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The specification of distributed sensing and control

Logical Sensor System Specification (LSS) has been introduced as a convenient means for specifying multi-sensor systems and their implementations. In this article we demonstrate how control issues can be handled in the context of LSS. In particular, the Logical Sensor Specification is extended to include a control mechanism which permits control information to (1) flow from more centralized processing to more peripheral processes, and (2) be generated locally in the logical sensor by means of a micro-expert system specific to the interface represented by the given logical sensor. Examples are given including a proposed scheme for controlling the Utah/MIT dextrous hand.     

Magnetization transfer for the assessment of bowel fibrosis in patients with Crohn’s disease: initial experience

Object

To assess the feasibility of magnetization transfer (MT) imaging of the bowel wall in patients with Crohn’s disease (CD), and to evaluate its utility for the detection of intestinal fibrosis.

Materials and methods

In this prospective study, 31 patients (age 39.0 ± 13.2 years) with CD were examined in a 1.5T MR scanner. To establish a standard of reference, two independent readers classified the patients in different disease states using standard MR enterography, available clinical data and histological findings. In addition to the standard protocol, a 2D gradient-echo sequence (TR/TE 32 ms/2.17 ms; flip angle 25°) with/without 1,100 Hz off-resonance prepulse was applied. MT ratios (MTR) of the small bowel wall were computed off-line on a pixel-by-pixel basis.

Results

The MT sequences acquired images of sufficient quality and spatial resolution for the evaluation of the small bowel wall without detrimental motion artefacts. In normal bowel wall segments, an intermediate MTR of 25.4 ± 3.4 % was measured. The MTR was significantly increased in bowel wall segments with fibrotic scarring (35.3 ± 4.0 %, p < 0.0001). In segments with acute inflammation, the mean MTR was slightly smaller (22.9 ± 2.2 %).

Conclusion

MT imaging of the small bowel wall is feasible in humans with sufficient image quality and may help with the identification of fibrotic scarring in patients with CD.     

Charge-induced asymmetrical displacement of an aligned carbon nanotube buckypaper actuator

Randomly dispersed carbon nanotube buckypaper (BP) actuation in open air, ambient conditions was shown to correlates well with the carbon-carbon bond length changes due to charge and discharge. The displacement of magnetically aligned BP actuators applied with a positive voltage was 450% higher than that for an applied negative voltage, which verifies the asymmetrical deformation characteristics of nanotube actuation. Charge-injected actuation of aligned BP can produce a 0.22% strain by applying a high voltage (1100 V). The aligned BP actuators exhibited a higher strain than did randomly dispersed BP actuators. The aligned BP actuators showed stable and fast responses under ambient, open air conditions without electrolytes, which offers direct experimental verification that BP actuation comes directly from carbon-carbon bond deformation due to charge and discharge processes. The nanotube BP actuators demonstrated a much faster response compared to other polymer-based actuators.     

Synthesis and processing of PMMA carbon nanotube nanocomposite foams

Poly(methyl methacrylate) (PMMA) multi-walled carbon nanotubes (MWCNTs) nanocomposites were synthesized by several methods using both pristine and surface functionalized carbon nanotubes (CNTs). Fourier transform infrared (FTIR) spectroscopy was used to characterize the presence and types of functional groups in functionalized MWCNTs, while the dispersion of MWCNTs in PMMA was characterized using scanning electron microscopy (SEM). The prepared nanocomposites were foamed using carbon dioxide (CO₂) as the foaming agent. The cell morphology was observed by SEM, and the cell size and cell density were calculated via image analysis. It was found that both the synthesis methods and CNTs surface functionalization affect the MWCNTs dispersion in the polymer matrix, which in turn profoundly influences the cell nucleation mechanism and cell morphology. The MWCNTs are efficient heterogeneous nucleation agents leading to increased cell density at low particle concentrations. A mixed mode of nucleation mechanism was observed in nanocomposite foams in which polymer rich and particle rich region co-exist due to insufficient particle dispersion. This leads to a bimodal cell size distribution. Uniform dispersion of MWCNTs can be achieved via synergistic combination of improving synthesis methodology and CNTs surface functionalization. Foams from these nanocomposites exhibit single modal cell size distribution and remarkably increased cell density and reduced cell size. An increase in cell density of ∼70 times and reduction of cell size of ∼80% was observed in nanocomposite foam with 1% MWCNTs.     

Effects of crack growth on the load-displacement characteristics of precracked specimens under bending

A critical evaluation of the feasibility of obtaining crack growth parameters from quasi-static bend tests is presented. First derived are the governing differential equations which characterize the time-history of bend test parameters for a given elastic material exhibiting power law crack growth behavior v = v_max(K_I/K_IC)^N. A numerical solution scheme is then developed which is capable of solving the initial value problem, thus quantitatively assessing the influence of crack growth on the load-displacement output. The results of this analysis indicate that in order to calculateK_IC accurately based on the peak load data, the loading rate has to be set sufficiently fast compared to v_max (but below dynamic rates), otherwise, it will generally overestimate its true value whenever slow crack growth occurs during the test; and that for high N materials the flexural test method gives a broad error band inN prediction and hence is not a reliable technique. However, it can be used by a designer to quickly screen the new materials with high Nvalues which are potential candidates for structural application.     

ERP systems adoption: An exploratory study of the organizational factors and impacts of ERP success

We examined the relationships between the success of ERP system adoption, extent of business process improvement (BPI), and organizational performance and investigated the associations between the outcomes of these initiatives and such organizational factors as strategic intent, senior management support, and the status of the IT function within a company. A correlation analysis of 96 firms was made to test our hypothesis that the strategic intent to use ERP was closely related to the success of BPI, ERP, and organizational performance. The results also demonstrated that CEO-IT distance may have little direct bearing on the outcomes of ERP and BPI initiatives. A closer CEO-IT reporting relationship, however, was found to be associated with higher levels of senior management support for both types of enterprise projects. This empirical evidence reinforced the long-held assumption that organization-level benefits, BPI, and ERP success were closely related; and that these relationships were subject to the influence of the organizational variables.     

Towards building large scale live media streaming framework for a U-city

This paper proposes camera and media stream management techniques at the middleware level for implementing a U-City (ubiquitous city). The study focuses on overcoming the difficulties associated with developing middleware capable of processing and streaming multimedia data from a large number of cameras by expanding the traditional media processing technology. The content of the study can be classified into two main categories: One is a camera array management technique that involves the middleware-level framework and protocol for managing the camera array. The other is the media stream management technique for effective delivery management and processing of the multimedia streams from the camera array.

Surface Chemical Study of Sheet Molded Composite (SMC) as Related to Adhesion

Surfaces of commercial sheet molded composite (SMC) materials have been characterized by X-ray photoelectron spectroscopy (XPS) before and after various surface treatments. Surface treatments included cleaning with methylene chloride, abrasion using methylene chloride and a Scotch Brite ® abrasive pad, and application of an isocyanate primer. The pretreated SMC materials were bonded using a polyurethane adhesive. Bonded coupons were tested under a variety of conditions using the lap shear technique. Lap shear test results for specimens bonded following the abrasion and primer pretreatment indicated a favorable fracture force and mode of failure. Surface analysis studies were used to characterize the pretreated and failed surfaces.