Vagus nerve stimulation for the treatment of depression.

Given the debilitating effects of chronic depression and its economic impact on medical care, there is a need for a well-tolerated and effective long-term treatment for patients who do not respond fully to first-line antidepressant therapies such as antidepressant drugs (ADD), psychotherapy and electroconvulsive therapy. This paper discusses a new treatment that can address this need - the vagus nerve stimulation (VNS) therapy system - an implantable device that can electrically pace the vagus nerve. The VNS technology consists of a pulse generator and a lead system. In the VNS system, just like in a cardiac pacemaker, the stimulator resides subcutaneously and sends an electrical pulse to an organ through an implanted electrode. The VNS pulse generator is a programmable bipolar stimulator. The VNS lead system comprises a bipolar electrode pair and a fixation anchor that are wrapped around the left vagus nerve in the neck, near the carotid artery. The clinical safety and effectiveness of the VNS system was assessed. At present, the VNS therapy system can now be used as treatment for chronic or recurrent depression for patients 18 years of age or older who are experiencing a major depressive episode. The system can only be used as adjunctive therapy, which means that patients still need to continue with their ADD medication.     

Customized interactive robotic treatment for stroke: EMG-triggered therapy.

A system for electromyographic (EMG) triggering of robot-assisted therapy (dubbed the EMG game) for stroke patients is presented. The onset of a patient's attempt to move is detected by monitoring EMG in selected muscles, whereupon the robot assists her or him to perform point-to-point movements in a horizontal plane. Besides delivering customized robot-assisted therapy, the system can record signals that may be useful to better understand the process of recovery from stroke. Preliminary experiments aimed at testing the proposed system and gaining insight into the potential of EMG-triggered, robot-assisted therapy are reported.     

Microelectronic packaging for retinal prostheses.

An innovative parylene-based high-density chip-level integrated interconnect (CL-I/sup 2/) packaging system for retinal implants id discussed. The implications of this CL-I/sup 2/ technology for retinal prosthesis packaging effort are far-reaching. This technology obviates the need for a technician to create electrical and mechanical connections one by one. Instead, the technology is limited only by standard photolithography and standard microfabrication techniques, providing the capability for a reduction of an order of magnitude or more in the center-to-center pad distances that can be accommodated in the process. High-density electrode arrays are thereby feasible, because the fabrication process places no limit on the number of output pads that can reasonably be connected to the array.     

Unbundling of transmission and ancillary services. I. Technicalissues

This paper presents derivations of basic formulae for computing the contributions of each economic transaction to the network power flows throughout the system in steady-state operation of interconnected electric power systems. It is shown that the net system power imbalance caused by each transaction can be obtained as a function of all transactions present on the system. In addition, formulae are proposed for calculating the contributions of every ancillary generation unit to each transaction. This generation is needed to balance the system in response to economic transactions. Formulae supporting this are based on reformulating the load flow problem in terms of distributed slack bus     

渭河发电有限公司电量平衡系统

为实时监视考核电能计量装置的运行状态，渭河发电有限公司建立了电量平衡系统。该系统能够实时准确地计算母线电量不平衡率和全厂电量不平衡率，为关口电能计量提供了有效的技术监督手段。系统运行效果良好，解决了电能计量装置故障诊断、追补电量及变损的准确可靠计算、电量统计等问题，为厂网分离、竞价上网奠定了良好的基础。     

Tremor suppression through impedance control.

This paper presents a method for designing tremor suppression systems that achieve a specified reduction in pathological tremor power through controlling the impedance of the human-machine interface. Position, rate, and acceleration feedback are examined and two techniques for the selection of feedback coefficients are discussed. Both techniques seek a desired closed-loop human-machine frequency response and require the development of open-loop human-machine models through system identification. The design techniques were used to develop a tremor suppression system that was subsequently evaluated using human subjects. It is concluded that nonadaptive tremor suppression systems that utilize impedance control to achieve a specified reduction in tremor power can be successfully designed when accurate open-loop human-machine models are available.     

