Application of modern reliability database techniques to military system data

This paper focuses on analysis techniques of modern reliability databases, with an application to military system data. The analysis of military system data base consists of the following steps: clean the data and perform operation on it in order to obtain good estimators; present simple plots of data; analyze the data with statistical and probabilistic methods. Each step is dealt with separately and the main results are presented.Competing risks theory is advocated as the mathematical support for the analysis. The general framework of competing risks theory is presented together with simple independent and dependent competing risks models available in literature. These models are used to identify the reliability and maintenance indicators required by the operating personnel. Model selection is based on graphical interpretation of plotted data.     

意大利面，还是法国菜？

当你看到这个标题的时候，是不是饿了？很遗憾，我说的是上届世界杯冠亚军今年早早被淘汰的事儿——意大利队太面了,法国队太菜了。“面”和“菜”本是食物界词语，但是北京话把这两个字赋予新的含义，“面”是望文生义，形容一个人懦弱、胆小或不敢承担责任。比如“你这人真够面的．他骂你都不还嘴？”，     

Potentials of using nanofiltration to recover phosphorus from sewage sludge.

Due to the depletion of mineral phosphorus resources there is an increasing demand for efficient phosphorus recovery technologies. In this study the potential of nanofiltration to recover phosphorus from pre-treated sewage sludge is investigated. The efficiency of three commercial nanofiltration membranes (Desal 5DK, NP030; MPF34) was tested using model solutions. Desal 5DK showed the best selectivity for phosphorus. A pH of lower than 1.5 was found to be most suitable. Desal 5DK was used on four different sewage sludge ash eluates and on one sewage sludge. In these experiments it was shown that a separation of phosphorus from undesired components such as heavy metals was possible with significant variations in the efficiency for the different ash and sludge types. Additionally the achievable product recovery was investigated with model solutions. A product recovery of 57.1% was attained for pH 1 and 41.4% for pH 1.5.     

Semi-centralised supply and treatment systems for (fast growing) urban areas.

Mega cities with rapid growth are challenged by two main problems concerning water supply and sanitation. One is water scarcity because local demand exceeds local supply. The other is that the infrastructure for water supply and the collection and treatment of wastewater cannot keep up with the rapid growth of the mega cities. The transfer of conventional centralised water and wastewater systems from industrialised countries to mega cities does not seem appropriate, because of the rapid and almost unpredictable growth in mega cities on the one hand and the regional shortage of water which requires an economical use and reuse wherever possible on the other hand. The transition from centralised to semi-centralised supply and treatment systems (SESATS) may be one method of resolution to the grave discrepancy between the rapid growth of cities and the provision of supply and treatment infrastructure. One important aspect of planning semi-centralised wastewater collection and treatment infrastructure including intra-urban water reuse is the assessment of the optimal size. Therefore, factors and indicators, which have an effect on the scale of semi-centralised sanitation systems, have to be developed. Beside the introduction in SESATS some of these factors, criteria and indicators and their effects on the system's scale will be introduced in this paper.     

Influence of a hydrophobin underlayer on the structuring and antimicrobial properties of ZnO films

Adhesion to substrate and antimicrobial efficiency of pulsed laser-deposited ZnO nanostructures were significantly increased by interposing a buffer nano-layer of hydrophobin. The hydrophobin interlayer increased by eight times the ZnO film resilience to wash in water, while in alkaline or acidic artificial sweat, it increased by 2 and 1.2 times, respectively, as compared to textiles covered with ZnO films only. Hydrophobin boosted the biocide effect of ZnO nanostructured films in case of Candida albicans and mold mix inoculum cultures by 50 and 30 %, respectively. An interpretation of these phenomena is advanced based upon the results of the structural investigations.     

Dobutamine-atropine stress echocardiography in elderly patients unable to perform an exercise test. Hemodynamic characteristics, safety, and prognostic value

