Aerodynamic instability: A case history

The identification, diagnosis, and final correction of complex machinery malfunctions typically require the correlation of many parameters such as mechanical construction, process influence, maintenance history, and vibration response characteristics. The progression is reviewed of field testing, diagnosis, and final correction of a specific machinery instability problem. The case history presented addresses a unique low frequency instability problem on a high pressure barrel compressor. The malfunction was eventually diagnosed as a fluidic mechanism that manifested as an aerodynamic disturbance to the rotor assembly

On the use of a continuous metabolic syndrome score in pediatric research

<p>Abstract</p> <p>Background</p> <p>The constellation of elevated levels of abdominal adiposity, blood pressure, glucose, and triglycerides and lowered high-density lipoprotein-cholesterol has been termed the metabolic syndrome. Given the current pediatric obesity epidemic, it is perhaps not surprising that recent reports suggest the emergence of the metabolic syndrome during childhood and adolescence. The aim of this paper is to provide an overview of the derivation and utility of the continuous metabolic syndrome score in pediatric epidemiologic research.</p> <p>Methods/Design</p> <p>Data were generated from published papers related to the topic.</p> <p>Conclusion</p> <p>Although there is no universal definition in children or adolescence, recent estimates indicate that approximately 2–10% of youth possess the metabolic syndrome phenotype. Since there is no clear definition and the prevalence rate is relatively low, several authors have derived a continuous score representing a composite risk factor index (i.e., the metabolic syndrome score). This paper provides an overview of the derivation and utility of the continuous metabolic syndrome score in pediatric epidemiological research.</p

Bad expression influences time to androgen escape in prostate cancer

&lt;b&gt;OBJECTIVE&lt;/b&gt;: To assess the role of selected downstream Bcl-2 family members (Bad, Bax, Bcl-2 and Bcl-xL) in the development of androgen-independent prostate cancer (AIPC), as androgen-deprivation therapy is the treatment of choice in advanced prostate cancer, yet patients generally relapse and progress to an AI state within 18–24 months. &lt;b&gt;PATIENTS, MATERIALS AND METHODS&lt;/b&gt;: The patient cohort was established by retrospectively selecting patients with prostate cancer who had an initial response to androgen-deprivation therapy, but subsequently relapsed with AIPC. In all, 58 patients with prostate cancer were included with matched androgen-dependent (AD) and AI prostate tumours available for immunohistochemical analysis; two independent observers using a weighted-histoscore method scored the staining. Changes in Bad, Bax, Bcl-2 and Bcl-xL expression during transition to AIPC were evaluated and then correlated to known clinical variables. &lt;b&gt;RESULTS&lt;/b&gt;: High Bad expression in AD tumours was associated with an increased time to biochemical relapse (&lt;i&gt;P&lt;/i&gt; = 0.007) and a trend towards improved overall survival (&lt;i&gt;P&lt;/i&gt; = 0.053). There were also trends towards a decrease in Bad (&lt;i&gt;P&lt;/i&gt; = 0.068) and Bax (&lt;i&gt;P&lt;/i&gt; = 0.055) expression with progression to AIPC. There were no significant results for Bcl-2 or Bcl-xL. &lt;b&gt;CONCLUSION&lt;/b&gt;: There is evidence to suggest that Bad expression levels at diagnosis influence time to biochemical relapse and overall survival, and that levels of pro-apoptotic proteins Bad and Bax fall during AIPC development. Bad might therefore represent a possible positive prognostic marker and potential therapeutic target for AIPC in the future

Use of a scanning optical profilometer for toolmark characterization

An optical profilometer has been used to obtain 3-dimensional data for use in two research projects concerning toolmark quantification and identification. In the first study quantitative comparisons between toolmarks made using data from the optical system proved superior to similar data obtained using a stylus profilometer. In the second study the ability of the instrument to obtain accurate data from two surfaces intersecting at a high angle (approximately 90 degrees) is demonstrated by obtaining measurements from the tip of a flat screwdriver. The data obtained was used to produce a computer generated virtual tool, which was then employed to create virtual tool marks. How these experiments were conducted and the results obtained will be presented and discussed

Why Proper Low Pass Filter Settings on Crosshead Vibration Signals are Crucial to Minimize Risk of Missed Detects

Case StudyCrosshead guide acceleration measurements have gained mainstream acceptance by operators of API 618 recips and now joins frame velocity as a recommended shutdown parameter in the 5th edition of the API 670 Machinery Protection Standard. Knowledge surrounding proper low pass filter settings for acquisition systems performing critical shutdown function is very limited and often misapplied. This case study illustrates why the common practice of setting low pass signal filters at 2 kHz introduces risk that serious failure modes go undetected compromising plant safety, health and the environment

