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Full-Text Articles in Physical Sciences and Mathematics

Enhancing Public Engagement On Offshore Wind Energy Using Genius Loci: A Case Study From A Lake Michigan Coastal Community, Erik Edward Nordman, Daniel O'Keefe, Erika Arndt Sep 2016

Enhancing Public Engagement On Offshore Wind Energy Using Genius Loci: A Case Study From A Lake Michigan Coastal Community, Erik Edward Nordman, Daniel O'Keefe, Erika Arndt

Erik Edward Nordman

We describe a novel approach to public engagement on offshore wind energy based on genius loci (“spirit of a place”). North America lacks offshore wind farms but they could be viable in the Great Lakes. Cultural ties between coastal Michigan, USA and the Netherlands offered opportunities to learn from the Dutch offshore wind experience. Residents from a Lake Michigan coastal community with Dutch heritage videoconferenced with a Dutch tourism specialist regarding the Egmond aan Zee offshore wind farm. Important differences and similarities between the regions emerged, including the clustering of technological expertise, tourism effects, and perspectives on working seascapes. Michigan ...


Teaching Big History, Richard B. Simon, Mojgan Behmand, Thomas Burke, Esther Quaedackers, Seohyung Kim, Kiowa Bower, Neal Wolfe, James B. Cunningham, Cynthia Taylor, Martin Anderson, J. Daniel May, Philip Novak, Debbie Daunt, Jaime Castner, Ethan Annis, Amy E. Gilbert, Anne Reid, Suzanne Roybal, Alan Schut, Cynthia Brown, Harlan Stelmach Jun 2016

Teaching Big History, Richard B. Simon, Mojgan Behmand, Thomas Burke, Esther Quaedackers, Seohyung Kim, Kiowa Bower, Neal Wolfe, James B. Cunningham, Cynthia Taylor, Martin Anderson, J. Daniel May, Philip Novak, Debbie Daunt, Jaime Castner, Ethan Annis, Amy E. Gilbert, Anne Reid, Suzanne Roybal, Alan Schut, Cynthia Brown, Harlan Stelmach

Harlan Stelmach

Big History is a new field on a grand scale: it tells the story of the universe over time through a diverse range of disciplines that spans cosmology, physics, chemistry, astronomy, geology, evolutionary biology, anthropology, and archaeology, thereby reconciling traditional human history with environmental geography and natural history.Weaving the myriad threads of evidence-based human knowledge into a master narrative that stretches from the beginning of the universe to the present, the Big History framework helps students make sense of their studies in all disciplines by illuminating the structures that underlie the universe and the connections among them.Teaching Big ...


Doing 'True Science': The Early History Of The 'Institutum Divi Thomae,' 1935-1951, John Alfred Heitmann Jun 2016

Doing 'True Science': The Early History Of The 'Institutum Divi Thomae,' 1935-1951, John Alfred Heitmann

John A. Heitmann

This essay focuses on the origins and early history of the Institutum Divi Thomae (hereafter referred to as the IDT or Institutum), thus describing one particularly rich episode illustrating the relationship between American Catholicism and science during the middle of the twentieth century. The IDT was established by the Archdiocese of Cincinnati in 1935; its faculty and students, while working in the area of cancer research, published hundreds of scientific and technical papers, developed a number of commercial products, and received considerable publicity in both the religious and secular press during the first two decades of its existence. However, with ...


The Logic Of Uncertain Justifications, Robert Milnikel May 2016

The Logic Of Uncertain Justifications, Robert Milnikel

Robert Milnikel

No abstract provided.


A New Angle On An Old Construction: Approximating Inscribed N-Gons, Robert Milnikel May 2016

A New Angle On An Old Construction: Approximating Inscribed N-Gons, Robert Milnikel

Robert Milnikel

No abstract provided.


