Physical Sciences and Mathematics Commons^™

A National Model Built With Partial Least Squares And Universal Kriging And Bootstrap-Based Measurement Error Correction Techniques: An Application To The Multi-Ethnic Study Of Atherosclerosis, Silas Bergen, Lianne Sheppard, Paul D. Sampson, Sun-Young Kim, Mark Richards, Sverre Vedal, Joel Kaufman, Adam A. Szpiro

UW Biostatistics Working Paper Series

Studies estimating health effects of long-term air pollution exposure often use a two-stage approach, building exposure models to assign individual-level exposures which are then used in regression analyses. This requires accurate exposure modeling and careful treatment of exposure measurement error. To illustrate the importance of carefully accounting for exposure model characteristics in two-stage air pollution studies, we consider a case study based on data from the Multi-Ethnic Study of Atherosclerosis (MESA). We present national spatial exposure models that use partial least squares and universal kriging to estimate annual average concentrations of four PM2.5 components: elemental carbon (EC), organic carbon (OC), …

Ctod: Collaborative Tree-Based Outlier Detection In Wireless Sensor Networks, Dylan Mcdonald, Sanjay Kumar Madria, Fikret Ercal, Ryan Birmingham, Thomas Lake

Computer Science Faculty Research & Creative Works

Outlier detection is a well-studied problem in various fields. the unique challenges of wireless sensor networks such as limited bandwidth, memory, energy, and unreliable communication make this problem especially difficult. Sensors can detect outliers for a plethora of reasons and these reasons need to be inferred in real time. Here, we present a new robust communication framework for the unsupervised in network detection of outliers in a wireless sensor network. First, communication is minimized through an ad-hoc collaborative communication scheme which controls sensor behavior to increase overall visibility of individual streaming data sets. Second, an outlier detection algorithm is tailored …

Tuning Parameter Selection In L1 Regularized Logistic Regression, Shujing Shi

Theses and Dissertations

Variable selection is an important topic in regression analysis and is intended to select the best subset of predictors. Least absolute shrinkage and selection operator (Lasso) was introduced by Tibshirani in 1996. This method can serve as a tool for variable selection because it shrinks some coefficients to exact zero by a constraint on the sum of absolute values of regression coefficients. For logistic regression, Lasso modifies the traditional parameter estimation method, maximum log likelihood, by adding the L1 norm of the parameters to the negative log likelihood function, so it turns a maximization problem into a minimization one. To …

College Of Engineering Senior Design Competition Fall 2012, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Senior Design Experience

Part of every UNLV engineering student's academic experience, the Senior Design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs and prototypes a product in this required element of the curriculum. Working in teams, the senior design project encourages students to use everything learned in the engineering and computer design programs to create a practical, real world solution to an engineering challenge.

Beyond the classroom ...

Because of the requirement to work in teams, students also build good communication skills, presentation skills and even business writing skills. They also have to …

Surreal Numbers, Joshua Hostetler

Theses and Dissertations

The purpose of this thesis is to explore the Surreal Numbers from an elementary, con- structivist point of view, with the intention of introducing the numbers in a palatable way for a broad audience with minimal background in any specific mathematical field. Created from two recursive definitions, the Surreal Numbers form a class that contains a copy of the real numbers, transfinite ordinals, and infinitesimals, combinations of these, and in- finitely many numbers uniquely Surreal. Together with two binary operations, the surreal numbers form a field. The existence of the Surreal Numbers is proven, and the class is constructed from …

Modelling Carbon Nanostructures For Filtering And Adsorbing Polycyclic Aromatic Hydrocarbons, Thien Tran-Duc, Ngamta Thamwattana