OBJECTIVE: To establish the hemodynamic effects, safety, and prognostic value of dobutamine-atropine stress echocardiography in patients 70 years of age or older. DESIGN AND SETTING: Observational study at a university hospital. PATIENTS: One hundred seventy-nine patients (mean age, 75 years; range, 70 to 90 years) referred for chest pain (n = 73) or preoperative risk assessment for major vascular noncardiac surgery (n = 106). MEASUREMENTS: All patients underwent clinical evaluation and dobutamine-atropine stress test. RESULTS: One hundred seventy-nine stress tests were performed. Test end points were the target heart rate (85% of theoretical maximum heart rate), reached in 165 tests (92%); inadequate echo images, two tests (1%); and side effects, 12 tests (7%). Side effects that caused a premature end of the test were severe chest pain (n = 5 [2.8%]), electrocardiographic changes (n = 1 [0.6%]), hypotension (n = 2 [1.1%]), chills (n = 2 [1.1%]), and cardiac arrhythmias (paroxysmal atrial fibrillation) (n = 2 [1.1%]). New wall motion abnormalities as a marker of myocardial ischemia occurred in 50 tests (28%). No death or myocardial infarction occurred during the test. Perioperative events occurred in 12 patients (four cardiac deaths, three myocardial infarctions, and five episodes of unstable angina). During 16 +/- 6 months (mean +/- SD) of follow-up of 166 patients, 22 cardiac events occurred (eight cardiac deaths, four myocardial infarctions, and 10 episodes of unstable angina pectoris). By multivariate regression analysis, only perioperative cardiac events (odds ratio, 51; 95% confidence interval, 5.8 to 454) and late cardiac events (odds ratio, 5.2; 95% confidence interval, 2.0 to 14) were correlated with new wall motion abnormalities during stress. CONCLUSION: Dobutamine-atropine stress echocardiography is a feasible and safe test for assessing elderly patients with suspected and/or proven coronary artery disease, providing useful prognostic information for perioperative and late cardiac risk with relatively few side effects.     

A robust, discrete, near time-optimal controller for hard disk drives

This paper presents a robust, discrete, near time-optimal control algorithm for hard disk drives. Building on the continuous-time control law of Newman [Trans. Automatic Control 35 (7) (1990) 841] and Newman and Souccar [J. Dynamic Syst. Measure. Control 113 (1991) 363], the chattering phenomenon for continuous-time systems is first examined, and it is shown how additional chattering can occur in the discrete-time case. A criterion for the selection of control parameters to prevent chattering in the discrete-time case while assuring controller stability is then suggested. The controller developed is applied to a commercial hard disk drive. Compared to the more commonly used PTOS, the proposed controller significantly reduces chattering while maintaining comparable seek time to reach the destination track.     

Improved identification of coronary artery disease in patients with left bundle branch block by use of dobutamine stress echocardiography and comparison with myocardial perfusion tomography

The purpose of this report is to compare a computed tomography (CT) injury severity scale for hepatic and splenic injury with the following outcome measures: requirement for surgical hemostasis, requirement for blood transfusion and late complications. Sixty-nine children with isolated hepatic injury and 53 with isolated splenic injury were prospectively classified at CT according to extent of parenchymal involvement. Clinical records were reviewed to determine clinical outcome. Ninety-seven children (80%) were managed non-operatively without transfusion. One child with hepatic injury required surgical hemostasis, and 17 (25%) required transfusion of blood. Increasing severity of hepatic injury at CT was associated with progressively greater frequency of transfusion (P = 0.002 by chi 2-test). One child with splenic injury underwent surgery and eight (15%) required transfusion of blood. Splenic injury grade at CT did not correlate with frequency (P = 0.41 by chi 2-test) or amount (P = 0.35 by factorial analysis of variance) of transfusion. There was one late complication in the nonsurgical group. A majority of children with hepatic and splenic injury were managed non-operatively without requiring blood transfusion. The severity of injury by CT scan did not correlate with need for surgery. Increasing grade of hepatic injury at CT was associated with increasing frequency of blood transfusion. CT staging was not discriminatory in predicting transfusion requirement in splenic injury.     

Active vibration control in palletised workholding system for milling

This paper presents the development implementation and testing of an active controlled palletised workholding system for milling operations. The traditional approach to controlling vibration in a machining system is to develop control systems for cutting tools or machine spindles as in the case of milling machines. This work is a deviation from the traditional approach and targets a workholding system for the control of unwanted vibration. Palletised workholding systems, due to their compact design, offer an opportunity to design active control systems that are economical and easier to implement in the case of milling machines. The active control system developed here is based on an adaptive filtering algorithm, the filtered X-LMS, and employs piezo-actuators for dynamic control force. The system has been tested experimentally to demonstrate the reduction in dynamic force due to vibration. Extensive testing has been carried out to validate the performance of the system in terms of parameters of practical importance such as improvement in surface finish and increase in tool life.