Si-based MOEMS. Their basic working principles, advantages, general materials and micromachining fabrication technologies are introduced concisely, followed by research progress of advanced Si-based MOEMS devices, including micromirrors/micromirror arrays, micro-spectrometers, and optical/photonic switches. Owing to the unique advantages of Si-based MOEMS in spatial light modulation and high-speed signal processing, they have several promising applications in optical communications, digital light processing, and optical sensing. Finally, future research and development prospects of Si-based MOEMS are discussed.     

A femtosecond waveform transfer technique using type II second harmonic generation

We present a novel waveform frequency conversion technique by type II second harmonic generation (SHG). We have theoretically studied and experimentally demonstrated femtosecond waveform transfer from 800 to 400 nm wavelength by type II SHG in a lithium triborate (LBO) crystal. The output second harmonic (SH) waveform is a temporally magnified or compressed version of the input fundamental waveform, depending on the experimental configuration. Our experiments demonstrate that this technique can transfer not only the intensity profiles of the fundamental waveform, but also the phase profiles. This technique shows promise for programmable generation of shaped ultrafast optical waveforms down to the UV range, where direct pulse shaping is challenging.     

A model for conduction in polycrystalline silicon—Part II: Comparison of theory and experiment

In the preceding paper [1], a new phenomenological model for the electrical conduction in polycrystalline silicon was developed. Electrical conduction in polycrystalline silicon was shown to be controlled by dopant segregation, carrier trapping, and carrier tunneling through the grain boundaries. In this paper, the theoretical model is compared to experiment. The electrical behavior of polycrystalline silicon is shown to be influenced by the properties of the grain boundaries. In arsenic and phosphorus-doped polycrystalline-silicon films the grain boundaries are best modeled by rectangular barriers with a height of 0.66 eV and an approximate width of 7 Å. The width of the grain-boundary barriers and the density of carrier trapping states are found to be weak functions of the dopant species and sample processing. The resistivity is found to be a strong function of dopant concentration, dopant species, and processing history at low and intermediate dopant concentrations, and the model can be used to predict this behavior.     

一种UHF频段小型圆极化微带天线

采用曲流技术在贴片内部开十字形缝隙,在贴片边缘开矩形缝隙,并通过对贴片切角形成微扰,设计了一种UHF频段小型圆极化微带天线。设计的贴片天线尺寸为59×59mm^2（即0．176λ）,与相同频率相同介质的普通微带贴片天线相比有约54％的尺寸下降。天线的实测结果显示,在898—925MHz内回波损耗小于-10dB,在910—920MHz实现圆极化特性。     

Art and technology II. A call for collaboration

As decribed in Part I, the collaboration of art and engineering in the creation of new art works has become a serious preoccupation of many modern artists, who are asking for the help of engineers. A number of organizations now exist whose aim is to facilitate the contact between artists and engineers and to help support them in their collaborative projects. You need not be a Renaissance Man, it is said, to apply for a match with an artist. It won't be all fun and games, although part of it will be, and you might even end up doing something so useless from an engineering point of view, and so right from another point of view, that you could begin wondering why engineering is practiced the way it is?i.e., you might get turned on. This article tells you a bit about what it was like for some others who have already tried, and calls on you to join the action.     

A propagation experiment combining reflection and diffraction

Measurements of propagation at a frequency of 1090 MHz over terrain that produces specular reflection and knife-edge diffraction are in good agreement with model calculations that use images to represent the effect of reflection. A hill covered with a pine forest formed the diffracting mask, and an airport area formed the reflecting surface. Agreement between measurements and model calculations required that the diffracting knife edge be located at treetop level. Optimum propagation into the shadow region was obtained when a maximum in the reflection-lobe pattern coincided with the mask angle.     

一种快速准确识别圆形目标的新算法

在对二值圆形图像深入认识的基础上,研究了自动提取图像中圆形目标的理论,提出了圆的两个重要参数:圆上像素数与半径比值参数,以及理想半径与圆上像素到圆心(实际半径)差值参数.首先对图像进行降噪和边缘提取,然后利用这两个重要参数,在二值边缘图像中非常快速、有效地提取出圆形目标,并输出其半径和圆心坐标参数.实验表明,该方法能够较高精度、较快速度地在大面积图像中识别圆形目标.