A circumferential slot In-line Virtual Impactor (IVI) has been designed using Computational Fluid Dynamics (CFD) simulation tools and experimentally characterized using monodispersed liquid aerosols to validate simulation results. The base design, IVI-100, has an application as a pre-separator for sampling inlets, where the device scalps large particles from the aerosol size distribution. The IVI-100 samples air in at 111 L/min and deliver the fine aerosol fraction in a 100 L/min flow and provide a cutpoint particle size of 10 µm, with a pressure drop of 45 Pa. An inverted dual cone configuration encased inside a tube provides the IVI-100 with a characteristic circumferential slot of width 0.254 mm (0.100 inches) and a slot length of 239 mm (9.42 inches) at the critical zone. The upper cone causes the flow to accelerate to an average throat velocity of 3.15 m/s, while the lower cone directs the major flow toward the exit port and minimizes recirculation zones that could cause flow instabilities in the major flow region. The cutpoint Stokes number is 0.73; however, the cutpoint can be adjusted by changing the geometrical spacing between the acceleration nozzle exit plane and a flow divider. Good agreement is obtained between numerically predicted and experimentally observed performance. An aerosol size selective inlet for bioaerosol and other air sampling applications using an upgraded prototype of IVI-100, mounted inside a BSI-100 inlet shell was tested in an aerosol wind tunnel over a speed range of 2 – 24 km/hr. The BSI-IVI-100 inlet has a cutpoint of 11 µm aerodynamic diameter and delivers the fine fraction at 100 L/m. The geometric standard deviation of the fractionation curve is 1.51 and the performance is not affected by wind speeds. An IVI-350, which is an adaptation of the IVI to be used as a powder fractionator, was designed based on computational simulations, and provides a cutpoint of 3 µm AD, while operating in a total flow rate of 350 L/min. Four Identical IVI -350 units will be operated in parallel to fractionate aerosolized powders in a 1400 L/min flow. An optimized inlet, with a contoured tear-drop shaped insert provides uniform flow to four identical IVI units and prevents powder accumulation in the system entrance.

This thesis is composed of six papers, all dealing with the issue of sampling from a finite population. We consider two different topics: real time sampling and distributions in sampling. The main focus is on Papers A–C, where a somewhat special sampling situation referred to as real time sampling is studied. Here a finite population passes or is passed by the sampler. There is no list of the population units available and for every unit the sampler should decide whether or not to sample it when he/she meets the unit. We focus on the problem of finding suitable sampling methods for the described situation and some new methods are proposed. In all, we try not to sample units close to each other so often, i.e. we sample with negative dependencies. Here the correlations between the inclusion indicators, called sampling correlations, play an important role. Some evaluation of the new methods are made by using a simulation study and asymptotic calculations. We study new methods mainly in comparison to standard Bernoulli sampling while having the sample mean as an estimator for the population mean. Assuming a stationary population model with decreasing autocorrelations, we have found the form for the nearly optimal sampling correlations by using asymptotic calculations. Here some restrictions on the sampling correlations are used. We gain most in efficiency using methods that give negatively correlated indicator variables, such that the correlation sum is small and the sampling correlations are equal for units up to lag m apart and zero afterwards. Since the proposed methods are based on sequences of dependent Bernoulli variables, an important part of the study is devoted to the problem of how to generate such sequences. The correlation structure of these sequences is also studied. The remainder of the thesis consists of three diverse papers, Papers D–F, where distributional properties in survey sampling are considered. In Paper D the concern is with unified statistical inference. Here both the model for the population and the sampling design are taken into account when considering the properties of an estimator. In this paper the framework of the sampling design as a multivariate distribution is used to outline two-phase sampling. In Paper E, we give probability functions for different sampling designs such as conditional Poisson, Sampford and Pareto designs. Methods to sample by using the probability function of a sampling design are discussed. Paper F focuses on the design-based distributional characteristics of the π-estimator and its variance estimator. We give formulae for the higher-order moments and cumulants of the π-estimator. Formulae of the design-based variance of the variance estimator, and covariance of the π-estimator and its variance estimator are presented.

