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In light of ever-increasing scale and sophistication of modern DDoS attacks, it is time to revisit in-network filtering or the idea of empowering DDoS victims to install in-network traffic filters in the upstream transit networks. Recent proposals show that filtering DDoS traffic at a handful of large transit networks can handle volumetric DDoS attacks effectively. However, the innetwork filtering primitive can also be misused. Transit networks can use the in-network filtering service as an excuse for any arbitrary packet drops made for their own benefit. For example, transit networks may intentionally execute filtering services poorly or unfairly to discriminate their competing neighbor ASes while claiming that they drop packets for the sake of DDoS defense. We argue that it is due to the lack of verifiable filtering - i.e., no one can check if a transit network executes the filter rules correctly as requested by the DDoS victims. To make in-network filtering a more robust defense primitive, in this paper, we propose a verifiable in-network filtering, called VIF, that exploits emerging hardware-based trusted execution environments (TEEs) and offers filtering verifiability to DDoS victims and neighbor ASes. Our proof of concept demonstrates that a VIF filter implementation on commodity servers with TEE support can handle traffic at line rate (e.g., 10 Gb/s) and execute up to 3,000 filter rules. We show that VIF can easily scale to handle larger traffic volume (e.g., 500 Gb/s) and more complex filtering operations (e.g., 150,000 filter rules) by parallelizing the TEE-based filters. As a practical deployment model, we suggest that Internet exchange points (IXPs) are the ideal candidates for the early adopters of our verifiable filters due to their central locations and flexible software-defined architecture.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is lnA with a negative coefficient.

Department: Exhibition Design.

Department: Exhibition Design.

This thesis encompasses a number of problems related to the number fluctuations from the ground state of ideal particles in different statistical ensembles. In the microcanonical ensemble most of these problems may be solved using number theory. Given an energy E, the well-known problem of finding the number of ways of distributing N bosons over the excited levels of a one-dimensional harmonic spectrum, for instance, is equivalent to the number of restricted partitions of E. As a result, the number fluctuation from the ground state in the microcanonical ensemble for this system may be found analytically. When the particles are fermions instead of bosons, however, it is difficult to calculate the exact ground state number fluctuation because the fermionic ground state consists of many levels. By breaking up the energy spectrum into particle and hole sectors, and mapping the problem onto the classic number partitioning theory, we formulate a method of calculating the particle number fluctuation from the ground state in the microcanonical ensemble for fermions. The same quantity is calculated for particles interacting via an inverse-square pairwise interaction in one dimension. In the canonical ensemble, an analytical formula for the ground state number fluctuation is obtained by using the mapping of this system onto a system of noninteracting particles obeying the Haldane-Wu exclusion statistics. In the microcanonical ensemble, however, the result can be obtained only for a limited set of values of the interacting strength parameter. Usually, for a discrete set of a mean-field single-article quantum spectrum and in the micro canonical ensemble, there are many combinations of exciting particles from the ground state. The spectrum given by the logarithms of the prime number sequence, however, is a counterexample to this rule. Here, as a consequence of the fundamental theorem of arithmetic, there is a one-to-one correspondence between the microstate and the macrostate, Doctor of Philosophy (PhD)

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is ln A with a negative coefficient., Comment: 15 pages, 1 figure

It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically and numerically by considering three simple thermodynamic models whose energy spectrum may be defined in terms of one quantum number only, as in a non-rotating black hole. The first two pertain to collections of noninteracting bosons, with logarithmic and power-law spectra. The last is an area ensemble for a black hole with equi-spaced area spectrum. In this case, the many-body degeneracy factor can be obtained analytically in a closed form. We also show that in this model, the leading term in the entropy is proportional to the horizon area A, and the next term is ln A with a negative coefficient., Comment: 15 pages, 1 figure

This report is the Final Report of a twelve-month program to develop an analog optical repeater for a 1 GHz-bandwidth recirculating delay line. The feasibility of using single mode fibers as the delay medium for a recirculating delay line of 1 GHz bandwidth and 1 ms delay time is investigated both theoretically and practically. Expected performances at both 1.3 micron and 1.5 micron wavelength with state-of-the-art optical components are indicated. Several key components that are essential for the delay line realization have been demonstrated. Optical receivers and transmitters with bandwidth exceeding 2 GHz have been achieved.