An Evaluation Of The Effects Of Alcohol Restrictions In Fitzroy Crossing Relating To Measurable Health And Social Outcomes, Community Perceptions And Alcohol Related Behaviours After Two Years, Stephen Kinnane, Fiona Farringdon, Lynette Henderson-Yates, Helen Parker May 2016

An Evaluation Of The Effects Of Alcohol Restrictions In Fitzroy Crossing Relating To Measurable Health And Social Outcomes, Community Perceptions And Alcohol Related Behaviours After Two Years, Stephen Kinnane, Fiona Farringdon, Lynette Henderson-Yates, Helen Parker

Fiona Farringdon

On 27 September 2007, the Director of Liquor Licensing released his decision on restricting the sale of packaged liquor in Fitzroy Crossing. It was his finding that as of 2 October 2007; the following restriction would be in place for six months:

The sale of packaged liquor, exceeding a concentration of ethanol in liquor of 2.7 per cent at 20 degrees Celsius, is prohibited to any person, other than a lodger (as defined in Section 3 of the Act).

On 16 May 2008, the Director of Liquor Licensing extended the restriction indefinitely beginning on the 18 May 2008, with ...


Scheduling Instruction Effects For A Statically Pipelined Processor, F. Rasapour, G. Cook, G.-R. Uh May 2016

Scheduling Instruction Effects For A Statically Pipelined Processor, F. Rasapour, G. Cook, G.-R. Uh

Gang-Ryung Uh

Statically pipelined processors have a fully exposed datapath where all portions of the pipeline are directly controlled by effects within an instruction, which simplifies hardware and enables a new level of compiler optimizations. This paper describes an effect scheduling strategy to aggressively compact instructions, which has a critical impact on code size and performance. Unique scheduling challenges include more frequent name dependences and fewer renaming opportunities due to static pipeline (SP) registers being dedicated for specific operations. We also realized the SP in a hardware implementation language (VHDL) to evaluate the real energy benefits. Despite the compiler challenges, we achieve ...


Oil Contamination In Ogoniland, Niger Delta, Olof Lindén, Jonas Pålsson May 2016

Oil Contamination In Ogoniland, Niger Delta, Olof Lindén, Jonas Pålsson

Jonas Pålsson

The study shows extensive oil contamination of rivers, creeks, and ground waters in Ogoniland, Nigeria. The levels found in the more contaminated sites are high enough to cause severe impacts on the ecosystem and human health: extractable petroleum hydrocarbons (EPHs) (>10-C40) in surface waters up to 7420 μg L−1, drinking water wells show up to 42 200 μg L−1, and benzene up to 9000 μg L−1, more than 900 times the WHO guidelines. EPH concentrations in sediments were up to 17 900 mg kg−1. Polycyclic aromatic hydrocarbons concentrations reached 8.0 mg kg−1, in the ...


Oil Contamination In The Niger Delta, Jonas Pålsson, Olof Lindén May 2016

Oil Contamination In The Niger Delta, Jonas Pålsson, Olof Lindén

Jonas Pålsson

Oil spills in the Niger Delta region of Nigeria has occurred frequently since oil extraction started in the 1950's. The oil spills originates from facilities and pipelines, leaks from ageing and abandoned infrastructure and from spills during transport and artisanal refining of stolen oil under primitive conditions. It is estimated that spills in Nigeria amount to 100 000 to 200 000 tons per year and have been doing so for almost 60 years. While a number of reports have been written about the Niger Delta and the civil unrest in this area during the last decades, very few scientific ...


Performance Analysis Of A Rankine Cycle Integrated With The Goswami Combined Power And Cooling Cycle, Ricardo Vasquez Padilla, Antonio Ramos Archibold, Gokmen Demirkaya, Saeb Besarati, D Yogi Goswami, Muhammad M. Rahman, Elias L. Stefanakos May 2016

Performance Analysis Of A Rankine Cycle Integrated With The Goswami Combined Power And Cooling Cycle, Ricardo Vasquez Padilla, Antonio Ramos Archibold, Gokmen Demirkaya, Saeb Besarati, D Yogi Goswami, Muhammad M. Rahman, Elias L. Stefanakos