Isotopic evidence of a wide spectrum of feeding strategies in Southern hemisphere humpback whale baleen records

Our current understanding of Southern hemisphere humpback whale (Megaptera novaeangliae) ecology assumes high-fidelity feeding on Antarctic krill in Antarctic waters during summer, followed by fasting during their annual migration to and from equatorial breeding grounds. An increase in the number of reported departures from this feeding/fasting model suggests that the current model may be oversimplified or, alternatively, undergoing contemporary change. Information about the feeding and fasting cycles of the two Australian breeding populations of humpback whales were obtained through stable isotope analysis of baleen plates from stranded adult individuals. Comparison of isotope profiles showed that individuals from the West Australian breeding population strongly adhered to the classical feeding model. By contrast, East Australian population individuals demonstrated greater heterogeneity in their feeding. On a spectrum from exclusive Antarctic feeding to exclusive feeding in temperate waters, three different strategies were assigned and discussed: classical feeders, supplemental feeders, and temperate zone feeders. Diversity in the interannual feeding strategies of humpback whales demonstrates the feeding plasticity of the species, but could also be indicative of changing dynamics within the Antarctic sea-ice ecosystem. This study presents the first investigation of trophodynamics in Southern hemisphere humpback whales derived from baleen plates, and further provides the first estimates of baleen plate elongation rates in the species

Componential coding in the condition monitoring of electrical machines Part 2: application to a conventional machine and a novel machine

This paper (Part 2) presents the practical application of componential coding, the principles of which were described in the accompanying Part 1 paper. Four major issues are addressed, including optimization of the neural network, assessment of the anomaly detection results, development of diagnostic approaches (based on the reconstruction error) and also benchmarking of componential coding with other techniques (including waveform measures, Fourier-based signal reconstruction and principal component analysis). This is achieved by applying componential coding to the data monitored from both a conventional induction motor and from a novel transverse flux motor. The results reveal that machine condition monitoring using componential coding is not only capable of detecting and then diagnosing anomalies but it also outperforms other conventional techniques in that it is able to separate very small and localized anomalies

Integrally Geared Compressor Failure due to excessive pipe strain

Case StudyFollowing a complete overhaul of an integrally geared compressor, the compressor failed upon startup. The compressor ran for 7 seconds before the machinery protection system tripped the machine. During disassembly, it was discovered that three of the four impellers rubber severely against the impeller eye labyrinth seals and the accompanying dry gas seals were destroyed from excessive pipe strain. This case study highlights the failure data, corrective actions taken in investigation and reassembly of the machine

Reciprocating Compressor Motor Vibration During Initial Start-up

Case StudyShortly after start-up of a new 4 throw 3 stage reciprocating compressor, high motor vibration was recorded on a machinery monitoring system. The single bearing motor vibration levels reached 260 microns (10.25 mils) during a run that dissipated to 25 microns (1 mil) after 20 minutes but repeated intermittently over following runs. An investigation identified several contributing factors that ultimately led to realignment of the motor and disassembly of the motor bearing seals, where damaged PTFE seals were discovered

Construct validity of a continuous metabolic syndrome score in children

Objective: The primary purpose of this study was to examine the construct validity of a continuous metabolic syndrome score (cMetS) in children. The secondary purpose was to identify a cutpoint value(s) for an adverse cMetS based on receiver operating characteristic (ROC) curve analysis. Methods: 378 children aged 7 to 9 years were assessed for the metabolic syndrome which was determined by age-modified cutpoints. High-density-lipoprotein cholesterol, triglycerides, the homeostasis assessment model of insulin resistance, mean arterial pressure, and waist circumference were used to create a cMetS for each subject. Results: About half of the subjects did not possess any risk factors while about 5% possessed the metabolic syndrome. There was a graded relationship between the cMetS and the number of adverse risk factors. The cMetS was lowest in the group with no adverse risk factors (-1.59 ± 1.76) and highest in those possessing the metabolic syndrome (≥3 risk factors) (7.05 ± 2.73). The cutoff level yielding the maximal sensitivity and specificity for predicting the presence of the metabolic syndrome was a cMetS of 3.72 (sensitivity = 100%, specificity = 93.9%, and the area of the curve = 0.978 (0.957-0.990, 95% confidence intervals). Conclusion: The results demonstrate the construct validity for the cMetS in children. Since there are several drawbacks to identifying a single cut-point value for the cMetS based on this sample, we urge researchers to use the approach herein to validate and create a cMetS that is specific to their study population