Two simple models of classical heat pumps

Motivated by recent studies on models of particle and heat quantum pumps, we study similar simple classical models and examine the possibility of heat pumping. Unlike many of the usual ratchet models of molecular engines, the models we study do not have particle transport. We consider a two-spin system and a coupled oscillator system which exchange heat with multiple heat reservoirs and which are acted upon by periodic forces. The simplicity of our models allows accurate numerical and exact solutions and unambiguous interpretation of results. We demonstrate that while both our models seem to be built on similar principles, one is able to function as a heat pump (or engine) while the other is not.Comment: 4 pages, 4 figure

Analog Single Sideband-Pulse Width Modulation Processor for Parametric Acoustic Arrays

Parametric acoustic arrays are ultrasonic-based loudspeakers that produce highly directive audio. The audio must first be preprocessed and modulated into an ultrasonic carrier before being emitted into the air, where it will self-demodulate in the far field. The resulting audio wave is proportional to the double time-derivative of the square of the modulation envelope. This thesis presents a fully analog processor which encodes the audio into two Pulse Width Modulated (PWM) signals in quadrature phase and sums them together to produce a Single Sideband (SSB) spectrum around the fundamental frequency of the PWM signals. The two signals are modulated between 8% and 24% duty cycle to maintain a quasi-linear relationship between the duty cycle and the output signal level. This also allows the signals to sum without overlapping each other, maintaining a two-level output. The system drives a network of narrowband transducers with a center frequency equal to the PWM fundamental. Because the transducers are voltage driven, they have a bandpass frequency response which behaves as a first-order integrator on the SSB signal, eliminating the need for two integrators in the processor. Results show that the “SSB-PWM” output wave has a consistent 20-30dB difference in magnitude between the upper sideband and lower sideband. In simulation, a single tone test shows higher total harmonic distortion for lower frequencies and higher modulation depth. A two-tone test creates a 2nd order intermodulation term that increases with the frequencies of the input signals

Dinesen’s Diana: The Transformative Power of Symbols in Ehrengard

This analysis of Dinesen\u27s Ehrengard aims to illuminate the subversive transformation of the titular character of the novel, using the literal and symbolic application of artistic power

Music Synthesizer Senior Project: Danalog

The Danalog is a 25 key portable digital music synthesizer that uses multiple synthesis methods and effects to generate sounds. Sound varieties included three synthesis methods including FM, subtractive, and sample-based, with up to eight adjustable parameters, at least four effects, including reverb, chorus, and flange, with five adjustable parameters, and at least two note polyphony, and a five band equalizer. The user would be able to adjust these effects using digital encoders and potentiometers and view the settings on two LCD screens. The finals project was unable to meet the original design requirements. The FM synthesis method was primarily working in the end product. The synthesizer was built to produce two note polyphony. The LCD screens displayed the information about the synthesis method as the user plays

Energy current magnification in coupled oscillator loops

Motivated by studies on current magnification in quantum mesoscopic systems we consider sound and heat transmission in classical models of oscillator chains. A loop of coupled oscillators is connected to two leads through which one can either transmit monochromatic waves or white noise signal from heat baths. We look for the possibility of current magnification in this system due to some asymmetry introduced between the two arms in the loop. We find that current magnification is indeed obtained for particular frequency ranges. However the integrated current shows the effect only in the presence of a pinning potential for the atoms in the leads. We also study the effect of anharmonicity on current magnification.Comment: 5 pages, 5 figure

Optimal Energy Rationing for Prepaid Electricity Customers

For a large (and recently increasing) number of households, affordability is a major hurdle in accessing sufficient electricity and avoiding service disconnections. For such households, in-home energy rationing, i.e. the need to actively prioritize how to use a limited amount of electricity, is an everyday reality. In this paper, we consider a particularly vulnerable group of customers, namely prepaid electricity customers, who are required to pay for their electricity a-priori. With this group of customers in mind, we propose an optimization-based energy management framework to effectively use a limited budget and avoid the disruptions and fees associated with disconnections. The framework considers forecasts of future use and knowledge of appliance power ratings to help customers prioritize and limit use of low-priority loads, with the goal of extending access to their critical loads. Importantly, the proposed management system has minimal requirements in terms of in-home hardware and remote communication, lending itself well to adoption across different regions and utility programs. Our case study demonstrates that by considering both current and future electricity consumption and more effectively managing access to low-priority loads, the proposed framework increases the value provided to customers and avoids disconnections.Comment: Accepted to IEEE PowerTech 2023, Belgrade, Serbia (6 pages, 4 figures

SI-based unreleased hybrid MEMS-CMOS resonators in 32nm technology

This work presents the first unreleased Silicon resonators fabricated at the transistor level of a standard CMOS process, and realized without any release steps or packaging. These unreleased bulk acoustic resonators are driven capacitively using the thin gate dielectric of the CMOS process, and actively sensed with a Field Effect Transistor (FET) incorporated into the resonant body. FET sensing using the high f[subscript T], high performance transistors in CMOS amplifies the mechanical signal before the presence of parasitics. This enables RF-MEMS resonators at orders of magnitude higher frequencies than possible with passive devices. First generation CMOS-MEMS Si resonators with Acoustic Bragg Reflectors are demonstrated at 11.1 GHz with Q~17 and a total footprint of 5μm × 3μm using IBM's 32nm SOI technology.United States. Defense Advanced Research Projects Agency. Leading Edge Access ProgramUnited States. National Security Agency. Trusted Access Program OfficeInternational Business Machines Corporatio

Curcumin Increases the Pathogenicity of Salmonella enterica Serovar Typhimurium in Murine Model

Curcumin has gained immense importance for its vast therapeutic and prophylactic applications. Contrary to this, our study reveals that it regulates the defense pathways of Salmonella enterica serovar Typhimurium (S. Typhimurium) to enhance its pathogenicity. In a murine model of typhoid fever, we observed higher bacterial load in Peyer's patches, mesenteric lymph node, spleen and liver, when infected with curcumin-treated Salmonella. Curcumin increased the resistance of S. Typhimurium against antimicrobial agents like antimicrobial peptides, reactive oxygen and nitrogen species. This increased tolerance might be attributed to the up-regulation of genes involved in resistance against antimicrobial peptides - pmrD and pmrHFIJKLM and genes with antioxidant function - mntH, sodA and sitA. We implicate that iron chelation property of curcumin have a role in regulating mntH and sitA. Interestingly, we see that the curcumin-mediated modulation of pmr genes is through the PhoPQ regulatory system. Curcumin downregulates SPI1 genes, required for entry into epithelial cells and upregulates SPI2 genes required to intracellular survival. Since it is known that the SPI1 and SPI2 system can be regulated by the PhoPQ system, this common regulator could explain curcumin's mode of action. This data urges us to rethink the indiscriminate use of curcumin especially during Salmonella outbreaks