Dr Ricardo Vasquez Padilla

Improving the efficiency of thermodynamic cycles plays a fundamental role in reducing the cost of solar power plants. These plants work normally with Rankine cycles which present some disadvantages due to the thermodynamic behavior of steam at low pressures. These disadvantages can be reduced by introducing alternatives such as combined cycles which combine the best features of each cycle. In this paper, a combined Rankine–Goswami cycle (RGC) is proposed and a thermodynamic analysis is conducted. The Goswami cycle, used as a bottoming cycle, uses ammonia–water mixture as the working fluid and produces power and refrigeration while power is ...


Thermodynamic Feasibility Of Alternative Supercritical Co2 Brayton Cycles Integrated With An Ejector, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Robbie Mcnaughton, Wes Stein May 2016

Thermodynamic Feasibility Of Alternative Supercritical Co2 Brayton Cycles Integrated With An Ejector, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Robbie Mcnaughton, Wes Stein

Dr Ricardo Vasquez Padilla

Supercritical CO2 Brayton cycle has emerged as an alternative power block for Concentrated Solar Thermal (CST) systems and nuclear plants. In order to optimise the thermal performance of the Supercritical CO2 Brayton cycles, a combination of high pressure and temperature are required. The high pressure of the S-CO2 Brayton cycles has a remarkable effect on not only the thermal performance of the cycle but also the thermodynamic and mechanical performance of the solar receiver. In this paper, three S-CO2 Brayton cycle configurations without reheat are proposed by introducing an ejector prior the heater, which reduces the ...


Exergetic Analysis Of Supercritical Co2 Brayton Cycles Integrated With Solar Central Receivers, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Wes Stein May 2016

Exergetic Analysis Of Supercritical Co2 Brayton Cycles Integrated With Solar Central Receivers, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Wes Stein

Dr Ricardo Vasquez Padilla

Concentrated Solar Power (CSP) is a promising alternative for generating renewable energy. One of the most prominent CSP technologies is the central receiver tower with heliostat field, which has received attention in the last decade due to its high achievable temperatures and potential cost reduction. In order to make this technology economically viable, research has been focused on the solar field, solar receiver, energy storage and power block. The power block is one of the important components since improving system efficiency leads to reductions in the storage, solar field and receiver sizes and costs. Recently, supercritical CO2 Brayton cycles ...


An Exergy Analysis Of Recompression Supercritical Co2 Cycles With And Without Reheating, Ricardo Vasquez Padilla, R G. Benito, Wes Stein May 2016

An Exergy Analysis Of Recompression Supercritical Co2 Cycles With And Without Reheating, Ricardo Vasquez Padilla, R G. Benito, Wes Stein

Dr Ricardo Vasquez Padilla

Concentrated Solar Power using supercritical CO2 (S-CO2) recompression Brayton cycles offer advantages of similar and even higher overall thermal efficiencies compared to power cycles using superheated or supercritical steam. The high efficiency and compactness of S-CO2, as compared with steam Rankine cycle at the same high temperature, make this cycle attractive for central receiver applications, since both attributes lead to decrease in levelized cost of energy and therefore make this technology economically feasible. The current research in S-CO2 is focused on thermodynamic analysis and system components. In this paper energy and exergy analyses of a supercritical ...


Experimental Characterization Of Thermal Hydraulic Performance Of Louvered Brazed Plate Fin Heat Exchangers, John Turizo-Santos, Oscar Barros-Ballesteros, Armando Fontalvo-Lascano, Ricardo Vasquez Padilla, Antonio Bula-Silvera May 2016

Experimental Characterization Of Thermal Hydraulic Performance Of Louvered Brazed Plate Fin Heat Exchangers, John Turizo-Santos, Oscar Barros-Ballesteros, Armando Fontalvo-Lascano, Ricardo Vasquez Padilla, Antonio Bula-Silvera

Dr Ricardo Vasquez Padilla

Louvered fins are commonly used in compact heat exchangers to increase the surface area, turbulence, and initiate new boundary layer growth required to improve the heat transfer performance without a significant increase in pressure drop compared with other fins. An experimental study on the air side heat transfer and pressure drop characteristics for a louvered fin with symmetrical patterns in brazed plate heat exchangers had been performed. Reynolds numbers ranged from 350 - 1270, based on the louver pitch while a constant 1.82 m3/h water flow was held. The heat transfer and pressure drop for the geometry tested was ...


