User-side adaptive protection of location privacy in participatory sensing

The participatory sensing paradigm, through the growing availability of cheap sensors in mobile devices, enables applications of great social and business interest, e.g., electrosmog exposure measurement and early earthquake detection. However, users’ privacy concerns regarding their activity traces need to be adequately addressed as well. The existing static privacy-enabling approaches, which hide or obfuscate data, offer some protection at the expense of data value. These approaches do not offer privacy guarantees and heterogeneous user privacy requirements cannot be met by them. In this paper, we propose a user-side privacy-protection scheme; it adaptively adjusts its parameters, in order to meet personalized location-privacy protection requirements against adversaries in a measurable manner. As proved by simulation experiments with artificial- and real-data traces, when feasible, our approach not only always satisfies personal location-privacy concerns, but also maximizes data utility (in terms of error, data availability, area coverage), as compared to static privacy-protection schemes.     

应对高浓度S02烟气的挑战

论述处理高浓度SO2烟气的技术现状，介绍不同工艺方案的技术条件及经济情况。现代富氧硫化矿冶炼技术提高了烟气SO2浓度，为大幅降低冶炼烟气处理费用创造了条件。大量的费用研究证明，生产硫酸仍然是从冶炼烟气中回收硫和减少SO2排放的首选方案。当采用高浓度制酸工艺时尤其如此。奥托昆普技术公司开发了一种能有效处理高浓度烟气的新工艺——Lurec^TM工艺，从而不必像传统工艺一样采用过量的空气稀释。Lurec^TM工艺不论对新建装置还是对装置扩建改造同样具有吸引力。     

Expertensysteme – ein Hilfsmittel der Prozeß-Synthese

Expert systems for process syntheses . Commercial programs used in computer-aided development of chemical processes need a process flowsheet as starting point. Preparation of flowsheets is based largely on human experience, an uncertain kind of knowledge expressed by heuristic rules. These rules are recognized as true and advantageous in most cases without having the validity of a law. Logic programming languages derived from research on artificial intelligence are proven tools for handling heuristics with so-called “expert systems”. The flowsheets proposed by the expert system reduce all theoretically possible results to a few structures. The example of structuring distillation sequences illustrates what can be expected using an “expert system” in the area of “problem solving” by comparing its proposed sequences with optimized problems.     

Neue Entwicklungen zur Druckwechsel-Adsorption

New developments in pressure swing adsorption. Continuing development of the adsorption agents and optimization of the process have permitted solution of new problems of selective separation and isolation of gases from gas mixtures and of gas purification by pressure swing adsorption. While processes have previously been developed in which the product gas is obtained during the adsorption step, more and more processes are now becoming available in which gases of high purity are obtained during the desorption step. After derivation of the fundamental desorption steps, the new techniques are illustrated in the case of the enrichment of CH₄, CO₂, and ozone, and for recovery of NO_x from nitric acid waste gases.     

Prediction of diallyl phthalate molding performance from laboratory tests I. Characterization and quality control of diallyl phthalate compounds

The purpose of this study was two-fold:

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Advantages of an Emulsion‐Produced Ziegler‐Natta Catalyst Over a Conventional Ziegler‐Natta Catalyst

Summary: Self‐supported and MgCl₂‐supported Ziegler‐Natta catalysts, produced by two catalyst synthesis methods are compared. Borealis Polymers OY (Finland), who supplied the catalysts, developed the catalyst synthesis methods. The first method (Method One) is based on an emulsion system and consists of an in situ single step preparation. The second method (Method Two) consists mainly of two steps: formation of the catalyst carrier particles, and their subsequent impregnation with the active material. The results showed that Method One produced catalysts of compact, spherical particles with good intra‐particle homogeneity and a narrow particle size distribution. On the other hand, Method Two produced catalyst particles whose properties depended directly on that of the catalyst carrier: they were spherical but very porous, with a broad particle size distribution. Polymer particles produced with the two catalyst systems are perfect replicas of the catalyst particles. Fines formed either during catalyst preparation or during polymerization were observed only with the catalyst prepared using Method Two. The particles of the catalysts produced using Methods One and Two had similar activities, independent of the initial particle size. Fragmentation of catalyst particles was very fast for both catalyst systems and was only observed to be 100% completed using the catalyst produced with Method One. Studies of the thermal properties showed that the catalyst prepared using Method One produced poly(propylene) of higher crystallinity and with a narrower melting peak.

SEM images of polymer particles produced by (A) Method One and (B) Method Two.     

USING IDENTITY PREMIUM FOR HONESTY ENFORCEMENT AND WHITEWASHING PREVENTION

One fundamental issue with existing reputation systems, particularly those implemented in open and decentralized environments, is whitewashing attacks by opportunistic participants. If identities are cheap, it is beneficial for a rational provider to simply defect when selling services to its clients, leave the system to avoid punishment and then rejoin with a new identity. Current work usually assumes the existence of an effective identity management scheme to avoid the problem, without proposing concrete solutions to directly prevent this unwanted behavior. This article presents and analyzes an incentive mechanism to effectively motivate honesty of rationally opportunistic providers in the aforementioned scenario, by eliminating incentives of providers to change their identities. The main idea is to give each provider an identity premium, with which the provider may sell services at higher prices depending on the duration of its presence in the system. Our price‐based incentive mechanism, implemented with the use of a reputation‐based provider selection protocol and a reverse auction scheme, is shown to significantly reduce the impact of malicious and strategic ratings, while still allowing explicit competition among the providers. It is proven that if the temporary cheating gain by a provider is bounded and small and given a trust model with a reasonable low error bound in identifying malicious ratings, our approach can effectively eliminate irrationally malicious providers and enforce honest behavior of rationally opportunistic ones, even when cheap identities are available. We suggest an identity premium function that helps such honesty to be sustained given a certain cost of identities and analyze incentives of participants in accepting the proposed premium. Related implementation issues in different application scenarios are also discussed.     

Filled temperature‐sensitive poly(vinyl methyl ether) hydrogels

Temperature‐sensitive hydrogels based on poly(vinyl methyl ether) (PVME) with ferroelectric or ferromagnetic properties were synthesized by high‐energy irradiation. Barium titanate and poly(vinylidene fluoride) (PVDF) were used as ferroelectric filler and Ni as ferromagnetic filler. The filled PVME hydrogels were synthesized by electron beam or γ‐ray irradiation (of a suspension with 5–50 wt % of filler (with respect to polymer mass) in a 20 wt % aqueous PVME solution). Filling of the gel reduces the absolute swelling degree at low temperatures, but do not influence the phase‐transition temperature of the gel. The particle distribution of the fillers inside the gel was visualized by field emission scanning electron microscopy. The fillers were incorporated in the PVME network and fixed because of their size (inorganic particles), as well as by chemical bonds (PVDF). The ferroelectric or ferromagnetic properties of the filled gels were proved. Measurements in a corresponding alternating field provide the hysteresis loop, for both the ferromagnetic and ferroelectric gel. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2253–2265, 2005