Continuous myoelectric control for powered prostheses using hidden Markov models

This paper represents an ongoing investigation of dexterous and natural control of upper extremity prostheses using the myoelectric signal. The scheme described within uses a hidden Markov model (HMM) to process four channels of myoelectric signal, with the task of discriminating six classes of limb movement. The HMM-based approach is shown to be capable of higher classification accuracy than previous methods based upon multilayer perceptrons. The method does not require segmentation of the myoelectric signal data, allowing a continuous stream of class decisions to be delivered to a prosthetic device. Due to the fact that the classifier learns the muscle activation patterns for each desired class for each individual, a natural control actuation results. The continuous decision stream allows complex sequences of manipulation involving multiple joints to be performed without interruption. The computational complexity of the HMM in its operational mode is low, making it suitable for a real-time implementation. The low computational overhead associated with training the HMM also enables the possibility of adaptive classifier training while in use.     

高速双极型晶体管和高速CMOSFET的兼容技术

第一阶段用3微米的设计规则开发了高速双极型晶体管和高速CMOSFET的兼容技术。采用具有N~+型掩埋层的外延片。用N阱硅栅CMOSFET兼容多晶硅掺杂发射极源（DOPOS）结构的双极型晶体管来实现工艺的兼容。用越来越简化工艺作为批量生产控制性的某种器件工艺。 双极型晶体管的截止频率f_T=2～4GH2。CMOS倒相器的传输延迟时间C_（pd）=1·2ns等所得到各种的特性是兼容技术的重要目标,完全能够达到分立器件的性能。考虑开发缩小到2微米规则的技术将作为将来第二阶段的发展方向。     

新型曼恩20/27四冲程柴油机

近年来的市场情况清楚地表明,功率在2,000千瓦以下的柴油机目前最受欢迎。船主常常希望,除主机之外,还能从同一个发动机制造厂得到辅机。此外,对小型固定式发动机发展成能发电并同时供热的联合装置的兴趣也增加了。鉴于上述原因,曼恩公司研制成功了一种经济性好,维修方便并适用未来燃料的20/27系列发动机。该机型能烧重油或煤气运行,单缸功率为100千瓦,转速为1,000转/分。     

阻燃剂对共混腈纶结构和性能的影响

采用广角X射线、扫描电子显微镜、极限氧指数测定和热分析等方法,对添加不同量含溴阻燃剂FR和协同剂Sb_2O_3的共混阻烯PAN纤维的结构和性能进行分析。研究表明,FR和Sb_2O_3的加入,降低了纤维高序区的规整性,但对结构单元的取向态结构和纤维的宏观形态结构的影响较小,FR和Sb_2O_3对PAN纤维具有良好的阻燃性,不会使纤维的物理机械性能明显劣化,但对纤维的热性能有不同程度的影响。     

Simulated-annealing-based genetic algorithm for modeling the optical constants of solids

We propose a simulated-annealing-based genetic algorithm for solving model parameter estimation problems. The algorithm incorporates advantages of both genetic algorithms and simulated annealing. Tests on computer-generated synthetic data that closely resemble optical constants of a metal were performed to compare the efficiency of plain genetic algorithms against the simulated-annealing-based genetic algorithms. These tests assess the ability of the algorithms to find the global minimum and the accuracy of values obtained for model parameters. Finally, the algorithm with the best performance is used to fit the model dielectric function to data for platinum and aluminum.     

Peer reviewed: environmental forensics unraveling site liability

An interdisciplinary analytical approach can unravel environmental liability at contaminated sites.     

Measurement of diffusive flux of ammonia from water

An instrument was developed for the measurement of gaseous ammonia concentration, NH(3(sw,eq)), in equilibrium with surface waters, notably ocean water. The instrument measures the ammonia flux from a flowing water surface under defined conditions and allows the calculation of NH(3(sw,eq)) from the principles of Fickian diffusion. The flux collector resembles a wetted parallel plate denuder previously developed for air sampling. The sample under study runs on one plate of the device; the ammonia released from the sample is collected by a slow flow of a receptor liquid on the other plate. The NH(3) + NH(4)(+) (hereinafter called N(T)) in the effluent receptor liquid is preconcentrated on a silica gel column and subsequently measured by a fluorometric flow injection analysis (FIA) system. With a 6-min cycle (4-min load, 2-min inject), the analytical system can measure down to 0.3 nM N(T) in the receptor liquid. Coupled with the flux collector, it is sufficiently sensitive to measure the ammonia flux from seawater. The instrument design is such that it is little affected by ambient ammonia. In both laboratory (N(T) 0.2-50 μM), and field investigations (N(T) 0.18-1.7 μM) good linearity between the ammonia flux and the N(T) concentration in seawater (spiked, synthetic, natural) was observed, although aged seawater, with depleted N(T) content, behaves in an unusual fashion upon N(T) addition, showing the existence of an "ammonia demand". NH(3(sw,eq)) levels from ocean water measured in the Coconut Island Laboratory, HI, ranged from 6.6 to 33 nmol/m(3) with an average of 17.4 ± 6.9 nmol/m(3), in comparison to 2.8-21 nmol/m(3) (average 10 ± 7 nmol/m(3)) NH(3(sw,eq)) values previously reported for the Central Pacific Ocean (Quinn, P. K.; et al. J. Geophys. Res. 1990, 95, 16405-16416).