Evaluation of flow regimes in a semi-cylindrical spouted bed through statistical, mutual information, spectral and Hurst`s analysis

Hydrodynamic studies were conducted in a semi-cylindrical spouted bed column of diameter 150 mm, height 1000 mm, conical base included angle of 60 degrees and inlet orifice diameter 25 mm. Pressure transducers at several axial positions were used to obtain pressure fluctuation time series with 1.2 and 2.4 mm glass beads at U/U-ms from 0.3 to 1.6, and static bed depths from 150 to 600 mm. The conditions covered several flow regimes (fixed bed, incipient spouting, stable spouting, pulsating spouting, slugging, bubble spouting and fluidization). Images of the system dynamics were also acquired through the transparent walls with a digital camera. The data were analyzed via statistical, mutual information theory, spectral and Hurst`s Rescaled Range methods to assess the potential of these methods to characterize the spouting quality. The results indicate that these methods have potential for monitoring spouted bed operation.

Kinematic and non-linear analysis of foldable barrel vaults

Kinematic analysis is conducted to derive the geometric constraints for the geometric design of foldable barrel vaults (FBV) composed of polar or angulated scissor units. Non-linear structural analysis is followed to determine the structural response of FBVs in the fully deployed configuration under static loading. Two load cases are considered: cross wind and longitudinal wind. The effect of varying member sizes, depth-to-span ratio and geometric imperfections is examined. (C) 2000 Elsevier Science Ltd. All rights reserved.

GLOBAL POSTURAL REEDUCATION AND STATIC STRETCHING EXERCISES IN THE TREATMENT OF MYOGENIC TEMPOROMANDIBULAR DISORDERS: A RANDOMIZED STUDY

Objective: The purpose of this study was to compare 2 different interventions, global postural reeducation (GPR) and static stretching exercises (SS), in the treatment of women with temporomandibular disorders (TMDs). Methods: A total of 28 subjects with TMDs were randomized into 2 treatment groups: GPR, where therapy involved muscle global chain stretching, or SS, with conventional static stretching; but only 24 completed the study. Eight treatment sessions lasting 40 minutes each (weekly) were performed. Assessments were conducted at baseline, immediately after treatment end, and 2 months later. Measurements included pain intensity at the temporomandibular joint, headache, cervicalgia, teeth clenching, ear symptoms, restricted sleep, and difficulties for mastication, using a visual analogue scale. In addition, electromyographic activity and pain thresholds were measured at the masseter, anterior temporalis, stemocleidomastoid, and upper trapezius muscles. Two-way analysis of variance with Tukey post hoc test was used for between-group comparisons. Significance level was .05. Results: Comparing the pain assessments using the visual analogue scale, no significant differences were seen with the exception of severity of headaches at treatment end (GPR, 3.92 +/- 2.98 cm; SS, 1.64 +/- 1.66 cm; P < .024). In addition, no significant differences were seen for pain thresholds and for electromyographic activity (P > .05). Conclusions: For the subjects in this study, both GPR and SS were similarly effective for the treatment of TMDs with muscular component. They equally reduced pain intensity, increased pain thresholds, and decreased electromyographic activity. (J Manipulative Physiol Ther 2010;33:500-507)

Photoelastic Stress Analysis of Different Designs of Cement-Retained Fixed Partial Dentures on Morse Taper Oral Implants

There is no consensus in literature regarding the best plan for prosthetic rehabilitation with partial multiple adjacent implants to minimize stress generated in the bone-implant interface. The aim of this study was to evaluate the biomechanical behavior of cemented fixed partial dentures, splinted and nonsplinted, on Morse taper implants and with different types of coating material (ceramic and resin), using photoelastic stress analysis. A photoelastic model of an interposed edentulous space, missing a second premolar and a first molar, and rehabilitated with 4 different types of cemented crowns and supported by 2 adjacent implants was used. Groups were as follows: UC, splinted ceramic crowns; IC, nonsplinted ceramic crowns; UR, splinted resin crowns; and IR, nonsplinted resin crowns. Different vertical static loading conditions were performed: balanced occlusal load, 10 kgf; simultaneous punctiform load on the implanted premolar and molar, 10 kgf; and alternate punctiform load on the implanted premolar and molar, 5 kgf. Changes in stress distribution were analyzed in a polariscope, and digital photographs were taken of each condition to allow comparison of stress pattern distribution around the implants. Cementation of the fixed partial dentures generated stresses between implants. Splinted restorations distributed the stresses more evenly between the implants than nonsplinted when force was applied. Ceramic restorations presented better distribution of stresses than resin restorations. Based on the results obtained, it was concluded that splinted ceramic restorations promote better stress distribution around osseointegrated implants when compared with nonsplinted crowns; metal-ceramic restorations present less stress concentration and magnitude than metal-plastic restorations.

