在GSM蜂窝电话基础设施中的蓝牙技术

我们在任何公共场所,甚至会议室都会听到独特的蜂窝电话振铃.声音透过空间传来好像近在咫尺,人们反应非常迅速,立刻检查衣袋、提包、皮带扣中的手机,看看有无亲友来电.似乎商业人士、家庭妇女、中学生和儿童都每人一个手机.然而,我们听到的只是小量辐射,未听到或见到的噪声才是真正的污染.工程师必须克服技术创新道路上的这些障碍.     

PIPELINE DEFECT PREDICTION USING SUPPORT VECTOR MACHINES

Oil and gas pipeline condition monitoring is a potentially challenging process due to varying temperature conditions, harshness of the flowing commodity and unpredictable terrains. Pipeline breakdown can potentially cost millions of dollars worth of loss, not to mention the serious environmental damage caused by the leaking commodity. The proposed techniques, although implemented on a lab scale experimental rig, ultimately aim at providing a continuous monitoring system using an array of different sensors strategically positioned on the surface of the pipeline. The sensors used are piezoelectric ultrasonic sensors. The raw sensor signal will be first processed using the discrete wavelet transform (DWT) as a feature extractor and then classified using the powerful learning machine called the support vector machine (SVM). Preliminary tests show that the sensors can detect the presence of wall thinning in a steel pipe by classifying the attenuation and frequency changes of the propagating lamb waves. The SVM algorithm was able to classify the signals as abnormal in the presence of wall thinning.     

Unveiling the complexity of human mobility by querying and mining massive trajectory data

The technologies of mobile communications pervade our society and wireless networks sense the movement of people, generating large volumes of mobility data, such as mobile phone call records and Global Positioning System (GPS) tracks. In this work, we illustrate the striking analytical power of massive collections of trajectory data in unveiling the complexity of human mobility. We present the results of a large-scale experiment, based on the detailed trajectories of tens of thousands private cars with on-board GPS receivers, tracked during weeks of ordinary mobile activity. We illustrate the knowledge discovery process that, based on these data, addresses some fundamental questions of mobility analysts: what are the frequent patterns of people’s travels? How big attractors and extraordinary events influence mobility? How to predict areas of dense traffic in the near future? How to characterize traffic jams and congestions? We also describe M-Atlas, the querying and mining language and system that makes this analytical process possible, providing the mechanisms to master the complexity of transforming raw GPS tracks into mobility knowledge. M-Atlas is centered onto the concept of a trajectory, and the mobility knowledge discovery process can be specified by M-Atlas queries that realize data transformations, data-driven estimation of the parameters of the mining methods, the quality assessment of the obtained results, the quantitative and visual exploration of the discovered behavioral patterns and models, the composition of mined patterns, models and data with further analyses and mining, and the incremental mining strategies to address scalability.     

Enhanced In Vivo Delivery of Stem Cells using Microporous Annealed Particle Scaffolds

Delivery to the proper tissue compartment is a major obstacle hampering the potential of cellular therapeutics for medical conditions. Delivery of cells within biomaterials may improve localization, but traditional and newer void‐forming hydrogels must be made in advance with cells being added into the scaffold during the manufacturing process. Injectable, in situ cross‐linking microporous scaffolds are recently developed that demonstrate a remarkable ability to provide a matrix for cellular proliferation and growth in vitro in three dimensions. The ability of these scaffolds to deliver cells in vivo is currently unknown. Herein, it is shown that mesenchymal stem cells (MSCs) can be co‐injected locally with microparticle scaffolds assembled in situ immediately following injection. MSC delivery within a microporous scaffold enhances MSC retention subcutaneously when compared to cell delivery alone or delivery within traditional in situ cross‐linked nanoporous hydrogels. After two weeks, endothelial cells forming blood vessels are recruited to the scaffold and cells retaining the MSC marker CD29 remain viable within the scaffold. These findings highlight the utility of this approach in achieving localized delivery of stem cells through an injectable porous matrix while limiting obstacles of introducing cells within the scaffold manufacturing process.     

Groundwater protection from cadmium contamination by permeable reactive barriers

This work studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable adsorbing barrier (PRB). In particular, it has been considered the case of a permeable adsorbing barrier (PAB) used to protect a river from a Cd(II) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing river pollution for several months.     

Wet‐dry process of HCL removal from flue gas: experimental study on operating parameters

Wet‐dry process of hydrogen chloride removal from flue gas has been studied at pilot scale. Hot gas produced by methane burner, added with gaseous hydrogen chloride, is contacted by an aqueous suspension of calcium hydroxide in a cylindrical steel vessel 0.25 m I.D. and 4 m high.

The effects of feed ratio Ca(OH)₂/HCl, hydrogen chloride concentration in the inlet gas, operating temperature and residence time on the amount of hydrogen chloride removed have been exstensively investigated. The effect of inside wall fouling by Ca(OH)₂ has also been evaluated.

The experimental results show that the overall amount of hydrogen chloride removed increases when the feed ratio and the gas inlet concentration are increased and the operating temperature is decreased. However, the HCL removal does not seem affected by the residence time within the short interval investigated.     

Odor and taste perception at normal and low atmospheric pressure in a simulated aircraft cabin

During flights, reduced odor and taste perception is reported. Passengers tend to prefer spicier meals than on the ground. The conditions on board were simulated at the Fraunhofer flight test facility in Holzkirchen, Germany, consisting of a front fuselage of an Airbus A310-200 in a huge metal tube in which all relevant parameters can be adjusted (humidity, temperature, pressure). Flight tests were carried out at low atmospheric pressure corresponding to cabin conditions on board at cruising altitude and were repeated at normal atmospheric pressure corresponding to ground conditions. All other parameters were kept constant. Under these conditions, test persons smelled and tasted food-safe flavorants to evaluate the mean odor and taste thresholds and tasted different flavored food. Even tomato juice and various wines were tasted for odor and taste qualities, intensities and individual preferences. At low pressure conditions, higher taste and odor thresholds of flavorants were generally observed with few exceptions. Salt, sugar, glutamate and most odorant thresholds increased clearly. Organic acids and some bitter tastants showed no change. Transferred to complete meals, more salt, sugar and herbs were necessary on board to serve meals that tasted similar to the way they did on the ground. Sour ingredients had to be reduced. The odor and taste spectrum of the beverages investigated changed in various ways. Light and fresh flavors decreased, whereas intensive flavors persisted.