Effect Of Pressure Drop And Reheating On Thermal And Exergetic Performance Of Supercritical Carbon Dioxide Brayton Cycles Integrated With A Solar Central Receiver, Ricardo Vasquez Padilla, Yen Chean Soo Too, Andrew Beath, Robbie Mcnaughton, Wes Stein May 2016

Effect Of Pressure Drop And Reheating On Thermal And Exergetic Performance Of Supercritical Carbon Dioxide Brayton Cycles Integrated With A Solar Central Receiver, Ricardo Vasquez Padilla, Yen Chean Soo Too, Andrew Beath, Robbie Mcnaughton, Wes Stein

Dr Ricardo Vasquez Padilla

Concentrated solar power using supercritical carbon dioxide (S-CO2) Brayton cycles offers advantages of similar or higher overall thermal efficiencies than conventional Rankine cycles using superheated or supercritical steam. The high efficiency and compactness of S-CO2, as compared with steam Rankine cycles operating at the same temperature, make this cycle attractive for solar central receiver applications. In this paper, S-CO2 Brayton cycle is integrated with a solar central receiver that provides heat input to the power cycle. Three configurations were analyzed: simple, recompression (RC), and recompression with main intercooling (MC). The effect of pressure drop in heat exchangers and solar receiver ...


Heat Transfer Analysis Of Parabolic Trough Solar Receiver, Ricardo Vasquez Padilla, Gokmen Demirkaya, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman May 2016

Heat Transfer Analysis Of Parabolic Trough Solar Receiver, Ricardo Vasquez Padilla, Gokmen Demirkaya, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman

Dr Ricardo Vasquez Padilla

Solar Parabolic Trough Collectors (PTCs) are currently used for the production of electricity and applications with relatively higher temperatures. A heat transfer fluid circulates through a metal tube (receiver) with an external selective surface that absorbs solar radiation reflected from the mirror surfaces of the PTC. In order to reduce the heat losses, the receiver is covered by an envelope and the enclosure is usually kept under vacuum pressure. The heat transfer and optical analysis of the PTC is essential to optimize and understand its performance under different operating conditions. In this paper a detailed one dimensional numerical heat transfer ...


Multi-Objective Thermodynamic Optimisation Of Supercritical Co2 Brayton Cycles Integrated With Solar Central Receivers, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Robbie Mcnaughton, Wes Stein May 2016

Multi-Objective Thermodynamic Optimisation Of Supercritical Co2 Brayton Cycles Integrated With Solar Central Receivers, Ricardo Vasquez Padilla, Yen Chean Soo Too, Regano Benito, Robbie Mcnaughton, Wes Stein

Dr Ricardo Vasquez Padilla

In this paper, optimisation of the supercritical CO Brayton cycles integrated with a solar receiver, which provides heat input to the cycle, was performed. Four S-CO Brayton cycle configurations were analysed and optimum operating conditions were obtained by using a multi-objective thermodynamic optimisation. Four different sets, each including two objective parameters, were considered individually. The individual multi-objective optimisation was performed by using Non-dominated Sorting Genetic Algorithm. The effect of reheating, solar receiver pressure drop and cycle parameters on the overall exergy and cycle thermal efficiency was analysed. The results showed that, for all configurations, the overall exergy efficiency of the ...


