Routing Optimization Based on OSPF in Multi-Layer Satellite Network

Multi-layer satellite network has become a hot spot for its wider coverage and higher bandwidth level. However, due to the frequent link changes and complexity of network, it is hard to find out a mechanism to handle well on long delay and high packet loss level. This paper proposes an optimized OSPF protocol called OOWLP to eliminate unnecessary routing convergence to optimize the packet loss level and delay ultimately. Link plan table, which records link contacting plan, will be used to update the link state database periodically so that we can eliminate the flooding procedure caused by scheduled link changes. On the other hand, Constrained Shortest Path First (CSPF) will be used to get business differentiated routes in multi-layer satellite network to optimized the throughput capacity in congestion scenario. We divide the sending packets into different businesses and get the routes for each business with longer duration limited by remaining bandwidth. Simulation results show that in normal scenario, average packet loss rate and delay performance are improved 17.42%, 51.44ms respectively, average packet loss rate and throughput capacity performance are optimized 79.05%, 9.81Mbps respectively in congestion scenario compared to standard OSPF. As a result, the proposed mechanism is able to shorten the average delay and lower the packet loss level in multi-layer satellite network.

A Key Flow Parameter to the Profile Loss of Low-Pressure Turbine Blades

For an optimum performance design of low-pressure turbine (LPT) blades, it is crucial to understand the generation mechanism of profile loss properly. As the profile loss is usually taken to be the loss generated inside the blade boundary layer due to viscous effects, most of the efforts for the performance optimization have concentrated on the reduction in the boundary layer loss using the flow parameters that represent the loss generation in the boundary layers. Kodama and Funazaki [1] investigated the generation mechanism of profile loss from a view point of blade drag forces, friction drag force and pressure drag force, and suggested that the loss due to pressure drag is dominant in the profile loss of a typical LPT blade. The loss due to pressure drag is not a boundary layer loss that is generated in the boundary layers, but a mixing loss that is generated downstream of the trailing edge. It is necessary to clarify a key flow parameter to the loss due to pressure drag for an effective performance optimization. This paper aims at investigating the flow parameter that is a measure of the profile loss. In the investigation, the profile loss is broken down into the loss components which are expressed by the boundary layer integral parameters at the trailing edge. Then the loss components are categorized into the loss due to friction drag or the loss due to pressure drag. The loss level of each component is evaluated by using the results of steady Reynolds Averaged Navier-Stokes (RANS) simulations to assess the contribution to the total profile loss. The evaluations are conducted for two kinds of blade profiles at three different Reynolds numbers. It is found that the largest contributor to the loss due to pressure drag, consequently to the total profile loss, is the loss associated with a mixing of accelerated free stream flow by the flow blockage at the trailing edge plane. The loss level is simply determined by the flow blockage. This suggests that the flow blockage at the trailing edge plane is the most important flow parameter for an optimum performance design of LPT blades.

CscGAN: Conditional Scale-Consistent Generation Network for Multi-Level Remote Sensing Image to Map Translation

Automatic remote sensing (RS) image to map translation is a crucial technology for intelligent tile map generation. Although existing methods based on a generative network (GAN) generated unannotated maps at a single level, they have limited capacity in handling multi-resolution map generation at different levels. To address the problem, we proposed a novel conditional scale-consistent generation network (CscGAN) to simultaneously generate multi-level tile maps from multi-scale RS images, using only a single and unified model. Specifically, the CscGAN first uses the level labels and map annotations as prior conditions to guide hierarchical feature learning with different scales. Then, a multi-scale discriminator and two multi-scale generators are introduced to describe both high-resolution and low-resolution representations, aiming to improve the similarity of generated maps and thus produce high-quality multi-level tile maps. Meanwhile, a level classifier is designed for further exploring the characteristics of tile maps at different levels. Moreover, the CscGAN is optimized by jointly multi-scale adversarial loss, level classification loss, and scale-consistent loss in an end-to-end manner. Extensive experiments on multiple datasets and study areas demonstrate that the CscGAN outperforms the state-of-the-art methods in multi-level map translation, with great robustness and efficiency.