Dr Ngamta Thamwattana

The discovery of carbon nanostructures, such as graphene and carbon nanotubes, has led to the creation of many novel nano-devices. In this paper, we consider an environmental application of carbon nanostructures for filtering and adsorbing polycyclic aromatic hydrocarbons (PAHs) which are environmental pollutants. We mathematically investigate the adsorption of PAHs onto a graphene sheet and determine the underlying mechanisms of suction of PAHs into a carbon nanotube. We adopt a continuum approach together with the semi-empirical Lennard-Jones potential to determine van der Waals interaction forces and energies. Results obtained here for certain PAHs are well in agreement with existing experimental …

Electric Field-Induced Force Between Two Identical Uncharged Spheres, B. J. Cox, N. Thamwattana, James M. Hill

Dr Ngamta Thamwattana

The problem of electric field-induced force between spheres is fundamental to electrorheological fluids. Previously published experimental results indicate that the interaction force between two spheres under an external field is not adequately explained by the existing approximate and numerical methods. The specific models compared were dipole, dipole with local field corrections and a finite-element analysis. This letter employs an exact solution (via the equivalent multipole-moment method) to the electrostatic problem which accurately predicts the low-frequency experimental results at all measured interstices. The solution presented later is self-contained and addresses specifically the geometry of the previously mentioned experimental results. While more …

Continuum Modelling For Carbon And Boron Nitride Nanostructures, James M. Hill, Ngamta Thamwattana

Dr Ngamta Thamwattana

Continmuum based models are presented here for certain boron nitride and carbon nanostructures.

A Survey Of Some Mathematical Results For Highly Frictional Granular Materials, Grant Cox, Ngamta Thamwattana, James Hill

Dr Ngamta Thamwattana

Recently the authors have exploited the notion of a highly frictional granular material to derive analytical solutions for certain problems. Generally, we use the term highly frictional granular material to refer to those materials which possess an angle of internal friction such that the trigonometric sine of the angle of internal friction is close to unity. There are many granular materials for which this is the case, such as black and brown coal and limestone powder. For such materials formal perturbation solutions can be derived for which the zeroth-order solution corresponds to an angle of internal friction precisely equal to …

Coulomb-Mohr Granular Materials: Quasi-Static Flows And The Highly Frictional Limit, James Hill, Grant Cox, Ngamta Thamwattana, Scott Mccue

Dr Ngamta Thamwattana

One approach to modeling fully developed shear flow of frictional granular materials is to use a yield condition and a flow rule, in an analogous way to that commonly employed in the fields of metal plasticity and soil mechanics. Typically, the yield condition of choice for granular materials is the CoulombMohr criterion, as this constraint is relatively simple to apply but at the same time is also known to predict stresses that are in good agreement with experimental observations. On the other hand, there is no strong agreement within the engineering and applied mechanics community as to which flow rule …

Mechanics Of Fullerene-Carbon Nanotube Bundle Oscillators, James Hill, Ngamta Thamwattana, Duangkamon Baowan, Barry Cox

Dr Ngamta Thamwattana

Carbon nanostructures, such as nanotubes and fullerenes, are of considerableinterest to a wide range of research communities. Owing to their unique properties, a numberof applications involving these structures have been proposed, one of which is the so-callednano-scaled oscillators, for which the resultant oscillatory frequencies are in the gigahertzrange. The phenomena of the gigahertz oscillations have also led to the possible creation offuture devices, such as ultra-fast optical filters and ultra-sensitive nano-antennae. In thispaper we present recent developments in this area and review the authors recent work,where we investigate the mechanics of a new type of gigahertz oscillator comprising afullerene C60 …

Mathematical Modelling For A C60 Carbon Nanotube Oscillator, Barry Cox, Ngamta Thamwattana, James Hill

Dr Ngamta Thamwattana

The discovery of fullerenes C60 and carbon nanotubes has created an enormous impact on nanotechnology. Because of their unique mechanical and electronic properties, such as low weight, high strength, flexibility and thermal stability, fullerenes C60 and carbon nanotubes are of considerable interest to researchers from many scientific areas. One problem that has attracted much attention is the creation of gigahertz oscillators. While there are difficulties for micromechanical oscillators, or resonators, to reach a frequency in the gigahertz range, it is possible for nanomechanical systems to achieve this. A number of studies have found that the sliding of the inner-shell inside …