Exergy Analysis Of A Combined Power And Cooling Cycle, Armando Fontalvo, Horacio Pinzon, Jorge Duarte, Antonio Bula, Arturo Gonzalez Quiroga, Ricardo Vasquez Padilla May 2016

Exergy Analysis Of A Combined Power And Cooling Cycle, Armando Fontalvo, Horacio Pinzon, Jorge Duarte, Antonio Bula, Arturo Gonzalez Quiroga, Ricardo Vasquez Padilla

Dr Ricardo Vasquez Padilla

This paper presents a comprehensive exergy analysis of a combined power and cooling cycle which combines a Rankine and absorption refrigeration cycle by using ammonia–water mixture as working fluid. A thermodynamic model was developed in Matlab® to find out the effect of pressure ratio, ammonia mass fraction at the absorber and turbine efficiency on the total exergy destruction of the cycle. The contribution of each cycle component on the total exergy destruction was also determined. The results showed that total exergy destruction decreases when pressure ratio increases, and reaches a maximum at x ≈ 0.5, when ammonia mass fraction ...


Analysis Of Power And Cooling Cogeneration Using Ammonia-Water Mixture, Ricardo Vasquez Padilla, Gokmen Demirkaya, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman May 2016

Analysis Of Power And Cooling Cogeneration Using Ammonia-Water Mixture, Ricardo Vasquez Padilla, Gokmen Demirkaya, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman

Dr Ricardo Vasquez Padilla

Development of innovative thermodynamic cycles is important for the efficient utilization of low-temperature heat sources such as solar, geothermal and waste heat sources. This paper presents a parametric analysis of a combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as the working fluid and produces power and cooling simultaneously. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using solar or geothermal energy. A thermodynamic study of power and cooling cogeneration is presented. The ...


Analysis Of A Combined Power And Cooling Cycle For Low-Grade Heat Sources, Gokmen Demirkaya, Ricardo Vasquez Padilla, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman May 2016

Analysis Of A Combined Power And Cooling Cycle For Low-Grade Heat Sources, Gokmen Demirkaya, Ricardo Vasquez Padilla, D Yogi Goswami, Elias Stefanakos, Muhammad M. Rahman

Dr Ricardo Vasquez Padilla

This paper presents a parametric analysis of a combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia–water mixture as the working fluid and produces power and refrigeration, while power is the primary goal. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low-temperature sources such as geothermal and solar energy. Optimum operating conditions were found for a range of ammonia concentration in the basic solution, isentropic turbine efficiency and boiler pressure. It is shown ...


Automatic Control Strategies For Hybrid Solar-Fossil Fuel Power Plants, Armando Fontalvo, Jesus Garcia, Marco Sanjuan, Ricardo Vasquez Padilla May 2016

Automatic Control Strategies For Hybrid Solar-Fossil Fuel Power Plants, Armando Fontalvo, Jesus Garcia, Marco Sanjuan, Ricardo Vasquez Padilla

Dr Ricardo Vasquez Padilla

Solar electrical generating systems are a class of solar energy systems which use parabolic trough collectors (PTC) to produce electricity from sunlight. In order to provide power production, one of the major challenges is to held the collector outlet temperature or steam temperature around of a specified set point by adjusting the flow rate of the heat transfer fluid (HTF) within upper and lower bounds. In some cases, an auxiliary heater can be used to provide heat in absence of solar radiation or during cloudy days. This paper presents a comprehensive study of three control schemes proposed to keep the ...


A Biomimetic Approach For Modeling Cloud Shading With Dynamic Behavior, Jesus M. Garcia, Ricardo Vasquez Padilla, Marco E. Sanjuan May 2016

A Biomimetic Approach For Modeling Cloud Shading With Dynamic Behavior, Jesus M. Garcia, Ricardo Vasquez Padilla, Marco E. Sanjuan

Dr Ricardo Vasquez Padilla

Clouds are a complex phenomenon which is the result of a strong interaction between multiple variables. Modeling its behavior through physical principles is a task that requires time and is computationally demanding. One of the main effects caused by clouds are the shadows produced over the earth's surface, a phenomenon inherently complex due its origin. This paper proposes a computationally low-demanding model for imitating (not predicting) the behavior of cloud shading by applying a biomimetic approach. This analogy relays on using a bacterial colony growth behavior. The aim of this paper is to establish a methodology to develop a ...


