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Auto-scaling is a major way of minimizing the gap between the demand and the availability of the computing resources for the applications with dynamic workloads. Even though a lot of effort has been taken to address the requirement of auto-scaling for the distributed systems, most of the available solutions are application-specific and consider only on fulfilling the application level requirements. Today, with the pay-as-you-go model of cloud computing, many different price plans have been offered by the cloud providers which leads the resource price to become an important decision-making criterion at the time of auto-scaling. One major step is using the spot instances which are more advantageous in the aspect of cost for elasticity. However, using the spot instances for auto-scaling should be handled carefully to avoid its drawbacks since the spot instances can be terminated at any time by the infrastructure providers. Despite the fact that some cloud providers such as Amazon Web Services and Google Compute Engine have their own auto-scaling solutions, they do not follow the goal of cost-effectiveness. In this work, we introduce our auto-scaling solution that is targeted for middle-layers in-between the cloud and the application, such as Karamel. Our work combines the aspect of minimizing the cost of the deployment with maintaining the demand for the resources. Our solution is a rule-based system that is built on top of resource utilization metrics as a more general metric for workloads. Further, the machine terminations and the billing period of the instances are taken into account as the cloud source events. Different strategies such as window based profiling, dynamic event profiling, and optimized scale-in strategy have been used to achieve our main goal of providing a cost-effective auto-scaling solution for cloud-based deployments. With the help of our simulation methodology, we explore our parameter space to find the best values under different workloads. Moreover, our cloud-based experiments show that our solution performs much more economically compare to the available cloud-based auto-scaling solutions.

<p> The performance index in teleoperation, transparency, is often defined as linear scaling of force and position between the master/ operator and slave/ environment. Motivated by applications involving soft tissue manipulation such as robotic surgery, the transparency objective is generalized in this thesis to include static nonlinear and linear-time-invariant filter mappings between the master I slave position and force signals. Lyapunov-based adaptive motion/ force controllers are proposed to achieve the generalized transparency objectives. Using Lyapunov stability theory the mapped position and force tracking errors are shown to converge in the presence of dynamic uncertainty in the master I slave robots and user I environment dynamics. Given a priori known bounds on unknown dynamic parameters, a framework for robust stability analysis is proposed that uses stability of Lur'ePostinkov systems and Nyquist/Bode envelopes of interval plant systems. Methods for finding the required Nyquist/Bode envelopes are presented in this thesis. A comprehensive stability analysis is performed under different sets of generalized mappings. For nonlinear mapping of either position or force, robust stability depends on stability of an equivalent Lur'e-Postinikov system. Stability results of such systems are discussed in this thesis. In particular, the on and off-axis circle theorems are utilized. Using these theorems, sufficient teleoperation stability regions are obtained that are far less conservative than those obtained from passivity. In the special case of LTI filtered force and position mappings the exact robust stability regions are obtained by showing stability of the relevant closed-loop characteristic polynomial. The proposed robust stability test uses the phase values of a limited set of extremal polynomials. </p> <P> To demonstrate the utility of the generalized performance measures, a stiffness discrimination tele-manipulation task is considered in which the user compares and contrasts the stiffness of soft environments via haptic exploration in the presence and absence of visual feedback. Using adaptive psychophysical perception experiments a nonlinear force mapping is shown to enhance stiffness discrimination thresholds. The design guidelines for this enhanced nonlinear force mapping are reported in this thesis. Generalized nonlinear and linear filtered mappings are achieved in experiments with a two-axis teleoperation system where the details of implementation are given. </p> / Thesis / Master of Applied Science (MASc)

Radioimmunotherapy consists in the use of beta radioactive labeled monoclonal antibodies as selective carriers of radiation to tumors. Internal spatially distributed sources created at the disease sites would deliver high radiation doses to tumors while the normal tissues would not be exposed to the intense radiation as in conventional forms of cancer treatments. A rapid and accurate estimation of the spatial dose distribution from nonuniform sources is essential for the optimization of this form of cancer therapy. The method used for such calculations is based on the knowledge of dose distributions around a unit source, quantities referred to as dose kernels. Thus far, the Monte Carlo technique is the most accurate way of the dose kernel determinations. However, for routine dosimetry simpler and less time consuming methods of adequate accuracy may appear more preferable. The "scaling factor" method is used to determine the depth dose distribution in a medium based on data about the dose distribution in an arbitrary reference medium (e.g. air, water). The transformation of the dose distribution curves from the reference medium to the desired new medium is done using a constant, known as scaling factor or relative dose attenuation, and a closely related renormalization factor imposed by the energy conservation. This work investigates the accuracy of the scaling factor method using a statistical approach (generalized chi-squared test), focusing on a particular case of potential practical interest, the scaling factor water to bone. The work also investigates a procedure for extending the applicability of the scaling factor method to dosimetry in dissimilar media, as a first step, a planar interface. / Thesis / Master of Science (MS)

No / While mining a data set of 554 chemicals in order to extract information on their toxicity value, we faced the problem of scaling all the data. There are numerous different approaches to this procedure, and in most cases the choice greatly influences the results. The aim of this paper is 2-fold. First, we propose a universal scaling procedure for acute toxicity in fish according to the Directive 92/32/EEC. Second, we look at how expert preprocessing of the data effects the performance of qualitative structure-activity relationship (QSAR) approach to toxicity prediction.