The reliability of video based time motion analysis

Time motion analysis is extensively used to assess the demands of team sports. At present there is only limited information on the reliability of measurements using this analysis tool. The aim of this study was to establish the reliability of an individual observer's time motion analysis of rugby union. Ten elite level rugby players were individually tracked in Southern Hemisphere Super 12 matches using a digital video camera. The video footage was subsequently analysed by a single researcher on two occasions one month apart. The test-retest reliability was quantified as the typical error of measurement (TEM) and rated as either good (10% TEM). The total time spent in the individual movements of walking, jogging, striding, sprinting, static exertion and being stationary had moderate to poor reliability (5.8-11.1% TEM). The frequency of individual movements had good to poor reliability (4.3-13.6% TEM), while the mean duration of individual movements had moderate reliability (7.1-9.3% TEM). For the individual observer in the present investigation, time motion analysis was shown to be moderately reliable as an evaluation tool for examining the movement patterns of players in competitive rugby. These reliability values should be considered when assessing the movement patterns of rugby players within competition.

Analysis of functionally graded sandwich plate structures with piezoelectric skins, using B-spline finite strip method

Functionally graded materials are composite materials wherein the composition of the constituent phases can vary in a smooth continuous way with a gradation which is function of its spatial coordinates. This characteristic proves to be an important issue as it can minimize abrupt variations of the material properties which are usually responsible for localized high values of stresses, and simultaneously providing an effective thermal barrier in specific applications. In the present work, it is studied the static and free vibration behaviour of functionally graded sandwich plate type structures, using B-spline finite strip element models based on different shear deformation theories. The effective properties of functionally graded materials are estimated according to Mori-Tanaka homogenization scheme. These sandwich structures can also consider the existence of outer skins of piezoelectric materials, thus achieving them adaptive characteristics. The performance of the models, are illustrated through a set of test cases. (C) 2012 Elsevier Ltd. All rights reserved.

Modelling and aerodynamic simulation of a vehicle and failure analysis of a laminated front fender

Master Thesis in Mechanical Engineering field of Maintenance and Production

Static and hydrodynamic monitoring of citalopram based on its electro-oxidation behavior at a glassy-carbon surface

The electrooxidative behavior of citalopram (CTL) in aqueous media was studied by cyclic voltammetry (CV) and square-wave voltammetry (SWV) at a glassy-carbon electrode. The electrochemical behaviour of CTL involves two electrons and two protons in the irreversible and diffusion controlled oxidation of the tertiary amine group. The maximum analytical signal was obtained in a phosphate buffer (pH ¼ 8.2). For analytical purposes, an SWV method and a flow-injection analysis (FIA) system with amperometric detection were developed. The optimised SWV method showed a linear range between 1.10 10 5–1.20 10 4 molL 1, with a limit of detection (LOD) of 9.5 10 6 molL 1. Using the FIA method, a linear range between 2.00 10 6–9.00 10 5 molL 1 and an LODof 1.9 10 6 molL 1 were obtained. The validation of both methods revealed good performance characteristics confirming applicability for the quantification of CTL in several pharmaceutical products.

Static-priority scheduling of sporadic messages on a wireless channel

Consider the problem of scheduling sporadic messages with deadlines on a wireless channel. We propose a collision-free medium access control (MAC) protocol which implements static-priority scheduling and present a schedulability analysis technique for the protocol. The MAC protocol allows multiple masters and is fully distributed; it is an adaptation to a wireless channel of the dominance protocol used in the CAN bus. But unlike that protocol, our protocol does not require a node having the ability to receive an incoming bit from the channel while transmitting to the channel.

