Joint angle control by FES using a feedback error learning controller.

The feedback error learning (FEL) scheme was studied for a functional electrical stimulation (FES) controller. This FEL controller was a hybrid regulator with a feedforward and a feedback controller. The feedforward controller learned the inverse dynamics of a controlled object from feedback controller outputs while control. A four-layered neural network and the proportional-integral-derivative (PID) controller were used for each controller. The palmar/dorsi-flexion angle of the wrist was controlled in both computer simulation and FES experiments. Some controller parameters, such as the learning speed coefficient and the number of neurons, were determined in simulation using an artificial forward model of the wrist. The forward model was prepared by using a neural network that can imitate responses of subject's wrist to electrical stimulation. Then, six able-bodied subjects' wrist was controlled with the FEL controller by delivering stimuli to one antagonistic muscle pair. Results showed that the FEL controller functioned as expected and performed better than the conventional PID controller adjusted by the Chien, Hrones and Reswick method for a fast movement with the cycle period of 2 s, resulting in decrease of the average tracking error and shortened delay in the response. Furthermore, learning iteration was shortened if the feedforward controller had been trained in advance with the artificial forward model.     

Energy losses at three-way circular drop manholes under surcharged conditions

Energy loss at manholes is of importance in the design of storm sewer networks and in flood-analysis. Some researchers have already investigated the energy loss at three-way manholes under surcharged conditions. However, formulation to calculate the energy loss at manholes, including all variables of structural elements of the pipes and of the manhole has not yet been accomplished. Therefore, more study to formulate the energy loss at three-way drop manholes is needed. In this study, the ratio of the diameter between inflow pipes and an outflow pipe, the ratio of flow rates between those pipes, water depth in a manhole and the drop gaps between those pipes are considered and the energy loss at three-way circular drop manholes is examined. Finally, a modified formula, more accurate than that in the U.S. Federal Highway Administration's 2001 Urban Drainage Design Manual is proposed. The proposed formula takes the influence of the ratio of the diameter between inflow pipes and outflow pipe and drop gaps between those pipes into consideration. The calculated energy loss coefficients in both straight-through and lateral pipes successfully reproduce the measured values.     

Albumin microvascular leakage in brains with diabetes mellitus

Their aim was to examine whether microvascular leakage of endogenous albumin, a representative marker for blood–brain barrier (BBB) damage, was induced in the periventricular area of diabetic db/db mice because periventricular white matter hyperintensity formation in magnetic resonance images was accelerating in elderly patients with diabetes mellitus. Using light and electron microscopes, and semi‐quantitative analysis techniques, immunoreactivity of endogenous albumin, indicating vascular permeability, was examined in the periventricular area and spinal cord of db/db mice and db/+m control mice. Greater immunoreactivity of albumin was observed in the vessel wall of the periventricular area of db/db mice than in controls. Additionally, weak immunoreactivity was observed in the spinal cord of both db/db mice and controls. The number of gold particles, indicating immunoreactivity of albumin, in the perivascular area of db/db mice was significantly higher than that of control mice, but there was no significant difference in the number of particles in the spinal cord between db/db mice and controls. These findings suggest that albumin microvascular leakage, or BBB breakdown, is induced in the periventricular area of diabetic mice. Microsc. Res. Tech. 79:833–837, 2016. © 2016 Wiley Periodicals, Inc.     

Topology optimization for worst load conditions based on the eigenvalue analysis of an aggregated linear system

This paper proposes a topology optimization for a linear elasticity design problem subjected to an uncertain load. The design problem is formulated to minimize a robust compliance that is defined as the maximum compliance induced by the worst load case of an uncertain load set. Since the robust compliance can be formulated as the scalar product of the uncertain input load and output displacement vectors, the idea of “aggregation” used in the field of control is introduced to assess the value of the robust compliance. The aggregation solution technique provides the direct relationship between the uncertain input load and output displacement, as a small linear system composed of these vectors and the reduced size of a symmetric matrix, in the context of a discretized linear elasticity problem, using the finite element method. Introducing the constraint that the Euclidean norm of the uncertain load set is fixed, the robust compliance minimization problem is formulated as the minimization of the maximum eigenvalue of the aggregated symmetric matrix according to the Rayleigh–Ritz theorem for symmetric matrices. Moreover, the worst load case is easily established as the eigenvector corresponding to the maximum eigenvalue of the matrix. The proposed structural optimization method is implemented using topology optimization and the method of moving asymptotes (MMA). The numerical examples provided illustrate mechanically reasonable structures and establish the worst load cases corresponding to these optimal structures.     