Precipitation of solids in plumbing systems (i.e., scaling) is a major problem in both traditional tank (electric and gas) and tank-less building hot water systems. Scaling can cause energy inefficiencies, flow reduction, pressure loss, and erosion corrosion damage. Consumers are also concerned with unsightly soap scum, cloudy water, discolored glassware, and failing infrastructure including appliances and fixtures. There are many treatments available that claim to ameliorate scaling problems, and several efforts have been made to develop standardized test protocols to verify and quantify their performance. This work critically evaluated previous testing efforts and revealed limitations in terms of reproducibility and a need to measure all key aspects of scale deposition including quantity, location, aesthetic and other issues. A Standardized Scaling Test Protocol (SSTP) was conceived and vetted to address these deficiencies and measure key parameters of calcium carbonate scaling throughout a model premise plumbing system, while using a synthesized test water that could provide reproducible results in any laboratory. This synthetic water and methodology was able to produce significant scaling in a model hot water system within the targeted 5-day experimental time frame. The average amount of scale recovered for the triplicate control tests (with no scale reduction device) was 25.1 grams of calcium carbonate with a 95% confidence interval of 20.3-29.8 grams of calcium carbonate. The approach also worked in recreating scaling in natural waters and was used to verify the performance of a wide array of scale reduction technologies including cation exchange softeners, electrochemical deionization, physical magnets or electric field generators, media induced precipitation, sacrificial media (phosphate), and sacrificial media (citric acid). While calcium carbonate precipitation within a water distribution system is generally undesirable; it was recently discovered that calcium carbonate particles are sometimes naturally clogging leaks in pipes and extending the lifetime of aging infrastructure. Corrosion inhibitors, mainly phosphates, have been increasingly dosed (up to 3.0 mg/L as PO4) into water to inhibit the corrosion of lead and copper pipelines in potable water systems since the advent of the Lead and Copper Rule (LCR) in 1991 by US Environmental Protection Agency (EPA). Phosphate corrosion inhibitors are now used at over 50% of water utilities in the United States and they can affect calcium carbonate scaling kinetics. In bench-scale experiments, the critical concentrations of phosphates that could inhibit leak repair over the short-term in one water tested were: tripolyphosphate (0.05 mg/L as P) < hexametaphosphate (0.1 mg/L) < orthophosphate (0.3 mg/L). The results prove that dosing of phosphates for corrosion control will also affect the kinetics and likelihood of calcium carbonate precipitation, with both beneficial and adverse consequences for pipes and consumers. Specifically, increased use of inhibitors for corrosion control is expected to reduce the likelihood of all calcium carbonate scaling problems while reducing the likelihood of autogenous pipe leak repair. In Providence, RI the dosing of orthophosphate at relatively high pH to control a lead corrosion problem, caused formation of a white precipitate, consumer reports of white water, clogging of aerators and loss of the added soluble phosphate corrosion control inhibitor due to precipitation. The precipitate was identified as a calcium phosphate solid. Field and lab scale tests suggest that at doses below 2 mg/L as PO4, precipitation did not occur in water at pH 10.4 even when the water was heated to 48°C. However, if the water was dosed above 2 mg/L as PO4 precipitation occurred within 5 minutes, and once pre-existing particles were formed precipitation tended to continue even at much lower phosphate doses. Virtually all of the phosphate precipitated within 4 hours at the upper range of 60°C that is commonly found in water heaters. Thus, dosing of phosphate can actually increase scaling problems in some circumstances. Prior work has highlighted a need for a simplified bench-scale test that can be used to rapidly screen for qualitative trends in scaling. The SSTP and practical experience showed that the vast majority of scaling occurred in the water heater. Therefore, a simplified