A novel MPT noise prediction methodology for highly-integrated propulsion systems with inlet flow distortion

Embedded propulsion systems, such as for example used in advanced hybrid-wing body aircraft, can potentially offer major fuel burn and noise reduction benefits but introduce challenges in the aerodynamic and acoustic integration of the high-bypass ratio fan system. A novel approach is proposed to quantify the effects of non-uniform flow on the generation and propagation of multiple pure tone noise (MPTs). The new method is validated on a conventional inlet geometry first. The ultimate goal is to conduct a parametric study of S-duct inlets in order to quantify the effects of inlet design parameters on the acoustic signature. The key challenge is that the mechanism underlying the distortion transfer, noise source generation and propagation through the non-uniform flow field are inherently coupled such that a simultaneous computation of the aerodynamics and acoustics is required. The technical approach is based on a body force description of the fan blade row that is able to capture the distortion transfer and the MPT noise generation mechanisms while greatly reducing computational cost. A single, 3-D full-wheel unsteady CFD simulation, in which the Euler equations are solved to second-order spatial and temporal accuracy, simultaneously computes the MPT noise generation and its propagation in distorted mean flow. Several numerical tools were developed to enable the implementation of this new approach. Parametric studies were conducted to determine appropriate grid and time step sizes for the propagation of acoustic waves. The Ffowcs-Williams and Hawkings integral method is used to propagate the noise to far field receivers. Non-reflecting boundary conditions are implemented through the use of acoustic buffer zones. The body force modeling approach is validated and proof-of-concept studies demonstrate the generation of disturbances at both blade-passing and shaft-order frequencies using the perturbed body force method. The full methodology is currently being validated using NASA's Source Diagnostic Test (SDT) fan and inlet geometry. Copyright © 2009 by Jeff Defoe, Alex Narkaj & Zoltan Spakovszky.

IGBT converters conducted EMI analysis by controlled multiple-slope switching waveform approximation

IGBTs realise high-performance power converters. Unfortunately, with fast switching of the IGBT-free wheel diode chopper cell, such circuits are intrinsic sources of high-level EMI. Therefore, costly EMI filters or shielding are normally needed on the load and supply side. In order to design these EMI suppression components, designers need to predict the EMI level with reasonable accuracy for a given structure and operating mode. Simplifying the transient IGBT switching current and voltage into a multiple slope switching waveform approximation offers a feasible way to estimate conducted EMI with some accuracy. This method is dependent on the availability of high-fidelity measurements. Also, that multiple slope approximation needs careful and time-costly IGBT parameters optimisation process to approach the real switching waveform. In this paper, Active Voltage Control Gate Drive(AVC GD) is employed to shape IGBT switching into several defined slopes. As a result, Conducted EMI prediction by multiple slope switching approximation could be more accurate, less costly but more friendly for implementation. © 2013 IEEE.

Designing and testing an advanced pneumatic braking system for heavy vehicles

Heavy goods vehicles exhibit poor braking performance in emergency situations when compared to other vehicles. Part of the problem is caused by sluggish pneumatic brake actuators, which limit the control bandwidth of their antilock braking systems. In addition, heuristic control algorithms are used that do not achieve the maximum braking force throughout the stop. In this article, a novel braking system is introduced for pneumatically braked heavy goods vehicles. The conventional brake actuators are improved by placing high-bandwidth, binary-actuated valves directly on the brake chambers. A made-for-purpose valve is described. It achieves a switching delay of 3-4 ms in tests, which is an order of magnitude faster than solenoids in conventional anti-lock braking systems. The heuristic braking control algorithms are replaced with a wheel slip regulator based on sliding mode control. The combined actuator and slip controller are shown to reduce stopping distances on smooth and rough, high friction (μ = 0.9) surfaces by 10% and 27% respectively in hardware-in-the-loop tests compared with conventional ABS. On smooth and rough, low friction (μ = 0.2) surfaces, stopping distances are reduced by 23% and 25%, respectively. Moreover, the overall air reservoir size required on a heavy goods vehicle is governed by its air usage during an anti-lock braking stop on a low friction, smooth surface. The 37% reduction in air usage observed in hardware-in-the-loop tests on this surface therefore represents the potential reduction in reservoir size that could be achieved by the new system. © 2012 IMechE.