Influence of Aluminum Titanate Formation on Sintering of Bimodal Size-Distributed Alumina Powder Mixtures

The sintering behavior of green compacts, in which coarse alumina particles formed a skeletal structure and fine alumina and/or fine titania particles filled the voids of the skeletal structure, was investigated. Sinterability of the green compacts changed according to the titania content in the fine powder. The titania content of 33 mol% was the most effective for the densification. The volume expansion due to the aluminum titanate formation occurred in the voids of the skeletal structure, and the densification of the skeletal structure progressed more because the grain growth between the fine and coarse alumina particles did not proceed. As the titania content decreased, the densification did not progress more than that of the compact with 33 mol% titania content because the grain growth proceeded more. As the titania content increased, the expansion of the compacts was larger, and large grains were formed by the reaction between the titania and coarse alumina particles. Therefore, densification became difficult.     

Hot Isostatic Pressing of Alumina and Examination of the Hot Isostatic Pressing Map

The hot isostatic pressing (HIP) of four alumina powders is studied in the temperature range 1100° to 1400°C, at 5- to 200-MPa applied pressure, and for times ranging from 0.5 to 4 h. Density increases with increasing HIP temperature, pressure, and time; decreasing grain size results in increased density after HIP. An empirical relation is derived for grain growth during HIP, and the HIP map proposed by Helle et al. is found applicable to the present results. Densification is governed by the grain-boundary diffusion of aluminum ions; with the transport coefficient and the grain-growth values found in the present study, the map can be used to express experimental results to within a factor of 4 for all densification stages except near full density.     

Direct Determination of Grain Growth Behavior in Zinc Oxide with Added Barium Oxide

Grain growth behavior in ZnO with 4 to 12 wt% BaCO₃ (3.12 to 9.59 wt% BaO) added was studied by a new method, in which the sintered specimen was treated with boiling water to separate the grains by dissolving the grain-boundary phase. The separated grains were examined with SEM to obtain quasi-three-dimensional information on the grain shape, size, and size distribution. The grains had a rounded shape, and the size distribution was found to be lognormal.     

Formation of porous poly(ethylene‐co‐vinyl alcohol) membrane via thermally induced phase separation

Crystalline poly(ethylene‐co‐vinyl alcohol) (EVOH) membranes were prepared by a thermally induced phase separation (TIPS) process. The diluents used were 1,3‐propanediol and 1,3‐butanediol. The dynamic crystallization temperature was determined by DSC measurement. No structure was detected by an optical microscope in the temperature region higher than the crystallization temperature. This means that porous membrane structures were formed by solid–liquid phase separation (polymer crystallization) rather than by liquid–liquid phase separation. The EVOH/butanediol system showed a higher dynamic crystallization temperature and equilibrium melting temperature than those of the EVOH/propanediol system. SEM observation showed that the sizes of the crystalline particles in the membranes depended on the polymer concentration, cooling rate, and kinds of diluents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2449–2455, 2001     

Esterification of cholesterol and hydrolysis of cholesteryl ester in alcohol induced fatty liver of rats

Repeated oral administrations of ethanol to rats induced accumulation of cholesteryl ester, as well as triglyceride in the livers. The contents of free cholesterol and phospholipid in the livers were not changed significantly in the present experiment in which ethanol ingestions were repeated four times. Although in vitro esterification of cholesterol by particle fractions of the alcoholic fatty liver was not affected, hydrolysis of cholesteryl palmitate by the supernatant fraction of the liver homogenate was reduced when compared with those of the control group which was given water or isocaloric glucose. The results of in vitro esterification of cholesterol and hydrolysis of cholesteryl palmitate in the liver of the rats which were ingested with glucose were larger than those of the control rats which were given water.     

Grain Growth During Hot Isostatic Pressing of Presintered Alumina

Grain growth during hot isostatic pressing is examined at 1373 to 1673 K at 5 to 200 MPa for 0.5 to 4 h on alumina presintered at 1723 to 1873 K. A linear relation is found between logarithms of grain size and porosity. To account for this result, the development of similar microstructures is suggested regardless of the histories of the starting powder and process. Temperature dependences of grain growth and densification must also be equal during hot isostatic pressing. Both grain growth and densification were controlled by the grain-boundary diffusion of the aluminum ions.