Introducing the VRT gas turbine combustor

An innovative annular combustor configuration is being developed for aircraft and other gas turbine engines. This design has the potential of permitting higher turbine inlet temperatures by reducing the pattern factor and providing a major reduction in NO(x) emission. The design concept is based on a Variable Residence Time (VRT) technique which allows large fuel particles adequate time to completely burn in the circumferentially mixed primary zone. High durability of the combustor is achieved by dual function use of the incoming air. The feasibility of the concept was demonstrated by water analogue tests and 3-D computer modeling. The computer model predicted a 50 percent reduction in pattern factor when compared to a state of the art conventional combustor. The VRT combustor uses only half the number of fuel nozzles of the conventional configuration. The results of the chemical kinetics model require further investigation, as the NO(x) predictions did not correlate with the available experimental and analytical data base

Chaotic behaviors of a digital filter with two’s complement arithmetic and arbitrary initial conditions and order

This letter shows some counter-intuitive simulation results that the symbolic sequences and the state variables of a digital filter with two’s complement arithmetic and arbitrary initial conditions and order will be eventually zero when all the filter parameters are even numbers, no matter the system matrix of the filter is stable or not

Gateway to Outdoors: Partnership and Programming of Outdoor Education Centers in Urban Areas

The purpose of the study is to understand the challenges and opportunities of urban outdoor education centers in partnership and programming. The context for this study involves efforts by all-season outdoor education centers, Outdoor Campus (OC), in two urban areas in South Dakota (SD). Outdoor education scope and social-ecological framework were applied to guide this qualitative study. Semi-structured interview questions were used to interview eight outdoor educators in 2019, including four individuals from each service location composed of three males and five female educators. Qualitative content analysis was applied to identify common themes and essential quotations that emerged from the data analyzed through the interviews. Three main themes emerged: (1) gateway to our outdoor legacy (2) working together for outdoor education, including three sub-themes: formal partnership, programmatic partnership, and finding balance in partnership, (3) challenges as opportunities in outdoor education programs, including two sub-themes: common challenges and evolving process

Superradiance for atoms trapped along a photonic crystal waveguide

We report observations of superradiance for atoms trapped in the near field of a photonic crystal waveguide (PCW). By fabricating the PCW with a band edge near the D$_1$ transition of atomic cesium, strong interaction is achieved between trapped atoms and guided-mode photons. Following short-pulse excitation, we record the decay of guided-mode emission and find a superradiant emission rate scaling as $\bar{\Gamma}_{\rm SR}\propto\bar{N}\cdot\Gamma_{\rm 1D}$ for average atom number $0.19 \lesssim \bar{N} \lesssim 2.6$ atoms, where $\Gamma_{\rm 1D}/\Gamma_0 =1.1\pm0.1$ is the peak single-atom radiative decay rate into the PCW guided mode and $\Gamma_{0}$ is the Einstein-$A$ coefficient for free space. These advances provide new tools for investigations of photon-mediated atom-atom interactions in the many-body regime.Comment: 11 pages, 10 figure

VLSI Implementation of Discrete Cosine Transform Based on the Shared-Multiplier Algorithm

In this paper a new algorithm for discrete cosine transform (DCT) is proposed. This algorithm is especially efficient for VLSI implementation because each multiplier in @e 1-D DCT is shared by two constants rather than one. This greatly reduces the chip area, and the high speed characteristics are still retained. Based on this algorithm, we have developed the corresponding bit-parallel, fully-pipelined architecture for the size-8 DCT. The core area of the chip is only 8.6mm x 8.5mm, using 1.2um double-metal single-poly CMOS technology. This chip is simulated for operation at the maximum speed of 100 MHz which far exceeds the speed requirement of the HDTV system (70 MHz)

Differences in Prevalence of Muscle Weakness (Sarcopenia) in Haemodialysis Patients Determined by Hand Grip Strength Due to Variation in Guideline Definitions of Sarcopenia

BACKGROUND: Muscle weakness is associated with increased mortality, and hemodialysis (HD) patients are at an increased risk for muscle loss. There is no agreed definition for muscle weakness, so we determined whether using different cut‐off criteria recommended by guideline groups altered the prevalence in HD patients. METHODS: We measured hand grip strength (HGS) in HD outpatients, comparing HGS with clinical guideline cut‐offs (European Working Group on Sarcopenia in Older People [EWGSOP] and North American Foundation for the National Institutes of Health Sarcopenia Project [FNIH]) used to define muscle wasting (sarcopenia) with age‐matched and gender‐matched normative data. RESULTS: We studied 459 patients, 61.4% male, 47.3% diabetic. The prevalence of muscle weakness was significantly different when measuring HGS; 84.5% using the EWGSOP cut‐off and 73.2% with FNIH criteria, and 75.2% using North American normative data and 56.6% U.K. normative data (P < .01). On logistic regression, muscle weakness was associated with age (odds ratio [OR] 1.05, P < .001), weight (OR 0.96, P < .001), serum albumin (OR 0.89, P = .007), and being nondiabetic (OR 0.31, P = .001). Of patients with no comorbidity, 66.7% were weak when compared with 93.8% with the highest comorbidity scores (P < .001). CONCLUSION: There is currently no agreed universal definition for sarcopenia, but the EWGSOP and FNIH advocate HGS cut‐offs as part of their definition. The prevalence of muscle weakness varies according to cut‐off and whether age‐matched and gender‐matched normative data are used. In addition, patient characteristics in terms of age and comorbidity determine the prevalence of muscle weakness

Flavor from M5-branes

We study various aspects of the defect conformal field theory that arises when placing a single M5-brane probe in AdS_4 x S^7. We derive the full set of fluctuation modes and dimensions of the corresponding dual operators. We argue that the latter does not depend on the presence of a non-trivial magnetic flux on the M5-brane world-volume. Finally we give a mass to the hypermultiplet living on the defect, and compute the resulting mesonic spectrum.Comment: 19 page

A Study of Anyon Statistics by Breit Hamiltonian Formalism

We study the anyon statistics of a $2 + 1$ dimensional Maxwell-Chern-Simons (MCS) gauge theory by using a systemmetic metheod, the Breit Hamiltonian formalism.Comment: 25 pages, LATE