Analysis of Aerosols from the World Trade Center Collapse Site,New York,October 2 to October 30, 2001

The collapse of the World Trade Center (WTC) buildings #2 (South Tower), #1 (North Tower), and #7 created an enormous collapse pile which emitted intense plumes of acrid smoke and dust until roughly mid-December, when the last spontaneous surface fire occurred. We collected particles by size (8 modes, ≈12 to 0.09 micrometers diameter) and time (typical resolution of 1 to 3 h) from October 2 until late December at the EML 201 Varick Street site roughly 1.8 km NNE of the collapse site and 50 m above ground level. Here we show some of the 70,000 mass and elemental data from the time period October 2 through October 30. Identification of a WTC collapse pile source for aerosols seen at the receptor site were based upon the simultaneous presence of finely powdered concrete, gypsum, and glass with intense very fine combustion mode mass episodes concurrent with winds from the southwest quadrant. The results, derived from seven independent beam-based analytical techniques, showed that while PM₁₀ and PM_2.5 24 h values rarely, if ever, violated federal air quality standards, WTC-derived plumes swept over lower Manhattan Island, resulting in intense aerosol impacts of duration a few hours at any one site. The WTC plume resembled in many ways those seen from municipal waste incinerators and high temperatures processes in coal-fired power plants. The size fractions above 1 micrometer contained finely powdered concrete, gypsum, and glass, with sootlike coatings and anthropogenic metals, but little asbestos. Composition in the very fine size range (0.26 > D_p > 0.09 μm) was dominated by sulfuric acid and organic matter, including polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and glasslike silicon-containing aerosols. Many metals were seen in this mode, most, but not all, at low concentrations. The concentrations of very fine silicon, sulfur, and many metals, as well as coarse anthropogenic metals, decreased markedly during October, probably in association with the cooling of the collapse piles. Values of very fine elements seen in May, 2002 at the WTC site were only a few percent of October values.     

Interactive Evolutionary Multi-Objective Optimization Algorithm Using Cone Dominance

As the number of objectives increases, the performance of the Pareto dominance-based Evolutionary Multi-objective Optimization (EMO) algorithms such as NSGA-II, SPEA2 severely deteriorates due to the drastic increase in the Pareto-incomparable solutions. We propose a sorting method which classifies these incomparable solutions into several ordered classes by using the decision maker's (DM) preference information. This is accomplished by designing an interactive evolutionary algorithm and constructing convex cones. This method allows the DMs to drive the search process toward a preferred region of the Pareto optimal front. The performance of the proposed algorithm is assessed for two, three, and four-objective knapsack problems. The results demonstrate the algorithm's ability to converge to the most preferred point. The evaluation and comparison of the results indicate that the proposed approach gives better solutions than that of NSGA-II. In addition, the approach is more efficient compared to NSGA-II in terms of the number of generations required to reach the preferred point.     

A method for determining the flow front velocity of a plastic melt in an injection molding process

During the filling phase of an injection molding process, the flow front velocity of the plastics melt has a decisive influence on the form part quality. It has been believed that a constant flow front velocity of the melt leads to distortion‐free and residual stress‐free form parts. A process control strategy based on a constant flow front velocity of the melt, however, requires the full understanding of the flow front position as a function of the screw position of the injection molding machine. With current methods, this can only be achieved by direct measurements using a number of sensors inside the mold, which leads to complicated structure, great efforts, and high cost for the tooling equipment. This article proposes, designs, and develops an innovative method for determining the flow front velocity of a plastic melt in an injection molding using only one pressure sensor at the front of the screw and based on the idea of mapping a simulated filling process to a real injection molding process. The mapping ensues that the characteristic event points are identified and matched for both the simulated and real filling process. The results of the simulation analysis and experimental evaluation show that the proposed method can be used to determine the flow front position and the resulting flow front velocity of the melt within the cavity of the mold and provide evidence that the new method offers great potential to process control strategies based on machine independent parameters. POLYM. ENG. SCI., 59:1132–1145 2019. © 2019 Society of Plastics Engineers     

The Well Mannered Wearable Computer

In this paper we describe continuing work being carried out as part of the Bristol Wearable Computing Initiative. We are interested in the use of context sensors to improve the usefulness of wearable computers. A CyberJacket incorporating a Tourist Guide application has been built, and we have experimented with location and movement sensing devices to improve its performance. In particular, we have researched processing techniques for data from accelerometers which enable the wearable computer to determine the user’s activity. We have experimented with, and review, techniques already employed by others; and then propose new methods for analysing the data delivered by these devices. We try to minimise the number of devices needed, and use a single X-Y accelerometer device. Using our techniques we have adapted our CyberJacket and Tourist Guide to include a multimedia presentation which gives the user information using different media depending on the user’s activity as well as location.     

The Shopping Jacket: Wearable computing for the consumer

As part of the Bristol Wearable Computing Initiative, we are exploring location-sensing systems suitable for use with wearable computing. In this paper we present our findings, and in particular a wearable application — the ‘Shopping Jacket’ — which relies on a minimal infrastructure to be effective. We use two positioning devices, ‘pingers’ and GPS. The pinger is used to signal the presence of a shop, and to indicate the type of shop and its website. The GPS is used to disambiguate which branch of a high street chain is being passed. The wearable uses this information to determine whether the wearer needs to be alerted that they are passing an interesting shop, or to direct the wearer around a shopping mall. The Shopping Jacket integrates a wearable CardPC, GPS and pinger receivers, a near-field radio link, hand-held display, GSM data telephone and a speech interface into a conventional sports blazer.     

测量复合视频信号性能:差分增益与差分相位

首先简要介绍了复合NSTC/PAL视频,并阐述差分增益与差分相位的重要性,随后,重点讨论了如何理解规格表中的各种规格及各种重要的DG/DP测量方法。     

U.K. National Radiological Protection Board Radon Calibration Procedures

A procedure for the calibration of instruments for the detection of ²²²Rn in air is described. The method is based on the alpha-spectrometric determination of the concentration in air of ²¹⁸Po in the calibration chamber. The calibration chamber is described, together with the method of maintaining a high aerosol concentration. The ²¹⁸Po concentration at steady state in the chamber is found to be 98% of the ²²²Rn concentration typically. An assessment of the sources of uncertainty in the method presented indicate that the ²²²Rn concentration in the chamber can be determined with an overall uncertainty of about 7% at the 95% confidence level.     

Enabling structural summaries for efficient update and workload adaptation

To facilitate queries over semi-structured data, various structural summaries have been proposed. Structural summaries are derived directly from data and serve as the indexes for evaluating path expressions. We introduce D(k)-index, an adaptive structural summary, for general graph-structured data. Building on previous 1-index and A(k)-index, D(k)-index is also based on the concept of bisimilarity. However, as a generalization of 1-index and A(k)-index, D(k)-index possesses the adaptive ability to adjust its structure to changes in query load. It also enables efficient update algorithms, which are crucial to real applications but have not been adequately addressed in previous literatures. Our experiments show that D(k)-index is a more effective structural summary than previous static ones as a result of its query load sensitivity. In addition, the update operations on it can be performed more efficient than on its predecessors.