Response time analysis of slotted WiDom in noisy wireless channels

WiDom is a wireless prioritized medium access control protocol which offers very large number of priority levels. Hence, it brings the potential to employ non-preemptive static-priority scheduling and schedulability analysis for a wireless channel assuming that the overhead of WiDom is modeled properly. Recent research has created a new version of WiDom (we call it: Slotted WiDom) which offers lower overhead compared to the previous version. In this paper we propose a new schedulability analysis for slotted WiDom and extend it to work for message streams with release jitter. Furthermore, to provide an accurate timing analysis, we must include the effect of transmission faults on message latencies. Thus, in the proposed analysis we consider the existence of different noise sources and develop the analysis for the case where messages are transmitted under noisy wireless channels. Evaluation of the proposed analysis is done by testing the slotted WiDom in two different modes on a real test-bed. The results from the experiments provide a firm validation on our findings.

Slotted wiDom: schedulability analysis and its experimental validation

WiDom is a wireless prioritized medium access control protocol which offers a very large number of priority levels. Hence, it brings the potential to employ non-preemptive static-priority scheduling and schedulability analysis for a wireless channel assuming that the overhead of WiDom is modeled properly. One schedulability analysis for WiDom has already been proposed but recent research has created a new version of WiDom (we call it: Slotted WiDom) with lower overhead and for this version of WiDom no schedulability analysis exists. In this paper we propose a new schedulability analysis for slotted WiDom and extend it to work also for message streams with release jitter. We have performed experiments with an implementation of slotted WiDom on a real-world platform (MicaZ). We find that for each message stream, the maximum observed response time never exceeds the calculated response time and hence this corroborates our belief that our new scheduling theory is applicable in practice.

Dimensioning and worst-case analysis of cluster-tree sensor networks

Modeling the fundamental performance limits of Wireless Sensor Networks (WSNs) is of paramount importance to understand their behavior under the worst-case conditions and to make the appropriate design choices. This is particular relevant for time-sensitive WSN applications, where the timing behavior of the network protocols (message transmission must respect deadlines) impacts on the correct operation of these applications. In that direction this paper contributes with a methodology based on Network Calculus, which enables quick and efficient worst-case dimensioning of static or even dynamically changing cluster-tree WSNs where the data sink can either be static or mobile. We propose closed-form recurrent expressions for computing the worst-case end-to-end delays, buffering and bandwidth requirements across any source-destination path in a cluster-tree WSN. We show how to apply our methodology to the case of IEEE 802.15.4/ZigBee cluster-tree WSNs. Finally, we demonstrate the validity and analyze the accuracy of our methodology through a comprehensive experimental study using commercially available technology, namely TelosB motes running TinyOS.

New schedulability analysis for WiDom

WiDom is a wireless prioritized medium access control (MAC) protocol which offers a very large number of priority levels. Hence, it brings the potential for employing non-preemptive static-priority scheduling and schedulability analysis for a wireless channel assuming that the overhead of WiDom is modeled properly. One schedulability analysis for WiDom has already been proposed but recent research has created a new version of WiDom with lower overhead (we call it: WiDom with a master node) and for this version of WiDom no schedulability analysis exists. Also, common to the previously proposed schedulability analyses for WiDom is that they cannot analyze message streams with release jitter. Therefore, in this paper we propose a new schedulability analysis for WiDom (with a master node). We also extend the WiDom analyses (with and without master node) to work also for message streams with release jitter.

Static-priority scheduling over wireless networks with multiple broadcast domains

We propose a wireless medium access control (MAC) protocol that provides static-priority scheduling of messages in a guaranteed collision-free manner. Our protocol supports multiple broadcast domains, resolves the wireless hidden terminal problem and allows for parallel transmissions across a mesh network. Arbitration of messages is achieved without the notion of a master coordinating node, global clock synchronization or out-of-band signaling. The protocol relies on bit-dominance similar to what is used in the CAN bus except that in order to operate on a wireless physical layer, nodes are not required to receive incoming bits while transmitting. The use of bit-dominance efficiently allows for a much larger number of priorities than would be possible using existing wireless solutions. A MAC protocol with these properties enables schedulability analysis of sporadic message streams in wireless multihop networks.

Schedulability analysis of generalized multiframe traffic on multihop-networks comprising software-implemented ethernet switches

Consider a multihop network comprising Ethernet switches. The traffic is described with flows and each flow is characterized by its source node, its destination node, its route and parameters in the generalized multiframe model. Output queues on Ethernet switches are scheduled by static-priority scheduling and tasks executing on the processor in an Ethernet switch are scheduled by stride scheduling. We present schedulability analysis for this setting.