Reliability Program Development and Implementation for a Remote Piloted Vehicle

This paper decribes the implementation of a Reliability Program from the definition of a major project throughout development, to operational flights. The Reliability Program enjoyed full support by IAI Engineering Division management without any outside (client) pressure and enabled the reliability group to prove its competence and usefulness to all levels of design engineers and prototype shop engineers and management. A life cycle cost analysis was used at the start of the program to determine reliability goals; systematic design reviews were conducted during the program; environmental testing was applied to all components and systems belonging to both the aircraft and the ground station; all failures were analysed and improvements were made whenever needed; prototype quality assurance was reorganized. All these were done while taking into account that the remote piloted aircraft was not manrated and had to fit quite tight cost levels. Reliability group was monitored during flight test and operational flight and significant improvements were achieved during these phases. In short, a text-book reliability program was successfully applied. The RPV is a most successful program from all points of view: proven operational capability, survivability and mission reliability. This project demonstrated that preliminary reliability evaluations can be achieved when there is a close partnership among project management, design engineering and reliability & maintainability engineering - and most important - full management support. The advantage of having a reliability and maintainability group completely dedicated to the project was proven.     

An iterative method for calculating the shielding effectiveness andlight transmittance of multilayered media

A simple, rapid, and accurate numerical method is presented for calculating the shielding effectiveness and the light transmittance of multilayered media. A uniform treatment is used to obtain the shielding effectiveness of the layers at microwave frequencies and their light transmittance at optical frequencies. The method is completely general and does not involve any approximation. It can be applied at any frequency, for vertical or oblique incidence, to lossless or lossy, isotropic or anisotropic media consisting of any number of dielectric and metallic layers. In order to illustrate the versatility of the method, the shielding effectiveness and the light transmittance of two different structures consisting of a gold film deposited over a plastic substrate and of a plastic substrate sandwiched between two gold films are analyzed under different conditions     

Stability of annular flow

A simple transient model using an unsteady state continuity equation and a quasi steady momentum equation is used to analyse the stability of co-current and counter-current annular flows. It is shown that unstable steady state solutions may take place in both cases. Application of the theory is demonstrated for the problem of flooding and flow reversal.     

IPSEP-COLA: an incremental procedure for separation constraint layout of graphs

Existing information-visualization techniques that target small screens are usually limited to exploring a few hundred items. In this article we present a scatterplot tool for personal digital assistants that allows the handling of many thousands of items. The application's scalability is achieved by incorporating two alternative interaction techniques: a geometric-semantic zoom that provides smooth transition between overview and detail, and a fisheye distortion that displays the focus and context regions of the scatterplot in a single view. A user study with 24 participants was conducted to compare the usability and efficiency of both techniques when searching a book database containing 7500 items. The study was run on a pen-driven Wacom board simulating a PDA interface. While the results showed no significant difference in task-completion times, a clear majority of 20 users preferred the fisheye view over the zoom interaction. In addition, other dependent variables such as user satisfaction and subjective rating of orientation and navigation support revealed a preference for the fisheye distortion. These findings partly contradict related research and indicate that, when using a small screen, users place higher value on the ability to preserve navigational context than they do on the ease of use of a simplistic, metaphor-based interaction style     

Matrix Factorization Techniques for Recommender Systems

As the Netflix Prize competition has demonstrated, matrix factorization models are superior to classic nearest-neighbor techniques for producing product recommendations, allowing the incorporation of additional information such as implicit feedback, temporal effects, and confidence levels.     

Hazards associated with the use of chlorinated oxidation pond effluents for irrigation

Eight milligrams per litre chlorine applied to oxidation pond effluents caused no algal kill within the first 2 h of contact. The available chlorine attacks bacteria causing coliform count to drop from 10⁵ 100 ml⁻¹ to a few tens. Enterovirus counts dropped from about 80 100 ml⁻¹ before chlorination to 37 100 ml⁻¹ (after chlorination). Vibrio cholerae (El-Tor) were killed under these adverse conditions, and MPN dropped from 10³ 100 ml⁻¹ in the influent wastes to 2 100 ml⁻¹ in the effluents. A 5 mg l⁻¹ dose of chlorine at 1 h contact time killed these sensitive bacteria decreasing MPN to less than 2 100 ml⁻¹.Differences between the efficiency of chlorination experiments under laboratory and field conditions would necessitate the application of 15 mg l⁻¹ chlorine for 2 h of contact.     

Viruses and bacteriophages

Many of the enteric viruses which are transmitted from person to person by thefecal-oral route are found in raw and treated wastewater, and because of their persistence under adverse conditions may also be found in slightly polluted waters.There is no routine examination procedure of water and wastewater for entero-viruses,mainly because of the cumbersome isolation techniques, high cost and the need for highly skilled laboratory personnel.Phages are specific to single species of bacteria, are known for many entericbacteria, and are very often used for final identification of enteric pathogenic bacteria.Coliphages are provalent in raw and treated sewage as well as in polluted water, where enteric viruses may also be found.Coliphages were often mentioned as possible viral indicators in polluted water.To be a perfect indicator, they should comply with minimum criteria as follows: (a) they should be present wherever human enteric viruses are present: (b) the coliphage numbers recovered should be equal to or larger than those of enteric viruses recovered: (c) the coliphages should be at least as resistant as enteric viruses to adverse environmental conditions: (d) isolation and quantification of the coliphage should be faster and less expensive than isolation of the enteroviruses.Comparative studies show that the coliphage to enterovirus ratio in wastewater is about 10³:1. Levels of poliovirus 1 (attenuated) to coliphage f2 remained stable for a few months in oxidation pond effluents.f2 coliphage exhibited higher resistance to chlorination than poliovirus 1 (attenuated). When the two strains were kept in water of different quality, f2 survived longer. In addition, all coliphage counts were completed within 24 h. while those of enteroviruses required about a week. Results indicate very strongly that coliphages can be used as viral indicators and this is already the practice in a few European and other countries.     

边坡地质勘察勘探点和勘探线布置的分析研究

了解边坡岩土地层情况最直接的方法是勘探作业。科学合理地布置边坡勘察勘探点和勘探线,对准确获取勘探范围内岩层物理性质、降低勘察费用以及缩短勘察外业工期等有重要意义。本文对现行规范中关于勘探点和勘探线的相关要求进行分析研究。