bench-scale test consisting of a heating element in a small volume of water could be used to focus on the most sensitive aspect of scaling. A 3-hour bench-scale test was developed to quickly examine scaling with orders of magnitude less volume, time, labor, cost, and space requirements. This approach was used to evaluate aspects of scaling in water heaters for the following illustrative examples: (1) scale impacts of combined phosphate corrosion inhibitor addition and partial water softening at centralized treatment plants, (2) role of silica concentration in scaling propensity and deposit durability, (3) effects of phosphate addition on scaling in a water known to cause erosion corrosion pipe damage. This dissertation reveals the complexity of scaling for consumers and water utilities and provides tools to systematically study and resolve these practical problems. Dosing of phosphate corrosion control inhibitors can increase scaling from calcium phosphate, decrease scaling of calcium carbonate, and in other cases will have little or no effect on scaling. Both calcium carbonate and calcium phosphate can contribute to scaling as controlled by pH, temperature, hardness, phosphate dose, and other circumstances. The standardized bench and pilot scale approaches developed herein, can serve as a basis for building knowledge reproducibly in any modern laboratory. These methods can also be used to verify performance claims for a wide range of scale reduction technologies, test treatments that could be applied at centralized treatment plants, and optimize water heater design dependent on water chemistry. / Doctor of Philosophy / Precipitation of solids in plumbing systems (i.e., scaling) is a major problem in both traditional tank (electric and gas) and tank-less hot water systems. In addition to scale build up within the hot water system, consumers are also concerned with unsightly soap scum, cloudy water, discolored glassware, and failing infrastructure including appliances and fixtures. There are many treatments available that claim to mitigate scaling problems, and several efforts have been made to develop standardized test protocols to verify and quantify their performance. This work evaluated previous testing efforts to determine limitations in their methodology. A Standardized Scaling Test Protocol (SSTP) was developed to address these deficiencies and measure key parameters of calcium carbonate scaling throughout a model home plumbing system, while using a test water that could provide reproducible results in any laboratory. The test water was able to produce significant scaling within a 5-day test period with reproducible results. While calcium carbonate precipitation within a water distribution system is generally undesirable; it was recently discovered that calcium carbonate particles are sometimes naturally repairing leaks in pipes and extending the lifetime of aging plumbing systems. An increasing number of water treatment plants are adding corrosion inhibitors to water to prevent the corrosion of lead and copper pipelines. Small scale lab experiments were run to determine how effective this natural leak repair was when there were corrosion inhibitors in the water. The results showed that most corrosion inhibitors also prevented or delayed calcium carbonate precipitation which reduced the likelihood of pipe repair through clogging leaks. In Providence, RI the addition of a corrosion inhibitor caused a white precipitate to form in the water which led to consumer complaints of white water and clogging of aerators. This was due to the uniquely high pH of the water. The precipitate was identified as a calcium phosphate solid. Field and lab scale tests suggest that there is a critical inhibitor dose, below which no precipitation occurred in the high pH water. However, if the water was dosed above this critical limit, precipitation occurred immediately and continued as time went on. Prior work has highlighted a need for a simplified bench-scale test that can be used to rapidly screen for qualitative trends in scaling. A 3-hour bench-scale test was developed to quickly examine key aspects of scaling with orders of magnitude less volume, time, labor, cost, and space requirements. This dissertation reveals the complexity of scaling for consumers and water utilities and provides tools to systematically study and resolve these practical problems.