One of the most popular and useful areas of graph theory is graph colorings. A graph coloring is an assignment of integers to the vertices of a graph so that no two adjacent vertices are assigned the same integer. This problem frequently arises in scheduling and channel assignment applications. A list coloring of a graph is an assignment of integers to the vertices of a graph as before with the restriction that the integers must come from specific lists of available colors at each vertex. For a physical application of this problem, consider a wireless network. Due to hardware restrictions, each radio has a limited set of frequencies through which it can communicate, and radios within a certain distance of each other cannot operate on the same frequency without interfering. We model this problem as a graph by representing the wireless radios by vertices and assigning a list to each vertex according to its available frequencies. We then seek a coloring of the graph from these lists. In this thesis, we give an overview of the last thirty years of research in list colorings. We begin with an introduction of the list coloring problem, as defined by Erdös, Rubin, and Taylor in [6]. We continue with a study of variations of the problem, including cases when all the lists have the same length and cases when we allow different lengths. We will briefly mention edge colorings and overview some restricted list colors such as game colorings and L(p, q)-labelings before concluding with a list of open questions. / Master of Science

IEEE 802.11 (WiFi) only has two modes of trust--complete trust or complete untrust. The lack of nuance leaves no room for sensors that a user does not fully trust, but wants to connect to their network, such as a WiFi sensor. Solutions exist, but they require advanced knowledge of network administration. We solve this problem by introducing a new way of modulating data in the latency of the network, called Latency Shift Keying. We use specific characteristics of the WiFi protocol to carefully control the latency of just one device on the network. We build a transmitter, receiver, and modulation scheme that is designed to encode data in the latency of a network. We develop an application, Wicket, that solves the WiFi trust issue using Latency Shift Keying to create a new security association between an untrusted WiFi sensor and a wired device on the trusted network. We evaluate its performance and show that it works in many network conditions and environments.

In the US, the 14.0-14.5 GHz band is allocated on a primary basis to the Radio-Navigation and the FSS with a secondary allocation to the LMSS. The Radio-Navigation service is the use of RADAR for navigation. An example of Radio-Navigation is the ground proximity radar used for airplane collision avoidance. FSS stands for the Fixed Satellite Service. In general, an FSS is a satellite network consisting of a geo-stationary satellite and non-movable earth stations on the ground. An example of an FSS is the earth terminals used at gas stations to verify credit cards and centrally track inventory. The 14.0-14.5 GHz band is also allocated on a secondary basis to the LMSS or Land Mobile Satellite Service. This is a satellite network with a satellite and a movable terrestrial non-aeronautical earth station. An example of an LMSS is a system called Omnitracs, which provides a satellite-based data connection for the trucking industry. AMSS stands for the Aeronautical Mobile Satellite Service. An AMSS is an LMSS dedicated only to airplanes. The CPM or Conference Preparatory Meeting after WRC or World Radio Conference-2000 decided there was an urgent need for technical and regulatory studies covering sharing between the FSS and the AMSS. The requirement for a report on the studies was added to the WRC-2003 agenda. The WRC also stipulated that the studies must demonstrate that sharing between the FSS and the AMSS is feasible enough to allocate AMSS a secondary status in the band. The studies need to be completed before WRC-2003. AMSS contends that sharing is feasible if their service can meet the same PFD limits of the LMSS. Presently, the FCC has licensed the AMSS on an experimental non-interference basis. The FSS contends that characteristics are needed of the AMSS system and a detailed sharing study be completed to verify sharing is feasible. The FSS believes that sharing may not be feasible if the same transponder is used for AMSS and FSS. The FSS perceives that the AMSS is asking for a super secondary status. Super secondary status implies that the AMSS would only be required to adhere to PFD limits on individual aircraft and not for multiple aircraft in view of a victim FSS receiver. Future studies will clarify this issue. The issues associated with the sharing analysis are; the modeling of the orbital separation of the satellites, the atmospheric interference into the communication link and the availability of the communication link between the FSS and the AMSS. The issues associated with modeling of the simulation are the static, verses dynamic modeling environments and developing a dynamic software tool to track airplane movement. This thesis plans to propose a new sharing methodology between the FSS and the AMSS that could be contributed to the WRC-2003 agenda. Three systems examples were provided at ITU meetings inresponse to the WRC-2003 agenda item. The three systems will abide by the ITU-R S.728 EIRP limits. The three systems indicate that static analysis shows that sharing is feasible involving only one aircraft as the interfere. This is not a reasonable solution for a real time environment because there is only one aircraft used. It is necessary for the link to support multiple aircraft. The factors that indicate sharing is feasible are: non-harmful interference to the victim and reasonable enough link margin in the interfere system to make it viable. A viable system in the case of aircraft would include high-speed internet and video. The AMSS interfere system cannot propose a power limit that will not allow it to close it's own link. In order to mitigate the interference, systems can agree to certain interference mitigation techniques. The different techniques are: transmitting power control, geostationary arc avoidance angle and orbital arc separation. Power control as described above is the centralized control of the interfering antenna into the victim. This is done by simulating the interference environment and pre-scheduling the decreases of the transmitting power. This is a feasible solution except that it decreases the availability and thru-put of the interfere system. This approach can make the system have unrealistic link margins and spotty availability due to the pre-scheduled power control. Another technique is the geostationary arc avoidance angle. This technique is not applicable since both the AMSS and FSS use geostationary orbits. The third technique is geostationary separation. This technique requires co-channel systems to maintain a certain orbital spacing between them. FSS systems in certain bands have a minimum of 3 degrees of orbital spacing between co-channel systems. Since the AMSS has 01/25/03 a mobile terrestrial system (aircraft) as part of the link, it requires a higher orbital separation between it and the FSS system. The results of dynamic analysis indicate that this technique is feasible at 10 degree orbital spacing. The Monte Carlo analysis completed for this thesis simulated the results of four scenarios: co-located, 3 degree, and 5 and 10-degree orbital separation. It can be determined from the results that the interference decreases as the orbital separation increases. These simulations were done based on a 10 aircraft interfere scenario. / Master of Science

