Fuel spray diagnostics

Several laser measurement methods are being studied to provide the capability to make droplet size and velocity measurements under a variety of spray conditions. The droplet sizing interferometer (DSI) promises to be a successful technique because of its capability for rapid data acquisition, compilation and analysis. Its main advantage is the ability to obtain size and velocity measurements in air-fuel mixing studies and hot flows. The existing DSI at NASA Lewis is a two-color, two-component system. Two independent orthogonal measurements of size and velocity components can be made simultaneously. It also uses an off-axis large-angle light scatter detection. The fundamental features of the system are optics, signal processing and data management system. The major component includes a transmitter unit, two receiver units, two signal processors, two data management systems, two Bragg cell systems, two printer/plotters, a laser, power supply and color monitor

Fuel Spray Diagnostics

Fundamental experimental data base for turbulent flow mixing models is provided and better prediction of the more complex turbulent chemical reacting flows. Analytical application to combustor design is provided and a better fundamental understanding of the combustion process

Magel2 and Hypothalamic POMC Neuron Modulation of Infant Mice Isolation-Induced Vocalizations

Abstract The proper development of infant mammals depends on infant vocalization. Infants vocalize (i.e., cry) when isolated from their caregivers, attracting their attention to receive nurture. Impaired vocal behavior can lead to maternal neglect and even death in some species. Similar to humans and other mammals, infant mice vocalize upon isolation from their nest and decrease vocalizations when reunited with their mother or littermates. Mouse pups vocalize above the human audible range, emitting ultrasonic vocalizations (USV). My thesis investigated the effects of the imprinted gene, Magel2, on mouse vocal behavior (Chapter 2; published in Genes, Brain, and Behavior) and also identified a population of neurons in the hypothalamus that modulate vocal behavior (Chapter 3; unpublished). Magel2 (or MAGEL2 in humans) is a paternal imprint gene and its loss of function is associated with atypical behaviors seen in autism spectrum disorders and in Prader-Willi Syndrome. In Chapter 2, I report the study of the emission of ultrasonic vocalizations by Magel2 deficient pups during their early postnatal development. I recorded and analyzed vocalizations from Magel2 deficient pups and their wildtype littermates during isolation from the home nest at postnatal days 6-12. I describe my findings showing that Magel2 deficient pups present a lower rate of vocalizations and altered vocal repertoire compared to wildtype littermates. Moreover, these results correlate with altered behavior of the dam towards their own pups: dams prefer to retrieve their wildtype offspring compared to their Magel2 deficient offspring. These results suggest that Magel2 affects the expression of infant vocalizations and also modulates the expression of maternal behaviors. In Chapter 3, I describe my discovery of a population of neurons in the mammalian hypothalamus that modulate the emission of ultrasonic vocalizations in mouse pups. The brain opioid theory of social attachment postulates that pups release opioids in the brain during caretaking behaviors, which reinforces the attachment bond between pups and caretakers. From the three main receptors known to bind different types of endogenous opioids, μ-opioid receptors (ORPM1) are thought to be important in the modulation of attachment behaviors and, consequently, emission of vocalizations. Whether endogenous opioids act on ORPM1-expressing cells to modulate vocalizations is unknow. Since the opioid with highest affinity for ORPM1 is β-endorphin, I determined the contribution of neurons that produce β-endorphin—POMC neurons—in infant vocalizations. Using genetic, chemogenomic, and pharmacogenetic approaches, my results show that mice deficient for β-endorphin vocalize more than controls, an effect that is mimicked by a pharmacological blocker of opioid receptors, naloxone. Importantly, naloxone fails to increase vocalizations in β-endorphin deficient pups. Moreover, using chemogenetics, activation of POMC neurons in the hypothalamus suppresses the emission of vocalizations, while ablation of these neurons increased the number of vocalizations. Finally, I show that activation of POMC neurons in mice deficient for the Orpm1 does not suppress the emission of vocalizations. Together, the results in Chapter 3 suggest that the emission of infant vocalizations is modulated by POMC neurons in the hypothalamus via the release of beta-endorphin that signals in downstream mu-opioid receptors. In sum, this dissertation reports novel findings on the effect of the Magel2 gene and of hypothalamic POMC neurons in the modulation of infant vocalization. As we learn more about the physiological and neuronal responses to distress that occurs in infants, we will more accurately understand the mechanisms involved in the affective emotional states that contribute to the normal and pathological development of infants

A single scaling parameter as a first approximation to describe the rainfall pattern of a place: application on Catalonia

As well as in other natural processes, it has been frequently observed that the phenomenon arising from the rainfall generation process presents fractal self-similarity of statistical type, and thus, rainfall series generally show scaling properties. Based on this fact, there is a methodology, simple scaling, which is used quite broadly to find or reproduce the intensity–duration–frequency curves of a place. In the present work, the relationship of the simple scaling parameter with the characteristic rainfall pattern of the area of study has been investigated. The calculation of this scaling parameter has been performed from 147 daily rainfall selected series covering the temporal period between 1883 and 2016 over the Catalonian territory (Spain) and its nearby surroundings, and a discussion about the relationship between the scaling parameter spatial distribution and rainfall pattern, as well as about trends of this scaling parameter over the past decades possibly due to climate change, has been presented.Peer ReviewedPostprint (author's final draft