Continuous And Semicontinuous Reaction Systems For High-Solids Enzymatic Hydrolysis Of Lignocellulosics, A González Quiroga, A Bula Silvera, Ricardo Vasquez Padilla, A C. De Costa, R Maciel Filho May 2016

Continuous And Semicontinuous Reaction Systems For High-Solids Enzymatic Hydrolysis Of Lignocellulosics, A González Quiroga, A Bula Silvera, Ricardo Vasquez Padilla, A C. De Costa, R Maciel Filho

Dr Ricardo Vasquez Padilla

An attractive operation strategy for the enzymatic hydrolysis of lignocellulosics results from dividing the process into three stages with complementary goals: continuous enzyme adsorption at low-solids loading (5% w/w) with recycling of the liquid phase; continuous liquefaction at high-solids content (up to 20% w/w); and, finally, continuous or semicontinuous hydrolysis with supplementation of fresh enzymes. This paper presents a detailed modeling and simulation framework for the aforementioned operation strategies. The limiting micromixing situations of macrofluid and microfluid are used to predict conversions. The adsorption and liquefaction stages are modeled as a continuous stirred tank and a plug flow ...


Alleviation Of Nickel-Induced Stress In Mungbean Through Application Of Gibberellic Acid, Muhammad A. Ali, Hafiz N. Asghar, Muhammad Y. Khan, Muhammad Saleem, Muhammad Naveed, Nabeel Khan Niazi Apr 2016

Alleviation Of Nickel-Induced Stress In Mungbean Through Application Of Gibberellic Acid, Muhammad A. Ali, Hafiz N. Asghar, Muhammad Y. Khan, Muhammad Saleem, Muhammad Naveed, Nabeel Khan Niazi

Dr Nabeel Khan Niazi

Nickel (Ni) is the most eco-toxic and harmful metal for soil biological activity, plant metabolism and health of animals and human beings. Elevated level of Ni in plants causes many nutritional and physiological disorders as well as perturbs in normal balance of phytohormones. Exogenous application of phytohormones can regulate plant growth and reduce inhibitory effect of toxic metals on plants. Therefore present study was conducted to assess the effect of Ni contamination on growth and yield of mungbean and role of gibberellic acid (GA3) to counteract negative effects of Ni contamination. Mungbean seeds were sown in potted soil contaminated with ...


Re-Establishing The Cycad 'Macrozamia Riedlei' Following Mining, Renae Douglas, Dylan Korczynskyj, John Koch Apr 2016

Re-Establishing The Cycad 'Macrozamia Riedlei' Following Mining, Renae Douglas, Dylan Korczynskyj, John Koch

Dylan Korczynskyj

Alcoa of Australia has mined bauxite for the production of aluminium since 1963 in Western Australia's northern Jarrah ('Eucalyptus marginata') forest. While the company has made significant advances in its rehabilitation methods some plant species still pose a challenge in restoring native Jarrah forest vegetation (Koch 2007). The cycad 'Macrozamia riedlei' (Zamia), is a key species in the Jarrah forest, but is under-represented on rehabilitated sites (around 50/ha) compared with densities in adjacent unmined forest (around 1000/ha).


Role Of Diffusive, Photovoltaic, And Thermal Effects In Beam Fanning In Linbo3, Jaw-Jueh Liu, Partha P. Banerjee, Q. W. Song Apr 2016

Role Of Diffusive, Photovoltaic, And Thermal Effects In Beam Fanning In Linbo3, Jaw-Jueh Liu, Partha P. Banerjee, Q. W. Song

Partha Banerjee

We analyze the steady-state (Gaussian) beam fanning in LiNbO3 from the nonlinearly coupled Kukhtarev equations by including both diffusive and photovoltaic effects and by adding the thermal effect in the calculation. There is good agreement between theory and experiment. The results show a symmetric beam-fanning pattern whose size depends on the beam waist and the power. Possible applications of our results in nondestructive testing of material parameters and optical limiting are discussed.