Design and market considerations for axial flux superconducting electric machine design

In this paper, the authors investigate a number of design and market considerations for an axial flux superconducting electric machine design that uses high temperature superconductors. The axial flux machine design is assumed to utilise high temperature superconductors in both wire (stator winding) and bulk (rotor field) forms, to operate over a temperature range of 65-77 K, and to have a power output in the range from 10s of kW up to 1 MW (typical for axial flux machines), with approximately 2-3 T as the peak trapped field in the bulk superconductors. The authors firstly investigate the applicability of this type of machine as a generator in small- and medium-sized wind turbines, including the current and forecasted market and pricing for conventional turbines. Next, a study is also carried out on the machine's applicability as an in-wheel hub motor for electric vehicles. Some recommendations for future applications are made based on the outcome of these two studies. Finally, the cost of YBCO-based superconducting (2G HTS) wire is analysed with respect to competing wire technologies and compared with current conventional material costs and current wire costs for both 1G and 2G HTS are still too great to be economically feasible for such superconducting devices.

SLP: A zero-contact non-invasive method for pulmonary function testing

Structured Light Plethysmography (SLP) is a novel non-invasive method that uses structured light to perform pulmonary function testing that does not require physical contact with a patient. The technique produces an estimate of chest wall volume changes over time. A patient is observed continuously by two cameras and a known pattern of light (i.e. structured light) is projected onto the chest using an off-the-shelf projector. Corner features from the projected light pattern are extracted, tracked and brought into correspondence for both camera views over successive frames. A novel self calibration algorithm recovers the intrinsic and extrinsic camera parameters from these point correspondences. This information is used to reconstruct a surface approximation of the chest wall and several novel ideas for 'cleaning up' the reconstruction are used. The resulting volume and derived statistics (e.g. FVC, FEV) agree very well with data taken with a spirometer. © 2010. The copyright of this document resides with its authors.

A screening study on persistent bioaccumulation toxins (PBT) in fuel combustion soot

Persistent bioaccumulative toxins (PBTs) are organic substances that are persistent, bioaccumulative and can cause severe toxic effects (e.g. potential oncogens, mutagenic, endocrine disrupters) to human health or environment which are the ones that need special attention. PBT chemicals could be released to the environment from several types of sources and are ubiquitous in environment. However, fast and efficiency monitoring and assessment methods to investigate PBTs in environment are still lacking. In this study, a cleaning-up procedure of analyzing PBTs in fuels combustion soot was developed and its performance was assessed through comparing the chromatograms of crude extracts with their cleaned extracts after the cleaning-up procedure. The results showed that polycyclic aromatic compounds (PACs) were the main components in fuel combustion soot and the clean-up procedure developed in this paper can be well used as the method of analyzing PBTs in fuels combustion soot.

Robotic body extension based on hot melt adhesives

The capability of extending body structures is one of the most significant challenges in the robotics research and it has been partially explored in self-reconfigurable robotics. By using such a capability, a robot is able to adaptively change its structure from, for example, a wheel like body shape to a legged one to deal with complexity in the environment. Despite their expectations, the existing mechanisms for extending body structures are still highly complex and the flexibility in self-reconfiguration is still very limited. In order to account for the problems, this paper investigates a novel approach to robotic body extension by employing an unconventional material called Hot Melt Adhesives (HMAs). Because of its thermo-plastic and thermo-adhesive characteristics, this material can be used for additive fabrication based on a simple robotic manipulator while the established structures can be integrated into the robot's own body to accomplish a task which could not have been achieved otherwise. This paper first investigates the HMA material properties and its handling techniques, then evaluates performances of the proposed robotic body extension approach through a case study of a "water scooping" task. © 2012 IEEE.