Effect of Non-Deceptive Placebo on Weight Loss: A Preliminary Study

PurposeThe high global prevalence of obesity calls for the development of new weight loss strategies. Open-label placebo (OLP) has ameliorated symptoms of several medical and psychological conditions but has not been tested for obesity. With OLP, participants know they are receiving a placebo. This study investigated the effect of OLP pills to increase weight loss and reduce food craving.MethodsN=31 adults of diverse sex and ethnicity with a mean BMI of 35 underwent a simple eight-week long weight-loss intervention called Gut-Cued Eating. They were randomly assigned to take two pills daily for the entirety of the study (OLP group) or no pills (no-OLP group). All participants were weighed and completed baseline surveys. The OLP group also completed an original OLP survey which assessed compliance and perceived influence of putative mechanisms behind the efficacy of OLP on their change in weight. ResultsOLP did not augment weight loss or further reduce food craving following GCE. Controlling for demographics and baseline trait suggestibility did not affect the results. While the study was preliminary due to a small sample and limited statistical power, the results did not approach significance. Furthermore, the OLP survey indicated that belief in the effect of the pills was very low to none. OLP may prove beneficial in obesity if general belief in OLPs is increased and if it is delivered in a modality different from a pill given the likely negative associations between weight-loss pills and successful weight loss. Level of EvidenceLevel 1, experimental study

ON THE IMPORTANCE OF TRANSITION CONTROL AT TRANSONIC COMPRESSOR BLADES

The flow through a transonic compressor cascade is characterized by high unsteadiness and a high loss level. In the case of a laminar shock wave boundary layer interaction the loss level is higher due to the occurrence of a laminar separation bubble below the shock wave compared to the shock wave interaction with a turbulent boundary layer. In addition, the oscillation of the shock position in both cases influences the working range concerning the point of stall onset as well as leading to an unsteady interaction with the blade, called buffeting. The reduction of losses and of unsteadiness in the shock wave oscillation, connected to a decrease of the blade buffeting effect, are the aims of the current investigation. Therefore, experimental investigations using a roughness patch as well as air jet vortex generators in order to control the transition in a transonic compressor cascade have been conducted at the transonic cascade wind tunnel of DLR at Cologne. At an inflow Mach number of 1.21 a loss reduction for both transition control cases is achieved. In spite of a nearly uninfluenced fluctuation range of the passage shock wave compared to the reference cascade, the oscillation spectra of the transition control cases show a reduction of the shock movement amplitude at a frequency below 500 Hz and above 1 kHz. In the closing section of the paper a detailed discussion on the reasons for the resulting flow behaviour based on PIV and High Speed Shadowgraphy data is given.

Leading edge redesign of dual-peak type variable inlet guide vane and its effect on aerodynamic performance

Recently, a new type airfoil for variable inlet guide vane (VIGV), featuring “dual-peak” surface velocity pattern at high incidence, is proposed and shows wide low-loss operation range. To further improve its performance, this paper researches the influence of leading edge (LE) thickness and shape on the loss level and surface velocity features of the “dual-peak” type airfoil. Firstly, a polynomial-based continuous-curvature leading edge design method was briefly introduced and used in the LE redesign of sample airfoils. Then, steady simulations based on Reynolds-Averaged Navier-Stokes method (RANS), carried out by commercial software CFX after grid independent study, were used to determine the aerodynamic performance, surface velocity distribution and boundary-layer behaviors of all research airfoils. Simulation results indicate that there exists an optimized range of LE relative thickness that can achieve lower airfoil loss level at high incidence condition. For Case 1 ([Formula: see text]) and Case 2 ([Formula: see text]), the optimized LE relative thickness range is [Formula: see text] and [Formula: see text]. The LE shape optimization can further reduce the maximum incidence condition loss coefficient with proportion up to 18% for airfoils with optimal LE thickness. Analysis of flow mechanism indicates that the optimized LE thickness and shape can reduce the suction spike height and subsequent adverse pressure gradient, therefore, decrease the LE separation scale and result in a lower loss coefficient. As an application, a dual peak VIGV with circular LE, presented in previous paper as the optimized VIGV, is redesigned in the LE portion according to the research findings and achieved 0.6 percent improvement in passage-averaged total pressure recovery coefficient [Formula: see text] at extreme high stagger angle point and the low-loss operation range extends with about 5°, which confirms the effectiveness of the research findings in three-dimensional environment.

Dual-band bandpass filter for software defined radio and 5G

This paper presents the filter design in the student design competition of EuMW 2019. This contest motivates students for the design and implementation of a dual-band bandpass filter able to get outstanding performance, where different implementation technologies, such as microstrip, coplanar, multilayer microstrip, substrate integrated waveguide, and some others can be effectively employed. Filters are evaluated by considering a figure of merit (FoM) defined by the insertion loss level, selectivity, spurious-free response, and size. To this end, three viable dual-band bandpass filters with different feeding technologies, resonators, and design topologies are investigated for the optimal FoM.