A PNEUMATIC POSITIONING DEVICE COUPLED WITH PIEZOELECTRIC SELF‐MOVING MECHANISM

This paper reports a new pneumatic positioning device coupled with a piezoelectric self‐moving mechanism to overcome the main disadvantages of the inherent poor positioning accuracy obtained by traditional pneumatic cylinder. The new driving mechanism is to mount a piezoelectric Impact Drive Mechanism (IDM) to the controlled sliding table driven by the pneumatic cylinder. Based on the configuration, the first step of positioning process is to actuate the sliding table with rough position accuracy but with the benefits of high‐speed and large‐range due to the pneumatic cylinder. The second step is to drive the sliding table with high position accuracy by utilizing the impact force of IDM. The experimental results show that the controlled sliding table is successfully positioned in 0.236 s with rough accuracy of 10 μm and with the stroke of 100 mm by utilizing the pneumatic cylinder, and the final positioning accuracy of 10 nm with respect to the terminated position of the first‐stage control is obtained in 1.479 s due to the actuations of IDM. It is shown that the pneumatic positioning device coupled with IDM has attractive practical applications in the field of precision industry.     

Effects of die location on hot-carrier response of plasma-etchedNMOS devices

Plasma-process-induced charging voltage for a device may be positive (gate is positive with respect to the substrate) or negative depending on the location of the device on the wafer. The negative charging damage increases the number of trapped holes closer to Si-SiO ₂ interface while the positive charging damage does not. This number of trapped holes also depends on the antenna ratio. The trapped holes closer to the Si-SiO₂ interface gets compensated by hot electrons injected during hot-carrier stressing. Thus, the type of charging voltage and the antenna size determines the hot-carrier response of a device. In addition, the differences in hot-carrier response for devices with varying antenna ratio are shown to be varying linearly with the differences in prestress subthreshold characteristics. This finding has the potential to reduce the hot-carrier stressing time or determine the most vulnerable devices without actually carrying out the experiments     

The bilayer lipid membrane (BLM) under electrical fields

Transmembrane voltage pulses are known to create transient "pores" in the lipid bilayer. This phenomenon, termed electroporation (EP), has been extensively investigated. EP occurs following electric field pulses of up to 10/sup 6/ V/cm with duration between /spl mu/s and ms to membranes in close contact and is believed to initiate primarily in the lipid bilayer. This paper begins with a brief summary of the origin of lipid bilayer research. One of practical applications of EP is cell transfection for gene expression. Other applications include encapsulation of drugs in controlled-release and insertion of proteins in living cells. It seems likely that the presence of membrane proteins affect the EP of the lipid bilayer by changing its mechanical properties. Transport of ions such as Na/sup +/, K/sup +/, Cl/sup -/ through membrane channels discharge the membrane potential, and at times an external pulse of sufficient amplitude and duration tends to cause dielectric breakdown of the lipid bilayer. Molecular transport through primary pores and pores enlarged by secondary processes provides the basis for transporting molecules into and out of cells. Some recent relevant papers on BLM under electric fields are referenced.     

Robust estimation for range image segmentation and reconstruction

This correspondence presents a segmentation and fitting method using a new robust estimation technique. We present a robust estimation method with high breakdown point which can tolerate more than 80% of outliers. The method randomly samples appropriate range image points in the current processing region and solves equations determined by these points for parameters of selected primitive type. From K samples, we choose one set of sample points that determines a best-fit equation for the largest homogeneous surface patch in the region. This choice is made by measuring a residual consensus (RESC), using a compressed histogram method which is effective at various noise levels. After we get the best-fit surface parameters, the surface patch can be segmented from the region and the process is repeated until no pixel left. The method segments the range image into planar and quadratic surfaces. The RESC method is a substantial improvement over the least median squares method by using histogram approach to inferring residual consensus. A genetic algorithm is also incorporated to accelerate the random search     

Static and dynamic approaches to modeling end-to-end routing in circuit-switched networks

We present two routing strategies, identified herein as static least loaded routing (SLLR) and dynamic least loaded routing (DLLR). Dynamic routing in circuit-switched networks has been an active research topic. The literature to date in this area has focused on how to choose the "best" alternate route for overflow traffic from a direct route, within a network setting referred to as the backbone network. The traffic type considered in the literature has typically been one with a single destination. Least loaded routing (LLR) is an example of a state-dependent routing that selects the least loaded two-link alternate route when traffic overflows from the direct route. Motivated by the development of an emerging traffic type, called multidestination traffic, whose destination is not necessarily limited to a single location, we provide two routing strategies that deal with both the routing of the multiple-destination traffic to the extended network dimension, which is referred to as the destination network, and the routing of the backbone network traffic via LLR. In selecting the destination for multidestination traffic, SLLR employs static information, whereas DLLR employs real-time load status information concerning the destination links. We develop fixed-point models for both DLLR and SLLR. We also validate and compare the models through simulation. The results suggest that DLLR outperforms SLLR in all the scenarios, demonstrating the benefit of state-dependent routing in an end-to-end network. Further, the DLLR scheme improves if an "incident preference" rule is adopted; the rule allows a multidestination call to first choose the incident destination link, if any.     

Mutual derivability of operations in program algebras. I

Translated from Kibernetika, No. 1, pp. 35–39, 49, January–February, 1988.     

Influence of the extraction order of attenuation poles in a lowpass filter

The choice of the extraction order of the attenuation poles in the classical synthesis of a ladder filter will influence the dispersion of the element values and the sensitivity of the transmittance s12 to the element values. The purpose of the letter is to investigate these two characteristics by an exhaustive study of a typical example.