Partial discharge. IV. Commercial PD testing

For pt.III see ibid., vol.6, no.6, p.11 et seq. (1990). Commercially available partial discharge (PD) detectors are described, along with their important characteristics. The primary characteristics that detectors have in common and that are used as a basis for classification are the number of inputs used, the bandwidth of the detector, and the method of display processing. Ancillary test components, which complete an integrated test system, are discussed. PD measurements for quality assurance require not only a detector, but an entire system coordinated to maximize the measurement sensitivity for the specific type of apparatus under test. To illustrate how a coordinated system is applied, examples of some systems in commercial use are provided     

Design of a haptic data visualization system for people with visual impairments.

Data visualization is a technique used to explore real or simulated data by representing it in a form more suitable for comprehension. This form is usually visual since vision provides a means to perceive large quantities of spatial information quickly. However, people who are blind or visually impaired must rely on other senses to accomplish this perception. Haptic interface technology makes digital information tangible, which can provide an additional medium for data exploration and analysis. Unfortunately, the amount of information that can be perceived through a haptic interface is considerably less than that which can be perceived through vision, so a haptic environment must be enhanced to aid the comprehension of the display. This enhancement includes speech output and the addition of object properties such as friction and texture. Textures are generated which can be modified according to a characteristic or property of the object to which it is applied. For example, textures can be used as an analog to color in graphical displays to highlight variations in data. Taking all of these factors into account, methods for representing various forms of data are presented here with the goal of providing a haptic visualization system without the need for a visual component. The data forms considered include one-, two-, and three-dimensional (1-D, 2-D, and 3-D) data which can be rendered using points, lines, surfaces, or vector fields similar to traditional graphical displays. The end result is a system for the haptic display of these common data sets which is accessible for people with visual impairments.     

An adaptive PMU based fault detection/location technique fortransmission lines. II. PMU implementation and performance evaluation

Part I of this paper set sets forth theory and algorithms for adaptive fault detection/location technique, which is based on phasor measurement unit (PMU). This paper is Part II of this paper set, A new timing device named “Global Synchronism Clock Generator, GSCG” including its hardware and software design is described in this paper, Experimental results show that the synchronized error of rising edge between the two GSCGs clock is well within 1 ps when the clock frequency is below 2.499 MHz. The measurement results between Chung-Jeng and Chang-Te 161 kV substations of Taiwan Power company by PMU equipped with GSCG is presented and the accuracy for estimating parameters of line is verified. The new developed DFT based method (termed as smart discrete Fourier transform, SDFT) and line parameter estimation algorithm are combined with PMU configuration to form the adaptive fault detector/locator system. Simulation results have shown that SDFT method can extract exact phasors in the presence of frequency deviation and harmonics, The parameter estimation algorithm can also trace exact parameters very well, The SDFT method and parameter estimation algorithm can achieve accuracies of up to 99.999% and 99.99%, respectively. The EMTP is used to simulate a 345 kV transmission line of Taipower System. Results have shown that the proposed technique yields correct results independent of fault types and is insensitive to the variation of source impedance, fault impedance and line loading. The accuracy of fault location estimation achieved can be up to 99.9% for many simulated cases, The proposed technique will be very suitable for implementation in an integrated digital protection and control system for transmission substations     

Performances evaluation and optimization of brain computer interface systems in a copy spelling task.

The evaluation of the performances of brain-computer interface (BCI) systems could be difficult as a standard procedure does not exist. In fact, every research team creates its own experimental protocol (different input signals, different trial structure, different output devices, etc.) and this makes systems comparison difficult. Moreover, the great question is whether these experiments can be extrapolated to real world applications or not. To overcome some intrinsic limitations of the most used criteria a new efficiency indicator will be described and used. Its main advantages are that it can predict with a high accuracy the performances of a whole system, a fact that can be used to successfully improve its behavior. Finally, simulations were performed to illustrate that the best system is built by tuning the transducer (TR) and the control interface (CI), which are the two main components of a BCI system, so that the best TR and the best CI do not exist but just the best combination of them.     