Orientation Of A Benzene Molecule Inside A Carbon Nanotube, Thien Tran-Duc, Ngamta Thamwattana, James Hill

Dr Ngamta Thamwattana

Benzene molecules confined in carbon nanotubes of varying radii are employed as semiconductors in electronic nanodevices, and their orientation determines the electrical properties of the system. In this paper, we investigate the interaction energy of all the possible configurations of a benzene molecule inside various carbon nanotubes and then we determine the equilibrium configuration. We adopt the continuous approach together with the semi-empirical Lennard-Jones potential function to model van der Waals interaction between a benzene molecule and a carbon nanotube. This approach results in an analytical expression, which accurately approximates the interaction energy and can be readily used to generate …

Continuum Modelling Of Gigahertz Nano-Oscillators, James Hill, Ngamta Thamwattana, Duangkamon Baowan, Tamsyn Hilder, Barry Cox

Dr Ngamta Thamwattana

Fullerenes and carbon nanotubes are of considerable interest throughout many scientific areas due to their unique and exceptional properties, such as low weight, high strength, flexibility, high thermal conductivity and chemical stability. These nanostructures have many potential applications in nano-devices. One concept that has attracted much attention is the creation of nano-oscillators, which can produce frequencies in the gigahertz range, for applications such as ultra-fast optical filters and nano-antennae. In this paper, we provide the underlying mechanisms of the gigahertz nano-oscillators and we review some recent results derived by the authors using the Lennard-Jones potential together with the continuum approach …

Spherical And Spheroidal Fullerenes Entering Carbon Nanotubes, James Hill, Ngamta Thamwattana, Barry Cox

Dr Ngamta Thamwattana

A continuous model of a fullerene inside a carbon nanotube and for which both the fullerene and carbon nanotube are treated as smooth surfaces with uniform atomic number densities and the van der Waals interaction is formulated using a 6-12 Lennard-Jones potential. From the model we derive acceptance conditions and suction energies for C60, C70 and C80 fullerenes. We show that for these systems where the fullerenes are not accepted by the nanotube, then the suction energy is particularly sensitive to the equatorial semi-axis length b. Alternatively, when the nanotube does accept the fullerene then an approximately equal suction energy …

Modelling Adsorption Of A Water Molecule Into Various Pore Structures Of Silica Gel, Duangkamon Baowan, Ngamta Thamwattana

Dr Ngamta Thamwattana

Silica gel is widely used in commercial applications as a water adsorbent due to its properties including hydrothermally stable, high water sorption capacity, low regeneration temperature, low cost and wide range of pore diameters. Since the water sorption capacity of silica gel strongly depends on the pore size and structure, which can be controlled during synthesis, this paper study the effect of pore shapes and dimensions of silica gel upon the adsorption of a water molecule aiming at maximising the water sorption capacity. In particular, we consider three types of pore structures, namely cylindrical, square prismatic and conical pores. On …

Magnetic Field Driven Nano Tippe Top, James Hill, Ngamta Thamwattana, Yue Chan

Dr Ngamta Thamwattana

We investigate the motion of a nano tippe top, which is formed from a C60 fullerene, and which is assumed to be spinning on either a graphene sheet or the interior of a single-walled carbon nanotube. We assume no specific geometric configuration for the top, however for example, the nano tippe top might be formed by joining a fullerene C60 with a small segment of a smaller radius carbon nanotube. We assume that it is spinning on a graphene sheet or a carbon nanotube surface only as a means of positioning and isolating the device, and the only effect of …

Mathematical Modelling In Nanotechnology, Ngamta Thamwattana, James M. Hill

Dr Ngamta Thamwattana

The interaction of nano particles with conventional materials dramatically changes all the physical parameters, which usually characterize the bulk material. The nano particles constitute highly reactive isolated sites to the extent that it leads to a change in the electronic structure of the nano composite, and accordingly all the physical properties, such as thermal, mechanical and electrical properties become different from those of the bulk material. To successfully exploit nano composites as components and devices, this fundamental shift of physical properties must be properly understood and accurately modelled. While experimentation is crucial, a theoretical understanding is also necessary and with …

Carbon Molecules Oscillating In Carbon Nanotube Bundles, Ngamta Thamwattana, B. J. Cox, James M. Hill

Dr Ngamta Thamwattana

Fullerenes C60 and carbon nanotubes are of considerable interest to researchers from many scientific areas due to their unique electronic and mechanical properties. One application of these carbon nanostructures that has recently attracted much attention is the creation of an oscillator that operates in the gigahertz range frequency. A number of studies have found that the sliding of the inner-shell inside the outershell of a multi-walled carbon nanotube can generate gigahertz oscillatory frequencies. In this paper, we investigate the mechanics of a gigahertz oscillator comprising a carbon nanotube oscillating within the centre of a uniform concentric ring or bundle of …

Modelling Peptide Nanotubes For Artificial Ion Channels, Ngamta Thamwattana, Barry Cox, Fainida Rahmat

Dr Ngamta Thamwattana

We investigate the van der Waals interaction of D,L-Ala cyclopeptide nanotubes and various ions, ion&¿water clusters and C60 fullerenes, using the Lennard-Jones potential and a continuum approach which assumes that the atoms are smeared over the peptide nanotube providing an average atomic density. Our results predict that Li + , Na + , Rb + and Cl &¿ ions and ion&¿water clusters are accepted into peptide nanotubes of 8.5 Å internal diameter whereas the C60 molecule is rejected. The model indicates that the C60 molecule is accepted into peptide nanotubes of 13 Å internal diameter, suggesting that the interaction energy …

Traceable And Retrievable Identity-Based Encryption, Man Ho Au, Qiong Huang, Joseph K. Liu, Willy Susilo, Duncan S. Wong, Guomin Yang

Professor Willy Susilo

Very recently, the concept of Traceable Identity-based Encryption (IBE) scheme (or Accountable Authority Identity based Encryption scheme) was introduced in Crypto 2007. This concept enables some mechanisms to reduce the trust of a private key generator (PKG) in an IBE system. The aim of this paper is threefold. First, we discuss some subtleties in the first traceable IBE scheme in the Crypto 2007 paper. Second, we present an extension to this work by having the PKG’s master secret key retrieved automatically if more than one user secret key are released. This way, the user can produce a concrete proof of …

Ste3d-Cap: Stereoscopic 3d Captcha, Willy Susilo, Yang-Wai Chow, Huayu Zhou

Professor Willy Susilo

We present STE3D-CAP (pronounced as “steed-cap” /'stidkæp/), a text-based CAPTCHA that is built from stereoscopic 3D images. This is a completely new direction in CAPTCHA techniques. Our idea is to incorporate stereoscopic 3D images in order to present the CAPTCHA challenge in 3D, which will be easy for humans to read (as the text stands out in the 3D scene) but hard for computers. The main idea is to produce a stereo pair, two images of the distorted 3D text objects generated from two different camera/eye viewpoints, that are presented to a human user’s left and right eyes, respectively. When …

Improving Bdd Cryptosystems In General Lattices, Willy Susilo, Thomas V. Plantard, Michael Rose

Professor Willy Susilo

No abstract provided.