Side-channel leakage, caused by imperfect implementation of cryptographic algorithms in hardware, has become a serious security threat for connected devices that generate and process sensitive data. This side-channel leakage can divulge secret information in the form of power consumption or electromagnetic emissions. The side-channel leakage of a crytographic device is commonly assessed after tape-out on a physical prototype. This thesis presents a methodology called Gate-level Leakage Assessment (GLA), which evaluates the power-based side-channel leakage of an integrated circuit at design time. By combining side-channel leakage assessment with power simulations on the gate-level netlist, GLA is able to pinpoint the leakiest cells in the netlist in addition to assessing the overall side-channel vulnerability to side-channel leakage. As the power traces obtained from power simulations are noiseless, GLA is able to precisely locate the sources of side-channel leakage with fewer measurements than on a physical prototype. The thesis applies the methodology on the design of a encryption co-processor to analyze sources of side-channel leakage. Once the gate-level leakage sources are identified, this thesis presents a logic level replacement strategy for the leakage sources that can thwart side-channel leakage. The countermeasures presented selectively replaces gate-level cells with a secure logic style effectively removing the side-channel leakage with minimal impact in area. The assessment methodology along with the countermeasures demonstrated is a turnkey solution for IP module designers and is also applicable to larger system level designs. / Master of Science / Consider how a lie detector machine works. It looks for subtle changes in a person’s pulse to tell if the person is telling the truth. This unintentional divulgence of secret information is called a side-channel leakage. Integrated circuits reveal secret information in a similar way through their power consumption. This is caused by the transistors, used to build these integrated circuits, switching in concert with the secret data being processed by the integrated circuit. Typically, integrated circuits are evaluated for side-channel leakage only after they have been manufactured into a physical prototype. If the integrated circuit is found vulnerable it is too expensive to manufacture the prototype again with an updated design. This thesis presents a methodology, Gate-level Leakage Assessment (GLA) to evaluate integrated circuits for side-channel leakage during their design process even before they are manufactured. This methodology uses simulations to identify the specific transistors in the design that cause side-channel leakage. Moreover, this thesis presents a technique to selectively replace these problematic transistors in the design with an implementation that thwarts side channel leakage.

Embedded systems are increasingly ubiquitous. Many of them have security requirements such as smart cards, mobile phones, and internet connected appliances. It can be a challenge to fulfill security requirements due to the constrained nature of embedded devices. This security challenge is worsened by the possibility of implementation attacks. Despite well formulated cryptosystems being used, the underlying hardware can often undermine any security proven on paper. If a secret key is at play, an adversary has a chance of revealing it by simply looking at the power variation. Additionally, an adversary can tamper with an embedded system's environment to get it to skip a security check or generate side channel information. Any adversary with physical access to an embedded system can conduct such implementation attacks. It is the focus of this work to explore different countermeasures against both side channel and fault attacks. A new countermeasure call Intra-instruction Redundancy, based on bit-slicing, or N-bit SIMD processing, is proposed. Another challenge with implementing countermeasures against implementation attacks, is that they need to be able to be combined. Most proposed side channel countermeasures do not prevent fault injection and vice versa. Combining them is non-trivial as demonstrated with a combined implementation attack. / Master of Science / Consider a mechanical dial lock that must be opened without knowing the correct combination. One technique is to use a stethoscope to closely listen to the internal mechanical sounds and try to pick out any biases in order to figure out the correct combination without having to go through an exhaustive search. This is what a side channel is. Embedded systems do not have mechanical sound side channels like mechanical locks but they do leak information through power consumption. This is the basis for power analysis attacks on embedded systems. By observing power, secret information from an embedded system can be revealed despite any cryptographic protections implemented. Another side channel is the behavior of the processor when it is physically tampered with, specifically known as a fault attack. It is important that embedded systems are able to detect when they are tampered with and respond accordingly to protect sensitive information. Side channel and fault attack countermeasures are methods for embedded systems to prevent such attacks. This work presents a new state of the art fault attack countermeasure and a framework for combining the countermeasure with existing side channel countermeasures. It is nontrivial to combine countermeasures as there is a potential for combined attacks which this work shows as well.

No / This paper presents issues associated with the needs of collaborative supply chain management (CSCM) and proposes a planning stage of a CSCM framework. The proposed planning stage of a CSCM framework incorporates issues of organisation profile, internal functional strategy and supplier-customer strategy. The gauging absence of prerequisites (GAP) analysis technique which embedded in the knowledge-based system is proposed in the planning stage to analyse the gap between the current and the desirable position (benchmark) for an effective implementation in organisation. The planning stage framework provides information specifically for designing a CSCM by focusing on the organisation capability and business processes and discussed the important issues in planning a CSCM for business organisations, specifically for a manufacturing environment. Further research could be carried out to capitalise the framework for improving the CSCM. Practical implications ¿ The proposed planning stage of a CSCM framework enables the chain members to identify key factors or issues for CSCM development.

No / channels that are critical for their development and function. Many ion channels contribute to T cell-mediated autoimmune and/or inflammatory responses, so they are attractive targets for pharmacological immune modulations. In this study, we conduct patch clamp experiments to exam the whole cell currents from lymphocytes after nanoparticles exposure with the aim to test if nanoparticles exposure brings any electrophysiological changes for lymphocytes, and to compare the electrophysiological responses of lymphocytes to drugs in nanoparticles forms. Our result suggests a potential inhibition of effects of IBU N on lymphocytes. Such cytotoxicity of nanoparticles in Lymphocytes may be mainly associated with the early membrane damage. These results are also mirrored by the DNA damages occurred on lymphocytes after exposure of nanoparticles. Further detailed investigation is needed to explain the changes of Lymphocytes in response to NPs in real time and dose differences. This would provide useful information in the evaluation of toxicology of nanoparticles and in understanding the underlying mechanism of their effects on ion channels in health and diseases.

Fluvial channel geometry is controlled by the interaction of a number of geologic and hydraulic variables. The width of mixed alluvial-bedrock channels generally is a function of discharge, with variations due to local conditions. The aspect ratio (width/depth) of channels is heavily influenced by substrate size and erodibility. How channel width and aspect ratio vary as a function of other variables, such as structure, lithology, slope, large scale valley topography, and rock uplift, has not been fully quantified. The New River is ideal for examining these relationships because it shows considerable variability in width and aspect ratio and flows through three structurally and lithologically distinct geologic provinces. Through these provinces, the New River does not follow the expected trends of channel widening with increasing drainage area. Topographic maps show that channel width of the New River has a significant variation that far outscores an overall widening downstream. Aspect ratios for the New River are also large, approaching 500. We collected a field data set of 29 sites of the river's channel geometry, along with characteristics of bedrock, sediment, and confinement. Fifteen of the 29 sites are bedrock reaches. The data set allows empirical analysis of how width and aspect ratio of the New River are related to different variables, including slope, discharge, flow velocity, curvature, trend, bedrock type, and structure. Sediment characteristics and confinement of the channel do not affect channel morphology. Bedrock is shown to affect channel width directly through the percent of bedrock exposed in the channel and indirectly through the modified rock mass strength, rock hardness, obliquity to regional strike, dip orientation, and degree of joint intersection. / Master of Science

Co-channel interference limits the capacity of cellular systems, reduces the throughput of wireless local area networks, and is the major hurdle in deployment of high altitude communication platforms. It is also a problem for systems operating in unlicensed bands such as the 2.4 GHz ISM band and for narrowband systems that have been overlaid with spread spectrum systems. In this work we have developed model-based techniques for the demodulation of co-channel MSK signals. It is shown that MSK signals can be written in the linear model form, hence a minimum variance unbiased (MVU) estimator exists that satisfies the Cramer-Rao lower bound (CRLB) with equality. This framework allows us to derive the best estimators for a single-user and a two-user case. These concepts can also be extended to wideband signals and it is shown that the MVU estimator for Direct Sequence Spread Spectrum signals is in fact a decorrelator-based multiuser detector. However, this simple linear representation does not always exist for continuous phase modulations. Furthermore, these linear estimators require perfect channel state information and phase synchronization at the receiver, which is not always implemented in wireless communication systems. To overcome these shortcomings of the linear estimation techniques, we employed an autoregressive modeling approach. It is well known that the AR model can accurately represent peaks in the spectrum and therefore can be used as a general FM demodulator. It does not require knowledge of the exact signal model or phase synchronization at the receiver. Since it is a non-coherent reception technique, its performance is compared to that of the limiter discriminator. Simulation results have shown that model-based demodulators can give significant gains for certain phase and frequency offsets between the desired signal and an interferer. / Master of Science

In modern wireless communication systems, such as satellite communications and wireless networks, the need for higher data rates without the need for additional transmit power has made Continuous Phase Modulation (CPM) one of the most attractive modulation schemes in band limited channels. However, as the data rates keep increasing, the spectral width of the CPM signal increases beyond the channel bandwidth and performance becomes constrained by the intersymbol interference (ISI) that results from band-limiting filters. We propose two approaches to the problem of equalization of band-limited CPM signals. First, our efforts are focused on shortening the channel impulse response so that we can use a low complexity MLSE equalizer. We implement the channel truncation structure by Falconer and Magee and adapt it to work with CPM signals. This structure uses a, a more derivable, pre-filter to shape the overall response of the channel, so that its impulse response is of shorter duration. Simulation results show that near-MLSE performance can be obtained while dramatically reducing MLSE equalizer complexity. In our second approach, we focus on eliminating the group-delay variations inside the channel passband using an FIR pre-filter. We assume the channel to be time-invariant and provide a method to design an FIR filter so that -when convolved with the band limiting filter - it results in more constant group-delay over the filter passband. Results show that eliminating the group-delay variations in the band limiting filter passband reduce the amount of ISI and improve bit error rate performance. / Master of Science