Based on different sampling theorem, for example classic Shannon’s sampling theorem and Papoulis’ generalized sampling theorem, signals are processed by the sampling devices without loss of information. As an interface between radio receiver front-ends and digital signal processing blocks, sampling devices play a dominant role in digital radio communications. Under the concept of Software Defined Radio (SDR), radio systems are going through the second evolution that mixes analog, digital and software technologies in modern radio designs. One design goal of SDR is to put the A/D converter as close as possible to the antenna. BandPass Sampling (BPS) enables one to have an interface between the RF or the higher IF signal and the A/D converter, and it might be a solution to SDR. However, three sources of performance degradation present in BPS systems, harmful signal spectral overlapping, noise aliasing and sampling timing jitter, hinder the conventional BPS theory from practical circuit implementations. In this thesis work, Generalized Quadrature BandPass Sampling (GQBPS) is first invented and comprehensively studied with focus on the noise aliasing problem. GQBPS consists of both BPS and FIR filtering that can use either real or complex coefficients. By well-designed FIR filtering, GQBPS can also perform frequency down-conversion in addition to noise aliasing reduction. GQBPS is a nonuniform sampling method in most cases. With respect to real circuit implementations, uniform sampling is easier to be realized compared to nonuniform sampling. GQBPS has been also extended to Generalized Uniform BandPass Sampling (GUBPS). GUBPS shares the same property of noise aliasing suppression as GQBPS besides that the samples are uniformly spaced. Due to the moving average operation of FIR filtering, the effect of sampling jitter is also reduced to a certain degree in GQBPS and GUBPS. By choosing a suitable sampling rate, harmful signal spectral overlapping can be avoided. Due to the property of quadrature sampling, the “self image” problem caused by I/Q mismatches is eliminated. Comprehensive theoretical analyses and program simulations on GQBPS and GUBPS have been done based on a general mathematic model. Circuit architecture to implementing GUBPS in Switched-Capacitor circuit technique has been proposed and analyzed. To improve the selectivity at the sampling output, FIR filtering is extended by adding a 1st order complex IIR filter in the implementation. GQBPS and GUBPS operate in voltage-mode. Besides voltage sampling, BPS can also be realized by charge sampling in current-mode. Most other research groups in this area are focusing on bandpass charge sampling. However, the theoretical analysis shows that our GQBPS and GUBPS in voltage mode are more efficient to suppress noise aliasing as compared to bandpass charge sampling with embedded filtering. The aliasing bands of sampled-data spectrum are always weighted by continuous-frequency factors for bandpass charge sampling with embedded filtering while discrete-frequency factors for GQBPS and GUBPS. The transmission zeros of intrinsic filtering will eliminate the corresponding whole aliasing bands of both signal and noise in GQBPS and GUBPS, while it will only cause notches at a limited set of frequencies in bandpass charge sampling. In addition, charge sampling performs an intrinsic continuous-time sinc function that always includes lowpass filtering. This is a drawback for a bandpass input signal. / QC 20100921

This paper focuses on the issue of sampling directly from the stationary distribution of Vervaat perpetuities. It improves upon an algorithm for perfect sampling first presented by Fill & Huber by implementing both a faster multigamma coupler and a moving value of Xmax to increase the chance of unification. For beta = 1 we are able to reduce the expected steps for a sample by 22%, and at just beta = 3 we lower the expected time by over 80%. These improvements allow us to sample in reasonable time from perpetuities with much higher values of beta than was previously possible.

Partially Recursive Acceptance Rejection (PRAR) and bounding chains used in conjunction with coupling from the past (CFTP) are two perfect simulation protocols which can be used to sample from a variety of unnormalized target distributions. This paper first examines and then implements these two protocols to sample from the hardcore gas process. We empirically determine the subset of the hardcore process's parameters for which these two algorithms run in polynomial time. Comparing the efficiency of these two algorithms, we find that PRAR runs much faster for small values of the hardcore process's parameter whereas the bounding chain approach is vastly superior for large values of the process's parameter.

Complex multidimensional capturing setups such as plenoptic cameras (PC) introduce a trade-off between various system properties. Consequently, established capturing properties, like image resolution, need to be described thoroughly for these systems. Therefore models and metrics that assist exploring and formulating this trade-off are highly beneficial for studying as well as designing of complex capturing systems. This work demonstrates the capability of our previously proposed sampling pattern cube (SPC) model to extract the lateral resolution for plenoptic capturing systems. The SPC carries both ray information as well as focal properties of the capturing system it models. The proposed operator extracts the lateral resolution from the SPC model throughout an arbitrary number of depth planes giving a depth-resolution profile. This operator utilizes focal properties of the capturing system as well as the geometrical distribution of the light containers which are the elements in the SPC model. We have validated the lateral resolution operator for different capturing setups by comparing the results with those from Monte Carlo numerical simulations based on the wave optics model. The lateral resolution predicted by the SPC model agrees with the results from the more complex wave optics model better than both the ray based model and our previously proposed lateral resolution operator. This agreement strengthens the conclusion that the SPC fills the gap between ray-based models and the real system performance, by including the focal information of the system as a model parameter. The SPC is proven a simple yet efficient model for extracting the lateral resolution as a high-level property of complex plenoptic capturing systems.