New Constructions Of Osbe Schemes And Their Applications In Oblivious Access Control, Jinguang Han, Willy Susilo, Yi Mu, Jun Yan

Professor Willy Susilo

Oblivious signature-based envelope (OSBE) schemes have demonstrated their potential applications in the protection of users privacy and rights. In an OSBE protocol, an encrypted message can only be decrypted by the receiver who holds a valid signature on a public message, while the sender (encrypter) does not know whether the receiver has the signature or not. Our major contributions in this work lie in the following aspects. We improve the notion of OSBE so that a valid credential holder cannot share his/her credential with other users (i. e., all-or-nothing non-transferability). We clarify the relationship between one-round OSBE and identity-based encryption …

Threshold Ring Signature Without Random Oracles, Tsz Hon Yuen, Joseph K. Liu, Man Ho Allen Au, Willy Susilo, Jianying Zhou

Professor Willy Susilo

In this paper, we present the notion and construction of threshold ring signature without random oracles. This is the first scheme in the literature that is proven secure in the standard model. Our scheme extends the Shacham-Waters signature from PKC 2007 in a non-trivial way. We note that our technique is specifically designed to achieve a threshold ring signature in the standard model. Interestingly, we can still maintain the signature size to be the same as the Shacham-Waters signature, while only a tiny computation cost is added.

Perfect Ambiguous Optimistic Fair Exchange, Yang Wang, Man Ho Allen Au, Willy Susilo

Professor Willy Susilo

Protocol for fair exchange of digital signatures is essential in many applications including contract signing, electronic commerce, or even peer-to-peer file sharing. In such a protocol, two parties, Alice and Bob, would like to exchange digital signatures on some messages in a fair way. It is known that a trusted arbitrator is necessary in the realization of such a protocol. We identify that in some scenarios, it is required that prior to the completion of the protocol, no observer should be able to tell whether Alice and Bob are conducting such an exchange. Consider the following scenario in which Apple …

Differential Fault Analysis Of Lex, Jianyong Huang, Willy Susilo, Jennifer Seberry

Professor Willy Susilo

LEX is a stream cipher based on the round transformation of the AES block cipher, and it was selected for the final phase evaluation of the eSTREAM project. LEX is 2.5 times faster than AES both in software and in hardware. In this paper, we present a differential fault attack on LEX. The fault model assumes that the attacker is able to flip a random bit of the internal state of the cipher but cannot control the exact location of the induced fault. Our attack requires 40 faults, and recovers the secret key with 216 operations.

Fault Analysis Of The Katan Family Of Block Ciphers, Shekh Faisal Abdul-Latip, Mohammad Reza Reyhanitabar, Willy Susilo, Jennifer Seberry

Professor Willy Susilo

In this paper, we investigate security of the KATAN family of block ciphers against differential fault attacks. KATAN consists of three variants with 32, 48 and 64-bit block sizes, called KATAN32, KATAN48 and KATAN64, respectively. All three variants have the same key length of 80 bits. We assume a single-bit fault injection model where the adversary is supposed to be able to corrupt a single random bit of the internal state of the cipher and this fault induction process can be repeated (by resetting the cipher); i.e., the faults are transient rather than permanent. First, we show how to identify …

Privacy Enhanced Data Outsourcing In The Cloud, Miao Zhou, Yi Mu, Willy Susilo, Jun Yan, Liju Dong

Professor Willy Susilo

How to secure outsourcing data in cloud computing is a challenging problem, since a cloud environment cannot been considered to be trusted. The situation becomes even more challenging when outsourced data sources in a cloud environment are managed by multiple outsourcers who hold different access rights. In this paper, we introduce an efficient and novel tree-based key management scheme that allows a data source to be accessed by multiple parties who hold different rights. We ensure that the database remains secure, while some selected data sources can be securely shared with other authorized parties.

Practical Compact E-Cash, Man Ho Au, Willy Susilo, Yi Mu

Professor Willy Susilo

Compact e-cash schemes allow a user to withdraw a wallet containing k coins in a single operation, each of which the user can spend unlinkably. One big open problem for compact e-cash is to allow multiple denominations of coins to be spent efficiently without executing the spend protocol a number of times. In this paper, we give a (partial) solution to this open problem by introducing two additional protocols, namely, compact spending and batch spending. Compact spending allows spending all the k coins in one operation while batch spending allows spending any number of coins in the wallet in a …