A new glucose affinity sensor based on a homogeneous fluorescence resonance energy transfer (FRET) assay system was developed to monitor the competitive binding between concanavalin A (ConA) and dextran. The FRET quenching kinetics of the donor were analyzed from frequency-domain (FD) measurements as functions of both glucose and acceptor-protein concentrations using a Förster-type decay kinetics model. The results showed that the FD measurements and donor decay kinetics can indicate quantitative changes in the presence of glucose at concentrations ranging from 0 to 224 mg/dL. The second set of experiments proved the feasibility of performing analyte sensing with FD lifetime spectroscopy using microsphere-based sensors in multiple scattering solutions. A well characterized pH-sensitive fluorophore was entrapped in poly(ethylene glycol) microspheres. The particles were then immersed in a buffered polystyrene solution of various pH. Measurements of phase shift and modulation of the generated and multiply scattered fluorescent light were acquired as the modulation frequency of the incident excitation light varied from 10 to 120 MHz. After the measured data were analyzed with the coupled diffusion equations, the obtained lifetimes from the scattering measurements matched values from non-scattering measurements. Lastly, a new two-speed Monte Carlo (MC) simulation was developed to predict light propagation through the sensors and thus was used to evaluate these sensors and to design these sensors for implantation. The model used random packing structure and considered geometric optics and two light propagation speeds. Experimental measurements of phase-shift and modulation of excitation light were made on a cubic phantom with non-fluorescent resin microspheres of 74 µm diameter, and compared to those computed from the MC simulation. The results showed that the mean phase shift (PS) deviation was 0.736° and the mean amplitude deviation was 42%. Quantitative changes in detected fluorescence phase-shift and modulation were investigated for microsphere diameter, volume fraction, refractive index, and fluorophore lifetime. We also found that even though the sensitivity of PS change in the presence of scattering was the same as the value without scattering, the values of PS were magnified due to the scattering effects.

Recent Botnets such as Conficker, Kraken and Torpig have used DNS based "domain fluxing" for command-and-control, where each Bot queries for existence of a series of domain names and the owner has to register only one such domain name. In this report, we develop a methodology to detect such "domain fluxes" in DNS traffic by looking for patterns inherent to domain names that are generated algorithmically, in contrast to those generated by humans. In particular, we look at distribution of alphanumeric characters as well as bigrams in all domains that are mapped to the same set of IP-addresses. We present and compare the performance of several distance metrics, including KL-distance and Edit distance. We train by using a good data set of domains obtained via a crawl of domains mapped to all IPv4 address space and modeling bad data sets based on behaviors seen so far and expected. We also apply our methodology to packet traces collected at two Tier-1 ISPs and show we can automatically detect domain fluxing as used by Conficker botnet with minimal false positives. We are also able to detect new botnets and other malicious networks using our method.

Abstract This thesis applies the method of finite-difference frequency -domain to solve the field when light propagating through the optical waveguide. Comparing with other method, method of finite-difference time-domain which required to be calculated with larger matrices and without any ideal approximate rapid solution, our method only needs to solve the joint equations. Method of finite-difference frequency -domain will be more efficient than method of finite- difference time-domain in optical waveguide simulation. However, all that we need to confer with are how to sample the effective indices for set grind points and the deal for the boundary conditions in partial differential equations, including electric wall, magnetic wall, absorption boundary and other boundary conditions, etc. Next, we confer with the difference deal between TE and TM waves respectively. Final, we confer with high-order finite-difference and the method for calculating extremely large area or extremely high precision in order to use the method of finite-difference frequency-domain to find the incident, reflective, and scattering fields by the fastest and the exactest procedures.

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Magnetism is one of material essential attributes, the different material¡¦s magnetic has been studied for many years as well as the application.The processing is smaller with recent years, and the submicro physical phenomenon adapt to more and more important. Microscopically, ferromagnetic material tend to reduce the total energy of the system, and the sample interior will response to devide several magnetic domains, however, from the article by G. Leaf et al[34], we saw the final domain structure at remanence of cobalt bar, which is not the configuration with lowest energy, is predicted from a high-field analysis of the frequencies of the standing spin waves. To further discuss this interesting phenomenon, we use the computer simulation method, and make a series of computation of cobalt disc with the various sizes and thickness. From this research, we will propose that the magnetic domain reverse process and mechanism, and also give showing relations to between the energy and the magnetic domain.

Peopel now use E-mail to communicate mutually is widespread. For example, schools convey information to students through e-mail, companies convey to the staff in charge of the task, friends to share the interested things of internet through e-mail and so on. Because of the imperfect of SMTP protocol, the spammer and phisher can delivery phishing e-mail or spam to unknown recipients widely and easily by the forged sender ID. It was result in the recipient's e-mail filled with numerous unsolicited advertising e-mail or faked electronic commerce e-mail. Some content of spam are advertising alone, but some are with harmful attachments, for instance, trojan or virus. Phishing use the name of online banking, Internet auction to delivery numerous e-mail, which let the recipient to believe the contents of the e-mail. By clicking the hyperlink connected to the website of the phishing, and input personal account, password, causing the recipient to lose their money or reputation. Information security software vendor SonicWall 2008¡¦s whitepaper points out that even if the obvious tips of the e-mail which is a phishing e-mail, some percent recipient still click on the hyperlink and input their personal ID and password. This means that the recipinet can easily pay attention to the hyperlink. In this research, by analysising of the information of the URL link in e-mail to detect whether the mail server have been recived phishing e-mail to protect users from phishing in the crisis.

Thesis (Ph. D.)--University of Chicago, Dept. of Economics, 1973. / Also available on the Internet.

Thesis (M.A.)--Zhong xing da xue. / Spine title. Reproduced from typescripts; on double leaves. Includes bibliographical references (leaves 1-2 (2nd group)).

Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 89-96).

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy