Voronoi-based coverage control with anisotropic sensors and experimental case study

In this paper, we investigate coverage control problem for mobile sensor networks. The novelty is to consider an anisotropic sensor model whose performance depends not only on the distance but also on the orientation to a target point. By adapting Lloyd algorithm, a distributed control law is derived. Aside from coverage, we also show that the control law guarantees collision avoidance between the agents. The performance of the control laws is demonstrated through not only numerical simulation but also experiments on a mobile robot test bed.     

Friction control by micro-vibration of a magnetic recording head under micro-load

To reduce the risk of a head crash in a hard disk drive by reducing stiction/friction at the head-disk interface, micro-vibration was applied to reduce such friction. This friction control between a head and a disk was investigated by means of a model head. The present study investigated the effect of micro-vibration on friction under micro-load conditions and the influence of surface roughness on friction reduction by micro-vibration. These investigations show that micro-vibration of the model head is effective to reduce friction when a slider contacts a smooth disk.     

Sugar-Induced Chiral Orientation of Boronic-Acid-Appended Amphiphile Clusters Formed in the Dipalmitoylphosphatidylcholine (DPPC) Membrane

A boronic-acid-appended amphiphile bearing an azobenzene chromophore in the chain center ( 3 ) was synthesized. Although 3 could not form the membrane-like, ordered aggregate by itself, it formed a phase-separated aggregate in a dipalmitoylphosphatidylcholine (DPPC) matrix membrane. When saccharides were added, the boronic acid group reversibly formed the saccharide complexes, and 3 in the DPPC matrix membrane became CD-active with the appearance of exciton-coupling bands. Comparison of the saccharide absolute configuration with the CD intensity established that the saccharide possessing the OH group (as 3-OH, 4-OH, and 5-CH₂OH) in the same side as the cis-1,2-diol gives the strong CD band. Judging from the structure of 3 –saccharide complexes, these “same-side” OH groups can enjoy intermolecular hydrogen-bonding interactions, which eventually induce the chiral orientation of azobenzene chromophores. This is a novel membrane system useful to read out the information stored in the saccharide structure and to create novel membrane structures by added saccharides.     

Model predictive control with adaptive disturbance prediction and its application to fatty acid distillation column control

This paper describes the results of a joint university-industry study to control a fatty acid distillation sequence, which is plagued with severe disturbance problems. In order to solve the disturbance problem, a model predictive control algorithm is modified in terms of disturbance prediction. Assuming that the dynamics of the unmeasured disturbances is generated by an auto-regressive form, the dynamics of the disturbance can be adaptively identified by using time series data of prediction errors and inputs. Using an identified disturbance model with a process model, future outputs are predicted. Control actions are determined so that the predicted output is as close to the target value as possible. This modified model predictive control aglorithm is applied to a ratio control scheme for three distillation columns. The control system developed has been in use sucessfully for more than six years to produce commercial products.     

Joining of NiAl to iron-based alloys by reactive casting

Nickel monoaluminide, NiAl, is exothermically synthesized from elemental liquids of aluminum and nickel and is simultaneously joined to iron-based alloys, such as carbon steels and stainless steels, by the reactive casting method, which is based on the pouring of the elemental liquids onto the base material. The exothermic reaction between the aluminum and nickel liquids produces extremely superheated NiAl liquid. Heat of the NiAl liquid is transferred to the base material, and the contact surface is melted to a depth depending on both the preheating temperature of the base material and the thickness of the NiAl produced. After solification on the base material, NiAl is strongly joined to the base material, showing a joint strength exceeding the inherent strength of NiAl. The high joint strength is attributed to a very fine, rodlike eutectic structure at the joint interface that consists of a mixture of β-NiAl and γ-iron with an interrod spacing of approximately 100 nm.     

用ESCA分析等离子体处理了的氟树脂表面

用微波炉产生的微波对氟树脂进行等离子体处理,用ESCA作了表面分析。处理后的试样在533eV处出现O_(1S)的一大峰,在292eV～285eV间出现C_(1S)的连续宽谱带。氧的导入量随着处理时容器内气压(P)的降低而增大,可见随着P的降低处理的效果增大。为了得到深度方向的分布,采用了氩离子剥蚀法和掠射法。随着剥蚀的进行,由等离子体处理所导入的氧急剧减少。用掠射法测定了刚经过处理的FEP和处理后放置了70小时后的FEP的深度分布。刚处理后的试样,氧量随出射角(θ)的减少(即随分析深度的减小)而增大,氟量则减小。相反,处理后放置70小时,在15°<θ<60°的范围内,氟量增加,氧量减少。这是因为低表面自由能的含氟键段移动到表面上所致。由深度方向的分布的结果可以推断,等离子体处理的效果达到了ESCA在θ=90°的分析深度的一半左右。     

Congestion control for TCP/AQM networks using state predictive control

The purpose of this paper is to design congestion controllers for TCP/AQM networks using state predictive control and to illustrate the effectiveness of the resulting congestion controllers via SIMULINK and the ns‐2 simulator. Linearized models of TCP/AQM networks can be simply described as linear systems with information delay. Using state predictive control, these linear systems with an information delay are equivalent to linear systems with no delay. Thus, congestion controllers (AQM mechanisms) can be designed by using linear control theory. In this paper, LQ control with an observer is adopted for linear systems with no delay which describe linearized systems of TCP/AQM networks. Finally the designed state predictive controllers using LQ control with an observer are implemented and some simulation results obtained with SIMULINK and the ns‐2 simulator are presented. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 41–47, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20405