Carbonation of concrete with construction and demolition waste based recycled aggregates and cement with recycled content

Durability is a major concern in concrete (particularly recycled concrete) structures exposed to carbonation-induced corrosion, given the social, economic, environmental and safety implications involved. This article explores carbonation performance in concrete with 25% or 50% mixed recycled construction and demolition waste aggregate, alone or in conjunction with cement containing 25% fired clay construction and demolition waste. Irrespective of cement type, the mean carbonation depth was slightly greater in materials with 25% or 50% recycled aggregate than in concretes with 100% natural aggregate, although the difference was not statistically significant for the 25% replacement ratio. In all the concretes studied, the carbonation coefficient was below the 4 mm/yr0.5 indicative of good quality. Based on the prediction model proposed in Spain’s concrete code, reinforcement passivity was guaranteed in all these types of concrete when exposed to class XC1 to XC4 carbonation environments for substantially longer than their 100 year design service life.This study was funded under research projects BIA 2013-48876-C3-1-R, BIA2013-48876-C3-2-R and BIA2016-76643-C3-1-R awarded by the Ministry of Science and Innovation and grant GR 18122 awarded to the MATERIA Research Group by the Regional Government of Extremadura and the European Regional Development Fund, ERDF. In 2016 University of Extremadura teaching and research personnel benefitted from a mobility grant (MOV15A029) awarded by the Regional Government of Extremadura and in 2018 from a José Castillejo (CAS17/00313) scholarship granted by the Spanish Ministry of Education, Culture and Sport. Philip Van den Heede is since October 2017 a postdoctoral fellow of the Research Foundation—Flanders (FWO) (project number 3E013917) and acknowledges its support.Peer reviewe

Sensor-Based Seeds for a Chaotic Stream Cipher

In this paper we have used a surface micromachined capacitive accelerometer in order to generate seeds that are suitable for secure communications between wireless smart sensors for IoT networks. These seeds have then been used in a chaotic stream cipher based on a Modified Logistic Map and a Linear Feedback Shift Register. The sequences generated by the chaotic stream cipher have been subjected to the randomness NIST tests. All the tests have been passed, proving that the proposed approach could be used for secure communications

Self-synchronized Encryption for Physical Layer in 10Gbps Optical Links

In this work a new self-synchronized encryption method for 10 Gigabit optical links is proposed and developed. Necessary modifications to introduce this kind of encryption in physical layers based on 64b/66b encoding, such as 10GBase-R, have been considered. The proposed scheme encrypts directly the 64b/66b blocks by using a symmetric stream cipher based on an FPE (Format Preserving Encryption) block cipher operating in PSCFB (Pipelined Statistical Cipher Feedback) mode. One of the main novelties in this paper is the security analysis done for this mode. For the first time, an expression for the IND-CPA (Indistinguishability under Chosen-Plaintext Attack) advantage of any adversary over this scheme has been derived. Moreover, it has been concluded that this mode can be considered secure in the same way of traditional modes are. In addition, the overall system has been simulated and implemented in an FPGA (Field Programmable Gate Array). An encrypted optical link has been tested with Ethernet data frames, concluding that it is possible to cipher traffic at this level, getting maximum throughput and hiding traffic pattern from passive eavesdroppers

A new simple technique for improving the random properties of chaos-based cryptosystems

A new technique for improving the security of chaos-based stream ciphers has been proposed and tested experimentally. This technique manages to improve the randomness properties of the generated keystream by preventing the system to fall into short period cycles due to digitation. In order to test this technique, a stream cipher based on a Skew Tent Map algorithm has been implemented on a Virtex 7 FPGA. The randomness of the keystream generated by this system has been compared to the randomness of the keystream generated by the same system with the proposed randomness-enhancement technique. By subjecting both keystreams to the National Institute of Standards and Technology (NIST) tests, we have proved that our method can considerably improve the randomness of the generated keystreams. In order to incorporate our randomness-enhancement technique, only 41 extra slices have been needed, proving that, apart from effective, this method is also efficient in terms of area and hardware resources

Introduction to Physically Unclonable Fuctions: Properties and Applications

During the last years, Physically Unclonable Functions (PUFs) have become a very important research area in the field of hardware security due to their capability of generating volatile secret keys as well as providing a low-cost authentication. In this paper, an introduction to Physically Unclonable Functions is given, including their definition, properties and applications. Finally, as an example of how to design a PUF, the general structure of a ring oscillator PUF is presented

Physical Layer Encryption for Industrial Ethernet in Gigabit Optical Links

Industrial Ethernet is a technology widely spread in factory floors and critical infrastructures where a high amount of data need to be collected and transported. Fiber optic networks at gigabit rates fit well with that type of environment, where speed, system performance, and reliability are critical. In this paper, a new encryption method for high-speed optical communications suitable for such kinds of networks is proposed. This new encryption method consists of a symmetric streaming encryption of the 8b/10b data flow at physical coding sublayer level. It is carried out thanks to a format preserving encryption block cipher working in CTR (counter) mode. The overall system has been simulated and implemented in a field programmable gate array. Thanks to experimental results, it can be concluded that it is possible to cipher traffic at this physical level in a secure way. In addition, no overhead is introduced during encryption, getting minimum latency and maximum throughput