Simulation Of Two-Dimensional Nonlinear Envelope Pulse Dynamics By A Two-Step Spatiotemporal Angular Spectrum Method, H. K. Sim, Adrianus Korpel, Karl E. Lonngren, Partha P. Banerjee Apr 2016

Simulation Of Two-Dimensional Nonlinear Envelope Pulse Dynamics By A Two-Step Spatiotemporal Angular Spectrum Method, H. K. Sim, Adrianus Korpel, Karl E. Lonngren, Partha P. Banerjee

Partha Banerjee

We present an extension of our previous nonlinear beam-simulation method to the propagation and interaction of pulse envelopes. The extra time dimension is applied in the context of a dispersive nonlinear medium that is described by a Klein–Gordon equation with an added cubically nonlinear, self-focusing term. Pulse propagation in this medium is modeled as the evolution of a spatiotemporal spectrum—i.e., the frequency-dependent angular spectrum of the pulse envelope—traversing a sequence of self-induced, thin, weak phase filters. Preliminary simulation experiments show agreement with known behavior in the absence of nonlinearity, confirm the existence of an (apparently unstable ...


Theoretical And Experimental Studies Of Propagation Of Beams Through A Finite Sample Of A Cubically Nonlinear Material, Partha P. Banerjee, Raj M. Misra, M. Maghraoui Apr 2016

Theoretical And Experimental Studies Of Propagation Of Beams Through A Finite Sample Of A Cubically Nonlinear Material, Partha P. Banerjee, Raj M. Misra, M. Maghraoui

Partha Banerjee

Propagation of an externally focused or defocused Gaussian beam in a cubically nonlinear material is studied analytically and experimentally. The theoretical analysis is applied to determine the sign and magnitude of n2 for a material by means of a single-beam experiment with a finite nonlinear sample within which propagational diffraction cannot be neglected. Experimental results for a solution of chlorophyll in ethanol are reported. Based on available theory, an average n2 can be defined for a nonlinearity of thermal origin, and this value is found to be in good agreement with experimental results. Finally, the theoretical analysis and ...


On A Simple Derivation Of The Fresnel Diffraction Formula And A Transfer Function Approach To Wave Propagation, Partha P. Banerjee, Ting-Chung Poon Apr 2016

On A Simple Derivation Of The Fresnel Diffraction Formula And A Transfer Function Approach To Wave Propagation, Partha P. Banerjee, Ting-Chung Poon

Partha Banerjee

The Fresnel diffraction formula is straightforwardly obtained by solving a partial differential equation (PDE) for envelope propagation using Fourier transform techniques. The PDE, in turn, can be derived from the dispersion relation of a linear medium by employing a simple operator formalism. The transfer function and impulse response of propagation follows as a spin‐off and is used to solve illustrative problems. Huygens’ principle is visualized as a consequence of the convolution property of linear systems.


Notch Spatial Filtering With An Acousto-Optic Modulator, Partha P. Banerjee, Dongqing Cao, Ting-Chung Poon Apr 2016

Notch Spatial Filtering With An Acousto-Optic Modulator, Partha P. Banerjee, Dongqing Cao, Ting-Chung Poon

Partha Banerjee

The role of acousto-optic (AO) modulators in programmable real-time image processing has recently been demonstrated. For fully investigating the image-processing capabilities of the AO modulator, general techniques to derive spatial transfer functions are needed for a variety of physical situations. We develop a technique to determine the spatial transfer functions numerically for various cases of beam incidence on an AO modulator. Normal incidence and incidence at twice the Bragg angle are investigated as examples for which double-sided and single-sided notch spatial filtering, respectively, are achieved. The observed spatial-filtering characteristics are reconciled with simple intuitive physical arguments.