Sparsity regularization method has been analyzed for linear and nonlinear inverse problems over the last years. The method is known to be simple for use and has many advantages for problems with sparse solutions. It has been well-developed for linear inverse problems. However, there have been few results proposed for nonlinear inverse problems. Recently, some numerical algorithms for the method have been introduced. Most of them are known to have a linear convergence rate and to be slow in practice, especially for nonlinear inverse problems. The subject of the thesis is to investigate sparsity regularization for nonlinear inverse problems. We aim at the following fields: First, the method is explored for the diffusion coefficient identification problem and electrical impedance tomography. In these problems, the energy functional approach (incorporating with sparsity regularization) is applied instead of the least squares approach. We will analyze advantages of the new approach as well as the well-posedness and some convergence rates of the method in each problem. Second, we propose numerical algorithms for minimization problems in sparsity regularization of nonlinear inverse problems. They consist of a gradient-type method, two accelerated versions, and semi-smooth Newton and quasi-Newton methods. We concentrate on the convergence of the methods. However, for some algorithms, the convergence rate as well as the decreasing rate of the objective functionals are also concerned. The algorithms are then carried out to two parameter identification problems above and the efficiency of the algorithms are examined and illustrated by some specfific examples.

Sparsity regularization method has been analyzed for linear and nonlinear inverse problems over the last years. The method is known to be simple for use and has many advantages for problems with sparse solutions. It has been well-developed for linear inverse problems. However, there have been few results proposed for nonlinear inverse problems. Recently, some numerical algorithms for the method have been introduced. Most of them are known to have a linear convergence rate and to be slow in practice, especially for nonlinear inverse problems. The subject of the thesis is to investigate sparsity regularization for nonlinear inverse problems. We aim at the following fields: First, the method is explored for the diffusion coefficient identification problem and electrical impedance tomography. In these problems, the energy functional approach (incorporating with sparsity regularization) is applied instead of the least squares approach. We will analyze advantages of the new approach as well as the well-posedness and some convergence rates of the method in each problem. Second, we propose numerical algorithms for minimization problems in sparsity regularization of nonlinear inverse problems. They consist of a gradient-type method, two accelerated versions, and semi-smooth Newton and quasi-Newton methods. We concentrate on the convergence of the methods. However, for some algorithms, the convergence rate as well as the decreasing rate of the objective functionals are also concerned. The algorithms are then carried out to two parameter identification problems above and the efficiency of the algorithms are examined and illustrated by some specfific examples.

Sparsity regularization method has been analyzed for linear and nonlinear inverse problems over the last years. The method is known to be simple for use and has many advantages for problems with sparse solutions. It has been well-developed for linear inverse problems. However, there have been few results proposed for nonlinear inverse problems. Recently, some numerical algorithms for the method have been introduced. Most of them are known to have a linear convergence rate and to be slow in practice, especially for nonlinear inverse problems. The subject of the thesis is to investigate sparsity regularization for nonlinear inverse problems. We aim at the following fields: First, the method is explored for the diffusion coefficient identification problem and electrical impedance tomography. In these problems, the energy functional approach (incorporating with sparsity regularization) is applied instead of the least squares approach. We will analyze advantages of the new approach as well as the well-posedness and some convergence rates of the method in each problem. Second, we propose numerical algorithms for minimization problems in sparsity regularization of nonlinear inverse problems. They consist of a gradient-type method, two accelerated versions, and semi-smooth Newton and quasi-Newton methods. We concentrate on the convergence of the methods. However, for some algorithms, the convergence rate as well as the decreasing rate of the objective functionals are also concerned. The algorithms are then carried out to two parameter identification problems above and the efficiency of the algorithms are examined and illustrated by some specfific examples.