Heavy metals in plants and phytoremediation - A state-of-the-art report with special reference to literature published in Chinese journals

Goal, Scope and Background. In some cases, soil, water and food are heavily polluted by heavy metals in China. To use plants to remediate heavy metal pollution would be an effective technique in pollution control. The accumulation of heavy metals in plants and the role of plants in removing pollutants should be understood in order to implement phytoremediation, which makes use of plants to extract, transfer and stabilize heavy metals from soil and water. Methods. The information has been compiled from Chinese publications stemming mostly from the last decade, to show the research results on heavy metals in plants and the role of plants in controlling heavy metal pollution, and to provide a general outlook of phytoremediation in China. Related references from scientific journals and university journals are searched and summarized in sections concerning the accumulation of heavy metals in plants, plants for heavy metal purification and phytoremediation techniques. Results and Discussion. Plants can take up heavy metals by their roots, or even via their stems and leaves, and accumulate them in their organs. Plants take up elements selectively. Accumulation and distribution of heavy metals in the plant depends on the plant species, element species, chemical and bioavailiability, redox, pH, cation exchange capacity, dissolved oxygen, temperature and secretion of roots. Plants are employed in the decontamination of heavy metals from polluted water and have demonstrated high performances in treating mineral tailing water and industrial effluents. The purification capacity of heavy metals by plants are affected by several factors, such as the concentration of the heavy metals, species of elements, plant species, exposure duration, temperature and pH. Conclusions. Phytoremediation, which makes use of vegetation to remove, detoxify, or stabilize persistent pollutants, is a green and environmentally-friendly tool for cleaning polluted soil and water. The advantage of high biomass productive and easy disposal makes plants most useful to remediate heavy metals on site. Recommendations and Outlook. Based on knowledge of the heavy metal accumulation in plants, it is possible to select those species of crops and pasturage herbs, which accumulate fewer heavy metals, for food cultivation and fodder for animals; and to select those hyperaccumulation species for extracting heavy metals from soil and water. Studies on the mechanisms and application of hyperaccumulation are necessary in China for developing phytoremediation.

Effects of heavy metals on plants and resistance mechanisms

Goal, Scope and Background. As one of the consequences of heavy metal pollution in soil, water and air, plants are contaminated by heavy metals in some parts of China. To understand the effects of heavy metals upon plants and the resistance mechanisms, would make it possible to use plants for cleaning and remediating heavy metal-polluted sites. Methods. The research results on the effects of heavy metals on plants and resistant mechanisms are compiled from Chinese publications from scientific journals and university journals, mostly published during the last decade. Results and Discussion. Effects of heavy metals on plants result in growth inhibition, structure damage, a decline of physiological and biochemical activities as well as of the function of plants. The effects and bioavailability of heavy metals depend on many factors, such as environmental conditions, pH, species of element, organic substances of the media and fertilization, plant species. But, there are also studies on plant resistance mechanisms to protect plants against the toxic effects of heavy metals such as combining heavy metals by proteins and expressing of detoxifying enzyme and nucleic acid, these mechanisms are integrated to protect the plants against injury by heavy metals. Conclusions. There are two aspects on the interaction of plants and heavy metals. On one hand, heavy metals show negative effects on plants. On the other hand, plants have their own resistance mechanisms against toxic effects and for detoxifying heavy metal pollution. Recommendations and Outlook. To study the effects of heavy metals on plants and mechanisms of resistance, one must select crop cultivars and/or plants for removing heavy metals from soil and water. More highly resistant plants can be selected especially for a remediation of the pollution site. The molecular mechanisms of resistance of plants to heavy metals should be studied further to develop the actual resistance of these plants to heavy metals. Understanding the bioavailability of heavy metals is advantageous for plant cultivation and phytoremediation. Decrease in the bioavailability to farmlands would reduce the accumulation of heavy metals in food. Alternatively, one could increase the bioavailability of plants to extract more heavy metals.

Investigation of a chemically treated InP(100) surface during hydrophilic wafer bonding process

Surface micro-roughness, surface chemical properties, and surface wettability are three important aspects of wafer surfaces during a wafer cleaning process, which determine the bonding quality of ordinary direct wafer bonding. In this study, InP wafers are divided into four groups and treated by different chemical processes. Subsequently, the characteristics of the treated InP surfaces are carefully studied by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements. The optimal wafer treatment method for wafer bonding is determined by comparing the results of the processes as a whole. This optimization is later evaluated by a scanning electronic microscope (SEM), and the ridge waveguide 1.55 mu m Si-based InP/InGaAsP multi-quantum-well laser chips are also fabricated. (c) 2005 Elsevier B.V. All rights reserved.

含油污泥清洗剂的合成及其性能评价

含油污泥已作为危险废物列入《国家危险废物名录》（HW08），其处理问题已成为环保领域研究的热点。热洗技术是含油污泥处理的主流技术，而清洗药剂作为该技术的核心，直接影响含油污泥的处理指标与效率。目前，适合热洗处理的化学药剂很少，迫切需要开发专用药剂技术。针对含油污泥清洗效率的难题，本文合成了一种新型高效的含油污泥清洗剂。 本文以甲基丙烯酸（MAA）、丙烯酸丁酯（BA）和苯乙烯（St）为混合单体，偶氮二异丁腈（AIBN）为引发剂，通过溶液聚合的方法探索合成了一种高分子聚合物（命名为MBS）。分析讨论了MBS关键单体的选择、合成设计及方法，检测了MBS有关物理化学性能，考察了单体、引发剂用量及清洗条件对MBS脱油性能的影响，探讨了MBS对含油污泥中原油不同组分的去除效率，并用红外光谱证实了MBS结构的官能团。 MBS在单体质量比为MAA：BA：St=21：62：17，引发剂AIBN为单体总量的1.2%时，含油污泥脱油率可达84%以上。MBS对于含油污泥中芳烃去除率最高，为93.0%；其次是烷烃，去除率为87.4%；沥青质、胶质最低，去除率为71.8%，具有良好的处理效果。 本文还针对目前国内尚无评价含油污泥清洗剂的标准方法，对清洗剂性能评价进行了初探，采用统一标准的模拟含油污泥进行清洗剂性能评价，并提出了制备方法，同时验证了在此基础上所建立的性能评价方法。结果证明，模拟含油污泥能够真实体现清洗剂的脱油性能，所建立的评价方法可以作为一种通用规范的含油污泥清洗剂性能评价的基本方法。

典型粘土矿物吸附原油的清洗技术研究

含油污泥是危险废物，已列入《国家危险废物名录》。目前，热水清洗法是含油污泥处理的核心技术之一，但因含油污泥来源不同，成分性质各异，含油污泥清洗技术的普适性及规律性差。粘土矿物作为含油污泥泥质的主要成分，其吸附原油的清洗是含油污泥清洗技术的关键环节，因此，从粘土矿物性质、原油组分、清洗剂性质三个方面对粘土矿物吸附原油的清洗技术进行研究，分析其内在的规律性，是获得普适性含油污泥清洗技术的突破口。 本文结合含油污泥的理化性质分析，选取粒径范围为0～100µm高岭石、蒙脱石、绿泥石和伊利石四种粘土矿物，在优化工艺条件的基础上，研究其吸附原油在不同表面活性剂作用下的解吸规律，分析原油中不同族组分的脱附特性，筛选了针对典型粘土矿物吸附原油的高效清洗剂。 四种粘土矿物吸附原油解吸效率的大小顺序为伊利石>蒙脱石>高岭石>绿泥石。不同表面活性剂对粘土矿物吸附原油清洗效率的大小顺序为阴离子表面活性剂>非离子表面活性剂>阳离子表面活性剂。粘土矿物吸附原油中三个族组分的脱附难易顺序为饱和烃>芳烃>胶质沥青质，饱和烃的脱附效率是控制粘土矿物吸附原油总体清洗效率的最重要参数。Dodec-MNS和NPS-10是良好的粘土矿物吸附原油清洗剂，NPS–10对含油率为18.32%和29.68%的含油污泥的脱附效率分别为78.43%和84.11%。 本文同时还针对含油污泥清洗技术中清洗剂复配，提出根据含油污泥族组分特性，选取亲油基性质与对应族组分性质接近的表面活性剂进行复配的方法，方法经实验验证可行，可作为一种含油污泥清洗剂复配的基本方法。