The inclusion of dynamic factors in statistical power system costmodels. II. Part loading and reserve costs

For pt.I see ibid., vol.4, no.2, p.419-25 (1989). Techniques are developed for analyzing the costs of maintaining adequate operating reserver on power systems, within probabilistic production costing models and other based on load distribution functions. The aim is to show that such models can be developed to approximate the full range of dynamic penalties associated with practical power system operation. Algorithms for costing predetermined part loading are presented, taking into account the need for bringing plant online out of strict merit order. The author describes how a prediction error function can be used to estimate the probability that the specified spinning reserve is insufficient and hence approximate for the cost of gas turbine or storage utilization for dynamic control. This allows estimation of optimal reserve levels. The author discusses the analysis of longer term reserve from banked thermal units. Some results of the model are compared to those reported from hourly simulation studies     

渭河3号机组励磁系统参数测试与仿真

给出了测试和计算渭河3号机组励磁系统参数的方法,总结了使用电力系统综合仿真分析程序PSASP进行空载阶跃仿真计算的步骤,并调整了仿真计算中的参数,得出了PSASP使用的励磁调节器的计算模型和参数,指出了励磁系统参数回归中应注意的问题。根据现场实测数据,得到了可用于电网稳定计算的渭河电厂3号机组励磁系统的实测模型和参数,仿真实验验证了上述方法的正确性和实用性。     

Acoustic analysis of pathological voices. A voice analysis systemfor the screening of laryngeal diseases

The authors propose a software system for pathological voice analysis and screening of laryngeal diseases that has the following properties: a) The analysis is totally noninvasive-the microphone is about 30 cm from the patient's mouth, and contact microphones or laryngophones are not used. b) The system is built around a low-cost personal computer (PC). The additional hardware consists of a standard sound card such as “Sound Blaster” (Creative Technology Inc., Paris, France). The card also includes a microphone. Any other analog-to-digital converter board allowing a sampling rate higher than 16 kHz, with 16 bit resolution (Sound Blaster and OROS have been already tested), and a linear phase condenser or electret microphone can be used to minimize the distortions during capture of the signal. c) The software is graphics-driven and user-friendly, therefore no special training is needed in using the system. d) The system is electrically safe since there is no electrical link between patient and PC     

A NEW APPROACH TO PERFORMANCE ANALYSIS OF CHOPPER CONTROLLED D.C. MOTOR DRIVE

ABSTRACT

An analytical method for performance analysis of a d.c. separately excited motor fed from a chopper is presented. The motor input voltage is represented as a series of step-voltages with a time phase difference. The system equations are solved to obtain closed-form solutions for motor current and speed, for transient as well as steady state conditions. The method presented is superior to existing methods in that the solution is in closed-form, and does not make recourse to recursive numerical techniques. The solutions for steady state condition corresponding to any set of operating conditions (voltage, chopper duty factor, load torque) can be directly obtained. The computational effort and time needed is therefore extremely small as compared to other methods.     

The Wadsworth BCI Research and Development Program: at home with BCI.

The ultimate goal of brain-computer interface (BCI) technology is to provide communication and control capacities to people with severe motor disabilities. BCI research at the Wadsworth Center focuses primarily on noninvasive, electroencephalography (EEG)-based BCI methods. We have shown that people, including those with severe motor disabilities, can learn to use sensorimotor rhythms (SMRs) to move a cursor rapidly and accurately in one or two dimensions. We have also improved P300-based BCI operation. We are now translating this laboratory-proven BCI technology into a system that can be used by severely disabled people in their homes with minimal ongoing technical oversight. To accomplish this, we have: improved our general-purpose BCI software (BCI2000); improved online adaptation and feature translation for SMR-based BCI operation; improved the accuracy and bandwidth of P300-based BCI operation; reduced the complexity of system hardware and software and begun to evaluate home system use in appropriate users. These developments have resulted in prototype systems for every day use in people's homes.     

