CONTROL OF TRANSIENT THERMOELASTIC DISPLACEMENT IN A COMPOSITE DISK

Control of displacement in a composite disk subjected to axisymmetric heating is investigated. The disk consists of a transversely isotropic structural layer to which is bonded a layer of piezoceramic material of crystal class 6mm. First, a solution procedure based on potential functions is used to analyze the elastic and electric fields induced in the disk when a transient ambient temperature acts on the free surface of the structural layer. Then a transient distribution of electric potential across the piezo-electric layer is determined such that the resultant displacement at the surface of the structural layer has a prescribed distribution. Numerical results are obtained for the resulting thermal, elastic, and electric fields.     

A case of anastomotic aneurysm-enteric fistula

Reimplantation failure of avulsed anterior teeth in an adolescent patient requires removal of the attempted-reimplanted teeth and consideration of several restorative options. These options may include a removable partial denture, as well as a transitional bridge or permanent fixed prosthesis. In all cases, the potential effects of the adolescent's expected amount and directions of maxillary and mandibular growth must be considered. A case is presented examining how maxillary growth may affect the restorative treatment options for avulsed anterior teeth replacement for an adolescent boy. Unfortunately, the patient and family were unable to complete treatment due to financial considerations. Consequently, the case presented here is submitted as a treatment planning exercise.     

Tip-sample distance control using photothermal actuation of a small cantilever for high-speed atomic force microscopy

We have applied photothermal bending of a cantilever induced by an intensity-modulated infrared laser to control the tip-surface distance in atomic force microscopy. The slow response of the photothermal expansion effect is eliminated by inverse transfer function compensation. By regulating the laser power and regulating the cantilever deflection, the tip-sample distance is controlled; this enables much faster imaging than that in the conventional piezoactuator-based z scanners because of the considerably higher resonant frequency of small cantilevers. Using this control together with other devices optimized for high-speed scanning, video-rate imaging of protein molecules in liquids is achieved.     

Superplasticity of Silicon Carbide

Nanocrystalline silicon carbide that was doped with boron and carbon (B,C-SiC) and contained 1 wt% boron additive and 3.5 wt% free carbon was fabricated using hot isostatic pressing under an ultrahigh pressure of 980 MPa and a temperature of 1600°C. The average grain size of the material was 200 nm. The tensile deformation behavior of this material at elevated temperature was investigated. The nanocrystalline B,C-SiC exhibited superplastic elongation of >140% at a temperature of 1800°C. High-resolution transmission electron microscopy observation and electron energy-loss spectroscopy analysis revealed that this nanocrystalline SiC did not have a secondary glassy phase at the grain boundary and the grain boundary had a strong covalent nature, which means that an intergranular glassy phase was not necessary to obtain superplasticity of covalent materials.     

Mechanics of shape evolution of particle aggregates in viscous sintering

Sintering of glass/amorphous particles takes place by viscous flow driven by surface tension. While the viscous sintering of two particles is described by the growth of contact area, the shape evolution of aggregates of particles is very complicated and requires analytical methods for the characterization. Here, we analyzed the viscous sintering of linear chains of particles by finite element simulation. Consider a plane which cuts the chain perpendicular to its axis. We show that the growth rate of cross-sectional area is driven by the difference between the integral of pressure on the cross-section and the surface tension acting along its circumference, i.e., the sintering force. The cross-sectional area increases when the sintering force is positive, and decreases when it is negative. This relationship is generalized to particles aggregate of any shape, so that its shape evolution is characterized by the distribution function of growth rate of cross-sectional area.     

In Vitro Investigation of Crosstalk between Fatty Acid and Polyketide Synthases in the Andrimid Biosynthetic Assembly Line

Andrimid (Adm) synthase, which belongs to the type II system of enzymes, produces Adm in Pantoea agglomerans. The adm biosynthetic gene cluster lacks canonical acyltransferases (ATs) to load the malonyl group to acyl carrier proteins (ACPs), thus suggesting that a malonyl‐CoA ACP transacylase (MCAT) from the fatty acid synthase (FAS) complex provides the essential AT activity in Adm biosynthesis. Here we report that an MCAT is essential for catalysis of the transacylation of malonate from malonyl‐CoA to AdmA polyketide synthase (PKS) ACP in vitro. Catalytic self‐malonylation of AdmA (PKS ACP) was not observed in reactions without MCAT, although many type II PKS ACPs are capable of catalyzing self‐acylation. This lack of self‐malonylation was explained by amino acid sequence analysis of the AdmA PKS ACP and the type II PKS ACPs. The results show that MCAT from the organism's FAS complex can provide the missing AT activity in trans, thus suggesting a protein–protein interaction between the fatty acid and polyketide synthases in the Adm assembly line.     

Traffic signal control based on a predicted traffic jam distribution

In this article, we propose a new method of traffic signal control based on the predicted distribution of traffic jams. First, we built a forecasting model to predict the probability distribution of vehicles being in a traffic jam during each period of the traffic signals. A dynamic Bayesian network was used as the forecasting model, and this predicted the probability distribution of the number of standing vehicles in a traffic jam. According to calculations by the dynamic Bayesian network, a prediction of the probability distribution of the number of standing vehicles at each time will be obtained, and a control rule to adjust the split and cycle of the signals to maintain the probability of a lower limit and a ceiling of standing vehicles is deduced. Through a simulation using the actual traffic data of a city, the effectiveness of our method is shown.     

Production adjusting method based on the predicted distribution of production and inventory using a dynamic Bayesian network

In general, production quantities and goods delivered are changed randomly, and then the total stock is also changed randomly. This article deals with the production and inventory control of an automobile production parts line using a dynamic Bayesian network. A Bayesian network indicates the quantitative relations between individual variables by conditional probability. The probabilistic distribution of the total stock is calculated through the propagation of the probability on the network. Moreover, an adjusting rule for the production quantities to maintain the probability of the lower and upper bound values of the total stock at certain values is shown.     

A procedure for designing robust control of systems with bounded uncertain parameters

In recent years, the robust control design problem has drawn considerable attention because it allows one to ensure desirable closed-loop properties in the presence of model uncertainties. As a result, several design methods have been developed. This paper discusses mainly the problem of robust control design of systems with bounded uncertain parameters, and presents a new design method, called “incentive design,” for this design problem. This method is based mainly on such a consideration whereby the designed robust control law can ensure a most favorable value of the cost functional regardless of how the uncertain parameters vary within given bounds. Therefore, in this sense, the existence of the uncertainty in controlled systems has at least no bad effect on the optimal value of the cost functional. This paper gives first the procedure for designing robust control of the systems with bounded uncertain parameters, in general. Then for a class of uncertain linear quadratic systems, a robust control law is designed concretely and a numerical example is presented. It is shown from this derivation and this numerical example that the method proposed in this paper is effective and feasible for some practical control problems with bounded uncertain parameters. The design method developed here may be expected to have some further applications for practical control problems in future.