1P1-G14 テレオペレーションの操作性向上のための状況に応じた力覚提示手法(コミュニケーション・ロボット)

This dissertation presents an investigation of non-uniform time sampling methods for spectral/temporal feature extraction in speech. Frame-based features were computed based on an encoding of the global spectral shape using a Discrete Cosine Transform. In most current “standard” methods, trajectory (dynamic) features are determined from frame-based parameters using a fixed time sampling, i.e., fixed block length and fixed block spacing. In this research, new methods are proposed and investigated in which block length and/or block spacing are variable. The idea was initially tested with HMM-based isolated word recognition, and a significant performance improvement resulted when a variable block length and variable block method were applied. An accuracy of 97.9% was obtained with an alphabet recognition task using the ISOLET database. This result is by far the highest reported in the literature. The variable block length method was then adapted to accommodate the complexity of continuous speech. Three methods were proposed and each was tested with the TIMIT and NTIMIT databases using HMM recognizers. Phone recognition experiments were conducted using the standard 39 phone set. Tuning of parameters was achieved with monophone models using a simple HMM configuration. The methods were also evaluated with more complex models, such as models with more mixture components, models with a full covariance matrix and right-context biphone models. Experimental results indicated that none of the proposed methods perform significantly better than the standard method. However, the absolute best result obtained with the proposed front end is comparable to those obtained with current state-of-the-art systems. Also, the performance achieved with monophone models is favorable to many context-dependent systems which are more complex.

Developing generalized single-tree biomass models suitable for forest biomass estimation is an effective way to provide scientific approaches. To simplify biomass modeling and improve the accuracy of model estimation for better understanding of biomass, carbon stocks, and dynamics in large-scale forests and to precisely estimate tree biomass, this study used stem, bark, needle, branch, and root biomass of Larix kaempferi of 161 sample trees in Gansu, Hubei, and Liaoning Provinces to generalize single-tree biomass equations suitable for different organs and regions using seemingly unrelated regression and dummy variable modeling methods. Results showed that the generalized biomass equations not only solved compatibility problems with different components but also increased accuracy with an average increase of 0.28%-0.44% in R2, decreased 0.40%-6.61% in the root mean square error (ERMS), and decreased 1.63%-6.61% in the mean abosolute bias (BMA). Effects due to region increased accuracy more than effects due to developmental stages. When both region and developmental stages were added to the dummy variable model, it was more accurate and produced the best equation. Therefore, we suggest that both regional and developmental stages be considered as dummy variables to establish generalized biomass equations in order to solve the compatibility problem with different components as well as for overcoming problems of generalizing with different regions.

We propose a new circuit analysis method, namely Semi-Implicit Linear-Centric Analysis (SILCA), for efficient SPICE-accurate transient simulation of deep-submicron VLSI circuits with strong parasitic coupling effects introduced by interconnect lines, common substrate, power/ground networks, etc. SILCA is based on two linear-centric techniques. First, a new semi-implicit iterative numerical integration scheme is developed, which applies dynamic time step control accounting for stiff systems and meanwhile keeps constant equivalent conductance for capacitor/inductor companion models. Its convergence and stability properties are characterized. Second, to achieve constant linearized conductance for nonlinear devices during nonlinear iteration process, a successive variable chord method is introduced as an alternative of the Newton-Raphson method and the rank-one update technique is implemented for fast LU factorization. With these techniques, SILCA reduces the number and cost of required LU factorizations dramatically. Experimental results on substrate and power/ground networks have demonstrated that SILCA yields SPICE-like accuracy with an over 80X reduction in LU factorization cost, and an about 20X overall CPU time speedup over SPICE3 for circuits with tens of thousands elements, and the efficiency increases further with the size of a circuit.

In this paper we investigate whether private sustainability standards in the coffee sector in Uganda live up to the promises they make to consumers to improve the welfare and productivity of smallholder farmers. We use cross-sectional household survey data from Eastern Uganda and instrumental variable methods to reveal how participation in two different coffee certification schemes affects smallholders. We find that smallholder participation in a double Fairtrade - Organic certification scheme neither increases producer income, nor reduces poverty. While certified producers do receive higher coffee prices, the certificate results in lower land and labour productivity and the price premium does not compensate for that. For participation in a triple Utz - Rainforest Alliance - 4C certification scheme, we find increases in coffee income, in land and labour productivity but no significant impact on poverty reduction. The results imply that almost a decade after their introduction, the certification schemes have failed to contribute to poverty reduction in a region that is faced with a high incidence of poverty. The results indicate that a price premium to producers is neither necessary, nor sufficient, for private sustainability standards to contribute to rural incomes, and that yields are more important than prices in increasing net returns to coffee farmers. In areas with degraded soils and low average yields, FT certification focusing on fair producer prices, might be better for smallholder coffee farmers when combined with standards that focus on good agricultural practices and productivity growth, such as Utz, than when combined with Organic standards. The results put doubt on the sincerity of private sustainability standards and the justification of the price premium consumers pay for certified products, as standards may not always live up to the expectations they create.

We propose a substitutive multi-degree-of-freedom force display method that utilizes vibrotactile phantom sensation (VPS), in which the tangential force is substituted by the VPS position displacement and the slip is displayed as the oscillatory displacement of the VPS position. Based on the proposed method, we prototyped a virtual object manipulation system that consists of two 20 mm × 20 mm × 20 mm fingertip-wearable devices with four vibrating pins, a magnetic tracking system, a potentiometer for finger position measurement, and a physics simulator. The preliminary experiments demonstrated the feasibility to display the mass of an object, the slipping-down of an object between fingers, and the reaction torque induced by the rotation of the object-grasping hand.