Unbundling of transmission and ancillary services. II. Cost-basedpricing framework

For pt.I see ibid., vol.12, no.2 (1997). This paper presents a systematic framework for pricing transmission and ancillary services in competitive power markets. This framework is based on the recovery of fixed and operating costs, and it meets the traditional revenue requirements. It is practical, feasible, easy to implement, and to regulate. It can be implemented with minimum transition cost. This network flow-dependent and nondiscriminatory framework is based on the decomposition approach presented in Part I of this paper. This decomposition forms an essential part of the proposed framework for usage-based recovery of the fixed and operating costs. The transmission system related fixed cost component is recovered from all transactions based on percentage utilization of the transmission system equipment. The charge is based on the actual network power flows. The ancillary service charge for a given transaction can be computed as the sum of the costs incurred at secondary generation for compensating the imbalance caused by that specific transaction. The “path providing” function of the transmission grid is viewed as a true monopolistic service, its pricing is cost based, and charge for its use is usage based; the generation based ancillary service supply can be made competitive, its pricing is market based, and charge for it is usage based. A global overview of the proposed pricing strategy is analyzed in the context of other alternatives, especially cost-based methods. A numerical example on a five-bus system is given to illustrate the use of this pricing strategy     

A fundamental approach to transformer thermal modeling. I. Theoryand equivalent circuit

A simple equivalent circuit to represent the thermal heat flow equations for power transformers is presented. Key features are the use of a current source analogy to represent heat input due to losses, and a nonlinear resistor analogy to represent the effect of air or oil cooling convection currents. The effect was first quantified in 1817. It is shown that the idea of “exponential response” is not the best way to think of the dynamics of the situation. It is also shown that one can consider ambient temperature to be a variable input to the system, and that it is properly represented as an ideal voltage source     

Accessory hardware for neuromuscular measurements during functional MRI experiments.

Functional magnetic resonance imaging (fMRI) is increasingly being used for human sensorimotor function research. Few studies, however, have been able to acquire peripheral neuromuscular data (e.g. joint force and electromyograms [EMG]) online with fMRI measurements. The lack of muscle output information hinders interpretation of fMRI data and prevents investigators from designing more sophisticated experiments. We developed a data-acquisition system that can record force and EMG data simultaneously with fMRI signals. This system included three major components: a hydraulic, pressure transducer-based force measurement device, a well-shielded EMG-recording apparatus, and a visual feedback setup. The three components were integrated with a laptop computer equipped with data acquisition hardware and software. System evaluation experiments demonstrated that no significant mutual interference occurred between the MRI environment and the force-EMG data-acquisition system, i.e. the system can record relatively noise-free force and EMG signals while maintaining the quality of fMRI data. The system has enabled us to study human motor control function involving motor tasks such as handgrip and finger pinch that require precision control of force and EMG. This accessory equipment can facilitate fMRI investigations of human sensorimotor function.     

Use of Magnetorheological fluid in a force feedback glove.

Magnetorheological fluid (MRF) is a smart material that has the property of changing its viscosity when exposed to a magnetic field. By placing this fluid into a sealed cylinder with an electromagnet piston as a core, a controllable resistance motion dampener can be created. A novel exoskeleton mechanical power transmission system was designed, utilizing rapid prototype parts, to transmit these resistive forces to the user's fingertips. A first iteration force feedback glove was developed and tested on human subjects for overall usability. The eventual goal of the system is to provide an alternative force producing system for exercises and rehabilitation. The entire system is lightweight, low power, and easily portable.     

Exploring the cost implications of increased renewable energy for the U.S. power system

Over the last decade, the fraction of annual U.S. electricity generation for renewable energy has doubled from 10 % to 20 %. This growth has been driven by several factors, including technology cost reductions and policy support. The share of renewable generation is projected to increase over time. Reference case scenarios from four different organizations show least-cost U.S. electricity buildouts with renewable energy generation fractions of 31–36 % by 2030 and 40–65 % by 2050. Using a capacity expansion modeling tool, we investigate how changing the amount of renewable energy from the least-cost solution impacts the cost of building and operating the electricity system. The relationship between system cost and renewable energy generation fraction is non-linear. Small deviations near the least-cost solution have minimal cost impacts (changing the renewable energy penetration by +/- 5% results in system cost changes of less than 1%), while similar deviations that are farther from the least-cost solution can result in large cost changes. Increased levels of RE lead to lower absolute emissions, and we evaluate the trade-offs between emissions savings and system costs for higher and lower levels of RE penetration.