In solving noise-free and noisy optimization problems, candidate initialization and sampling play a key role, but are not deeply investigated. It is of interest to know if the entire search space has the same quality for candidate-solutions during solving different type of optimization problems. In this thesis, a comprehensive investigation is conducted in order to clear those doubts, and to examine the effects of variant sampling methods on solving challenging optimization problems, such as large-scale, noisy, and multi-modal problems. As a result, the search space is segmented by using seven segmentation schemes, namely: Center-Point, Center-Based, Modula-Opposite, Quasi-Opposite, Quasi-Reflection, Supper- Opposite, and Opposite-Random. The introduced schemes are studied using Monte-Carlo simulation, on various types of noise-free optimization problems, and ultimately ranked based on their performance in terms of probability of closeness, average distance to unknown solution, number of solutions found, and diversity. Based on the results of the experiments, high-ranked schemes are selected and utilized on well-known metaheuristic algorithms, as case studies. Two categories of case studies are targeted; one for a singlesolution- based metaheuristic (S-metaheuristic) and another one for a population based metaheuristic (P-metaheuristic). A high-ranked single-solution-based scheme is utilized to accelerate Simulated Annealing (SA) algorithm, as a noise-free S-metaheuristic case study. Similarly, for noise-free P-metaheuristic case study, an effective population-based algorithm, Differential Evolution (DE), has been utilized. The experiments confirm that the new algorithms outperform the parent algorithm (DE) on large-scale problems. In the same direction, with regards to solving noisy problems more efficiently, a Shaking-based sampling method is introduced, in which the original noise is tackled by adding an additional noise into the search process. As a case study, the Shaking-based sampling is utilized on the DE algorithm, from which two variant algorithms have been developed and showed impressive performance in comparison to the classical DE, in tackling noisy largescale problems. This thesis has created an opportunity for a comprehensive investigation on search space segmentation schemes and proposed new sampling methods. The current study has provided a guide to use appropriate sampling schemes for a given types of problems such as noisy, large-scale and multi-modal optimization problems. Furthermore, this thesis questions the effectiveness of uniform-random sampling method, which is widely used in of S-Metaheuristic and P-Metaheuristic algorithms. / UOIT

This thesis works towards a theory of creative appropriation as critical praxis. Defining ‘appropriation’ as the re-use of already-authored cultural matter, I investigate how the ubiquity of aesthetically and commercially motivated appropriative practices has impacted concepts of creativity, originality, authorship and ownership. Throughout this thesis, appropriation is understood as bridging the artistic, political, economic, and scientific realms. As such, it strongly affects cultural and socio-political landscapes, and has become an ideal vehicle for effectively criticizing and, perhaps, radically changing dominant aesthetic, legal and ethical discourses regarding the (re)production, ownership and circulation of knowledge, artifacts, skills, resources, and cultural matter in general. Critical appropriation is thus posited as a political strategy that can draw together the different causes motivating appropriative processes across the globe, and organize them for the benefit of a multitude which values concepts of reusing, sharing and collectivity over concepts of the individually authored and the privately owned. My arguments regarding this critical potentiality are based on concrete practices emanating from several media (textual – visual – sonic – digital). The corpus includes Berlin Dadaist collage, ‘found footage’ filmmaking, audio sampling, and digital media art. It is critically contextualized in the fields of philosophy, law, and aesthetics, and paired with relevant examples from extra-aesthetic arenas (economics, industrial production and science). Following a trajectory from the analog to the digital, my thesis traces the emergence and tactical employment of critical appropriative practices in the context of different historical, philosophical, technological and economic circumstances. Focussing on conceptual and practical shifts from the analog to the digital furthermore enables me to draw connections between analytic perspectives founded in dialectic materialism and contemporary theories foregrounding issues of immaterial labor. The important qualitative changes that practices and perceptions of appropriation have undergone are argue to significantly amplify the critical potential of all appropriative practices. Ultimately, my comparative analyses thus establish appropriation as an ideal site for effectively challenging – both in terms of form and content – the ingrained, restrictive notions of original genius and naturalized authorship-qua-ownership on which present cultures and technologies of global capitalism are so heavily based.

For ultra-wideband (UWB) communications, acquisition is challenging. The reason is from the ultra short pulse shape and ultra dense multipath interference. Ultra short pulse indicates the acquisition region is very narrow. Sampling is another challenge for UWB design due to the need for ultra high speed analog-to digital converter.<p>A sub-optimum and under-sampling scheme using pilot codes as transmitted reference is proposed here for acquisition. The sampling rate for the receiver is at the symbol rate. A new architecture, the reference aided matched filter is studied in this project. The reference aided matched filter method avoids using complex rake receiver to estimate channel parameters and high sampling rate for interpolation. A limited number of matched filters are used as a filter bank to search for the strongest path. Timing offset for acquisition is then estimated and passed to an advanced verification algorithm. For optimum performance of acquisition, the adaptive post detection integration is proposed to solve the problem from dense inter-symbol interference during the acquisition. A low-complex early-late gate tracking loop is one element of the adaptive post detection integration. This tracking scheme assists in improving acquisition accuracy. The proposed scheme is evaluated using Matlab Simulink simulations in term of mean acquisition time, system performance and false alarm. Simulation results show proposed algorithm is very effective in ultra dense multipath channels. This research proves reference aided acquisition with tracking loop is promising in UWB application.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.